RESUMO
Impairment of glucose-stimulated insulin secretion caused by the lipotoxicity of palmitate was found in ß-cells. Recent studies have indicated that defects in autophagy contribute to pathogenesis in type 2 diabetes. Here, we report that autophagy-related 7 (Atg7) induced excessive autophagic activation in INS-1(823/13) cells exposed to saturated fatty acids. Atg7-induced cathepsin B (CTSB) overexpression resulted in an unexpected significant increase in proinflammatory chemokine and cytokine production levels of IL-1ß, monocyte chemotactic protein-1, IL-6, and TNF-α. Inhibition of receptor-interacting protein did not affect the inflammatory response, ruling out involvement of necrosis. CTSB siRNA suppressed the inflammatory response but did not affect apoptosis significantly, suggesting that CTSB was a molecular linker between autophagy and the proinflammatory response. Blocking caspase-3 suppressed apoptosis but did not affect the inflammatory response, suggesting that CTSB induced inflammatory effects independently of apoptosis. Silencing of Nod-like receptor 3 (NLRP3) completely abolished both IL-1ß secretion and the down-regulation effects of Atg7-induced CTSB overexpression on glucose-stimulated insulin secretion impairment, thus identifying the NLRP3 inflammasome as an autophagy-responsive element in the pancreatic INS-1(823/13) cell line. Combined together, our results indicate that CTSB contributed to the Atg7-induced NLRP3-dependent proinflammatory response, resulting in aggravation of lipotoxicity, independently of apoptosis in the pancreatic INS-1(823/13) cell line.
Assuntos
Catepsina B/metabolismo , Inflamassomos/metabolismo , Insulinoma/metabolismo , Proteínas de Neoplasias/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Enzimas Ativadoras de Ubiquitina/metabolismo , Animais , Proteína 7 Relacionada à Autofagia , Proteínas de Transporte , Catepsina B/genética , Linhagem Celular Tumoral , Citocinas/biossíntese , Citocinas/genética , Regulação Neoplásica da Expressão Gênica/genética , Glucose/genética , Glucose/metabolismo , Inflamassomos/genética , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Insulinoma/genética , Insulinoma/patologia , Proteína 3 que Contém Domínio de Pirina da Família NLR , Proteínas de Neoplasias/genética , Ratos , Receptores Citoplasmáticos e Nucleares/genética , Enzimas Ativadoras de Ubiquitina/genéticaRESUMO
A new difluoroalkylation reagent Sulfox-CF2SO2Ph bearing both sulfoximine and sulfone moieties was prepared from commercially available SulfoxFluor and PhSO2CF2H. On one hand, the Sulfox-CF2SO2Ph reagent could act as a (phenylsulfonyl)difluoromethyl radical source under photoredox catalysis, in which the arylsulfoximidoyl group is selectively removed. On the other hand, under basic conditions, Sulfox-CF2SO2Ph could serve as a difluorocarbene precursor for S- and O-difluoromethylations with S- and O-nucleophiles, respectively, in which the phenylsulfonyl group in Sulfox-CF2SO2Ph is selectively removed (followed by α-elimination of the arylsulfoximidoyl group).
Assuntos
Povo Asiático/genética , Adolescente , Adulto , Criança , China , Surdez/genética , Feminino , Humanos , Masculino , Linhagem , Adulto JovemRESUMO
High-fat diet (HFD) and inflammation are the key contributors to insulin resistance and type 2 diabetes (T2D). Previous study shows fatty acid-induced accumulation of damaged, reactive oxygen species (ROS)-generating mitochondria, and this in turn activates the NLRP3 inflammasome interference with insulin signaling. Our previous research shows NLRP3 inflammasome activation signal originates from defects in autophagy. Yet how the fatty acid related to mitophagy alteration leads to the activation of NLRP3-ASC inflammasome has not been considered. Here we demonstrated that palmitate (PA) induced mitophagy deficiency, leading to damaged mitochondrion as characterized by mito-ROS production and loss of membrane potential. Antioxidant APDC or Ca(2+) signaling inhibitor Nifedipine blocked PA-induced NLRP3 inflammasome activation. Further, we provided evidences that PA reduced the expression of Ras homolog enriched in brain (Rheb) and disrupted Rheb recruitment to the mitochondrial outer membrane. In addition, sustained PA caused disassociation of kinesin family member 5B (KIF5B) from binding with mitochondria via Ca(2+)-dependent effects. Disruption of Rheb and KIF5B interaction with mitochondria blocked mitochondrial degradation along with IL-1ß dependent insulin resistance, which was majorly attenuated by Rheb/KIF5B overexpression. In a consequence, defective mitophagy led to the accumulation of damaged-ROS-generating mitochondria, down pathway of NLRP3-ASC-Caspase 1 activation, and subsequently, insulin resistance. These findings provide insights into the association of inflammation, mitophagy and T2D.