The role of CTGF in bone cell development and function

CTGF在骨细胞发育和功能中的作用

• 批准号: 7846787
• 负责人: STEVEN N. POPOFF
• 金额: $ 32.67万
• 依托单位: TEMPLE UNIV OF THE COMMONWEALTH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7846787
• 关键词: Ablation; Affect; Age; Alleles; Biological; Bone Development; Breeding; Cell physiology; Cell surface; Cells; Chondrogenesis; Cytoskeletal Modeling; Data; Defect; Development; Diagnosis; Disease; Epiphysial cartilage; Exhibits; Extracellular Matrix; Focal Adhesions; Fracture; Funding; Genetically Engineered Mouse; Growth Factor; Hand; Health Care Costs; Healthcare; Hospitalization; Incidence; Integrin Signaling Pathway; Integrins; Investigation; Knock-out; Knockout Mice; Laboratories; Mediating; Mediator of activation protein; Molecular; Mus; Osteoblasts; Osteoclasts; Osteogenesis; Osteopenia; Osteoporosis; PTK2 gene; Patients; Phenotype; Physicians; Process; Production; Protein Binding; Proteins; Recombinants; Regulation; Role; Secondary to; Signal Transduction; Skeletal Development; Stromal Cells; Testing; Tissues; Transgenic Mice; Transgenic Organisms; Up-Regulation; Visit; Work; angiogenesis; bone; bone cell; bone growth factor; bone loss; bone mass; clinically significant; connective tissue growth factor; in vivo; interest; mineralization; novel; novel therapeutics; osteoblast differentiation; public health relevance; research study; skeletal; skeletogenesis

DESCRIPTION (provided by applicant): CTGF has recently emerged as an important growth factor in osteogenesis. Previous studies in our laboratory and others have demonstrated that recombinant CTGF promotes proliferation, matrix production and differentiation of osteoblasts in culture. The importance of CTGF in skeletogenesis was confirmed in CTGF null (KO) mice; they exhibited multiple skeletal dysmorphisms as a result of defects in endochondral ossification. During the previous funding period, we established a colony of heterozygous breeders for the CTGF null (KO) allele (CTGFLacZ), and also generated several lines of transgenic (TG) mice (CTGF pOBCol3.6) that over-express CTGF in bone. More recently, we obtained CTGFflox/+ mice and are in the process of breeding them with Col I 3.6-Cre mice to generate osteoblast-specific CTGF null mice. Preliminary data from KO and TG mice support the hypothesis that CTGF is an anabolic bone growth factor that directly regulates osteoblast differentiation and function. In addition to its effects on osteoblasts, we present data showing that CTGF ablation (KO mice) or over-expression (TG mice) affects osteoclast formation. We hypothesize that these abnormalities in osteoclast number are secondary to altered production of osteoclastogenic factors (e.g. RANK-L) by stromal cells/osteoblasts in the bone microenvironment. Having these genetically-engineered mice in hand, studies in Aim 1 propose to evaluate the effects of CTGF absence (KO) or over-expression (TG) on bone in vivo, and to assess the differentiation and function of bone cells (osteoblasts and osteoclasts) derived from these mice in primary cultures. Studies have established that CTGF can function as an ECM-associated (matricellular) protein through unique interaction with specific integrins expressed by a given target cell, and the subsequent activation of integrin signaling pathways provides a mechanistic interpretation for some of its biological activities. We have demonstrated that osteoblasts attach to CTGF via the av¿5 integrin, resulting in the formation of focal adhesions, cytoskeletal reorganization and the activation of FAK and Erk. We also have preliminary data demonstrating that osteoclasts attach to CTGF via the av¿3 integrin. Studies in aim 2 will test the hypothesis that CTGF acts as a matricellular protein that binds to specific cell surface integrins on osteoblasts and osteoclasts to initiate integrin-activated signaling, cytoskeletal reorganization, and regulate cell function. We recently demonstrated that TGF-¿1 is a potent inducer of CTGF expression and that CTGF is a downstream mediator of TGF-¿1-induced ECM production in osteoblasts. We present preliminary data that Smad, Erk and Src signaling are required for TGF-¿1 up-regulation of CTGF in osteoblasts, and studies in Aim 3 propose to investigate the interaction between Src and Erk, the effects of activating Smad, Src and/or Erk signaling on CTGF expression in the absence of TGF-¿1, the mechanism whereby Erk potentiates Smad signaling, and the requirement for Src, Erk and Smad signaling for CTGF dependent ECM production in osteoblasts. Proposed experiments are expected to generate novel information regarding the effects of CTGF deficiency or over-expression on bone development in vivo, its mechanisms of action on osteoblasts and osteoclasts, and the molecular requirements for CTGF induction by TGF-¿1 in osteoblasts. PUBLIC HEALTH RELEVANCE. Osteoporosis is a major health care problem since approximately 10 million people over the age of 50 have been diagnosed with the disease and 33.6 million more are estimated to have low bone mass (osteopenia). Low bone mass is accompanied by an increased incidence of fracture, and it is estimated that the direct health care costs from fractures related to osteopenia (hospitalizations, ER visits, physician visits, etc.) ranges from $12-$18 billion annually. CTGF is a novel growth factor in bone and the proposed studies will generate new information regarding its effects and mechanisms of action on bone cell development and function. Once we understand its full effects on bone and how it works to promote bone formation, this information will be helpful in developing new therapeutic strategies to selectively enhance bone formation in patients with clinically significant bone loss.

