Medical Center of Hip, Luoyang Orthopedic-Traumatological Hospital, Orthopedics Hospital of Henan Province, Luoyang City, Henan Province, China.
J Cell Physiol. 2020 Jul;235(7-8):5511-5524. doi: 10.1002/jcp.29261. Epub 2020 Feb 4.
There is now increasing evidence which suggests a key role for osteoblast apoptosis in the pathogenesis of postmenopausal osteoporosis. Here, we evaluated the role and mechanism of proteasome 26S subunit, ATPase (PSMC) 6, a protein that is highly expressed in bone. Gene expression pattern had been extracted based on database of Gene Expression Omnibus (GEO). GEO2R was employed for analyses, while the DAVID database was adopted to further analyze the gene ontology (GO) as well as Kyoto Encyclopedia of Genomes pathway (KEGG) enrichment. Then, the Search Tool Retrieval of Interacting Genes (STRING) was utilized to carry out interaction regulatory network for the top 200 differentially expressed genes (DEGs). A key gene, called PSMC6, was identified by Cytoscape 3.6.0. The OVX osteoporosis model was established in female C57BL/6 mice by full bilateral ovariectomy. According to our findings, PSMC6 gene knockout would elevate bone mineral density (BMD) and the phosphorylation level of PI3K protein and increased the protein level of cleaved caspase-3/-9 in OVX osteoporosis mice. Further, MTT, bromodeoxyuridine, and flow cytometry assays revealed that PSMC6 inhibition promoted the progression of cell cycle and cell proliferation, whereas, PSMC6 overexpression promoted the apoptosis and inhibited cell cycle progression and cell proliferation in vitro. Besides, we found that PI3K activation significantly decreased PSMC6-induced osteoblast apoptosis and promoted cell proliferation through regulating the protein levels of p53, cyclinD1, and cleaved caspase-3/9. In conclusion, PSMC6 aggravated the degree of OVX-induced osteoporosis by inhibiting the PI3K/AKT signal transduction pathway, thereby promoting the apoptosis of osteoblasts.
现在有越来越多的证据表明，成骨细胞凋亡在绝经后骨质疏松症的发病机制中起关键作用。在这里，我们评估了蛋白酶体 26S 亚基、ATP 酶（PSMC）6 的作用和机制，这是一种在骨骼中高度表达的蛋白质。基因表达模式是基于基因表达综合数据库（GEO）提取的。采用 GEO2R 进行分析，而 DAVID 数据库则用于进一步分析基因本体论（GO）和京都基因与基因组百科全书通路（KEGG）富集。然后，利用 Search Tool Retrieval of Interacting Genes（STRING）为前 200 个差异表达基因（DEG）构建相互作用调控网络。通过 Cytoscape 3.6.0 鉴定出关键基因 PSMC6。通过双侧卵巢切除术对雌性 C57BL/6 小鼠建立 OVX 骨质疏松症模型。根据我们的研究结果，PSMC6 基因敲除会增加骨矿物质密度（BMD）和 PI3K 蛋白的磷酸化水平，并增加 OVX 骨质疏松症小鼠中 cleaved caspase-3/-9 的蛋白水平。进一步的 MTT、溴脱氧尿苷和流式细胞术检测显示，PSMC6 抑制促进细胞周期和细胞增殖的进展，而 PSMC6 过表达促进细胞凋亡并抑制体外细胞周期进程和细胞增殖。此外，我们发现 PI3K 激活通过调节 p53、cyclinD1 和 cleaved caspase-3/9 的蛋白水平，显著降低 PSMC6 诱导的成骨细胞凋亡并促进细胞增殖。总之，PSMC6 通过抑制 PI3K/AKT 信号转导通路加重 OVX 诱导的骨质疏松症程度，从而促进成骨细胞凋亡。
