Ubiquitination Lens Proliferation/Differentiation

描述(申请人提供)：晶状体的形成需要按时间顺序和空间上执行的细胞分裂和增殖程序，以及退出细胞周期和分化为晶状体纤维。在大多数细胞类型中，这些过程是由泛素蛋白酶体途径(UPPs)及时降解细胞周期调节因子控制的。在这些过程中，异常通常会导致小眼炎或白内障。然而，很少有已发表的论文讨论晶状体细胞周期或其受-UPP的控制。在正在进行的资助中，我们证明了Ub和Ubc3(一种Ub连接酶)是增殖和分化所必需的。然而，这些部分对细胞周期的调节发生在G2/M转变，而不是像预测的那样，发生在G1/S。我们现在试图通过将突变Ub的表达定向到上皮细胞和在转基因动物中分化晶状体细胞来确定是否在体内观察到同样的对照。我们最近的数据得出了两个新的总体假设：1)涉及Ub和Ubc3的蛋白分解是体内增殖、分化和晶状体形成所必需的；2)涉及未知的Ubc3-E3相互作用的UPP参与控制晶状体中的G2/M事件。这些假设分为4个特定的目标，以检验假设：在体内的增殖、分化和晶状体形成需要活跃的UPP；晶状体细胞周期需要泛素化，特别是在G2/M期；晶状体Ubc3与E3合作，我们将确定E3，以控制G2/M转变；以及细胞控制：G2/M周期需要在Ubc3依赖的过程中泛素化APC调节器。这些研究将解决NEI晶状体和白内障计划的一个主要目标：表征晶状体细胞分裂和分化的控制，以及它们在继发性白内障形成中的作用。长期目标是通过更好地了解控制晶状体细胞增殖和分化以及晶状体形成的过程来延长自然晶状体的功能，以及2)通过限制由于过度生长而导致的继发性白内障来植入晶状体。我们最近的论文表明，这些结果也将有助于更好地理解角膜伤口愈合和视网膜对压力的反应。这些信息，以及我们的新“试剂”，也将被用于限制继发性白内障、延长青光眼药物的作用、限制癌症和抗击其他增殖性疾病的新方法。优秀的合作者加入了我们的这一努力，他们每个人都是自己领域的领导者。

DESCRIPTION (provided by applicant): Lens formation requires a chronologically and spatially executed program of cell division and proliferation, as well as exit from the cell cycle and differentiation into lens fibers. These processes are controlled in most cell types by the timely degradation of cell cycle regulators by Ubiquitin Proteasome Pathways (UPPs). Aberrations, in these processes frequently result in microphthalmia or cataract. Yet there are few published papers that address either the lens cell cycle or its control by- UPPs. During the ongoing grant, we demonstrated that Ub and Ubc3 (a Ub ligase) are required for proliferation and differentiation. However, regulation of the cell cycle by-these moieties occurs at the G2/M transition and not, as predicted, at G1/S. We now seek to determine if the same controls are observed in vivo by directing expression of mutant Ub to the epithelial and differentiating lens cells in transgenic animals. Our recent data beget two new overall hypotheses: 1) proteolysis involving Ub and Ubc3 is required for proliferation, differentiation, and lens formation in vivo; 2) a UPP which involves an undescribed Ubc3-E3 interaction is involved in control of G2/M events in lens. These overall hypotheses are separated into 4 specific aims, to test the hypotheses that: an active UPP is required for proliferation, differentiation and lens formation in vivo; ubiquitination is required for the lens cell cycle, particularly in G2/M; lens Ubc3 cooperates with an E3, which we will identify, to control the G2/M transition; and control of the cell: cycle at G2/M requires ubiquitination of the APC regulators in a Ubc3-dependent process. These studies will address a major objective of the NEI lens and cataract program: to characterize controls of lens cell division and differentiation, and their roles in formation of secondary cataract. The long-term objective is to prolong function of 1) the natural lens by gaining a better understanding of processes involved in control of lens cell proliferation and differentiation, as well as in lens formation, and 2) implanted lenses by limiting secondary cataract due to overgrowth. Our recent papers show that these results will also lead to a better understanding of corneal wound healing and retina responses to stress. This information, and our novel "reagents", will also find use in new ways to limit secondary cataract, prolong function of glaucoma medication, limit cancer and in fighting other proliferative maladies. We are joined in this effort by excellent collaborators, each of whom is a leader in his field.