描述（由适用提供）：CTGF最近成为成骨的重要生长因子。我们实验室和其他人的先前研究表明，重组CTGF促进培养中成骨细胞的增殖，基质产生和分化。 CTGF NULL（KO）小鼠证实了CTGF在骨骼生成中的重要性。由于内侧软骨骨化缺陷，他们暴露了多个骨骼畸形。在上一个资金期间，我们为CTGF NULL（KO）等位基因（CTGFLACZ）建立了一个杂合潜水员的菌落，还产生了几行转基因（TG）小鼠（CTGF POBCOL3.6），骨中过表达CTGF。最近，我们获得了CTGFFLOX/+小鼠，并正在用Col I 3.6-Cre小鼠繁殖它们，以生成成骨细胞特异性的CTGF NULL小鼠。来自KO和TG小鼠的初步数据支持CTGF是一种合成代谢骨生长因子，可直接调节成骨细胞分化和功能。除了其对成骨细胞的影响外，我们还提供数据表明CTGF消融（KO小鼠）或过表达（TG小鼠）会影响破骨细胞的形成。我们假设破骨细胞数中的这些异常是由于骨微环境中基质细胞/成骨细胞/成骨细胞的骨质质构成因子的产生而改变的。 AIM 1提出的研究具有这些遗传学工程的小鼠，以评估CTGF吸收（KO）或过表达（TG）对体内骨骼的影响，并评估骨细胞的分化和功能（成骨细胞和成骨细胞）的分化和功能。研究已经确定，通过与给定靶细胞表达的特定整合蛋白的独特相互作用，CTGF可以充当ECM相关的（基础化）蛋白，随后激活整合素信号通路的激活为其某些生物学活性提供了一种机械解释。我们已经证明，成骨细胞通过AV¿5整合素附着在CTGF上，从而形成了局灶性粘连，细胞骨架重组和FAK和ERK的激活。我们还拥有初步数据，表明破骨细胞通过AV¿3整合素附着在CTGF上。 AIM 2中的研究将检验以下假设：CTGF充当基质蛋白，该基质蛋白与成骨细胞和破骨细胞上的特定细胞表面整合蛋白结合以启动整联蛋白激活的信号传导，细胞骨架重组，并调节细胞功能。我们最近证明，TGF-€1是CTGF表达的潜在诱导剂，CTGF是TGF- - 1诱导的成骨细胞ECM产生的下游介体。 We present preliminary data that Smad, Erk and Src signaling are required for TGF-¿ 1 up-regulation of CTGF in osteoblasts, and studies in Aim 3 proposal to investigate the interaction between Src and Erk, the effects of activating Smad, Src and/or Erk signaling on CTGF expression in the absence of TGF-¿ 1, the mechanism whereby Erk potentiates Smad signaling,以及SRC，ERK和SMAD信号对成骨细胞中依赖性ECM产生的需求。预计提出的实验将产生有关CTGF缺乏症或过度表达对体内骨发育的影响的新信息，其对成骨细胞和成骨细胞的作用机理以及Osteoblasts中TGF-¿1对CTGF诱导CTGF诱导的分子需求。公共卫生相关性。骨质疏松症是一个主要的医疗保健问题，因为大约50岁以上的人被诊断出患有该疾病，据估计还有3360万人患有骨质较低（骨质减少）。低骨质量是通过增加的骨折事件来实现的，据估计，与骨质减少症有关的骨折的直接医疗保健费用（住院，急诊就诊，身体就诊等）每年12至180亿美元不等。 CTGF是骨骼中的新生长因子，拟议的研究将生成有关其作用和作用机理对骨细胞发育和功能的新信息。一旦我们了解了其对骨骼的全部影响及其如何促进骨形成的作用，该信息将有助于开发新的治疗策略，以选择性地增强临床上骨质损失显着的患者的骨骼形成。