Dysfunction of autophagy, which regulates cellular homeostasis by degrading organelles and proteins, is associated with pathogenesis of various diseases such as cancer, neurodegeneration and metabolic disease. Trehalose, a naturally occurring nontoxic disaccharide found in plants, insects, microorganisms and invertebrates, but not in mammals, was reported to function as a mechanistic target of the rapamycin (mTOR)-independent inducer of autophagy. In addition, trehalose functions as an antioxidant though its underlying molecular mechanisms remain unclear. In this study, we showed that trehalose not only promoted autophagy, but also increased p62 protein expression, in an autophagy-independent manner. In addition, trehalose increased nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in a p62-dependent manner and enhance expression of its downstream antioxidant factors, heme oxygenase-1 (Ho-1) and nicotinamide adenine dinucleotide phosphate quinone dehydrogenase 1 (Nqo1). Moreover, treatment with trehalose significantly reduced amount of reactive oxygen species. Collectively, these results suggested that trehalose can function as a novel activator of the p62–Keap1/Nrf2 pathway, in addition to inducing autophagy. Therefore, trehalose may be useful to treat many chronic diseases involving oxidative stress and dysfunction of autophagy.

Obesity, caused by the dysfunction of white adipose tissue (WAT), is reportedly accompanied by exacerbation of lipolysis. Perilipin 1 (PLIN1), which forms a coat around lipid droplets, interacts with several lipolysis proteins to regulate lipolysis. While it is known that perilipin family proteins are degraded in lysosomes, the underlying molecular mechanisms related to the downregulated expression of PLIN1 in obese WAT remain unknown. Recently, we found that lysosomal dysfunction originating from an abnormality of cathepsin B (CTSB), a lysosomal representative protease, occurs in obese WAT. Therefore, we investigated the effect of CTSB alterations on PLIN1 expression in obese WAT. PLIN1 protein disappeared and CTSB protein appeared in the cytoplasm of adipocytes in the early stage of obese WAT. Overexpression of CTSB reduced PLIN1 protein in 3T3L1 adipocytes, and treatment with a CTSB inhibitor significantly recovered this reduction. In addition, CTSB overexpression induced the dysfunction of lipolysis in 3T3L1 adipocytes. Therefore, we concluded that upregulation of CTSB induced the reduction of PLIN1 protein in obese WAT, resulting in lipolysis dysfunction. This suggests a novel pathology of lipid metabolism involving PLIN1 in adipocytes and that CTSB might be a therapeutic candidate molecule for obese WAT.

Flavonoids have been reported to possess strong antioxidant activities that moderate endothelial dysfunction and demonstrate protective effects on cardiovascular disease. Our previous studies confirmed that flavonoids, including hesperidin, naringin and nobiletin, inhibited thrombogenesis and hypertension in stroke prone spontaneously hypertensive rats (SHRSP) by protecting the endothelium from the adverse effects of free radical formation. We have now further investigated the protective effects of myricetin and hesperidin on cerebral thrombosis and atherogenesis in apolipoprotein E (apoE) and lowdensity lipoprotein receptor (LDLR) deficient (Apoe −/− and Ldlr −/− double knockout) mice. Three groups of mice were fed high fat diet alone and high fat diet mixed with myricetin (100 mg/kg/day and 200 mg/kg/day) or glucosyl hesperidin (G-hesperidin; 250 mg/kg/day and 500 mg/kg/day) for 8 weeks. There were no differences in body weight related to administration of the flavonoids. Thrombotic tendency was assessed using a He-Ne laser technique in the murine cerebral pial vessels. In addition, atherogenesis was quantified histologically after dissection of the aorta from each mouse and staining with Oil Red O solution. The percentages of stained area to whole area of dissected aorta were calculated as indices of anti-atherogenic activity. Both myricetin and G-hesperidin significantly inhibited thrombogenesis in vivo and significantly inhibited atherogenesis compared to control mice (p < 0.001). These findings demonstrated that daily intake of myricetin and hesperidin suppressed the development of atherogenesis and thrombogenesis, possibly associated with the potent antioxidant effects of the flavonoids.How to cite this paper: