During development and in the context of different morphogenetic events, epithelial cells undergo a process called epithelial to mesenchymal transition or transdifferentiation （EMT）. In this process, the cells lose ...During development and in the context of different morphogenetic events, epithelial cells undergo a process called epithelial to mesenchymal transition or transdifferentiation （EMT）. In this process, the cells lose their epithelial characteristics, including their polarity and specialized cell-cell contacts, and acquire a migratory behavior, allowing them to move away from their epithelial cell community and to integrate into surrounding tissue, even at remote locations. EMT illustrates the differentiation plasticity during development and is complemented by another process, called mesenchymal to epithelial transition （MET）. While being an integral process during development, EMT is also recapitulated under pathological conditions, prominently in fibrosis and in invasion and metastasis of carcinomas. Accordingly, EMT is considered as an important step in tumor progression. TGF-β signaling has been shown to play an important role in EMT. In fact, adding TGF-β to epithelial cells in culture is a convenient way to induce EMT in various epithelial cells. Although much less characterized, epithelial plasticity can also be regulated by TGF-β-related bone morphogenetic proteins （BMPs）, and BMPs have been shown to induce EMT or MET depending on the developmental context. In this review, we will discuss the induction of EMT in response to TGF-β, and focus on the under- lying signaling and transcription mechanisms.展开更多
Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit th...Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.展开更多
The WRKY gene family is among the largest families of transcription factors （TFs） in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes ...The WRKY gene family is among the largest families of transcription factors （TFs） in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress, Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mecha- nisms. However, very li2ttle summarization has been done to review their research progress. Not iust important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senes- cence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box （TGACC （A/T）） in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses.展开更多
Plants of Artemisia annua produce artemisinin, a sesquiterpene lactone widely used in malaria treatment. Amorpha-4,11-diene synthase （ADS）, a sesquiterpene synthase, and CYP71AV1, a P450 monooxygenase, are two key e...Plants of Artemisia annua produce artemisinin, a sesquiterpene lactone widely used in malaria treatment. Amorpha-4,11-diene synthase （ADS）, a sesquiterpene synthase, and CYP71AV1, a P450 monooxygenase, are two key enzymes of the artemisinin biosynthesis pathway. Accumulation of artemisinin can be induced by the phytohormone jasmonate （JA）. Here, we report the characterization of two JA-responsive AP2 family transcription factors-AaERF1 and AaERF2-from A. annua L. Both genes were highly expressed in inflorescences and strongly induced by JA. Yeast one- hybrid and electrophoretic mobility shift assay （EMSA） showed that they were able to bind to the CRTDREHVCBF2 （CBF2） and RAVlAAT （RAA） motifs present in both ADS and CYP71AV1 promoters. Transient expression of either AaERF1 or AaERF2 in tobacco induced the promoter activities of ADS or CYP71AV1, and the transgenic A. annua plants overexpressing either transcription factor showed elevated transcript levels of both ADS and CYP71AV1, resulting in increased accumulation of artemisinin and artemisinic acid. By contrast, the contents of these two metabolites were reduced in the RNAi transgenic lines in which expression of AaERF1 or AaERF2 was suppressed. These results demonstrate that AaERF1 and AaERF2 are two positive regulators of artemisinin biosynthesis and are of great value in genetic engineering of arte- misinin production.展开更多
MYB-type transcription factors contain the conserved MYB DNA-binding domain of approximately 50 amino acids and are involved in the regulation of many aspects of plant growth, development, metabolism and stress respon...MYB-type transcription factors contain the conserved MYB DNA-binding domain of approximately 50 amino acids and are involved in the regulation of many aspects of plant growth, development, metabolism and stress responses. From soybean plants, we identified 156 GmMYB genes using our previously obtained 206 MYB unigenes, and 48 were found to have full-length open-reading frames. Expressions of all these identified genes were examined, and we found that expressions of 43 genes were changed upon treatment with ABA, salt, drought and/or cold stress. Three GmMYB genes, GmMYB76, GmMYB92 and GmMYB177, were chosen for further analysis. Using the yeast assay system, GmMYB76 and GmMYB92 were found to have transactivation activity and can form homodimers. GmMYB177 did not appear to have transactivation activity but can form heterodimers with GmMYB76. Yeast onehybrid assay revealed that all the three GmMYBs could bind to cis-elements TAT AAC GGT TTT TT and CCG GAA AAA AGG AT, but with different affinity, and GmMYB92 could also bind to TCT CAC CTA CC. The transgenic Arabidopsis plants overexpressing GmMYB 76 or GmMYB177 showed better performance than the GmMYB92-transgenic plants in salt and freezing tolerance. However, these transgenic plants exhibited reduced sensitivity to ABA treatment at germination stage in comparison with the wild-type plants. The three GmMYB genes differentially affected a subset of stress-responsive genes in addition to their regulation of a common subset of stress-responsive genes. These resuits indicate that the three GmMYB genes may play differential roles in stress tolerance, possibly through regulation of stress-responsive genes.展开更多
Long non-coding RNAs （ineRNAs） play important roles in cancer. They are involved in chromatin remodeling, as well as transcriptional and post-transcriptional regulation, through a vari- ety of chromatin-based mechan...Long non-coding RNAs （ineRNAs） play important roles in cancer. They are involved in chromatin remodeling, as well as transcriptional and post-transcriptional regulation, through a vari- ety of chromatin-based mechanisms and via cross-talk with other RNA species, lncRNAs can func- tion as decoys, scaffolds, and enhancer RNAs. This review summarizes the characteristics of lncRNAs, including their roles, functions, and working mechanisms, describes methods for identi- fying and annotating lncRNAs, and discusses future opportunities for lncRNA-based therapies using antisense oligonucleotides.展开更多
