Differential Regulation and Roles of A-type Lamins in Early G1

简要说明 我们资助的工作集中在核纤层蛋白A（laA）和核纤层蛋白C（laC）在细胞凋亡中的作用。 当细胞退出有丝分裂并进入早期G1时，基因组重组和核功能。A-- 型核纤层蛋白及其相互作用蛋白与一系列疾病有关， 包括过早衰老、肌肉萎缩症、心肌病和癌症（其中 其他）。核纤层（A型和B型）形成一个相互作用的网络 与内核膜蛋白（INM）。核纤层蛋白 和INM对于细胞核的3D结构，基因组的支架， 和关键细胞类型特异性基因的调节，DNA修复，核膜完整性， 剪接、机械感觉和信号衰减。LaA和LaC是拼接的 由LMNA基因座编码的变体。LaA有一个独特的C-末端尾巴， laC，而laC只有六个独特的氨基酸，使其区别于laA，也在 C末端尾部由于难以特异性靶向laC同种型，因此 缺乏对laA和laC的不同作用和调节的研究。最近的工作 在我们实验室中发现，laA和laC显示出不同亚核分布 和有丝分裂后的动力学和进入早期G1。我们最近的数据进一步表明， A和C有一些不重叠的功能，特别是在有丝分裂出口，一个关键阶段 在细胞周期中，基因组重组，细胞和细胞核 重建特别是，我们发现，核纤层蛋白C是唯一需要的高阶 与核纤层相关的异染色质的组织以及核被膜的修复。 这些数据还表明，时间和同种型特异性机制的本地化， laA和laC从末期到早期G1，可能通过翻译后 修饰（PTM），这种时空调节对于它们的生物学行为非常重要。 function（s）.除了定向蛋白质组学和基因组作图策略，我们的 受资助的提案严重依赖于正常细胞或细胞中的单细胞成像（活的和固定的）。 核纤层蛋白和核纤层蛋白相关蛋白功能被破坏的细胞。给定 这些蛋白质中致病突变的数量，了解这些蛋白质中致病突变的数量是至关重要的。 laA和laC在动态基因组调控和核调控中的重叠和不同作用 功能

SUMMARY STATEMENT Our funded work focuses on the role that lamin A (laA) and lamin C (laC) play in genome re-organization and nuclear function as cells exit mitosis and enter early G1. A- type lamins and their interacting proteins have been implicated in a range of diseases, including premature aging, muscular dystrophy, cardiomyopathy, and cancer (among others). The nuclear lamins (A- and B-type) form a meshwork underlying and interacting with proteins of the inner nuclear membrane (INM). The proteins of the nuclear lamina and INM are important for the 3D structure of the nucleus, scaffolding of the genome and regulation of key cell type specific genes, DNA repair, nuclear envelope integrity, splicing, mechanosensation, and attenuation of signaling. LaA and laC are splice variants encoded by the LMNA locus. LaA has a unique C-terminal tail that is absent in laC, while laC has only six unique amino acids that differentiate it from laA, also at the C-terminal tail. Because of the difficulty in specifically targeting the laC isotype, there is a paucity of studies into the differential roles and regulation of laA and laC. Recent work in our laboratory has shown that laA and laC display different sub-nuclear distribution and dynamics after mitosis and into early G1. Our recent data further indicate that lamin A and C have some non-overlapping functions, particularly at mitotic exit, a critical stage of the cell cycle where the genome is reorganizing and the cell and nucleus are rebuilding. In particular, we find that lamin C is uniquely required for higher order organization of lamina associated heterochromatin and also nuclear envelope repair. These data also suggest temporal and isotype-specific mechanisms of localization of laA and laC from telophase to early G1, perhaps through post-translational modifications (PTMs), and that this spatio-temporal regulation is important for their function(s). In addition to directed proteomics and genome mapping strategies, our funded proposal relies heavily on single cell imaging (live and fixed) in normal cells or in cells that have had lamin and lamin associated proteins functionality disrupted. Given the number of disease-causing mutations in these proteins it is vital to understand the overlapping and distinct roles of laA and laC in dynamic genome regulation and nuclear function.