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This study focuses on the histone arginine demethylase JMJD7, clarifying its indispensable anabolic role in maintaining bone homeostasis. The absence of JMJD7 inhibits the production of α-ketoglutarate through epigenetic pathways, interfering with mitochondrial energy metabolism and Runx2 signaling, thereby inducing osteoporosis. Exogenous supplementation of α-ketoglutarate can reverse these abnormal regulatory processes, restore osteogenic differentiation and bone formation, and alleviate bone loss caused by estrogen deficiency, confirming that JMJD7 can achieve positive regulation of bone formation by regulating α-ketoglutarate metabolism.
01 Research Background
Histone methylation modifications can regulate chromatin accessibility and the process of gene transcription. Abnormal modifications are closely related to the occurrence and development of various diseases such as osteoporosis. JMJD7, as a protein containing the Jumonji C domain, can catalyze the demethylation of arginine residues in histones, thereby affecting tissue metabolism and structural integrity. However, the specific function of JMJD7 in bone tissue and the molecular mechanism regulating bone metabolism have not been clearly and systematically elucidated.
02 Main Content
Stability. This study aims to explore the core role of JMJD7 in bone development and bone homeostasis maintenance, analyze the molecular pathways regulating bone formation; clarify the intrinsic mechanism of bone metabolic abnormalities caused by JMJD7 deficiency, verify its effects on cellular energy metabolism and epigenetic modifications; and investigate the rescue effect of α-ketoglutarate as a key metabolic intermediate on bone formation disorders caused by JMJD7 deficiency, improving the theoretical framework of coordinated regulation of bone formation by epigenetics and energy metabolism.
03 Research Design
1. Clinical sample analysis: Detect the expression level of JMJD7 in human bone biopsy tissues with osteoporosis; 2. Animal model construction: Establish an osteoblast-specific Jmjd7 knockout mouse model, observe the bone and systemic phenotypes of newborn mice, adult female and male mice, and construct a Jmjd7 overexpression model to evaluate its effect on estrogen deficiency-induced bone loss; 3. Molecular level detection: Combine transcriptome and epigenome analysis to explore the effects of Jmjd7 deficiency on gene expression and histone H3R2me1 modification, clarify the key regulatory targets downstream; 4. Metabolic and functional detection: Analyze the effects of Jmjd7 deficiency on cellular energy metabolism patterns and mitochondrial function, detect changes in related metabolic enzymes and intermediate products; 5. Intervention experiments: Observe the reversing effects of exogenous supplementation of α-ketoglutarate on epigenetic modifications, post-translational modifications of proteins, osteogenic differentiation and bone formation.
04 Results
1. Clinical and animal phenotypes: The expression of JMJD7 is deficient in human bone tissue with osteoporosis; after knockout of Jmjd7 in osteoblasts specifically, there is delayed closure of cranial sutures and premature death; adult female knockout mice have a smaller body size and present osteoporosis and abnormal visceral fat phenotypes, while male mice do not have this phenotype; overexpression of Jmjd7 can alleviate bone loss caused by estrogen deficiency.
2. Epigenetic and differentiation regulation: JMJD7 deficiency alters the transcriptome characteristics, promotes the enrichment of histone H3R2me1 modification, inhibits osteogenic differentiation of bone marrow mesenchymal cells, and Runx2 is the key epigenetic genome regulatory target of JMJD7.
3. Energy metabolism mechanism: JMJD7 deficiency causes the cell energy metabolism to shift towards anaerobic glycolysis, inhibits the mitochondrial oxidative phosphorylation process; this metabolic transformation is achieved by reducing the activity of mitochondrial complex I, decreasing isocitrate dehydrogenase and its intermediate product α-ketoglutarate. 4. Interventional rescue effect: Supplementing α-ketoglutaric acid can reverse the transcriptional inhibition mediated by H3R2me1, reduce the arginine methylation of related proteins, isocitrate dehydrogenase and Runx2, and restore the ability of mineralized matrix synthesis; at the same time, it can enhance osteogenic differentiation and bone formation levels, and improve the osteoporosis phenotype caused by Jmjd7 deficiency and estrogen deficiency.
05 Extension of ideas
1. JMJD7 can serve as a key molecule in regulating bone homeostasis, providing a new molecular target for the basic mechanism research of bone metabolic disorders such as osteoporosis;
2. This study reveals a new association between epigenetic modification and cellular energy metabolism in the coordinated regulation of bone development, expanding the molecular network of bone development and bone homeostasis regulation;
3. α-ketoglutaric acid, as a key metabolic cofactor in the JMJD7 regulatory pathway, has important research value in promoting bone formation and maintaining bone mass, and can provide new research directions and experimental ideas for basic research on bone metabolism.