Toll-like receptors （TLRs） recognize distinct microbial components to initiate the innate and adaptive immune responses. TLR activation culminates in the expression of appropriate pro-inflammatory and immunomodulato...Toll-like receptors （TLRs） recognize distinct microbial components to initiate the innate and adaptive immune responses. TLR activation culminates in the expression of appropriate pro-inflammatory and immunomodulatory factors to meet pathogenic challenges. The transcription factor NF-kB is the master regulator of all TLR-induced responses and its activation is the pivotal event in TLR-mediated activation of the innate immune response. Many of the key molecular events required for TLR-induced NF-r.B activation have been elucidated. However, much remain to be learned about the ability of TLRs to generate pathogen-specific responses using a limited number of transcription factors. This review will focus on our current understanding of NF-kB activation by TLRs and potential mechanisms for achieving a signal-specific response through NF-kB. Cellular ＆ Molecular Immunology. 2007;4（1）：31-41.展开更多
Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide. However, the mechanism underlying drought tolerance in plants is unclear. WRKY transcription factor...Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide. However, the mechanism underlying drought tolerance in plants is unclear. WRKY transcription factors are known to function in adaptation to abiotic stresses. By screening a pool of WRKY-associated T-DNA insertion mutants, we isolated a gain-of-function mutant, acquired drought tolerance （adt）, showing improved drought tolerance. Under drought stress conditions, adt accumulated higher levels of ABA than wild-type plants. Stomatal aperture analysis indi- cated that adt was more sensitive to ABA than wild-type plants. Molecular genetic analysis revealed that a T-DNA inser- tion in adt led to activated expression of a WRKY gene that encodes the WRKR57 protein. Constitutive expression of WRKY57 also conferred similar drought tolerance. Consistently with the high ABA content and enhanced drought tol- erance, three stress-responsive genes （RD29A, NCED3, and ABA3） were up-regulated in adt. ChIP assays demonstrated that WRKY57 can directly bind the W-box of RD29A and NCED3 promoter sequences. In addition, during ABA treatment, seed germination and early seedling growth of adt were inhibited, whereas, under high osmotic conditions, adt showed a higher seed germination frequency. In summary, our results suggested that the activated expression of WRKY57 improved drought tolerance of Arabidopsis by elevation of ABA levels. Establishment of the functions of WRKY57 will enable improvement of plant drought tolerance through gene manipulation approaches.展开更多
PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of...PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of Chinese-Language Literature (1997 - 2000). STUDY SELECTION: Data from published articles about TGF-beta signal transduction in recent domestic and foreign literature were selected. DATA EXTRACTION: Data were mainly extracted from 22 articles which are listed in the reference section of this review. RESULTS: Smad proteins mediate signal transduction induced by the TGF-beta superfamily. Based on their structural and functional properties, Smad proteins are divided into three groups. The first group, receptor-regulated Smads (R-Smads), are phosphorylated by activated type I receptors and form heteromeric complexes with the second group of Smads, common mediator Smads (Co-Smads). These Smad complexes translocate into the nucleus to influence gene transcription. Inhibitory Smads (I-Smads) are the third group and these antagonize the activity of R-Smads. In the nucleus, Smads can directly contact Smad-binding elements (SBE) in target gene promoters. Through interaction with different transcription factors, transcriptional co-activators or co-repressors, Smads elicit different effects in various cell types. The aberrance of Smad proteins has been noted in several human disorders such as fibrosis, hypertrophic scarring and cancer. CONCLUSION: The structure of Smads determines their function as transcriptional factors which translocate signals from the cell surface to the nucleus where Smads regulate TGF-beta superfamily-dependent gene expression.展开更多
MAP kinases transduce signals that are involved in a multitude of cellular pathways and functions in response to a variety of ligands and cell stimuli. Aberrant or inappropriate functions of MAPKs have now been identi...MAP kinases transduce signals that are involved in a multitude of cellular pathways and functions in response to a variety of ligands and cell stimuli. Aberrant or inappropriate functions of MAPKs have now been identified in diseases ranging from cancer to inflammatory disease to obesity and diabetes. In many cell types, the MAPKs ERK1/2 are linked to cell proliferation. ERK1/2 are thought to play a role in some cancers, because mutations in Ras and B-Raf, which can activate the ERK1/2 cascade, are found in many human tumors. Abnormal ERK1/2 signaling has also been found in polycystic kidney disease, and serious developmental disorders such as cardio-facio-cutaneous syndrome arise from mutations in components of the ERK1/2 cascade. ERK1/2 are essential in well-differentiated cells and have been linked to long-term potentiation in neurons and in maintenance of epithelial polarity. Additionally, ERK1/2 are important for insulin gene transcription in pancreatic beta cells, which produce insulin in response to increases in circulating glucose to permit efficient glucose utilization and storage in the organism. Nutrients and hormones that induce or repress insulin secretion activate and/or inhibit ERK1/2 in a manner that reflects the secretory demand on beta cells. Disturbances in this and other regulatory pathways may result in the contribution of ERK1/2 to the etiology of certain human disorders.展开更多
WRKY transcription factors have many regulatory roles we isolated a rice WRKY gene （OsWRKY31） that is induced in response to biotic and abiotic stresses. In this study, by the rice blast fungus Magnaporthe grisea an...WRKY transcription factors have many regulatory roles we isolated a rice WRKY gene （OsWRKY31） that is induced in response to biotic and abiotic stresses. In this study, by the rice blast fungus Magnaporthe grisea and auxin. This gene encodes a polypeptide of 211 amino-acid residues and belongs to a subgroup of the rice WRKY gene family that probably originated after the divergence of monocot and dicot plants. OsWRKY31 was found to be localized to the nucleus of onion epidermis cells to transiently express OsWRKY31-eGFP fusion protein. Analysis of OsWRKY31 and its mutants fused with a Gal4 DNA-binding domain indicated that OsWRKY31 has transactivation activity in yeast. Overexpression of the OsWRKY31 gene was found to enhance resistance against infection with M. grisea, and the transgenic lines exhibited reduced lateral root formation and elongation compared with wild-type and RNAi plants. The lines with overexpression showed constitutive expression of many defense-related genes, such as PBZI and OsSci2, as well as early auxin-response genes, such as OslAA4 and OsCrll genes. Furthermore, the plants with overexpression were less sensitive to exogenously supplied IBA, NAA and 2,4-1） at high concentrations, suggesting that overexpression of the OsWRKY31 gene might alter the auxin response or transport. These results also suggest that OsWRKY31 might be a common component in the signal transduction pathways of the auxin response and the defense response in rice.展开更多
