The role of autophagy in bone remodeling

自噬在骨重塑中的作用

基本信息

批准号：
10495747
负责人：
Melda Onal
金额：
$ 29.42万
依托单位：
UNIV OF ARKANSAS FOR MED SCIS
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-02-16 至 2028-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10495747
关键词：
Address Affect Apoptosis Autophagocytosis Autophagosome Biogenesis Biomechanics Bone Formation Stimulation Bone Matrix Bone Resorption Bone Surface Bone remodeling CRISPR-mediated transcriptional activation Cell Lineage Cells Cellular Stress Cessation of life Collagen Fracture Functional disorder Genes Genetic Human Individual Induction of Apoptosis Knockout Mice Lysosomes Measures Mechanics Mediating Membrane Modeling Molecular Molecular Chaperones Mus Musculoskeletal Diseases Organelles Osteoblasts Osteoclasts Osteocytes Osteogenesis Osteogenesis Imperfecta Pathology Pathway interactions Phenotype Process Production Proliferating Proteins Research Role Signal Transduction System TNFSF11 gene Therapeutic Intervention Vesicle bone bone mass bone strength cell type conditional knockout cytokine endoplasmic reticulum stress genetic approach improved in vivo insight mechanical load mouse model new therapeutic target novel osteoblast differentiation osteoblast proliferation prevent progenitor protein aggregation proteostasis response restraint single-cell RNA sequencing skeletal skeletal disorder stressor tibia trafficking transcription factor

项目摘要

PROJECT SUMMARY/ABSTRACT – PROJECT 1 Osteoblasts are bone-forming cells that produce large amounts of collagen and must maintain protein homeostasis to prevent cell dysfunction and death. Altered protein homeostasis in osteoblasts may contribute to the pathology of skeletal diseases such as Osteogenesis Imperfecta (OI). Autophagy recycles cellular components by delivering them to lysosomes for degradation. In macroautophagy, cargo, such as aggregated protein, is sequestered in double-membrane vesicles and delivered to lysosomes, while in chaperone-mediated autophagy (CMA), individual proteins are delivered by chaperones. We have shown that deletion of Atg7, a gene essential for macroautophagy, from osteoblasts causes low bone mass and fractures. This was associated with low osteoblast number and disruption of the osteocyte network. Osteocytes, which differentiate from osteoblasts, are buried in the bone matrix and sense changes in biomechanical load to orchestrate bone formation and resorption. The mechanisms by which loss of macroautophagy in osteoblasts and osteocytes cause low bone mass remain unclear. To examine the role of CMA in osteoblasts and osteocytes, we created mice lacking Lamp2a, which is essential for CMA, and this also caused low bone mass, but to a milder degree than loss of macroautophagy. Studies in other cell types suggest that CMA may be important mainly under conditions of cellular stress, such as endoplasmic reticulum stress. In line with this, we found that osteoblasts lacking CMA are more vulnerable to apoptosis induced by endoplasmic reticulum stress and produce more RANKL, a cytokine that stimulates formation of bone-resorbing osteoclasts. Based on this, we hypothesize that macroautophagy and CMA promote the differentiation, survival, and function of osteoblast lineage cells by maintaining proteostasis and we propose the following aims. Aim 1 will identify mechanisms by which deletion of Atg7 reduces osteoblast number by measuring proliferation and apoptosis, and by using single cell RNA sequencing to examine differentiation. We will also determine if loss of Atg7 alters the response of the tibia to mechanical loading. Aim 2 will determine if loss of CMA worsens the skeletal phenotype of a murine model of OI to reveal if CMA protects osteoblasts and osteocytes from endoplasmic reticulum stress. Aim 3 will determine whether genetic stimulation of macroautophagy improves osteoblast function and reduces endoplasmic reticulum stress in a murine model of OI. Successful completion of these studies will clarify the role of macroautophagy and CMA in osteoblast lineage cells may identify new targets for therapeutic intervention in conditions such as OI.

项目摘要/摘要 - 项目1 成骨细胞是产生大量胶原蛋白的骨形成细胞，必须维持蛋白质稳态以防止细胞功能障碍和死亡。成骨细胞中蛋白质稳态的改变可能有助于骨骼病的病理，例如成骨（OI）。自噬回收细胞通过将其输送到溶酶体以降解来分量。在宏观哲学中，货物，例如聚合蛋白质随后以双膜蔬菜出售并送到溶酶体，而在伴侣介导自噬（CMA），单个蛋白质由伴侣传递。我们已经证明了ATG7的缺失，一个基因来自成骨细胞至关重要的是骨细胞会导致低骨质量和骨折。这与成骨细胞数量低和骨细胞网络的破坏。与成骨细胞不同的骨细胞，建立在骨基质中，并感觉到生物力学负载的变化以编排骨骼形成和解决。成骨细胞和骨细胞中大噬菌体损失的机制导致低骨头质量仍然不清楚。为了检查CMA在成骨细胞和骨细胞中的作用，我们创建了缺乏的小鼠 LAMP2A，这对于CMA至关重要，这也导致骨质较低，但米勒程度比丧失宏观哲学。其他细胞类型的研究表明，CMA可能主要是在细胞应激，例如内质网应激。与此相一致，我们发现缺乏CMA的成骨细胞更容易受到内质网应激引起的凋亡，并产生更多的RANKL，一种细胞因子这刺激了骨呈现破骨细胞的形成。基于此，我们假设那个大噬菌 CMA通过维持成骨细胞谱系细胞的分化，生存和功能 Proteostasis，我们提出以下目的。 AIM 1将确定删除ATG7的机制通过测量增殖和凋亡来减少成骨细胞数，并使用单细胞RNA测序检查分化。我们还将确定ATG7的损失是否改变了胫骨对机械的反应加载中。 AIM 2将确定CMA的丢失是否使OI鼠模型的骨骼表型恶化，以揭示是否是否 CMA可保护成骨细胞和骨细胞免受内质网应激。 AIM 3将确定是否遗传刺激大自自噬可改善成骨细胞功能并减少内质网应激在OI的鼠模型中。这些研究的成功完成将阐明大自源和CMA的作用在成骨细胞中，在OI等条件下，可以鉴定出用于治疗干预的新靶标。