The mechanism of beta-cell regeneration

描述（由申请人提供）：该应用侧重于刺激细胞再生作为治疗糖尿病的长期目标。控制¿-细胞周期进程的机制使它们处于极低的增殖状态，并随着年龄的增长而进一步减少。利用我们之前展示的增强细胞再生的模型，我们计划验证p16和细胞周期蛋白D对观察到的缓慢再生表型负责的假设。PTEN（10号染色体上缺失的磷酸酶和紧张素同源物）是一种特殊的细胞有丝分裂信号PI3K/AKT的负调节因子。我们已经表明，在¿-细胞中PTEN的损失导致胰岛质量和有丝分裂活性增加。为了评估这种表型的分子机制，我们探索了各种细胞周期调节因子，发现细胞周期蛋白D和p16在胰岛中显著改变。我们遵循了这一初步观察结果，并利用胶质瘤细胞系证实了PTEN可以直接调节p16和细胞周期蛋白D。由于p16的上调与衰老细胞再生能力的丧失相关，我们假设PTEN的丧失可能能够在更老的小鼠中诱导¿-细胞的再生。我们的初步数据表明，这在没有发育性Pten缺失的成年小鼠中是可能的。为了证明这一结果，我们采用了一种可以诱导成年小鼠Pten缺失的模型。在一起,这些数据导致当前假设PTEN调节b细胞的再生通过p16和细胞周期蛋白d测试这一假说,我们计划三个具体目标:首先,我们将在他们的调查是否有丝分裂活动的肽PTEN引起的损失取决于p16和细胞周期蛋白d。第二,我们将决定如果害怕失去PTEN能够诱导再生的肽在老鼠身上除了生理刺激的年龄(1年)不再害怕加强细胞再生。第三，我们将确定PTEN是否通过PI3K/AKT信号调控p16。这项分析的结果将大大提高对细胞如何再生的理解，并阐明需要操纵哪些分子来促进细胞再生。

DESCRIPTION (provided by applicant): This application focuses on the long term goal of stimulating ¿-cell regeneration as a cure for diabetes. The mechanism controlling the cell cycle progression of ¿-cells keeps them at an extremely low proliferating state that decreases further with age. Using a model that we have previously shown to exhibit enhanced ¿-cell regeneration, we plan to test the hypothesis that p16 and cyclin D are responsible for the observed slow regeneration phenotype. PTEN (phosphatase and tensin homologue deleted on chromosome 10) is a negative regulator of a particular ¿-cell mitogenic signal, PI3K/AKT. We have shown that loss of PTEN in ¿- cells leads to increased islet mass and mitotic activity. To evaluate the molecular mechanisms responsible for this phenotype, we explored various cell cycle regulators and discovered that cyclin D and p16 are significantly altered in the islets. We followed this initial observation and confirmed that PTEN can directly regulate p16 and cyclin D using a glioma cell line. Because of the correlation of p16 upregulation with loss of regeneration in aged ¿-cells, we hypothesized that PTEN loss may be capable of inducing regeneration of ¿- cells in even older mice. Our preliminary data showed that this is possible in adult mice without the contribution of developmental deletion of Pten. To demonstrate this result, we employed a model that can induce the deletion of Pten in adult mice. Together, these data led to the current hypothesis that PTEN regulates regeneration of b-cells through p16 and cyclin D. To test this hypothesis, we have planned three specific aims: First, we will investigate whether the mitotic activity in ¿-cells induced by PTEN loss depends on p16 and cyclin D. Second, we will determine if loss of PTEN is capable of inducing regeneration of ¿-cells in mice beyond the age (1 year) at which physiological stimuli can no longer enhance ¿-cell regeneration. Third, we will determine whether PTEN regulates p16 through PI3K/AKT signaling. The results from this analysis will substantially improve the understanding of how ¿-cells regenerate and shed light on what molecules need to be manipulated to promote their regeneration.