目的构建带Flag标签的RING结构泛素连接酶26(Ring finger protein 26,RNF26)真核表达载体,表达Flag-RNF26的融合蛋白,通过细胞免疫荧光实验,观察其在人肝癌细胞HepG2中的定位及与带绿色荧光蛋白标签的死骨片1(sequestosome 1,SQSTM1)是...目的构建带Flag标签的RING结构泛素连接酶26(Ring finger protein 26,RNF26)真核表达载体,表达Flag-RNF26的融合蛋白,通过细胞免疫荧光实验,观察其在人肝癌细胞HepG2中的定位及与带绿色荧光蛋白标签的死骨片1(sequestosome 1,SQSTM1)是否存在共定位。方法以人乳腺文库为模板,应用PCR技术扩增出RNF26的编码区序列,双酶切后插入带Flag标签的pCMV-Tag2B载体中,构建pCMV-Tag2B-RNF26重组质粒;将测序正确的重组质粒和pCMV-Tag2B空载体分别转染人胚肾293T细胞中,Western印迹检测融合蛋白表达情况,将成功表达的质粒pCMV-Tag2B-RNF26与pEGFP-SQSTM1质粒转染至人肝癌细胞HepG2中,进行免疫荧光染色,荧光显微镜观察SQSTM1和RNF26的共定位情况。结果插入片段的DNA序列测序结果与目的基因序列相同,Western印迹检测提示,融合蛋白成功表达;免疫荧光结果表明,RNF26与SQSTM1蛋白在细胞质中存在共定位。结论pCMVTag2B-RNF26真核表达载体构建成功。带Flag标签的人RNF26蛋白在HepG2细胞内成功表达,且与SQSTM1蛋白存在共定位,为进一步研究RNF26和SQSTM1的相互作用关系建立了实验基础。展开更多
Mutations or inactivation of parkin, an E3 ubiquitin ligase, are associated with familial form or sporadic Parkinson＇s disease （PD）, respectively, which manifested with the selective vulnerability of neuronal ceils...Mutations or inactivation of parkin, an E3 ubiquitin ligase, are associated with familial form or sporadic Parkinson＇s disease （PD）, respectively, which manifested with the selective vulnerability of neuronal ceils in substantia nigra （SN） and striatum （STR） regions. However, the underlying molecular mechanism linking parkin with the etiology of PD remains elusive. Here we report that p62, a critical regulator for protein quality control, inclusion body formation, selective autophagy and diverse signaling pathways, is a new substrate of parkin. P62 levels were increased in the SN and STR regions, but not in other brain regions in parkin knockout mice. Parkin directly interacts with and ubiquitinates p62 at the K13 to promote proteasomal degradation of p62 even in the absence of ATG5. Pathogenic mutations, knockdown of parkin or mutation of p62 at K13 prevented the degradation of p62. We further showed that parkin deficiency mice have pronounced loss of tyrosine hydroxylase positive neurons and have worse performance in motor test when treated with 6-hydroxydopamine hydrochloride in aged mice. These results suggest that, in addition to their critical role in regulating autophagy, p62 are subjected to parkin mediated proteasomal degradation and implicate that the dysregulation of parkin/p62 axis may involve in the selective vulnerability of neuronal cells during the onset of PD pathogenesis.展开更多
The sequestosome 1/p62 protein has been implicated in the regulation of a multitude of cellular processes such as NF-κB signaling, NRF2-driven oxidative stress response, protein turnover through the ubiquitin-proteas...The sequestosome 1/p62 protein has been implicated in the regulation of a multitude of cellular processes such as NF-κB signaling, NRF2-driven oxidative stress response, protein turnover through the ubiquitin-proteasome pathway and the autophagosome/lysosome pathway, apoptosis and cellular metabolism. The domain structure of p62 also reflects this functional complexity since the protein appears to be a mosaic of protein interaction domains and motifs. Deregulation of the level and function of p62 and/or p62 mutations have been linked to a number of human diseases including Paget＇s disease of the bone, obesity, liver diseases, tumorigenesis and neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer＇s disease. In this article, we review the current understanding of the involvement of p62 in cellular processes under physiologic and pathological conditions.展开更多
