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，造成大量残疾。目前用于恢复骨量的疗法是有限的，并且主要集中在破骨细胞活性的衰减上。刺激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，我们对调节成骨分化和骨形成的潜在机制的理解仍然不完整。这项研究旨在通过评估蛋白激酶C δ（PKC？）在骨中的作用，扩大我们对骨量获得所涉及的分子机制的了解。虽然PKC-/-小鼠表现出胚胎骨形成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 <$参与胚胎成骨，PKC <$在出生后成骨细胞功能中的作用以及骨骼细胞中PKC <$作用的分子靶点尚未确定。我们的实验室已经表明，PKC调节Runx 2活性，这是成骨的主要调节因子之一，从而提出了PKC影响成骨分化的可能机制。这项拨款申请的中心假设是，PKC是多个信号级联中的关键因素，这些信号级联聚集在Runx 2上，促进骨生成和增加骨形成。有两个具体的目标来解决这个假设。（具体目的1）体外研究蛋白激酶C缺乏对多种促成骨因子下游骨合成代谢信号传导的影响。（具体目的2）表征成骨细胞系细胞中PKC？缺失对出生后骨形成的体内影响。细胞和分子生物学以及体内遗传模型将用于解决有关PKC在骨中作用的关键知识缺口。明确这些机制将有助于深入了解PKC最终如何影响成骨细胞功能和骨量获得。希望从这些研究中收集到的知识将有助于开发针对低骨量疾病的合理疗法，这些疗法通过靶向经由PKC调节聚集在Runx 2上的通路来刺激骨形成。

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.