Insulin-responsive GLUT4(glucose transporter 4) translocation plays a major role in regulating glucose uptake in adipose tissue and muscle.Whether or not there is a specialized secretory GSV(GLUT4 storage vesicle) poo...Insulin-responsive GLUT4(glucose transporter 4) translocation plays a major role in regulating glucose uptake in adipose tissue and muscle.Whether or not there is a specialized secretory GSV(GLUT4 storage vesicle) pool,and more importantly how GSVs are translocated to the PM(plasma membrane) under insulin stimulation is still under debate.In the present study,we systematically analyzed the dynamics of a large number of single GLUT4-containing vesicles in 3T3-L1 adipocytes by TIRFM(total internal reflection fluorescence microscopy).We found that GLUT4-containing vesicles can be classified into three groups according to their mobility,namely vertical,stable,and lateral GLUT4-containing vesicles.Among these groups,vertical GLUT4-containing vesicles exclude transferrin receptors and move towards the PM specifically in response to insulin stimulation,while stable and lateral GLUT4-containing vesicles contain transferrin receptors and show no insulin responsiveness.These data demonstrate that vertical GLUT4-containing vesicles correspond to specialized secretory GSVs,which approach the PM directly and bypass the constitutive recycling pathway.展开更多
<span style="font-family:Verdana;">With the increasing demand for imaging quality, many scientists constantly explore new imaging instruments to meet the requirements. The total internal reflection flu...<span style="font-family:Verdana;">With the increasing demand for imaging quality, many scientists constantly explore new imaging instruments to meet the requirements. The total internal reflection fluorescence microscopy has some incomparable </span><span style="font-family:Verdana;"><span style="font-family:Verdana;">superiorities</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">, so it has become one of the research hotspots in recent years. It can show great performance in single-molecule imaging because it has unique imaging principles. This apparatus is used mainly in two fields, biomolecule research and clinical medicine. To know this instrument’s function, the summary of application</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> in these two parts was given in this article. Now, scientists who ha</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">ve</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> been focusing on this apparatus try to </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">make</span></span><span><span style="font-family:""><span style="font-family:Verdana;"> this microscope combined with other late-model precise instruments that probe some unknown interac</span><span style="font-family:Verdana;">tion mechanism of action. The TIRFM will show extraordinary talents in</span><span style="font-family:Verdana;"> many aspects, and it will become a powerful tool for people to explore the mysteries of life.</span></span></span>展开更多
B lymphocyte cell senses and acquires foreign anti-gens through clonal distributed B cell receptors(BCRs)expressed on the surface of plasma membrane.The presentation formats of antigens are quite diverse.Based on thei...B lymphocyte cell senses and acquires foreign anti-gens through clonal distributed B cell receptors(BCRs)expressed on the surface of plasma membrane.The presentation formats of antigens are quite diverse.Based on their Brownian diffusion mobility,there are three forms:free mobile soluble antigens,lateral mobile membrane bound antigens,and fixed immobile anti-gens.Here,using high resolution high speed live cell imaging approaches,we provide evidence that BCR microclusters are formed on the surface of B cells shortly after B cell’s encountering of antigens with each format of motion features.Through high speed live cell imaging,we determine that these BCR microclusters show dynamic growth feature and by doing so function as the basic platforms for B cells to acquire the anti-gens.We propose that the formation and dynamic growth of BCR microcluster is a universal mechanism for B cell to response to antigens with diverse motion features.展开更多
Phototropin （phot）-mediated signaling initiated by blue light （BL） plays a critical role in optimizing photosyn- thetic light capture at the plasma membrane （PM） in plants. However, the mechanisms underlying the...Phototropin （phot）-mediated signaling initiated by blue light （BL） plays a critical role in optimizing photosyn- thetic light capture at the plasma membrane （PM） in plants. However, the mechanisms underlying the regu- lation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and stepwise photobleaching analysis of photl-GFP proteins we demonstrated that in the dark photl proteins remain in an inactive state and mostly exist as monomers. Dimerization and the diffusion rate of photl-GFP increased in a dose-dependent manner in response to BL. In contrast, BL did not affect the lateral diffusion of kinase-inactive photlD806N-GFP but did enhance its dimerization, suggesting that photl dimerization is independent of phosphorylation. Forster resonance energy transfer-fluorescence life- time imaging microscopy analysis revealed that the interaction between photl-GFP and a marker of sterol- rich lipid environments, AtRem1.3-mCherry, was enhanced with increased time of BL treatment. However, this BL-dependent interaction was not obvious in plants co-expressing phot1D806N-GFP and AtRem1.3- mCherry, indicating that BL facilitates the translocation of functional photl-GFP into AtRem1.3-1abeled microdomains to activate phot-mediated signaling. Conversely, sterol depletion attenuated photl-GFP dynamics, dimerization, and phosphorylation. Taken together, these results indicate that membrane micro- domains act as organizing platforms essential for the proper function of activated photl at the PM.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 30470448 and 30130230)the National key Basic Research Program of China (Grant No. 2004CB720000)+1 种基金the Knowledge Innovative Program of The Chinese Academy of Sciences (Grant Nos. KSCX2-SW-224 and Y2004018)the Li Foundation and the Sinogerman Scientific Center