Jasmonic acid （JA） is an important phytohormone that regulates plant defense responses against herbivore attack, pathogen infection and mechanical wounding. In this report, we provided biochemical and genetic eviden...Jasmonic acid （JA） is an important phytohormone that regulates plant defense responses against herbivore attack, pathogen infection and mechanical wounding. In this report, we provided biochemical and genetic evidence to show that the Arabidopsis thaliana NAC family proteins ANAC019 and ANAC055 might function as transcription activators to regulate JA-induced expression of defense genes. The role of the two NAC genes in JA signaling was examined with the anacO19 anac055 double mutant and with transgenic plants overexpressing ANACO19 or ANAC055. The anacO19 anac055 double mutant plants showed attenuated JA-induced VEGETATIVE STORAGE PROTEIN1 （VSP1） and LIPOXYGENASE2 （LOX2） expression, whereas transgenic plants overexpressing the two NAC genes showed enhanced JA-induced VSP1 and LOX2 expression. That the JA-induced expression of the two NAC genes depends on the function of COIl and AtMYC2, together with the finding that overexpression of ANACO19 partially rescued the JA-related phenotype of the atmyc2-2 mutant, has led us to a hypothesis that the two NAC proteins act downstream of AtMYC2 to regulate JA-signaled defense responses. Further evidence to substantiate this idea comes from the observation that the response of the anacO19 anac055 double mutant to a necrotrophic fungus showed high similarity to that of the atmyc2-2 mutant.展开更多
WRKY family proteins are a class of plant specific transcription factors that involve in many stress response pathways. It has been shown that one Arabidopsis WRKY protein, AtWRKY29/22, is activated by MAP kinase sign...WRKY family proteins are a class of plant specific transcription factors that involve in many stress response pathways. It has been shown that one Arabidopsis WRKY protein, AtWRKY29/22, is activated by MAP kinase signaling cascade and confers resistance to both bacterial and fungal pathogens. However, little is known about the biological roles of WRKY proteins in rice. In this study, we investigated the expression patterns of rice AtWRKY29/22 homolog, OsWRKY03, under different conditions, and also its possible role involved in plant defense. Our results showed that OsWRKY03 was up-regulated by several defense signaling molecules or different treatments. Further analysis revealed that the expression of OsWRKY03 was light dependent. Transcriptional activation activity of OsWRKY03 was also demonstrated by yeast functional assay. Transient expression of OsWRKY03-GFP fusion protein in onion epidermis cells showed that OsWRKY03 was a nuclear localized protein. OsNPR1 as well as several other pathogenesis-related genes, such as OsPRlb, phenylalanine ammonia-lyase （ZB8） and peroxidase （POX22.3）, were induced in OsWRKYO3-overexpressing transgenic plants. These results indicated that OsWRKY03 is located upstream of OsNPR 1 as a transcriptional activator in salicylic acid （SA）-dependent or jasmonic acid （JA）-dependent defense signaling cascades.展开更多
Iron is an essential element for plant growth and development. Iron homeostasis in plants is tightly regulated at both transcriptional and posttranscriptional level. Several bHLH transcription factors involved in iron...Iron is an essential element for plant growth and development. Iron homeostasis in plants is tightly regulated at both transcriptional and posttranscriptional level. Several bHLH transcription factors involved in iron homeostasis have been identified recently. However, their regulatory mechanisms remain unknown. In this work, we demonstrate that the transcription factor FIT interacted with AtbHLH38 and AtbHLH39 and directly conferred the expression regulation of iron uptake genes for iron homeostasis in Arabidopsis. Yeast two-hybrid analysis and transient expression in Arabidopsis protoplasts showed that AtbHLH38 or AtbHLH39 interacted with FIT, a central transcription factor involved in iron homeostasis in Arabidopsis. Expression of FIT/AtbHLH38 or FIT/AtbHLH39 in yeast cells activated GUS expression driven by ferric chelate reductase （FRO2） and ferrous transporter （IRT1） promoters. Overexpression of FITwith either AtbHLH38 or AtbHLH39 in plants converted the expression of the iron uptake genes FRO2 and IRT1 from induced to constitutive. Further analysis revealed that FRO2 and IRT1 were not regulated at the posttranscriptional level in these plants because IRT1 protein accumulation and high ferric chelate reductase activity were detected in the overexpression plants under both iron deficiency and iron sufficiency. The double overexpression plants accumulated more iron in their shoots than wild type or the plants overexpressing either AtbHLH38, AtbHLH39 or FIT. Our data support that ferric-chelate reductase FRO2 and ferrous-transporter IRT1 are the targets of the three transcription factors and the transcription of FRO2 and IRT1 is directly regulated by a complex of FIT/AtbHLH38 or FIT/AtbHLH39.展开更多
The heat shock transcription factors （HSFs） are the major heat shock factors regulating the heat stress response. They participate in regulating the expression of heat shock proteins （HSPs）, which are critical in ...The heat shock transcription factors （HSFs） are the major heat shock factors regulating the heat stress response. They participate in regulating the expression of heat shock proteins （HSPs）, which are critical in the protection against stress damage and many other important biological processes. Study of the HSF gene family is important for understanding the mechanism by which plants respond to stress. The completed genome sequences of rice （Oryza sativa） and Arabidopsis （Arabidopsis thaliana） constitute a valuable resource for comparative genomic analysis, as they are representatives of the two major evolutionary lineages within the angiosperms： the monocotyledons and the dicotyledons. The identification of phylogenefic relationships among HSF proteins in these species is a fundamental step to unravel the functionality of new and yet uncharacterized genes belonging to this family.In this study, the full complement of HSF genes in rice and Arabidopsis has probably been identified through the genome-wide scan. Phylogenetic analyses resulted in the identification of three major clusters of orthologous genes that contain members belonging to both species, which must have been represented in their common ancestor before the taxonomic splitting of the angiosperms. Fttrther analysis of the phylogenetic tree reveals a possible dicot specific gene group. We also identified nine pairs of paralogs, as evidence for studies on the evolution history of rice HSF family and rice genome evolution. Expression data analysis indicates that HSF proteins are widely expressed in plants. These results provide a solid base for future functional genomic studies of the HSF gene family in rice and Arabidopsis.展开更多
Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental diff...Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription： it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV （DHBV）, now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ~ RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.展开更多
Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nan...Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nanog, is one of the key downstream effectors of these signals. Elevated level of Nanog can maintain the mouse ES cell self-renewal independent of LIF and enable human ES cell growth without feeder cells. In addition to the external signal pathways, intrinsic transcription factors such as FoxD3, P53 and Oct4 are also involved in regulating the expression of Nanog. Functionally, Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that have important functions in ES cell pluripotency. These key factors form a regulatory network to support or limit each other＇s expression level, which maintains the properties of ES cells.展开更多
AIM:To investigate the roles and mechanism of signal transducer and activator of transcription 3 (STAT3) in invasion of human colon cancer cells by RNA interference. METHODS: Small interfering RNA (siRNA) targeting Si...AIM:To investigate the roles and mechanism of signal transducer and activator of transcription 3 (STAT3) in invasion of human colon cancer cells by RNA interference. METHODS: Small interfering RNA (siRNA) targeting Signal transducer and activator of transcription 3 (STAT3) was transfected into HT29 colon cancer cells. STAT3 protein level and DNA-binding activity of STAT3 was evaluated by western blotting and electrophoretic mobility shift assay (EMSA), respectively. We studied the anchorage-independent growth using colony formation in soft agar, and invasion using the boyden chamber model, anoikis using DNA fragmentation assay and terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL), respectively. Western blot assay was used to observe the protein expression of Bcl-xL and survivin in colon cancer HT29 cells. RESULTS: RNA interference (RNAi) mediated by siRNA leads to suppression of STAT3 expression in colon cancer cell lines. Suppression of STAT3 expression by siRNA could inhibit anchorage-independent growth, and invasion ability, and induces anoikis in the colon cancer cell line HT29. It has been shown that knockdown of STAT3 expression by siRNA results in a reduction in expression of Bcl-xL and survivin in HT29 cells. CONCLUSION: These results suggest that STAT3 siRNA can inhibit the invasion ability of colon cancer cells through inducing anoikis, which antiapoptotic genes survivin and Bcl-xL contribute to regulation of anoikis.These studies indicate STAT3 siRNA could be a useful therapeutic tool for the treatment of colon cancer.展开更多
Previous results indicated that in grapevine （Vitis vinifera）, regulation of the flavonoid pathway genes by MYB transcription factors depends on their interaction with basic helix-loop-helix proteins （bHLHs）. The ...Previous results indicated that in grapevine （Vitis vinifera）, regulation of the flavonoid pathway genes by MYB transcription factors depends on their interaction with basic helix-loop-helix proteins （bHLHs）. The present study describes the first functional characterization of a bHLH factor from grapevine named VvMYC1. This transcription factor is phylogenetically related to Arabidopsis bHLH proteins, which participate in the control of flavonoid biosynthesis and epidermal cell fate. Transient promoter and yeast two-hybrid assays demonstrated that VvMYC1 physically interacts with MYB5a, MYB5b, MYBA1/A2, and MYBPA1 to induce promoters of flavonoid pathway genes involved in anthocyanin and/ or proanthocyanidin （PA） synthesis. Additionally, transient promoter assays revealed that VvMYC1 is involved in feedback regulation of its own expression. Transcript levels of VvMYC1 during berry development correlate with the synthesis of anthocyanins and PAs in skins and seeds of berries, suggesting that VvMYC1 is involved in the regulation of anthocyanins and PA synthesis in these organs. Likewise, transient expression of VvMYC1 and VvMYBA1 induces anthocyanin synthesis in grapevine suspension cells. These results suggest that VvMYCl is part of the transcriptional cascade controlling antho- cyanin and PA biosynthesis in grapevine.展开更多
文摘During development and in the context of different morphogenetic events, epithelial cells undergo a process called epithelial to mesenchymal transition or transdifferentiation （EMT）. In this process, the cells lose their epithelial characteristics, including their polarity and specialized cell-cell contacts, and acquire a migratory behavior, allowing them to move away from their epithelial cell community and to integrate into surrounding tissue, even at remote locations. EMT illustrates the differentiation plasticity during development and is complemented by another process, called mesenchymal to epithelial transition （MET）. While being an integral process during development, EMT is also recapitulated under pathological conditions, prominently in fibrosis and in invasion and metastasis of carcinomas. Accordingly, EMT is considered as an important step in tumor progression. TGF-β signaling has been shown to play an important role in EMT. In fact, adding TGF-β to epithelial cells in culture is a convenient way to induce EMT in various epithelial cells. Although much less characterized, epithelial plasticity can also be regulated by TGF-β-related bone morphogenetic proteins （BMPs）, and BMPs have been shown to induce EMT or MET depending on the developmental context. In this review, we will discuss the induction of EMT in response to TGF-β, and focus on the under- lying signaling and transcription mechanisms.
文摘Abiotic stresses and soil nutrient limitations are major environmental conditions that reduce plant growth,productivity and quality.Plants have evolved mechanisms to perceive these environmental challenges,transmit the stress signals within cells as well as between cells and tissues,and make appropriate adjustments in their growth and development in order to survive and reproduce.In recent years,significant progress has been made on many fronts of the stress signaling research,particularly in understanding the downstream signaling events that culminate at the activation of stress-and nutrient limitation-responsive genes,cellular ion homeostasis,and growth adjustment.However,the revelation of the early events of stress signaling,particularly the identification of primary stress sensors,still lags behind.In this review,we summarize recent work on the genetic and molecular mechanisms of plant abiotic stress and nutrient limitation sensing and signaling and discuss new directions for future studies.
