Division of Molecular Signaling and Biochemistry, Department of Health Promotion, Kyushu Dental University, 2-6-1, Manazuru, Kitakyushu, Fukuoka 8038580, Japan.
Division of Molecular Signaling and Biochemistry, Department of Health Promotion, Kyushu Dental University, 2-6-1, Manazuru, Kitakyushu, Fukuoka 8038580, Japan; Division of Oral Medicine, Department of Physical Functions, Kyushu Dental University, Kitakyushu, Japan.
Bone. 2020 Mar;132:115209. doi: 10.1016/j.bone.2019.115209. Epub 2019 Dec 20.
Osteoclasts are multinuclear cells which maintain bone homeostasis by resorbing bone. During bone resorption, osteoclasts attach to the bone matrix via a sealing zone formed by an actin ring. Rous sarcoma oncogene (Src) is essential for actin ring formation and bone resorption. Recently, we demonstrated that plectin, a cytolinker protein, is a Src-binding protein in osteoclasts. However, the function of plectin in osteoclasts remains unknown. In this study, we demonstrated that shRNA knockdown of plectin in RAW 264.7 cells resulted in tartrate resistant acid phosphatase positive multinuclear cells (TRAP (+) MNCs) with impaired actin ring formation and bone resorption activity. Moreover, we found that in plectin-silenced TRAP (+) MNCs, Src and protein tyrosine kinase 2 beta (Pyk2), two critical kinases in osteoclastic bone resorption, were inactivated and microtubule polarity was disturbed. These results suggest that plectin plays a critical role in osteoclast biology by acting as a scaffold to facilitate Src and Pyk2 activation during microtubule organization.
破骨细胞是多核细胞，通过吸收骨来维持骨稳态。在骨吸收过程中，破骨细胞通过由肌动蛋白环形成的封闭区附着在骨基质上。劳斯肉瘤癌基因 (Src) 是肌动蛋白环形成和骨吸收所必需的。最近，我们证明了细胞连接蛋白网蛋白 (plectin) 是破骨细胞中的 Src 结合蛋白。然而，plectin 在破骨细胞中的功能仍然未知。在这项研究中，我们证明了 RAW 264.7 细胞中 plectin 的 shRNA 敲低导致抗酒石酸酸性磷酸酶阳性多核细胞 (TRAP(+)MNCs) 形成受损，肌动蛋白环形成和骨吸收活性受损。此外，我们发现，在 plectin 沉默的 TRAP(+)MNCs 中，两种在破骨细胞骨吸收中起关键作用的激酶Src 和蛋白酪氨酸激酶 2β (Pyk2) 失活，微管极性受到干扰。这些结果表明，plectin 通过作为支架在微管组织过程中促进 Src 和 Pyk2 的激活，在破骨细胞生物学中发挥关键作用。
