LncRNA MALAT1 cessation antagonizes hypoxia/reoxygenation injury in hepatocytes by inhibiting apoptosis and inflammation via the HMGB1-TLR4 axis

Abstract

Hepatic ischemia-reperfusion (I/R) injury frequently occurs after liver transplantation, stroke, and trauma, resulting in organ dysfunction and failure. Hepatocyte apoptosis and inflammation are identified as the hallmarks of liver I/R injury. Long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is induced following hypoxia or ischemic stimulation, and exerts the contradictory roles in various injury progression. However, its role and mechanism lying beneath hepatic I/R remains ill defined. In this study, elevation of MALAT1 expression was corroborated in human hepatocytes under hypoxia/reoxygenation (H/R)H/R condition. Of interest, depression of MALAT1 blunted H/R-inhibited cell viability, and counteracted lactate dehydrogenase (LDH) and malondialdehyde release. Additionally, MALAT1 cessation antagonized H/R-evoked cell apoptosis and caspase-3 activity. Simultaneously, the increased inflammatory reaction triggered by H/R stimulation was also abrogated following MALAT1 suppression by reducing pro-inflammatory cytokine transcripts and productions including IL-1β and TNF-α. Mechanistically, H/R exposure activated the pathway of high-mobility group box1 (HMGB1)-TLR4, which was muted after MALAT1 inhibition. More importantly, elevation of HMGB1 reversed MALAT1 down-regulation-mediated inhibition in cell injury and inflammation. Moreover, blocking the TLR4 signaling also ameliorated H/R-evoked hepatocyte apoptosis and inflammatory response. Consequently, these data suggest that MALAT1 may aggravate hepatic I/R injury by regulating the HMGB1-TLR4-triggered cell apoptosis and inflammation, implying a promising therapeutic strategy to fight liver I/R injury.