基金supported by the Natural Science Foundation of China(No.31301790)Guangdong Natural Science Foundation (S2013040016220)+1 种基金China Postdoctoral Science Foundation (2013M530375,2014T70827)Shenzhen Vegetable Molecular Biotechnological Engineering Lab Scheme (Development and Reform Commission of Shenzhen Municipal Government)
文摘The WRKY gene family is among the largest families of transcription factors （TFs） in higher plants. By regulating the plant hormone signal transduction pathway, these TFs play critical roles in some plant processes in response to biotic and abiotic stress, Various bodies of research have demonstrated the important biological functions of WRKY TFs in plant response to different kinds of biotic and abiotic stresses and working mecha- nisms. However, very li2ttle summarization has been done to review their research progress. Not iust important TFs function in plant response to biotic and abiotic stresses, WRKY also participates in carbohydrate synthesis, senes- cence, development, and secondary metabolites synthesis. WRKY proteins can bind to W-box （TGACC （A/T）） in the promoter of its target genes and activate or repress the expression of downstream genes to regulate their stress response. Moreover, WRKY proteins can interact with other TFs to regulate plant defensive responses. In the present review, we focus on the structural characteristics of WRKY TFs and the research progress on their functions in plant responses to a variety of stresses.
基金This research was supported by State Key Basic Research Program of China （2007CB108800）, the National Natural Science Foundation of China （30630008）, and the National HighTech Program of China （2007AA021501 ）.ACKNO WLEDGMENTS We thank CYP71AV1. discussions Ke-Xuan Tang for supplying the promoter sequence of We thank Ji-Rong Huang and Gao-Jie Hong for he pfu No conflict of interest declared
文摘Plants of Artemisia annua produce artemisinin, a sesquiterpene lactone widely used in malaria treatment. Amorpha-4,11-diene synthase （ADS）, a sesquiterpene synthase, and CYP71AV1, a P450 monooxygenase, are two key enzymes of the artemisinin biosynthesis pathway. Accumulation of artemisinin can be induced by the phytohormone jasmonate （JA）. Here, we report the characterization of two JA-responsive AP2 family transcription factors-AaERF1 and AaERF2-from A. annua L. Both genes were highly expressed in inflorescences and strongly induced by JA. Yeast one- hybrid and electrophoretic mobility shift assay （EMSA） showed that they were able to bind to the CRTDREHVCBF2 （CBF2） and RAVlAAT （RAA） motifs present in both ADS and CYP71AV1 promoters. Transient expression of either AaERF1 or AaERF2 in tobacco induced the promoter activities of ADS or CYP71AV1, and the transgenic A. annua plants overexpressing either transcription factor showed elevated transcript levels of both ADS and CYP71AV1, resulting in increased accumulation of artemisinin and artemisinic acid. By contrast, the contents of these two metabolites were reduced in the RNAi transgenic lines in which expression of AaERF1 or AaERF2 was suppressed. These results demonstrate that AaERF1 and AaERF2 are two positive regulators of artemisinin biosynthesis and are of great value in genetic engineering of arte- misinin production.
基金Acknowledgments This work was supported by the National Natural Science Foundation of China （30490254, 30671316）, the National Basic Research Program of China （2006CB100102）, and the Hi-Tech Research and Development Program of China （2006AA10Z113, 2006AA10A111）.
文摘MYB-type transcription factors contain the conserved MYB DNA-binding domain of approximately 50 amino acids and are involved in the regulation of many aspects of plant growth, development, metabolism and stress responses. From soybean plants, we identified 156 GmMYB genes using our previously obtained 206 MYB unigenes, and 48 were found to have full-length open-reading frames. Expressions of all these identified genes were examined, and we found that expressions of 43 genes were changed upon treatment with ABA, salt, drought and/or cold stress. Three GmMYB genes, GmMYB76, GmMYB92 and GmMYB177, were chosen for further analysis. Using the yeast assay system, GmMYB76 and GmMYB92 were found to have transactivation activity and can form homodimers. GmMYB177 did not appear to have transactivation activity but can form heterodimers with GmMYB76. Yeast onehybrid assay revealed that all the three GmMYBs could bind to cis-elements TAT AAC GGT TTT TT and CCG GAA AAA AGG AT, but with different affinity, and GmMYB92 could also bind to TCT CAC CTA CC. The transgenic Arabidopsis plants overexpressing GmMYB 76 or GmMYB177 showed better performance than the GmMYB92-transgenic plants in salt and freezing tolerance. However, these transgenic plants exhibited reduced sensitivity to ABA treatment at germination stage in comparison with the wild-type plants. The three GmMYB genes differentially affected a subset of stress-responsive genes in addition to their regulation of a common subset of stress-responsive genes. These resuits indicate that the three GmMYB genes may play differential roles in stress tolerance, possibly through regulation of stress-responsive genes.
基金supported by the National Research Foundation(NRF)of Singapore through an NRF fellowship awarded to MJF(Grant No.NRFF2012-054)NTU startup funds+3 种基金Yale-NUS startup funds awarded to MJFsupported by funds given to the Cancer Science Institute(CSI),National University of Singapore(NUS)by the NRF and the Ministry of Education-Singapore under the Research Center of Excellence fundingsupported by the RNA Biology Center at the CSI,NUS,as part of the funding under the Tier 3 grants of the Ministry of Education,Singapore
文摘Long non-coding RNAs （ineRNAs） play important roles in cancer. They are involved in chromatin remodeling, as well as transcriptional and post-transcriptional regulation, through a vari- ety of chromatin-based mechanisms and via cross-talk with other RNA species, lncRNAs can func- tion as decoys, scaffolds, and enhancer RNAs. This review summarizes the characteristics of lncRNAs, including their roles, functions, and working mechanisms, describes methods for identi- fying and annotating lncRNAs, and discusses future opportunities for lncRNA-based therapies using antisense oligonucleotides.
