MINK1 deficiency stimulates nucleus pulposus cell pyroptosis and exacerbates intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration, induced by aging and irregular mechanical strain, is highly prevalent in the elderly population, serving as a leading cause of chronic low back pain and disability. Evolving evidence has revealed the involvement of nucleus pulposus (NP) pyroptosis in the pathogenesis of IVD degeneration, while the precise regulatory mechanisms of NP pyroptosis remain obscure. Misshapen/Nck-interacting kinase (NIK)-related kinase 1 (MINK1), a serine-threonine protein kinase, has the potential to modulate the activation of NLRP3 inflammasome, indicating its pivotal role in governing pyroptosis. In this study, to assess the significance of MINK1 in NP pyroptosis and IVD degeneration, NP tissues from patients with varying degrees of IVD degeneration, and IVD tissues from both aging-induced and lumbar spine instability (LSI) surgery-induced IVD degeneration mouse models, with or without MINK1 ablation, were meticulously evaluated. Our findings indicated a notable decline in MINK1 expression in NP tissues of patients with IVD degeneration and both mouse models as degeneration progresses, accompanied by heightened matrix degradation and increased NP pyroptosis. Moreover, MINK1 ablation led to substantial activation of NP pyroptosis in both mouse models, and accelerating ECM degradation and intensifying the degeneration phenotype in mechanically stress-induced mice. Mechanistically, MINK1 deficiency triggered NF-κB signaling in NP tissues. Overall, our data illustrate an inverse correlation between MINK1 expression and severity of IVD degeneration, and the absence of MINK1 stimulates NP pyroptosis, exacerbating IVD degeneration by activating NF-κB signaling, highlighting a potential innovative therapeutic target in treating IVD degeneration.

Arsenic inhibited cholesterol efflux of THP-1 macrophages via ROS-mediated ABCA1 hypermethylation.

Growing evidences indicate that epigenetic modification involves in the mechanisms of atherosclerosis, which intersects with oxidative stress pathway. Arsenic is an important environmental contaminant and has been linked to atherosclerosis. However, the exact mechanism is not well understood. In the present study, we analyzed the effect of arsenic on oxidative stress, ABCA1 promoter methylation and cholesterol efflux of THP-1 macrophages. Results showed that arsenic could induce ROS-mediated DNA methyltransferase 1 (DNMT1) transcription and activity up-regulation, causing ABCA1 promoter to be hypermethylated with repressed expression. In addition, arsenic depleted the methyl donor S-adenosylmethionine (SAM) and induced global DNA hypomethylation. Arsenic inhibited cholesterol efflux of THP-1 macrophages, which could be attenuated after pretreatment with NAC or DNMT inhibitor 5-Aza-2'-deoxycytidine, but not with SAM. All of the findings suggest that arsenic inhibit cholesterol efflux of THP-1 macrophages via ROS-mediated ABCA1 hypermethylation.