Piezo1-mediated fluid shear stress promotes OPG and inhibits RANKL via NOTCH3 in MLO-Y4 osteocytes

Abstract

Piezo1, a mechanosensitive ion channel, participates in a variety of biological processes in maintaining bone homeostasis. As the most abundant cells in bones of the mammals, osteocytes play an essential role in bone formation, remodeling, and bone mass maintenance. Here, by exposing MLO-Y4 osteocytes to the fluid shear stress (FSS) microenvironment, we explored the effect of Piezo1-mediated FSS on the expression of the molecules critical to the process of bone formation and resorption, Receptor Activator of Nuclear Factor-Kappa-B Ligand (RANKL) and Osteoprotegerin (OPG). It was found that 9 dyne/cm 2 loading for 30 minutes showed an upregulation trend on Piezo1 when MLO-Y4 osteocytes were exposed to an FSS microenvironment. FSS promotes the expression of OPG and inhibits the expression of RANKL. The blocker of Piezo1, GsMTx4, downregulates the effect of FSS on the expression of these two molecules. In addition, NOTCH3 was involved in this process. Thus, the results demonstrated that Piezo1-mediated FSS promotes the expression of OPG and inhibits the expression of RANKL via NOTCH3 in MLO-Y4 osteocytes.

The role of mechanically sensitive ion channel Piezo1 in bone remodeling

“…The expression of Piezo1 is significantly higher in osteocytes than Piezo2 ( Li et al, 2019 ). Fluid-flow stimulation on mature osteocytes can activate and upregulate Piezo1 channels ( Li et al, 2019 ; Liu Z. et al, 2022 ). Yoda1 can enhance intracellular calcium mobilization and inhibit sclerostin (Sost) expression in osteocytes in a dose-dependent manner, thus promoting osteoblast differentiation ( Sasaki et al, 2020 ).…”

“…Piezo1 is expressed and functions in various mechanical sensor cells, including osteoblasts ( Sun et al, 2019 ; Song et al, 2020 ), osteoclasts ( Wang et al, 2020 ), osteocytes ( Liu Z. et al, 2022 ), bone marrow mesenchymal stem/stromal cells (BMSCs) ( Zhou et al, 2020 ), chondrocytes ( Hendrickx et al, 2021 ), periodontal ligament fibroblasts (PDLFs) ( Kang et al, 2014 ), and periodontal ligament stem cells (PDLSCs) ( Lin Y. Y. et al, 2022 ). These cells participate in bone formation and resorption, ultimately maintaining bone homeostasis.…”

Distinct and overlapping functions of YAP and TAZ in tooth development and periodontal homeostasis

“…Osteocytes, which originate from mature osteoblasts when they become embedded in the bone matrix, have traditionally been considered inactive bone matrix placeholder cells. Recently, they have been recognized as the major mechanosensory cells, and their importance in mechanical signal transduction is increasingly appreciated, especially in fluid shear–mediated bone remodeling ( Dole et al, 2021 ; Liu et al, 2022 ). In the study by Li et al, fluid shear force activated the nuclear expression of YAP through the ion channel Piezo1 and stimulated the upregulation of Wnt1 expression in bone cells, thereby significantly increasing the bone mass and strength of mice ( Li X. et al, 2019 ).…”

The emerging role of Piezo1 in the musculoskeletal system and disease

“…Additionally, these activated channels promote ATP release, which in turn activates P2X receptors and sustains intracellular Ca 2+ signaling 50 . In MLOY4 osteocytes, Piezo1-mediated FSS enhances Osteoprotegerin (OPG) expression and reduces nuclear factor-Kappa-B Ligand (RANKL) expression through NOTCH3 87 . Knockdown of Piezo1 in osteocytes reduces osteogenic makers in osteoblasts, even when exposed to LIPUS 88 .…”