Centriolar-ciliary signaling mechanisms in tissue regeneration and differentiation

 描述（由申请人提供）：初级纤毛是存在于多种组织中的大多数脊椎动物细胞上，特别是祖细胞上的信号传导中心，与调节感觉细胞和其它信号传导细胞的增殖和分化的作用一致。纤毛在调节间充质谱系决定中是重要的（例如，通过Sonic Hedgehog信号传导）。我们发现纤毛是脂肪形成所必需的，并且从成年小鼠中分离的CD 34+前脂肪细胞均匀地纤毛。具体来说，初级纤毛通过组织致敏的IGF 1受体来刺激胰岛素信号传导。我们已经鉴定了不对称细胞分裂调节剂AGS 3作为脂肪生成中的新中心粒/纤毛参与者：AGS 3缺失小鼠对高脂肪饮食诱导的脂肪组织扩张具有抗性，导致肥胖，并且AGS 3缺失的CD 34+前脂肪细胞具有纤毛形成和脂肪生成缺陷。我们发现AGS 3定位于中心体，并直接结合胰岛素底物受体2（IRS 2-一种中心胰岛素/IGF 1效应子），导致胰岛素治疗后IRS 2和AKT显著易位到中心粒。易位是前脂肪细胞有丝分裂的脱定居和刺激所必需的，而前脂肪细胞有丝分裂对于脂肪细胞分化至关重要。我们假设纤毛CD 34+间充质干细胞在其他间充质谱系和实质器官中发挥作用，并且初级纤毛和中心粒AKT在纤毛祖细胞中广泛发挥作用，以感知分化信号并将脱纤毛与有丝分裂和分化偶联。所提出的目标是针对（1）理解Ags 3-Irs 2-Akt纤毛信号传导网络以在中心体激活Akt，包括寻找在脂肪细胞中重要的纤毛GPCR;（2）理解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)通过各种组织的组织学分析和通过检查肝再生的小鼠模型和骨生成的体外模型进一步验证纤毛干细胞的作用。从我们发现的与睫状体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转化潜力，可以为再生性疾病、肥胖和癌症定义新的诊断和治疗靶点。

 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.