comparative analyses of suv420h1 isoforms and suv420h2 reveal differences in their cellular localization and effects on myogenic differentiation比较分析suv420h1亚型和suv420h2揭示差异对肌原性的分化的细胞定位和影响.pdfVIP

Comparative Analyses of SUV420H1 Isoforms and SUV420H2 Reveal Differences in Their Cellular Localization and Effects on Myogenic Differentiation 1 1 1,2 Leanna W. K. Tsang , Ninghe Hu , D. Alan Underhill * 1 Department of Medical Genetics, School of Human Development, University of Alberta, Edmonton, Alberta, Canada, 2 Department of Oncology, School of Cancer, Engineering, and Imaging Sciences, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada Abstract Background: Methylation of histone H4 on lysine 20 plays critical roles in chromatin structure and function via mono- (H4K20me1), di- (H4K20me2), and trimethyl (H4K20me3) derivatives. In previous analyses of histone methylation dynamics in mid-gestation mouse embryos, we documented marked changes in H4K20 methylation during cell differentiation. These changes were particularly robust during myogenesis, both in vivo and in cell culture, where we observed a transition from H4K20me1 to H4K20me3. To assess the significance of this change, we used a gain-of-function strategy involving the lysine methyltransferases SUV420H1 and SUV420H2, which catalyze H4K20me2 and H4K20me3. At the same time, we characterized a second isoform of SUV420H1 (designated SUV420H1_i2) and compared the activity of all three SUV420H proteins with regard to localization and H4K20 methylation. Principal Findings: Immunofluorescence revealed that exogenous SUV420H1_i2 was distributed throughout the cell, while a substantial portion of SUV420H1_i1 and SUV420H2 displayed the expected association with constitutive heterochromatin. Moreover, SUV420H1_i2 distribution was unaffected by co-expression of heterochromatin protein-1a, which increased the ta