Dynein light chain LC8 alleviates nonalcoholic steatohepatitis by inhibiting NF-κB signaling and reducing oxidative stress.

Nonalcoholic steatohepatitis (NASH) is a liver disease characterized by fat accumulation and chronic inflammation in the liver. Dynein light chain of 8 kDa (LC8) was identified previously as an inhibitor of nuclear factor kappa B (NF-κB), a key regulator of inflammation, however, its role in NASH remains unknown. In this study, we investigated whether LC8 can alleviate NASH using a mouse model of methionine and choline-deficient (MCD) diet-induced NASH and examined the underlying mechanism. LC8 transgenic (Tg) mice showed lower hepatic steatosis and less progression of NASH, including hepatic inflammation and fibrosis, compared to wild-type (WT) mice after consuming an MCD diet. The hepatic expression of lipogenic genes was lower, while that of lipolytic genes was greater in LC8 Tg mice than WT mice, which might be associated with resistance of LC8 Tg mice to hepatic steatosis. Consumption of an MCD diet caused oxidative stress, IκBα phosphorylation, and subsequent p65 liberation from IκBα and nuclear translocation, resulting in induction of proinflammatory cytokines and chemokines. However, these effects of MCD diet were reduced by LC8 overexpression. Collectively, these results suggest that LC8 alleviates MCD diet-induced NASH by inhibiting NF-κB through binding to IκBα to interfere with IκBα phosphorylation and by reducing oxidative stress via scavenging reactive oxygen species. Thus, boosting intracellular LC8 could be a potential therapeutic strategy for patients with NASH.

Flunarizine inhibits osteoclastogenesis by regulating calcium signaling and promotes osteogenesis.

Many bone diseases such as osteoporosis and periodontitis are caused by hyperactivation of osteoclasts. Calcium (Ca2+ ) signals are crucial for osteoclast differentiation and function. Thus, the blockade of Ca2+ signaling may be a strategy for regulating osteoclast activity and has clinical implications. Flunarizine (FN) is a Ca2+ channel antagonist that has been used for reducing migraines. However, the role of FN in osteoclast differentiation and function remains unknown. Here, we investigated whether FN regulates osteoclastogenesis and elucidated the molecular mechanism. FN inhibited osteoclast differentiation along with decreased expression of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), and attenuated osteoclast maturation and bone resorption. FN inhibition of osteoclast differentiation was restored by ectopic expression of constitutively active NFATc1. FN reduced calcium oscillations and its inhibition of osteoclast differentiation and resorption function was reversed by ionomycin, an ionophore that binds Ca2+ . FN also inhibited Ca2+ /calmodulin-dependent protein kinase IV (CaMKIV) and calcineurin leading to a decrease in the cAMP-responsive element-binding protein-dependent cFos and peroxisome proliferator-activated receptor-γ coactivator 1ß expression, and NFATc1 nuclear translocation. These results indicate that FN inhibits osteoclastogenesis via regulating CaMKIV and calcineurin as a Ca2+ channel blocker. In addition, FN-induced apoptosis in osteoclasts and promoted osteogenesis. Furthermore, FN protected lipopolysaccharide- and ovariectomy-induced bone destruction in mouse models, suggesting that it has therapeutic potential for treating inflammatory bone diseases and postmenopausal osteoporosis.