Advances in molecular function of p62 protein and its role in diseases / 生物工程学报

Sequestosome 1 (SQSTM1/p62) is a selective autophagy adaptor protein that plays an important role in the clearance of proteins to be degraded as well as in the maintenance of cellular proteostasis. p62 protein has multiple functional domains, which interact with several downstream proteins to precisely regulate multiple signaling pathways, thereby linking p62 to oxidative defense systems, inflammatory responses and nutrient sensing. Studies have shown that mutation or abnormal expression of p62 is closely related to the occurrence and development of various diseases, including neurodegenerative diseases, tumors, infectious diseases, genetic diseases and chronic diseases. This review summarizes the structural features and molecular functions of p62. Moreover, we systematically introduce its multiple functions in protein homeostasis and regulation of signaling pathways. Furthermore, the complexity and versatility of p62 in the occurrence and development of diseases are summarized, with the aim to provide a reference for understanding the function of p62 protein and facilitating related disease research.

Anthelmintics nitazoxanide protects against experimental hyperlipidemia and hepatic steatosis in hamsters and mice

Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis. It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis. Nitazoxanide is an FDA-approved oral antiprotozoal drug with excellent pharmacokinetic and safety profile. We found that nitazoxanide and its metabolite tizoxanide induced mild mitochondrial uncoupling and subsequently activated AMPK in HepG2 cells. Gavage administration of nitazoxanide inhibited high-fat diet (HFD)-induced increases of liver weight, blood and liver lipids, and ameliorated HFD-induced renal lipid accumulation in hamsters. Nitazoxanide significantly improved HFD-induced histopathologic changes of hamster livers. In the hamsters with pre-existing hyperlipidemia and hepatic steatosis, nitazoxanide also showed therapeutic effect. Gavage administration of nitazoxanide improved HFD-induced hepatic steatosis in C57BL/6J mice and western diet (WD)-induced hepatic steatosis in Apoe -/- mice. The present study suggests that repurposing nitazoxanide as a drug for hyperlipidemia and hepatic steatosis treatment is promising.

Moxibustion improves cardiac function by up-regulating autophagy-related proteins of cardiomyocytes in rats with chronic heart failure / 针刺研究

OBJECTIVE: To observe the effect of moxibustion on cardiac function and the expression of autophagy-related proteins microtubule-associated protein 1 light chain 3 (LC3) and selective autophagy receptor signaling adaptor sequestosome 1 (SQSTM1/p62) in rats with chronic heart failure (CHF), so as to explore its underlying mechanisms in preventing and treating CHF. METHODS: Sixty male SD rats were randomly divided into normal, model, moxibustion, autophagy inhibitor 3-methyladenine (3-MA) and autophagy agonist rapamycin (RAPA) groups (n＝12 rats/group). The CHF model was established by intrape-ritoneal injection of adriamycin (ADR, 2 mg/kg, once every week for 12 weeks). Mild moxibustion was applied to bilateral "Feishu" (BL13) and "Xinshu" (BL15) for 20 min every time. Rats of the 3-MA group were treated by intraperitoneal injection of 3-MA suspension (15 mg/kg), and those of the RAPA group treated by gavage of RAPA suspension (2 mg/kg). All the treatments were given once a day for 3 weeks. The heart rate (HR), cardiac output (CO), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP) and maximum rising and lowering rates of left ventricular pressure (±dp/dtmax) were measured for assessing the cardiac performance. Histopathological changes of the left ventricular myocardium were observed by HE staining. The expression levels of LC3-Ⅰ， LC3-Ⅱ and p62 proteins of the left ventricle myocardium tissue were detected by Western blot. RESULTS: After modeling, the pathological changes of myocardium (as myocardial cell swelling with vacuoles, myocardial fibre breakage, etc.) were obvious, and the HR, LVEDP, LC3-Ⅱ and LC3-Ⅱ/Ⅰ protein expression levels were significantly increased in the model group compared with the normal group (P<0.01), while the CO, LVSP, ±dp/dtmax, and the expression of p62 protein were significantly down-regulated (P<0.01). Following the interventions, the myocardial injury was reduced, the HR, LVEDP, LC3-Ⅱ and LC3-Ⅱ/Ⅰ levels in both moxibustion and 3-MA groups were significantly decreased (P<0.05, P<0.01), while the CO, LVSP, ±dp/dtmax and p62 expression level were significantly increased relevant to the model group (P<0.05, P<0.01). In addition, the ratio of LC3-Ⅱ/Ⅰ was significantly increased, and the expression level of p62 significantly down-regulated in the RAPA group compared with the model group (P<0.01). CONCLUSION: Moxibustion can improve cardiac function in CHF rats, which may be related to its effects in down-regulating the ratio of LC3-Ⅱ/Ⅰ and up-regulating the expression of p62 protein to inhibit cardiomyocyte autophagy.

To screen for SQSTM1/p62 gene in Chinese patients with familial amyotrophic lateral sclerosis carrying superoxide dismutase 1 mutation / 中华内科杂志

Objective To explore the clinical features and SQSTM1/p62 gene mutations in Chinese Han patients with familial amyotrophic lateral sclerosis linked superoxide dismutase 1 (SOD1) mutation (FALS-SOD1).Methods A total of 13 FALS-SOD1 probands and 100 healthy controls were studied,with DNA extracted from the peripheral blood.Sequencing was carried out at 8 exons,intron-exon boundaries and promoter region (2-kb upstream from the coding sequence) of SQSM1/p62.Clinical data were collected and all patients were followed-up.Phenotype-genotype relationship was analyzed.Results The insertion of T was found in intron 5 of SQSTM1/p62 gene [+ 1 insert T (TT ＞ TG)] in a FALS-SOD1 G16A male proband,with limbs as the symptom onset and faster disease progression than the other two SOD1 G16A probands without SQSTM1/p62 gene mutation.Conclusions The insertion of T in the intron 5 of SQSTM1/ p62 gene may promote the ALS progression by damaging p62 function in the FALS-SOD1 G16A proband.