RESUMO
BACKGROUND: Hepatic ischemia-reperfusion (HIR) injury is a pathological condition initiated by interrupted hepatic blood supply and exaggerated after reperfusion, which is one of the most lethal risks in liver transplantation and other liver surgeries. We aimed to investigate the protective mechanism of octreotide (Oct) against HIR injury. METHODS: The function of Oct was evaluated in the in vivo mouse model of HIR injury. Histological examinations were performed to assess the pathological changes. Serum parameters including ALT and AST were measured to evaluate the liver damage. qRT-PCR and western blot analysis were employed to determine the levels of long non-coding RNA SNHG12 (SNHG12) and autophagy or apoptosis-related proteins. RNA pull-down and RIP assays were used to verify the interaction between SNHG12 and TAF15. The transcriptional regulation of TAF15 in YAP1 was validated by ChIP and luciferase reporter assays. RESULTS: In the in vivo HIR injury model, Oct efficiently alleviated HIR-caused hepatic damage by suppressing apoptosis and activating autophagy. However, silencing of SNHG12 abrogated the protective effects of Oct via inactivating autophagy. Further mechanism investigation revealed that SNHG12 promoted the stabilization of Sirt1 and increased YAP1 transcriptional activity via interacting with TAF15. Up-regulation of Sirt1 and YAP1 was essential for maintaining the protective effect of Oct against HIR injury through increasing autophagic flux and suppressing apoptosis. CONCLUSIONS: Oct-induced up-regulation of SNHG12 attenuated HIR injury via promoting Sirt1 stabilization and YAP1 transcription to activate autophagy and repress apoptosis.
Assuntos
Hepatopatias , Octreotida , RNA Longo não Codificante , Traumatismo por Reperfusão , Sirtuína 1 , Fatores Associados à Proteína de Ligação a TATA , Proteínas de Sinalização YAP , Animais , Apoptose , Hepatopatias/tratamento farmacológico , Hepatopatias/patologia , Hepatopatias/prevenção & controle , Camundongos , Octreotida/farmacologia , Octreotida/uso terapêutico , RNA Longo não Codificante/genética , Traumatismo por Reperfusão/tratamento farmacológico , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/metabolismo , Sirtuína 1/genética , Fatores Associados à Proteína de Ligação a TATA/farmacologia , Transcrição Gênica , Proteínas de Sinalização YAP/genéticaRESUMO
The ATF7 proteins, which are members of the cyclic AMP responsive binding protein (CREB)/activating transcription factor (ATF) family of transcription factors, display quite versatile properties: they can interact with the adenovirus E1a oncoprotein, mediating part of its transcriptional activity; they heterodimerize with the Jun, Fos or related transcription factors, likely modulating their DNA-binding specificity; they also recruit to the promoter a stress-induced protein kinase (JNK2). In the present study, we investigate the functional relationships of ATF7 with hsTAF12 (formerly hsTAF(II)20/15), which has originally been identified as a component of the general transcription factor TFIID. We show that overexpression of hsTAF12 potentiates ATF7-induced transcriptional activation through direct interaction with ATF7, suggesting that TAF12 is a functional partner of ATF7. In support of this conclusion, chromatin immunoprecipitation experiments confirm the interaction of ATF7 with TAF12 on an ATF7-responsive promoter, in the absence of any artificial overexpression of both proteins. We also show that the TAF12-dependent transcriptional activation is competitively inhibited by TAF4. Although both TAF12 isoforms (TAF12-1 and -2, formerly TAF(II)20 and TAF(II)15) interact with the ATF7 activation region through their histone-fold domain, only the largest, hsTAF12-1, mediates transcriptional activation through its N-terminal region.
