Blockade of Drp1 rescues oxidative stress-induced osteoblast dysfunction

Abstract

Osteoblast dysfunction, induced by oxidative stress, plays a critical role in the pathophysiology of osteoporosis. However, the underlying mechanisms remain unclarified. Imbalance of mitochondrial dynamics has been closely linked to oxidative stress. Here, we reveal an unexplored role of dynamic related protein 1(Drp1), the major regulator in mitochondrial fission, in the oxidative stress-induced osteoblast injury model. We demonstrate that levels of phosphorylation and expression of Drp1 significantly increased under oxidative stress. Blockade of Drp1, through pharmaceutical inhibitor or gene knockdown, significantly protected against H2O2-induced osteoblast dysfunction, as shown by increased cell viability, improved cellular alkaline phosphatase (ALP) activity and mineralization and restored mitochondrial function. The protective effects of blocking Drp1 in H2O2-induced osteoblast dysfunction were evidenced by increased mitochondrial function and suppressed production of reactive oxygen species (ROS). These findings provide new insights into the role of the Drp1-dependent mitochondrial pathway in the pathology of osteoporosis, indicating that the Drp1 pathway may be targetable for the development of new therapeutic approaches in the prevention and the treatment of osteoporosis.

Drp1-dependent mitochondrial fission mediates osteogenic dysfunction in inflammation through elevated production of reactive oxygen species

“…Since a functional link exists between increased mitochondrial fragmentation and osteogenic dysfunction induced by H 2 O 2 [26], we next investigated whether abnormal mitochondrial morphological transition is induced in an osteoblast inflammatory model. To visualize mitochondrial morphology, Mitotracker Red staining was used for labeling the mitochondria.…”

“…Consistent with these phenomena, TNF-α highly increased Drp1 expression level as compared to the vehicle-treated group. Since Drp1 may be indirectly regulated by ROS-triggered oxidative stress in physiological and pathological processes [20, 26, 40], our results raise the question whether increased Drp1 expression leads to osteogenic dysfunction driven by oxidative stress in the osteoblast inflammatory model. Mdivi-1, a selective inhibitor of Drp1, was used to further verify the role of Drp1 in oxidative stress-modulating inflammatory response of MC3T3-E1 cells.…”

“…Since mitochondria are the major victims of oxidative stress, alterations of mitochondrial function in bone remodeling progression are well established [27, 28]. Moreover, H 2 O 2 -triggered mitochondrial excessive fission suppresses osteoblast differentiation through the mitochondrial ROS-Drp1 axis [26], which prompted us to investigate whether mitochondrial function plays a vital role in inflammation-induced osteogenic impairment. In the present study, we confirmed the osteogenic dysfunction of MC3T3-E1 cells after TNF-α treatment and demonstrated the potential mechanisms by which cells in the TNF-α-treated group undergo excessive mitochondrial fragmentation through oxidative stress-driven up-regulation of Drp1.…”

“…However, the relevant regulatory mechanisms need further validation. Given that Drp1 act as a downstream factor of ROS in H 2 O 2 -induced osteoblast dysfunction [26], it will be very interesting to investigate whether mitochondrial dynamics and Drp1 expression change during the pathological process of inflammation. If so, further questions will be raised on whether the fluctuating Drp1 level is responsible for osteogenic alterations during inflammation, and whether the suppression of ROS could rescue the impaired mitochondrial function and alleviate osteogenic dysfunction.…”

Attenuation of Oxidative Stress-Induced Osteoblast Apoptosis by Curcumin is Associated with Preservation of Mitochondrial Functions and Increased Akt-GSK3β Signaling

“…Cells were treated with H 2 O 2 and other test compounds for 1 h. Then, the cells were incubated in fresh culture medium containing 2.5 µM MitoSOX for 30 min. To assess the mitochondrial membrane potential, cells were co-stained with MT Green (100 nM) and TMRM (100 nM) for 30 min, according to our previous study [37].…”