文摘Insulin-responsive GLUT4(glucose transporter 4) translocation plays a major role in regulating glucose uptake in adipose tissue and muscle.Whether or not there is a specialized secretory GSV(GLUT4 storage vesicle) pool,and more importantly how GSVs are translocated to the PM(plasma membrane) under insulin stimulation is still under debate.In the present study,we systematically analyzed the dynamics of a large number of single GLUT4-containing vesicles in 3T3-L1 adipocytes by TIRFM(total internal reflection fluorescence microscopy).We found that GLUT4-containing vesicles can be classified into three groups according to their mobility,namely vertical,stable,and lateral GLUT4-containing vesicles.Among these groups,vertical GLUT4-containing vesicles exclude transferrin receptors and move towards the PM specifically in response to insulin stimulation,while stable and lateral GLUT4-containing vesicles contain transferrin receptors and show no insulin responsiveness.These data demonstrate that vertical GLUT4-containing vesicles correspond to specialized secretory GSVs,which approach the PM directly and bypass the constitutive recycling pathway.
文摘<span style="font-family:Verdana;">With the increasing demand for imaging quality, many scientists constantly explore new imaging instruments to meet the requirements. The total internal reflection fluorescence microscopy has some incomparable </span><span style="font-family:Verdana;"><span style="font-family:Verdana;">superiorities</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">, so it has become one of the research hotspots in recent years. It can show great performance in single-molecule imaging because it has unique imaging principles. This apparatus is used mainly in two fields, biomolecule research and clinical medicine. To know this instrument’s function, the summary of application</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> in these two parts was given in this article. Now, scientists who ha</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">ve</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"> been focusing on this apparatus try to </span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;">make</span></span><span><span style="font-family:""><span style="font-family:Verdana;"> this microscope combined with other late-model precise instruments that probe some unknown interac</span><span style="font-family:Verdana;">tion mechanism of action. The TIRFM will show extraordinary talents in</span><span style="font-family:Verdana;"> many aspects, and it will become a powerful tool for people to explore the mysteries of life.</span></span></span>
文摘B lymphocyte cell senses and acquires foreign anti-gens through clonal distributed B cell receptors(BCRs)expressed on the surface of plasma membrane.The presentation formats of antigens are quite diverse.Based on their Brownian diffusion mobility,there are three forms:free mobile soluble antigens,lateral mobile membrane bound antigens,and fixed immobile anti-gens.Here,using high resolution high speed live cell imaging approaches,we provide evidence that BCR microclusters are formed on the surface of B cells shortly after B cell’s encountering of antigens with each format of motion features.Through high speed live cell imaging,we determine that these BCR microclusters show dynamic growth feature and by doing so function as the basic platforms for B cells to acquire the anti-gens.We propose that the formation and dynamic growth of BCR microcluster is a universal mechanism for B cell to response to antigens with diverse motion features.
基金This work is supported by the National Natural Science Foundation of China （31530084, 31270224） and the Program of Introducing Talents of Discipline to Universities （111 project, B13007）.
文摘Phototropin （phot）-mediated signaling initiated by blue light （BL） plays a critical role in optimizing photosyn- thetic light capture at the plasma membrane （PM） in plants. However, the mechanisms underlying the regu- lation of phot activity at the PM in response to BL remain largely unclear. In this study, by single-particle tracking and stepwise photobleaching analysis of photl-GFP proteins we demonstrated that in the dark photl proteins remain in an inactive state and mostly exist as monomers. Dimerization and the diffusion rate of photl-GFP increased in a dose-dependent manner in response to BL. In contrast, BL did not affect the lateral diffusion of kinase-inactive photlD806N-GFP but did enhance its dimerization, suggesting that photl dimerization is independent of phosphorylation. Forster resonance energy transfer-fluorescence life- time imaging microscopy analysis revealed that the interaction between photl-GFP and a marker of sterol- rich lipid environments, AtRem1.3-mCherry, was enhanced with increased time of BL treatment. However, this BL-dependent interaction was not obvious in plants co-expressing phot1D806N-GFP and AtRem1.3- mCherry, indicating that BL facilitates the translocation of functional photl-GFP into AtRem1.3-1abeled microdomains to activate phot-mediated signaling. Conversely, sterol depletion attenuated photl-GFP dynamics, dimerization, and phosphorylation. Taken together, these results indicate that membrane micro- domains act as organizing platforms essential for the proper function of activated photl at the PM.
