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

摘要报表 我们资助的工作重点是层粘连蛋白A(Laa)和层粘连蛋白C(Lac)在 随着细胞退出有丝分裂并进入早期G1期，基因组重组和核功能发挥作用。阿- 类型层蛋白及其相互作用蛋白与一系列疾病有关， 包括早衰、肌营养不良、心肌病和癌症(包括 其他)。核纤层(A-型和B-型)在下面形成网络并相互作用 与内核膜蛋白(INM)结合。核膜的蛋白质 和INM对于核的3D结构、基因组的支架很重要 以及对关键细胞类型特定基因的调控，DNA修复，核膜完整性， 信号的拼接、机械感觉和衰减。Laa和Lac是拼接 由LMNA基因座编码的变体。LAA有一个独特的C-末端尾巴，这是 Lac，虽然Lac只有六种独特的氨基酸将其与Laa区分开来，但在 C-末端尾巴。由于很难特别针对Lac同种类型，因此存在 缺乏对Laa和Lac的不同作用和调控的研究。近期工作 本实验室已发现Laa和Lac表现出不同的亚核分布 以及有丝分裂后进入早期G1期的动力学。我们最近的数据进一步表明，Lamin A和C有一些不重叠的功能，特别是在有丝分裂退出时，这是一个关键阶段 在细胞周期中，基因组正在重组，细胞和细胞核 重建。特别是，我们发现层粘连蛋白C对于更高的阶数是唯一需要的 板层相关异染色质的组织和核膜修复。 这些数据也提示了本地化的时间和同种类型特定的机制 Laa和Lac从末期到G1期早期，可能是通过翻译后 修饰(PTM)，并且这种时空调节对于它们的 函数(S)。除了定向蛋白质组学和基因组图谱绘制策略外，我们的 资助的提案在很大程度上依赖于正常细胞或 具有层粘连蛋白和层粘连蛋白相关蛋白功能中断的细胞。vt.给出 这些蛋白质中致病突变的数量对于理解 Laa和Lac在动态基因组调控和核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.