重启内源干细胞基因将成熟体细胞诱导成多能干细胞（sdPS）及其在眼部的定向分化研究

Ocular degeneration is a difficult eye disease to all ophthalmologists in the world, but with the hope that the progress of stem cell-based regenerative medicine researches could lead to a new solution to treat this disease. There are many ethic and technique problems and challenges involved in both embryonic and adult stem cell preparations, thus hampering their applications in the clinic. Induced pluripotent stem cells (iPSC) can solve most of the aforementioned problems as they can be manufactured in vitro from patient's biopsies. It is important to know the mechanism(s) in generation of iPSC.RB, as the first discovered tumor suppressor, inhibits tumor initiation by blocking the cell cycle in combination with E2F and other proteins, and restricts the process that a differentiated cell might reprogram back to a stem-like status. Recent studies showed that Zeb1 can inhibit the activity of RB by inhibiting some CDKs.In addition to these two master regulators, there are more modulators including some microRNAs that might also be involved. Zeb1, RB and microRNA may constitute an important regulatory network in the formation and differentiation of iPSC.This experiment intends to establish a model of mice in vitro and reprogram somatic differentiated cells into sdPS by manipulating culture conditions in order to activate the endogenous stem cell transcription factors. Our preliminary observations have demonstrated that the sdPS can direct differentiate into the eye tissues, therefore we propose here to investigate the possible mechanism(s) which Zeb1, RB and microRNAs regulate the formation of sdPS.

眼部退行性变是困扰眼科医生的难题，以干细胞为核心的再生医学为其研究带来生机。目前干细胞制备面临诸多问题和挑战，阻碍其临床应用。因此，发现干细胞形成的新机制成为当务之急。RB，最早发现的肿瘤抑制因子，能够同E2F等蛋白结合阻止细胞周期的进行，抑制肿瘤发生，同时限制了成体细胞逆转为干细胞的过程。研究发现，Zeb1能够通过对某些周期素依赖激酶的抑制作用抑制RB的活性。即二者之间存在一个回馈平衡，能够影响干细胞的形成和分化。并且，二者基因调控主线之上还有主控者，特别是近几年发现的microRNA。由此推测，Zeb1、RB及miRs可能在干细胞的形成和分化过程中构成了重要的调控网络。本项目拟建立鼠体外细胞模型，通过控制培养条件，启动细胞自身内源干细胞转录因子，经重编程将体细胞转化为多能干细胞（sdPS），初步观察sdPS向眼组织定向分化能力，并探讨RB、Zeb1和miRs调控形成sdPS的可能机制