The Second Hospital of Lanzhou University, Orthopaedic Clinical Research Center of Gansu Province, Intelligent Orthopaedic Industry Technology Center of Gansu Province, Lanzhou, Gansu, China; Department of Joint Surgery, Honghui Hospital, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
The Second Hospital of Lanzhou University, Orthopaedic Clinical Research Center of Gansu Province, Intelligent Orthopaedic Industry Technology Center of Gansu Province, Lanzhou, Gansu, China.
Biochem Biophys Res Commun. 2024 Oct 20;730:150391. doi: 10.1016/j.bbrc.2024.150391. Epub 2024 Jul 11.
Glucocorticoid-induced osteoporosis serves as a primary cause for secondary osteoporosis and fragility fractures, representing the most prevalent adverse reaction associated with prolonged glucocorticoid use. In this study, to elucidate the impact and underlying mechanisms of fluid shear stress (FSS)-mediated Piezo1 on dexamethasone (Dex)-induced apoptosis, we respectively applied Dex treatment for 6 h, FSS at 9 dyne/cm for 30 min, Yoda1 treatment for 2 h, and Piezo1 siRNA transfection to intervene in MLO-Y4 osteocytes. Western blot analysis was used to assess the expression of Cleaved Caspase-3, Bax, Bcl-2, and proteins associated with the PI3K/Akt pathway. Additionally, qRT-PCR was utilized to quantify the mRNA expression levels of these molecules. Hoechst 33258 staining and flow cytometry were utilized to evaluate the apoptosis levels. The results indicate that FSS at 9 dyne/cm for 30 min significantly upregulates Piezo1 in osteocytes. Following Dex-induced apoptosis, the phosphorylation levels of PI3K and Akt are markedly suppressed. FSS-mediated Piezo1 exerts a protective effect against Dex-induced apoptosis by activating the PI3K/Akt pathway. Additionally, downregulating the expression of Piezo1 in osteocytes using siRNA exacerbates Dex-induced apoptosis. To further demonstrate the role of the PI3K/Akt signaling pathway, after intervention with the PI3K pathway inhibitor, the activation of the PI3K/Akt pathway by FSS-mediated Piezo1 in osteocytes was significantly inhibited, reversing the anti-apoptotic effect. This study indicates that under FSS, Piezo1 in MLO-Y4 osteocytes is significantly upregulated, providing protection against Dex-induced apoptosis through the activation of the PI3K/Akt pathway.
糖皮质激素诱导性骨质疏松症是继发性骨质疏松症和脆性骨折的主要原因，也是与长期使用糖皮质激素相关的最常见不良反应。在这项研究中，为了阐明流体切应力（FSS）介导的 Piezo1 对地塞米松（Dex）诱导的凋亡的影响及其潜在机制，我们分别用 Dex 处理 6 h、FSS 处理 9 达因/平方厘米 30 分钟、Yoda1 处理 2 h 和 Piezo1 siRNA 转染干预 MLO-Y4 破骨细胞。采用 Western blot 分析检测 Cleaved Caspase-3、Bax、Bcl-2 和与 PI3K/Akt 通路相关的蛋白表达。此外，采用 qRT-PCR 定量这些分子的 mRNA 表达水平。采用 Hoechst 33258 染色和流式细胞术评估细胞凋亡水平。结果表明，9 达因/平方厘米 30 分钟的 FSS 可显著上调破骨细胞中的 Piezo1。在 Dex 诱导的凋亡后，PI3K 和 Akt 的磷酸化水平明显受到抑制。FSS 介导的 Piezo1 通过激活 PI3K/Akt 通路对 Dex 诱导的凋亡发挥保护作用。此外，用 siRNA 下调破骨细胞中的 Piezo1 表达会加剧 Dex 诱导的凋亡。为了进一步证明 PI3K/Akt 信号通路的作用，在用 PI3K 通路抑制剂干预后，FSS 介导的 Piezo1 在破骨细胞中对 PI3K/Akt 通路的激活被显著抑制，逆转了抗凋亡作用。本研究表明，在 FSS 作用下，MLO-Y4 破骨细胞中的 Piezo1 明显上调，通过激活 PI3K/Akt 通路对 Dex 诱导的凋亡起保护作用。