文摘Toll-like receptors （TLRs） recognize distinct microbial components to initiate the innate and adaptive immune responses. TLR activation culminates in the expression of appropriate pro-inflammatory and immunomodulatory factors to meet pathogenic challenges. The transcription factor NF-kB is the master regulator of all TLR-induced responses and its activation is the pivotal event in TLR-mediated activation of the innate immune response. Many of the key molecular events required for TLR-induced NF-r.B activation have been elucidated. However, much remain to be learned about the ability of TLRs to generate pathogen-specific responses using a limited number of transcription factors. This review will focus on our current understanding of NF-kB activation by TLRs and potential mechanisms for achieving a signal-specific response through NF-kB. Cellular ＆ Molecular Immunology. 2007;4（1）：31-41.
基金This research was supported by the Science Foundation of the Ministry of Agriculture of the Peoples' Republic of China，the Science Foundation of the Chinese Academy of Sciences，the National Natural Science Foundation of China
文摘Drought is one of the most serious environmental factors that limit the productivity of agricultural crops worldwide. However, the mechanism underlying drought tolerance in plants is unclear. WRKY transcription factors are known to function in adaptation to abiotic stresses. By screening a pool of WRKY-associated T-DNA insertion mutants, we isolated a gain-of-function mutant, acquired drought tolerance （adt）, showing improved drought tolerance. Under drought stress conditions, adt accumulated higher levels of ABA than wild-type plants. Stomatal aperture analysis indi- cated that adt was more sensitive to ABA than wild-type plants. Molecular genetic analysis revealed that a T-DNA inser- tion in adt led to activated expression of a WRKY gene that encodes the WRKR57 protein. Constitutive expression of WRKY57 also conferred similar drought tolerance. Consistently with the high ABA content and enhanced drought tol- erance, three stress-responsive genes （RD29A, NCED3, and ABA3） were up-regulated in adt. ChIP assays demonstrated that WRKY57 can directly bind the W-box of RD29A and NCED3 promoter sequences. In addition, during ABA treatment, seed germination and early seedling growth of adt were inhibited, whereas, under high osmotic conditions, adt showed a higher seed germination frequency. In summary, our results suggested that the activated expression of WRKY57 improved drought tolerance of Arabidopsis by elevation of ABA levels. Establishment of the functions of WRKY57 will enable improvement of plant drought tolerance through gene manipulation approaches.
基金supported by a grant from the National Natural Science Foundation of China(No．G1999054204)； the National Prominent Youth Science Foundation of China(No．39525024)．
文摘PURPOSE: To review the recent developments in the structure and function of Smad proteins. DATA SOURCES: Both Chinese- and English-language literatures were searched using MEDLINE/CD-ROM (1997 - 2000) and the Index of Chinese-Language Literature (1997 - 2000). STUDY SELECTION: Data from published articles about TGF-beta signal transduction in recent domestic and foreign literature were selected. DATA EXTRACTION: Data were mainly extracted from 22 articles which are listed in the reference section of this review. RESULTS: Smad proteins mediate signal transduction induced by the TGF-beta superfamily. Based on their structural and functional properties, Smad proteins are divided into three groups. The first group, receptor-regulated Smads (R-Smads), are phosphorylated by activated type I receptors and form heteromeric complexes with the second group of Smads, common mediator Smads (Co-Smads). These Smad complexes translocate into the nucleus to influence gene transcription. Inhibitory Smads (I-Smads) are the third group and these antagonize the activity of R-Smads. In the nucleus, Smads can directly contact Smad-binding elements (SBE) in target gene promoters. Through interaction with different transcription factors, transcriptional co-activators or co-repressors, Smads elicit different effects in various cell types. The aberrance of Smad proteins has been noted in several human disorders such as fibrosis, hypertrophic scarring and cancer. CONCLUSION: The structure of Smads determines their function as transcriptional factors which translocate signals from the cell surface to the nucleus where Smads regulate TGF-beta superfamily-dependent gene expression.
文摘MAP kinases transduce signals that are involved in a multitude of cellular pathways and functions in response to a variety of ligands and cell stimuli. Aberrant or inappropriate functions of MAPKs have now been identified in diseases ranging from cancer to inflammatory disease to obesity and diabetes. In many cell types, the MAPKs ERK1/2 are linked to cell proliferation. ERK1/2 are thought to play a role in some cancers, because mutations in Ras and B-Raf, which can activate the ERK1/2 cascade, are found in many human tumors. Abnormal ERK1/2 signaling has also been found in polycystic kidney disease, and serious developmental disorders such as cardio-facio-cutaneous syndrome arise from mutations in components of the ERK1/2 cascade. ERK1/2 are essential in well-differentiated cells and have been linked to long-term potentiation in neurons and in maintenance of epithelial polarity. Additionally, ERK1/2 are important for insulin gene transcription in pancreatic beta cells, which produce insulin in response to increases in circulating glucose to permit efficient glucose utilization and storage in the organism. Nutrients and hormones that induce or repress insulin secretion activate and/or inhibit ERK1/2 in a manner that reflects the secretory demand on beta cells. Disturbances in this and other regulatory pathways may result in the contribution of ERK1/2 to the etiology of certain human disorders.
文摘WRKY transcription factors have many regulatory roles we isolated a rice WRKY gene （OsWRKY31） that is induced in response to biotic and abiotic stresses. In this study, by the rice blast fungus Magnaporthe grisea and auxin. This gene encodes a polypeptide of 211 amino-acid residues and belongs to a subgroup of the rice WRKY gene family that probably originated after the divergence of monocot and dicot plants. OsWRKY31 was found to be localized to the nucleus of onion epidermis cells to transiently express OsWRKY31-eGFP fusion protein. Analysis of OsWRKY31 and its mutants fused with a Gal4 DNA-binding domain indicated that OsWRKY31 has transactivation activity in yeast. Overexpression of the OsWRKY31 gene was found to enhance resistance against infection with M. grisea, and the transgenic lines exhibited reduced lateral root formation and elongation compared with wild-type and RNAi plants. The lines with overexpression showed constitutive expression of many defense-related genes, such as PBZI and OsSci2, as well as early auxin-response genes, such as OslAA4 and OsCrll genes. Furthermore, the plants with overexpression were less sensitive to exogenously supplied IBA, NAA and 2,4-1） at high concentrations, suggesting that overexpression of the OsWRKY31 gene might alter the auxin response or transport. These results also suggest that OsWRKY31 might be a common component in the signal transduction pathways of the auxin response and the defense response in rice.
