Centriolar-ciliary signaling mechanisms in tissue regeneration and differentiation

 描述(申请人提供)：初级纤毛是存在于不同组织中大多数脊椎动物细胞上的信号中心，特别是在祖细胞上，与调节感觉和其他信号细胞的增殖和分化的作用一致。纤毛在调节间充质谱系的决定中很重要(例如，通过Sonic Hedgehog信号)。我们发现纤毛是脂肪形成所必需的，从成年小鼠分离的CD34前脂肪细胞是均匀纤毛的。具体地说，初级纤毛通过组织敏化的IGF1受体来刺激胰岛素信号。我们已经确定不对称细胞分裂调节因子AGS3是脂肪形成中的一个新的中心粒/纤毛参与者：AGS3缺失的小鼠对高脂饮食诱导的脂肪组织膨胀导致肥胖具有抵抗力，AGS3缺失的CD34前体脂肪细胞存在调节和脂肪生成缺陷。我们发现AGS3定位于中心体，并直接与胰岛素底物受体2(IRS2-一个中心的胰岛素/IGF1效应因子)结合，导致胰岛素治疗后IRS2和AKT显着易位到中心粒。易位是脂肪细胞前有丝分裂的分解和刺激所必需的，对脂肪细胞的分化至关重要。我们假设纤毛CD34间充质干细胞在其他间充质谱系和实质器官中发挥作用，初级纤毛和中心粒AKT在纤毛前体细胞中广泛发挥作用，感知分化信号，并将有丝分裂和分化联系起来。建议的目标是：(1)了解在中心体激活Akt的Ags3-Irs2-Akt纤毛信号网络，包括寻找在脂肪细胞中重要的纤毛GPCRs；(2)了解Akt有丝分裂途径如何触发分化，包括寻找新的有丝分裂和表观遗传因子；以及 (3)通过对不同组织的组织学分析和对小鼠肝再生模型和体外成骨模型的研究，进一步验证纤毛干细胞的作用。从我们发现的与睫毛干细胞功能有关的新基因中，我们将与人类和癌症遗传学实验室合作，寻找我们新基因的疾病等位基因。我们的研究具有很强的翻译潜力，可以为再生疾病、肥胖和癌症定义新的诊断和治疗目标。

 DESCRIPTION (provided by applicant): Primary cilia are signaling centers present on the majority of vertebrate cells in diverse tissues, particularly on progenitor cells, consistent with role in regulating proliferation and differentiation of sensory and other signaling cells. Cilia ar important in regulating mesenchymal lineage decisions (e .g, by Sonic Hedgehog signaling). We find that cilia are required for adipogenesis and that CD34+ pre-adipocytes isolated from adult mice are uniformly ciliated. Specifically, primary cilia stimulate insulin signaling by organizing sensitized IGF1 receptors. We have identified the asymmetric cell division regulator AGS3 as a new centriolar/ciliary player in adipogenesis: AGS3-null mice are resistant to high fat diet-induced adipose tissue expansion leading to obesity, and AGS3-null CD34+ pre-adipocytes have a ciliation and adipogenesis defect. We show that AGS3 localizes to centrosomes and directly binds insulin substrate receptor 2 (IRS2 - a central insulin/IGF1 effector) to cause a striking translocation of IRS2 and AKT to centrioles upon insulin treatment. Translocation is required for deciliation and stimulation of pre-adipocyte mitoses critical for adipocyte differentiation. We hypothesize that ciliated CD34+ mesenchymal stem cells play a role in other mesenchymal lineages and parenchymal organs, and that the primary cilium and centriolar AKT broadly function in ciliated progenitor cells to sense differentiation signals and to couple deciliation to mitosis and differentiation. The proposed aims are directed toward (1) understanding the Ags3-Irs2-Akt ciliary signaling network for activating Akt at centrosomes, including looking for ciliary GPCRs important in adipocytes; (2) understanding how the Akt mitotic pathway triggers differentiation, including finding new mitotic and epigenetic factors; and (3) further validating the role of ciliated stem cells by histological analysis of various tissues nd by examining a mouse model of liver regeneration and an in vitro model of osteogenesis. From new genes we find implicated in ciliary stem cell function, we will collaborate with human and cancer genetics labs to look for disease alleles of our new genes. Our study has strong translational potential to define new diagnostics and therapeutic targets for regenerative diseases, obesity and cancer.