TRPM8 is a novel regulator of bone homeostasis through neural and cell-autonomous mechanisms

TRPM8 是一种通过神经和细胞自主机制调节骨稳态的新型调节剂

• 批准号: 9108599
• 负责人: Katherine Jean Motyl
• 金额: $ 12.68万
• 依托单位: MAINEHEALTH
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-10 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9108599
• 关键词: Absence of pain sensation; Adipocytes; Adipose tissue; Adult; Afferent Neurons; Alleles; Body Temperature; Bone Density; Bone Growth; Bone Marrow; Bone Resorption; Bone remodeling; Breeding; CRISPR/Cas technology; Calvaria; Cations; Cell Communication; Cells; Coculture Techniques; Collaborations; Conditioned Culture Media; Cyclic AMP-Dependent Protein Kinases; Data; Defect; Dendrites; Development; Ear; Employee Strikes; Esthesia; Femur; Figs - dietary; Foundations; Future; Genes; Homeostasis; In Vitro; Injection of therapeutic agent; Length; Marrow; Mediating; Menthol; Mesenchymal; Microfluidics; Mus; Nerve Fibers; Neurons; Obesity; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Pain; Pathway interactions; Phenotype; Role; Signal Transduction; Site; Stromal Cells; Sympathetic Nervous System; TRPV1 gene; Techniques; Temperature Sense; Testing; Thermogenesis; Thick; Transgenic Mice; Work; adipocyte differentiation; bone; bone cell; bone loss; bone mass; cell type; in vitro Model; in vivo; knock-down; lipid metabolism; long bone; novel; osteoblast differentiation; osteogenic; paracrine; public health relevance; receptor; relating to nervous system; release of sequestered calcium ion into cytoplasm; research study; skeletal; small hairpin RNA; spine bone structure; substantia spongiosa; voltage

 DESCRIPTION (provided by applicant): The discovery of modulators of bone remodeling is crucial to developing new treatments for osteoporosis. The transient receptor potential melastatin 8 (TRPM8, a.k.a the cold and menthol receptor) is a voltage-gated cation channel that is open below 26°C. Neural TRPM8 is important for cold sensation, cold pain and cold analgesia, and thermogenesis. However, a non-neuronal role for TRPM8 is beginning to emerge. Adult Trpm8- /- mice have reduced trabecular bone volume fraction in the vertebrae and to a lesser extent in the long bones. This could be due to suppressed bone formation and/or increased bone resorption. In vitro, we found no difference in Trpm8-/- osteoclast differentiation compared to wildtype. Alternately, Trpm8-/- bone marrow stromal cells (BMSCs) and calvarial osteoblasts (OB) have reduced differentiation. Consistent with the in vivo phenotype of reduced bone marrow adiposity, BMSCs and ear MSCs (eMSCs) fail to fully differentiate into adipocytes in vitro. This novel finding demonstrates there is a significant defect in differentiation into eiter OBs or adipocytes. However, the majority of TRPM8 expression in vivo is on sensory neurons and we have evidence that neurons expressing TRPM8 are present in the bone marrow cavity. These could influence osteoblasts through paracrine pathways. My overarching hypotheses are that TRPM8 supports osteoblast and adipocyte differentiation through its direct expression in MSC-derived precursors (Aim 1) and that neural TRPM8 supports osteoblast differentiation through paracrine mechanisms (Aim 2). Finally, I will utilize novel Trpm8fl/fl mice to selectively delete Trpm8 in mesenchymal cells versus sensory neurons (Aim 3), where I will be able to delineate the extent to which each cell type contributes to the reduced bone mass phenotype. SPECIFIC AIM 1: In this aim, I will test the hypothesis that TRPM8 signaling in mesenchymal cells activates PKA to promote adipocyte and osteoblast differentiation utilizing shRNA and calcium flux analyses. SPECIFIC AIM 2: Despite striking in vitro differences in MSC differentiation in the absence of TRPM8, the majority of TRPM8 expression in vivo is on sensory neurons. Aim 2a: Test the hypothesis that sensory neurons expressing TRPM8 are present in bone. Aim 2b: Test the hypothesis that TRPM8 activation in sensory neurons supports osteoblast differentiation through dendrite:osteoblast contact. SPECIFIC AIM 3: Trpm8fl/fl mice will be crossed with SynapsinCre/+ and Prrx1Cre/+ mice to test whether effects of in vivo Trpm8 deletion are mediated through neural or osteoblast TRPM8 expression, respectively. The proposed experiments will identify mechanisms though which TRPM8 regulates osteoblast and adipocyte lineage, generate novel data on neural- mesenchymal cell interactions, and set forth a foundation for future work examining sensory neuron control of bone remodeling.