基金Acknowledgments We are grateful to Dr Xinnian Dong （Duke University, Durham, NC, USA） for critical reading of the manuscript and valuable suggestions. We thank Dr Jianmin Zhou （National Institute of Biological Sciences, Beijing, China） for providing the fungus strain Botrytis cinerea, Dr Salome Prat （Institut de Biologia Molecular de Barcelona, Barcelona, Spain） for providing homozygous atmyc2-2 （T-DNA insertion line SALK_083483） seeds and Dr Daoxin Xie （Tsinghua University, Beijing, China） for providing the coil-I seeds. This work was supported by grants from The National Natural Science Foundation of China （30530440）, The Ministry of Science and Technology of China （2006CB 102004, 2006AA10A 116）, and The Chinese Academy of Sciences （KSCX2-YW-N-045）.
文摘Jasmonic acid （JA） is an important phytohormone that regulates plant defense responses against herbivore attack, pathogen infection and mechanical wounding. In this report, we provided biochemical and genetic evidence to show that the Arabidopsis thaliana NAC family proteins ANAC019 and ANAC055 might function as transcription activators to regulate JA-induced expression of defense genes. The role of the two NAC genes in JA signaling was examined with the anacO19 anac055 double mutant and with transgenic plants overexpressing ANACO19 or ANAC055. The anacO19 anac055 double mutant plants showed attenuated JA-induced VEGETATIVE STORAGE PROTEIN1 （VSP1） and LIPOXYGENASE2 （LOX2） expression, whereas transgenic plants overexpressing the two NAC genes showed enhanced JA-induced VSP1 and LOX2 expression. That the JA-induced expression of the two NAC genes depends on the function of COIl and AtMYC2, together with the finding that overexpression of ANACO19 partially rescued the JA-related phenotype of the atmyc2-2 mutant, has led us to a hypothesis that the two NAC proteins act downstream of AtMYC2 to regulate JA-signaled defense responses. Further evidence to substantiate this idea comes from the observation that the response of the anacO19 anac055 double mutant to a necrotrophic fungus showed high similarity to that of the atmyc2-2 mutant.
文摘WRKY family proteins are a class of plant specific transcription factors that involve in many stress response pathways. It has been shown that one Arabidopsis WRKY protein, AtWRKY29/22, is activated by MAP kinase signaling cascade and confers resistance to both bacterial and fungal pathogens. However, little is known about the biological roles of WRKY proteins in rice. In this study, we investigated the expression patterns of rice AtWRKY29/22 homolog, OsWRKY03, under different conditions, and also its possible role involved in plant defense. Our results showed that OsWRKY03 was up-regulated by several defense signaling molecules or different treatments. Further analysis revealed that the expression of OsWRKY03 was light dependent. Transcriptional activation activity of OsWRKY03 was also demonstrated by yeast functional assay. Transient expression of OsWRKY03-GFP fusion protein in onion epidermis cells showed that OsWRKY03 was a nuclear localized protein. OsNPR1 as well as several other pathogenesis-related genes, such as OsPRlb, phenylalanine ammonia-lyase （ZB8） and peroxidase （POX22.3）, were induced in OsWRKYO3-overexpressing transgenic plants. These results indicated that OsWRKY03 is located upstream of OsNPR 1 as a transcriptional activator in salicylic acid （SA）-dependent or jasmonic acid （JA）-dependent defense signaling cascades.
基金The authors thank ProfMary Lou Guerinot （Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire） for providing IRT1 peptide antibody and for the critical reading of the manuscript. We are also grateful to Drs Zhentao Lin and Yongfu Fu （Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing） for providing the BiFC assay system and technical supporting. This work was supported by the National Natural Science Foundation of China （Grant nos, 30530460 and 30521001） and the Ministry of Science and Technology of China （Grant nos, 2005cb20904 and 2006AA 10A 105） and Chinese Academy of Sciences （Grant no. KSCX2-YW-N- 001） as well as by the Harvest Plus-China Program.
文摘Iron is an essential element for plant growth and development. Iron homeostasis in plants is tightly regulated at both transcriptional and posttranscriptional level. Several bHLH transcription factors involved in iron homeostasis have been identified recently. However, their regulatory mechanisms remain unknown. In this work, we demonstrate that the transcription factor FIT interacted with AtbHLH38 and AtbHLH39 and directly conferred the expression regulation of iron uptake genes for iron homeostasis in Arabidopsis. Yeast two-hybrid analysis and transient expression in Arabidopsis protoplasts showed that AtbHLH38 or AtbHLH39 interacted with FIT, a central transcription factor involved in iron homeostasis in Arabidopsis. Expression of FIT/AtbHLH38 or FIT/AtbHLH39 in yeast cells activated GUS expression driven by ferric chelate reductase （FRO2） and ferrous transporter （IRT1） promoters. Overexpression of FITwith either AtbHLH38 or AtbHLH39 in plants converted the expression of the iron uptake genes FRO2 and IRT1 from induced to constitutive. Further analysis revealed that FRO2 and IRT1 were not regulated at the posttranscriptional level in these plants because IRT1 protein accumulation and high ferric chelate reductase activity were detected in the overexpression plants under both iron deficiency and iron sufficiency. The double overexpression plants accumulated more iron in their shoots than wild type or the plants overexpressing either AtbHLH38, AtbHLH39 or FIT. Our data support that ferric-chelate reductase FRO2 and ferrous-transporter IRT1 are the targets of the three transcription factors and the transcription of FRO2 and IRT1 is directly regulated by a complex of FIT/AtbHLH38 or FIT/AtbHLH39.