文摘目的构建带Flag标签的RING结构泛素连接酶26(Ring finger protein 26,RNF26)真核表达载体,表达Flag-RNF26的融合蛋白,通过细胞免疫荧光实验,观察其在人肝癌细胞HepG2中的定位及与带绿色荧光蛋白标签的死骨片1(sequestosome 1,SQSTM1)是否存在共定位。方法以人乳腺文库为模板,应用PCR技术扩增出RNF26的编码区序列,双酶切后插入带Flag标签的pCMV-Tag2B载体中,构建pCMV-Tag2B-RNF26重组质粒;将测序正确的重组质粒和pCMV-Tag2B空载体分别转染人胚肾293T细胞中,Western印迹检测融合蛋白表达情况,将成功表达的质粒pCMV-Tag2B-RNF26与pEGFP-SQSTM1质粒转染至人肝癌细胞HepG2中,进行免疫荧光染色,荧光显微镜观察SQSTM1和RNF26的共定位情况。结果插入片段的DNA序列测序结果与目的基因序列相同,Western印迹检测提示,融合蛋白成功表达;免疫荧光结果表明,RNF26与SQSTM1蛋白在细胞质中存在共定位。结论pCMVTag2B-RNF26真核表达载体构建成功。带Flag标签的人RNF26蛋白在HepG2细胞内成功表达,且与SQSTM1蛋白存在共定位,为进一步研究RNF26和SQSTM1的相互作用关系建立了实验基础。
基金We are grateful to Drs. Ted Dawson and Jian Feng for generously providing the plasmids. We are also grateful to Professor Mark Bartlam from Nankai University, Tianjin, China for a critical reading of the manuscript. The research was supported by the National Basic Research Program （973 Program） （No. 2011 CB910903） from MOST and project （Grant Nos. 81130045, 31471300, 31271529, 301520103904） from the National Natural Science Foundation of China.
文摘Mutations or inactivation of parkin, an E3 ubiquitin ligase, are associated with familial form or sporadic Parkinson＇s disease （PD）, respectively, which manifested with the selective vulnerability of neuronal ceils in substantia nigra （SN） and striatum （STR） regions. However, the underlying molecular mechanism linking parkin with the etiology of PD remains elusive. Here we report that p62, a critical regulator for protein quality control, inclusion body formation, selective autophagy and diverse signaling pathways, is a new substrate of parkin. P62 levels were increased in the SN and STR regions, but not in other brain regions in parkin knockout mice. Parkin directly interacts with and ubiquitinates p62 at the K13 to promote proteasomal degradation of p62 even in the absence of ATG5. Pathogenic mutations, knockdown of parkin or mutation of p62 at K13 prevented the degradation of p62. We further showed that parkin deficiency mice have pronounced loss of tyrosine hydroxylase positive neurons and have worse performance in motor test when treated with 6-hydroxydopamine hydrochloride in aged mice. These results suggest that, in addition to their critical role in regulating autophagy, p62 are subjected to parkin mediated proteasomal degradation and implicate that the dysregulation of parkin/p62 axis may involve in the selective vulnerability of neuronal cells during the onset of PD pathogenesis.
文摘The sequestosome 1/p62 protein has been implicated in the regulation of a multitude of cellular processes such as NF-κB signaling, NRF2-driven oxidative stress response, protein turnover through the ubiquitin-proteasome pathway and the autophagosome/lysosome pathway, apoptosis and cellular metabolism. The domain structure of p62 also reflects this functional complexity since the protein appears to be a mosaic of protein interaction domains and motifs. Deregulation of the level and function of p62 and/or p62 mutations have been linked to a number of human diseases including Paget＇s disease of the bone, obesity, liver diseases, tumorigenesis and neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer＇s disease. In this article, we review the current understanding of the involvement of p62 in cellular processes under physiologic and pathological conditions.
