SNX10-mediated degradation of LAMP2A by NSAIDs inhibits chaperone-mediated autophagy and induces hepatic lipid accumulation

Abstract

Rationale: While some non-steroidal anti-inflammatory drugs (NSAIDs) are reported to induce hepatic steatosis, the molecular mechanisms are poorly understood. This study presented the mechanism by which NSAIDs induce hepatic lipid accumulation. Methods: Mouse primary hepatocytes and HepG2 cells were used to examine the underlying mechanism of NSAID-induced hepatic steatosis. Lipid accumulation was measured using Nile-red assay and BODIPY 493/503. The activity of chaperone-mediated autophagy (CMA) was determined by western blotting, qRT-PCR, and confocal imaging. The effect of NSAID on CMA inhibition was evaluated in vivo using diclofenac and CMA activator (AR7) administered mice. Results: All tested NSAIDs in this study accumulated neutral lipids in hepatocytes, diclofenac having demonstrated the most potency in that regard. Diclofenac-induced lipid accumulation was confirmed in both mouse primary hepatocytes and the liver of mice. NSAIDs inhibited CMA, as reflected by the decreased expression of lysosome-associated membrane glycoprotein 2 isoform A (LAMP2A) protein, the increased expression of CMA substrate proteins such as PLIN2, and the decreased activity of photoactivatable KFERQ-PAmCherry reporter. Reactivation of CMA by treatment with AR7 or overexpression of LAMP2A inhibited diclofenac-induced lipid accumulation and hepatotoxicity. Upregulation of sorting nexin 10 (SNX10) via the CHOP-dependent endoplasmic reticulum stress response and thus maturation of cathepsin A (CTSA) was shown to be responsible for the lysosomal degradation of LAMP2A by diclofenac. Conclusion: We demonstrated that NSAIDs induced SNX10- and CTSA-dependent degradation of LAMP2A, thereby leading to the suppression of CMA. In turn, impaired CMA failed to degrade PLIN2 and disrupted cellular lipid homeostasis, thus leading to NSAID-induced steatosis and hepatotoxicity.

SNX10 regulates the clearance of mitochondrial proteins and mitochondrial bioenergetics

“…Previous studies have linked the depletion of SNX10 to reduced maturation of CTSA (Cathepsin A), and increased levels of LAMP2A 36,37 . Thus, it is tempting to speculate that the large vacuoles observed upon SNX10 overexpression, could be caused by a downregulation of LAMP2A, leading to reduced fusion between late endosomes and lysosomes 38 .…”

“…through its C-terminal intrinsically disordered region (IDR), as IDRs generally are known for their dynamic and adaptable nature, existing in a repertoire of structurally distinct conformations that rapidly interconvert based on their cellular context 16 . Previous studies have linked the depletion of SNX10 to reduced maturation of CTSA (Cathepsin A), and increased levels of LAMP2A 36,37 . Thus, it is tempting to speculate that the large vacuoles observed upon SNX10 overexpression, could be caused by a downregulation of LAMP2A, leading to reduced fusion between late endosomes and lysosomes 38 .…”

The Role of Chaperone-Mediated Autophagy in Tissue Homeostasis and Disease Pathogenesis

“…CMA protects hepatocytes from lipotoxicity and oxidative stress in normal conditions [43,44]. In contrast, reduced levels of LAMP-2A and other positive regulators of CMA in the liver of non-alcoholic and alcoholic fatty liver patients, including hepatic steatosis, drive deficient CMA that unbalances the lipid metabolism in response to oxidative stress [103][104][105].…”

Osteopetrosis associated with PLEKHM1 and SNX10 genes, both involved in osteoclast vesicular trafficking

“…However, there is emerging evidence that SNX10 plays a role outside the skeletal system, i.e. in cancer, metabolic diseases and chaperone-mediated autophagy [30,[38][39][40].…”