Cadmium is known as an environmental pollutant that contributes to pancreatic damage and the pathogenesis of diabetes. However, less attention has been devoted to elucidating the mechanisms underlying Cd-induced pancreatic β-cell dysfunction and the role of Cd toxicity in the development of diabetes. In this study, we demonstrated that exposure to Cd caused remarkable pancreatic β-cell dysfunction and death, both in vitro and in vivo. Lipidomic analysis of Cd-exposed pancreatic β-cells using high-resolution mass spectrometry revealed that Cd exposure altered the profile and abundance of lipids. Cd exposure induced intracellular lipid accumulation, promoted lipid biogenesis, elevated pro-inflammatory lipid contents and inhibited lipid degradation. Furthermore, Cd exposure upregulated the expression levels of TNF-α, IL-1β and IL-6 in pancreatic β-cells and elevated the TNF-α, IL1-β and IL-6 levels in the serum and pancreas. Taken together, the results of our study demonstrated that environmental relevant Cd exposure causes pro-inflammatory lipids elevation and insulin secretion dysfunction in β-cells and hence exaggerates diabetes development. Combined exposure to environmental hazardous chemicals might markedly increase the probability of developing diabetes in humans. This study provides new metabolic and pharmacological targets for antagonizing Cd toxicity.

Oral squamous cell carcinoma (OSCC) is the most common type of oral malignancy, and metastasis accounts for the poor prognosis of OSCC. Autophagy is considered to facilitate OSCC development by mitigating various cellular stresses; nevertheless, the mechanisms of autophagy in OSCC cell proliferation and metastasis remain unknown. In our study, high-sensitivity label-free quantitative proteomics analysis revealed nuclear protein 1 (NUPR1) as the most significantly upregulated protein in formalin-fixed paraffin-embedded tumour samples derived from OSCC patients with or without lymphatic metastasis. Moreover, NUPR1 is aberrantly expressed in the OSCC tissues and predicts low overall survival rates for OSCC patients. Notably, based on tandem mass tag-based quantitative proteomic analysis between stable NUPR1 knockdown OSCC cells and scrambled control OSCC cells, we confirmed that NUPR1 maintained autophagic flux and lysosomal functions by directly increasing transcription factor E3 (TFE3) activity, which promoted OSCC cell proliferation and metastasis in vitro and in vivo. Collectively, our data revealed that the NUPR1–TFE3 axis is a critical regulator of the autophagic machinery in OSCC progression, and this study may provide a potential therapeutic target for the treatment of OSCC.

Trimethyltin chloride (TMT) is widely used as a constituent of fungicides and plastic stabilizers in the industrial and agricultural fields, and is generally acknowledged to have potent neurotoxicity, especially in the hippocampus; however, the mechanism of induction of neurotoxicity by TMT remains elusive. Herein, we exposed Neuro-2a cells to different concentrations of TMT (2, 4, and 8 μM) for 24 h. Proteomic analysis, coupled with bioinformatics analysis, revealed the important role of macroautophagy/autophagy-lysosome machinery in TMT-induced neurotoxicity. Further analyses indicated significant impairment of autophagic flux by TMT via suppressed lysosomal function, such as by inhibiting lysosomal proteolysis and changing the lysosomal pH, thereby contributing to defects in autophagic clearance and subsequently leading to nerve cell death. Mechanistically, molecular interaction networks of Ingenuity Pathway Analysis identified a downregulated molecule, KIF5A (kinesin family member 5A), as a key target in TMT-impaired autophagic flux. TMT decreased KIF5A protein expression, disrupted the interaction between KIF5A and lysosome, and impaired lysosomal axonal transport. Moreover, Kif5a overexpression restored axonal transport, increased lysosomal dysfunction, and antagonized TMT-induced neurotoxicity in vitro. Importantly, in TMT-administered mice with seizure symptoms and histomorphological injury in the hippocampus, TMT inhibited KIF5A expression in the hippocampus. Gene transfer of Kif5a enhanced autophagic clearance in the hippocampus and alleviated TMT-induced neurotoxicity in vivo. Our results are the first to demonstrate KIF5A-dependent axonal transport deficiency to cause autophagic flux impairment via disturbance of lysosomal function in TMT-induced neurotoxicity; manipulation of KIF5A may be a therapeutic approach for antagonizing TMT-induced neurotoxicity.

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent diseases worldwide. Exercise is a first‐line therapy and an important preventive measure for patients with NAFLD, but the underlying mechanisms are not clear. C57BL/6 mice were fed a high‐fat diet (HFD) and subjected to 12 wk swimming exercise. Exercise protected against hepatic lipid accumulation and alleviated hepatocyte damage in HFD mice. Tandem mass tag—based quantitative proteomic analyses and ingenuity pathway analysis revealed that exercise down‐regulated fatty acid‐binding protein (FABP) 1 signaling pathway, which was most closely associated with lipid metabolism. Moreover, exercise significantly decreased FABP1 expression, and liver‐specific overexpression of FABP1 abolished the protective effect of exercise in NAFLD mice. Specifically, exercise significantly increased autophagic flux via restoring lysosomal function, including lysosomal proteolysis and lysosomal acidification maintenance, contributing to enhancement in autophagic clearance and subsequently alleviation of hepatic steatosis. Conversely, Fabp1 overexpression in the mouse liver blocked the protective effect of exercise via inhibiting autophagy flux. The present study identified FABP1 inhibition‐mediated replenishment of the autophagy‐lysosomal machinery as a novel endogenous mechanism whereby long‐term exercise improves lipid homeostasis and ameliorates hepatic steatosis in NAFLD.—Pi, H., Liu, M., Xi, Y., Chen, M., Tian, L., Xie, J., Chen, M., Wang, Z., Yang M., Yu, Z., Zhou, Z., Gao, F. Long‐term exercise prevents hepatic steatosis: a novel role of FABP1 in regulation of autophagy‐lysosomal machinery. FASEB J. 33, 11870‐11883 (2019). www.fasebj.org