Fluid Shear Stress Regulates Osteogenic Differentiation via AnnexinA6-Mediated Autophagy in MC3T3-E1 Cells

Abstract

Fluid shear stress (FSS) facilitates bone remodeling by regulating osteogenic differentiation, and extracellular matrix maturation and mineralization. However, the underlying molecular mechanisms of how mechanical stimuli from FSS are converted into osteogenesis remain largely unexplored. Here, we exposed MC3T3-E1 cells to FSS with different intensities (1 h FSS with 0, 5, 10, and 20 dyn/cm2 intensities) and treatment durations (10 dyn/cm2 FSS with 0, 0.5, 1, 2 and 4 h treatment). The results demonstrate that the 1 h of 10 dyn/cm2 FSS treatment greatly upregulated the expression of osteogenic markers (Runx2, ALP, Col I), accompanied by AnxA6 activation. The genetic ablation of AnxA6 suppressed the autophagic process, demonstrating lowered autophagy markers (Beclin1, ATG5, ATG7, LC3) and decreased autophagosome formation, and strongly reduced osteogenic differentiation induced by FSS. Furthermore, the addition of autophagic activator rapamycin to AnxA6 knockdown cells stimulated autophagy process, and coincided with more expressions of osteogenic proteins ALP and Col I under both static and FSS conditions. In conclusion, the findings in this study reveal a hitherto unidentified relationship between FSS-induced osteogenic differentiation and autophagy, and point to AnxA6 as a key mediator of autophagy in response to FSS, which may provide a new target for the treatment of osteoporosis and other diseases.

Autophagy regulates age‐related delayed jawbone regeneration and decreased osteoblast osteogenesis by degrading FABP3

“…Treatment of N‐OBs with 3‐MA resulted in aging‐related features and notable inhibition of osteogenesis. Conversely, RAPA could increase the autophagy level of S‐OBs, decrease the expression of aging‐related markers, and promote osteogenesis, consistent with the findings of previous research 38,39 . Moreover, our study indicated that the activation of autophagy can mitigate the aging‐related phenotypes of S‐OBs and enhance the regenerative capacity of aged mouse jawbones.…”

“…Conversely, RAPA could increase the autophagy level of S-OBs, decrease the expression of aging-related markers, and promote osteogenesis, consistent with the findings of previous research. 38,39 Moreover, our study indicated that the activation of autophagy can mitigate the aging-related phenotypes of S-OBs and enhance the regenerative capacity of aged mouse jawbones. This finding underscores the importance of changes in autophagy levels as a mechanism through which aging impacts osteogenic capability.…”

METTL3-mediated m6A modification increases Hspa1a stability to inhibit osteoblast aging

“…Certain factors, such as hormones [ 25 , 26 ], growth factors [ 27 , 28 ], and fluid shear stress (FSS) [ 29 , 30 ], have been shown to positively stimulate osteoblast activity. Drawing from previous studies [ 31 , 32 ] and our preliminary findings, FSS has been confirmed to promote the physiological function of osteoblasts, leading to increased bone formation and reduced risk of the developing osteoporosis [ 33 – 36 ]. Therefore, considering all factors, osteoblast function was stimulated through FSS to explore the regulatory role of METTL3.…”

AnnexinA6: a potential therapeutic target gene for extracellular matrix mineralization

“…However, deterministic conclusions still need to be justified by many studies. Given the vital role of AnxA6 in ECM mineralization and osteogenesis ( Bolean et al, 2020 ; Bozycki et al, 2021 ; Mroczek et al, 2022 ; Pei et al, 2022 ), we reviewed the biological function of AnxA6 in regulating physiological and pathological ECM mineralization. We illustrated the underlying mechanisms to provide novel perspectives for mineralization-associated studies and contribute to treating mineralization-related diseases.…”