文摘The heat shock transcription factors （HSFs） are the major heat shock factors regulating the heat stress response. They participate in regulating the expression of heat shock proteins （HSPs）, which are critical in the protection against stress damage and many other important biological processes. Study of the HSF gene family is important for understanding the mechanism by which plants respond to stress. The completed genome sequences of rice （Oryza sativa） and Arabidopsis （Arabidopsis thaliana） constitute a valuable resource for comparative genomic analysis, as they are representatives of the two major evolutionary lineages within the angiosperms： the monocotyledons and the dicotyledons. The identification of phylogenefic relationships among HSF proteins in these species is a fundamental step to unravel the functionality of new and yet uncharacterized genes belonging to this family.In this study, the full complement of HSF genes in rice and Arabidopsis has probably been identified through the genome-wide scan. Phylogenetic analyses resulted in the identification of three major clusters of orthologous genes that contain members belonging to both species, which must have been represented in their common ancestor before the taxonomic splitting of the angiosperms. Fttrther analysis of the phylogenetic tree reveals a possible dicot specific gene group. We also identified nine pairs of paralogs, as evidence for studies on the evolution history of rice HSF family and rice genome evolution. Expression data analysis indicates that HSF proteins are widely expressed in plants. These results provide a solid base for future functional genomic studies of the HSF gene family in rice and Arabidopsis.
文摘Hepadnaviruses, including human hepatitis B virus （HBV）, replicate through reverse transcription of an RNA intermediate, the pregenomic RNA （pgRNA）. Despite this kinship to retroviruses, there are fundamental differences beyond the fact that hepadnavirions contain DNA instead of RNA. Most peculiar is the initiation of reverse transcription： it occurs by protein-priming, is strictly committed to using an RNA hairpin on the pgRNA, ε, as template, and depends on cellular chaperones; moreover, proper replication can apparently occur only in the specialized environment of intact nucleocapsids. This complexity has hampered an in-depth mechanistic understanding. The recent successful reconstitution in the test tube of active replication initiation complexes from purified components, for duck HBV （DHBV）, now allows for the analysis of the biochemistry of hepadnaviral replication at the molecular level. Here we review the current state of knowledge at all steps of the hepadnaviral genome replication cycle, with emphasis on new insights that turned up by the use of such cellfree systems. At this time, they can, unfortunately, not be complemented by three-dimensional structural information on the involved components. However, at least for the ~ RNA element such information is emerging, raising expectations that combining biophysics with biochemistry and genetics will soon provide a powerful integrated approach for solving the many outstanding questions. The ultimate, though most challenging goal, will be to visualize the hepadnaviral reverse transcriptase in the act of synthesizing DNA, which will also have strong implications for drug development.
文摘Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nanog, is one of the key downstream effectors of these signals. Elevated level of Nanog can maintain the mouse ES cell self-renewal independent of LIF and enable human ES cell growth without feeder cells. In addition to the external signal pathways, intrinsic transcription factors such as FoxD3, P53 and Oct4 are also involved in regulating the expression of Nanog. Functionally, Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that have important functions in ES cell pluripotency. These key factors form a regulatory network to support or limit each other＇s expression level, which maintains the properties of ES cells.
基金the Program of Science and Technology, Zhenjiang City, No. SH2006019
文摘AIM:To investigate the roles and mechanism of signal transducer and activator of transcription 3 (STAT3) in invasion of human colon cancer cells by RNA interference. METHODS: Small interfering RNA (siRNA) targeting Signal transducer and activator of transcription 3 (STAT3) was transfected into HT29 colon cancer cells. STAT3 protein level and DNA-binding activity of STAT3 was evaluated by western blotting and electrophoretic mobility shift assay (EMSA), respectively. We studied the anchorage-independent growth using colony formation in soft agar, and invasion using the boyden chamber model, anoikis using DNA fragmentation assay and terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL), respectively. Western blot assay was used to observe the protein expression of Bcl-xL and survivin in colon cancer HT29 cells. RESULTS: RNA interference (RNAi) mediated by siRNA leads to suppression of STAT3 expression in colon cancer cell lines. Suppression of STAT3 expression by siRNA could inhibit anchorage-independent growth, and invasion ability, and induces anoikis in the colon cancer cell line HT29. It has been shown that knockdown of STAT3 expression by siRNA results in a reduction in expression of Bcl-xL and survivin in HT29 cells. CONCLUSION: These results suggest that STAT3 siRNA can inhibit the invasion ability of colon cancer cells through inducing anoikis, which antiapoptotic genes survivin and Bcl-xL contribute to regulation of anoikis.These studies indicate STAT3 siRNA could be a useful therapeutic tool for the treatment of colon cancer.
文摘Previous results indicated that in grapevine （Vitis vinifera）, regulation of the flavonoid pathway genes by MYB transcription factors depends on their interaction with basic helix-loop-helix proteins （bHLHs）. The present study describes the first functional characterization of a bHLH factor from grapevine named VvMYC1. This transcription factor is phylogenetically related to Arabidopsis bHLH proteins, which participate in the control of flavonoid biosynthesis and epidermal cell fate. Transient promoter and yeast two-hybrid assays demonstrated that VvMYC1 physically interacts with MYB5a, MYB5b, MYBA1/A2, and MYBPA1 to induce promoters of flavonoid pathway genes involved in anthocyanin and/ or proanthocyanidin （PA） synthesis. Additionally, transient promoter assays revealed that VvMYC1 is involved in feedback regulation of its own expression. Transcript levels of VvMYC1 during berry development correlate with the synthesis of anthocyanins and PAs in skins and seeds of berries, suggesting that VvMYC1 is involved in the regulation of anthocyanins and PA synthesis in these organs. Likewise, transient expression of VvMYC1 and VvMYBA1 induces anthocyanin synthesis in grapevine suspension cells. These results suggest that VvMYCl is part of the transcriptional cascade controlling antho- cyanin and PA biosynthesis in grapevine.
