PKC delta as a central mediator of osteogenic signaling

描述(申请人提供)：低骨量疾病，特别是骨质疏松症，严重影响社会，导致大量残疾。目前恢复骨量的治疗方法有限，主要集中在减弱破骨细胞的活性上。促进成骨细胞活性和骨量获得的合成代谢疗法的发展是必不可少的；然而，我们对调控成骨分化和骨形成的潜在机制的了解仍然不完整。这项资助中提出的工作旨在通过评估蛋白激酶C增量(PKC)在骨骼中的作用来扩大我们对涉及骨量获得的分子机制的了解。虽然PKC？-/-小鼠表现出胚胎成骨减少和胚胎肢体原始培养成骨细胞分化的细胞自主缺陷，表明PKC？参与胚胎成骨，但PKC？在出生后成骨细胞功能中的作用和骨骼细胞中PKC作用的分子靶点尚未确定。我们的实验室已经证明，PKC？调节Runx2的活性，而Runx2是成骨的主要调节因子之一，从而提出了一种可能的机制，即PKC？可以影响成骨分化。这项拨款申请的中心假设是，PKC？是汇聚在Runx2上的多个信号级联中的关键因素，并促进成骨和增加骨形成。有两个具体的目标来解决这一假设。(1)体外研究PKC缺乏对多种促成骨因子下游骨合成代谢信号的影响。(特定目的2)研究成骨细胞系细胞中PKC的缺失对出生后骨形成的影响。细胞和分子生物学以及体内遗传模型将被用来解决关于PKC在骨骼中的作用的关键知识空白。明确这些机制将提供对PKC最终如何影响成骨细胞功能和骨量获取的关键理解。希望从这些研究中获得的知识将有助于针对低骨量疾病的合理治疗的开发，这些疾病通过调节PKC来靶向聚集在Runx2上的通路来刺激骨的形成。

DESCRIPTION (provided by applicant): Diseases of low bone mass, particularly osteoporosis, have gravely impacted society, causing massive disability. Current therapies for the restoration of bone mass are limited and focus primarily on the attenuation of osteoclast activity. The development of anabolic therapies that stimulate osteoblast activity and bone mass acquisition is essential; however, our understanding of the underlying mechanisms regulating osteogenic differentiation and bone formation is still incomplete. The work proposed in this grant aims to expand on our knowledge of the molecular mechanisms involved in bone mass acquisition by assessing the role of protein kinase C delta (PKC¿) in bone. Although PKC¿-/- mice exhibit reduced embryonic bone formation and a cell autonomous defect in osteoblast differentiation from embryonic limb primordial cultures, indicating involvement of PKC¿ in embryonic osteogenesis, a role for PKC¿ in post-natal osteoblast function and the molecular targets of PKC¿ action in skeletal cells have not been established. Our lab has shown that PKC¿ regulates the Runx2 activity, one of the master regulators of osteogenesis, thereby presenting a possible mechanism by which PKC¿ can impact osteogenic differentiation. The central hypothesis of this grant application is that that PKC¿ is a critical factor in multiple signaling cascades that converge on Runx2 and promote osteogenesis and increased bone formation. There are two specific aims to address this hypothesis. (Specific Aim 1) To examine the effect of PKC¿ deficiency on osteoanabolic signaling downstream of multiple pro-osteogenic factors in vitro. (Specific Aim 2) To characterize the in vivo impact of loss of PKC¿ in the cells of the osteoblastic lineage on post-natal bone formation. Cell and molecular biology, as well as in vivo genetic models, will be used to resolve key knowledge gaps regarding the role of PKC¿ in bone. Defining these mechanisms will provide critical understanding into how PKC¿ ultimately affects osteoblast function and bone mass acquisition. Hopefully, the knowledge gleaned from these studies will aid in the development of rational therapies against low bone mass disorders that stimulate the formation of bone by targeting pathways that converge on Runx2 via PKC¿ modulation.