CSF-1 Gene Expression in Osteoclast Biology

破骨细胞生物学中的 CSF-1 基因表达

• 批准号: 8631392
• 负责人: SHERRY L ABBOUD-WERNER
• 金额: $ 30.65万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-30 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8631392
• 关键词: Age; Aging; Albers-Schonberg disease; Apoptosis; Biology; Bone Diseases; Bone remodeling; Breeding; Cell surface; Connexin 43; Connexins; Data; Defect; Dominant-Negative Mutation; Enzyme-Linked Immunosorbent Assay; Fracture; Gap Junctions; Gene Expression; Gene Expression Profile; Genes; Genetic; Goals; Health; Histology; Homeostasis; In Situ Hybridization; Knock-out; Lead; Longevity; Macrophage Colony-Stimulating Factor; Mechanics; Mitochondria; Modeling; Morbidity - disease rate; Mus; NADPH Oxidase; Osteoblasts; Osteoclasts; Osteocytes; Osteogenesis; Oxidases; Oxidation-Reduction; Oxidative Stress; Pathway interactions; Pattern; Phenotype; Protein Isoforms; Relative (related person); Reverse Transcriptase Polymerase Chain Reaction; Role; Signal Transduction; Small Interfering RNA; TNFSF11 gene; Testing; Therapeutic; Transgenic Organisms; Work; activity marker; age related; bone; bone loss; bone mass; bone strength; bone turnover; human FRAP1 protein; improved; insight; interest; laser capture microdissection; new therapeutic target; novel; novel therapeutics; overexpression; oxidant stress; prevent; public health relevance; receptor; skeletal; therapeutic target

ABSTRACT Bone loss and fracture are leading causes of morbidity with aging. The mechanisms of age-related bone disease have not been defined. Our studies suggest that CSF-1 deficiency and increased Nox4 oxidase expression in osteocytes are key determinants of oxidant stress that impact osteocyte survival/function that is essential for bone remodeling. The long-term goal of this proposal is to delineate mechanistic pathways by which CSF-1/oxidative stress regulate osteocyte homeostasis and identify therapeutic targets to prevent bone loss with age. CSF-1 and CSF-1R are expressed by osteocytes. The mechanisms by which CSF-1 or its isoforms, soluble (s) and cell-surface (cs) CSF-1, regulate osteocyte survival/function have not been explored. Oxidative stress contributes to osteocyte demise and bone loss with aging. Our findings indicate that, with aging, CSF-1 expression declines in osteocytes. We generated mice with global CSF-1 deficiency (CSF-1KO) that show osteopetrosis with increased fractures and osteocyte defects including apoptosis, associated with increased NADPH oxidase Nox4 expression/activity and reduced Cx43 expression. CSF-1 decreases NADPH oxidase activity in cultured osteocytes and CSF-1KO bone osteocytes show elevated Nox4 and activation of the mTOR pathway compared to WT osteocytes, suggesting that CSF-1 protects from oxidant stress. DMP1Cre-CSF-1cKO mice with conditional knockout (cKO) of CSF-1 in osteocytes/late osteoblasts also show increased Nox4, osteocyte defects, reduced osteoclasts and bone formation, predisposing to bone loss and fracture with age. We hypothesize that: a) osteocyte cKO of CSF-1 increases Nox4 and oxidative stress, impairs osteocytes and accelerates bone defects with age, b) deletion of Nox4 in CSF-1cKO osteocytes decreases oxidative stress, restores osteocyte function/bone remodeling with age, c) expression of sCSF-1 in CSF-1cKO osteocytes promotes osteocyte survival and proper bone remodeling to a greater extent than csCSF-1 during aging. We will test these hypotheses in the following specific aims: 1) Determine the effect of CSF-1cKO in osteocytes on bone phenotype and redox state during aging. WT and CSF-1cKO mice will be examined for bone phenotype and osteocytes will be assessed for apoptosis, Nox4 and gene expression profile; 2) Determine the role of Nox4 in osteocytes of CSF-1cKO mice and mechanisms by which CSF-1 regulates osteocyte survival. To dissect the interplay between CSF-1 and Nox4, mice with cKO of CSF-1 and Nox4 in osteocytes will be generated and signaling mechanisms by which CSF-1 regulates osteocyte survival will be analyzed in cultured osteocytes; 3) Determine the ability of CSF-1 isoforms to rescue bone defects in CSF-1cKO mice. This will be accomplished using a transgenic approach to target sCSF-1 or csCSF-1 in osteocytes of CSF-1cKO mice. These studies will provide new mechanistic insights by which CSF-1 controls osteocyte survival/function and may lead to novel therapeutic strategies for improving osteocyte viability crucial for bone strength and longevity.

摘要