Sirtuin 2 aggravates postischemic liver injury by deacetylating mitogen‐activated protein kinase phosphatase‐1

Abstract

Sirtuin 2 (Sirt2) is known to negatively regulate anoxia‐reoxygenation injury in myoblasts. Because protein levels of Sirt2 are increased in ischemia‐reperfusion (I/R)‐injured liver tissues, we examined whether Sirt2 is protective or detrimental against hepatic I/R injury. We overexpressed Sirt2 in the liver of C57BL/6 mice using a Sirt2 adenovirus. Wild‐type and Sirt2 knockout mice were subjected to a partial (70%) hepatic ischemia for 45 minutes, followed by various periods of reperfusion. In another set of experiments, wild‐type mice were pretreated intraperitoneally with AGK2, a Sirt2 inhibitor. Isolated hepatocytes and Kupffer cells from wild‐type and Sirt2 knockout mice were subjected to hypoxia‐reoxygenation injury to determine the in vitro effects of Sirt2. Mice subjected to I/R injury showed typical patterns of hepatocellular damage. Prior injection with Sirt2 adenovirus aggravated liver injury, as demonstrated by increases in serum aminotransferases, prothrombin time, proinflammatory cytokines, hepatocellular necrosis and apoptosis, and neutrophil infiltration relative to control virus‐injected mice. Pretreatment with AGK2 resulted in significant improvements in serum aminotransferase levels and histopathologic findings. Similarly, experiments with Sirt2 knockout mice also revealed reduced hepatocellular injury. The molecular mechanism of Sirt2's involvement in this aggravation of hepatic I/R injury includes the deacetylation and inhibition of mitogen‐activated protein kinase phosphatase‐1 and consequent activation of mitogen‐activated protein kinases. Conclusion: Sirt2 is an aggravating factor during hepatic I/R injury. (Hepatology 2017;65:225‐236).

Hepatocyte‐specific sirtuin 6 deletion predisposes to nonalcoholic steatohepatitis by up‐regulation of Bach1, an Nrf2 repressor

“…Primary hepatocytes were prepared from 6‐ to 8‐wk‐old KO mice and WT littermates by perfusion with collagenase type IV (Sigma‐Aldrich, St. Louis, MO, USA) as previously described (24). To express exogenous proteins for promoter assay, HepG2 cells obtained from American Type Culture Collection (Manassas, VA, USA) were transfected with 2 μg of pFlag or pFlag‐Sirt6 with 0.5 μg of antioxidant response element (ARE)‐promoter and 20 ng of pRL‐TK (Promega, Madison, WI, USA) using the Lipofectamin 2000 (Thermo Fisher Scientific).…”

Overexpression of SIRT1 prevents hypoxia-induced apoptosis in osteoblast cells

“…Analysis of cell viability. An MTT assay was used to estimate cell viability (12,13). Briefly, cells were plated at a density of 1x10 4 cells/well in α-MEM medium supplemented with 10% FBS and antibiotics in 96-well plates.…”

“…Reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The relative levels of SIRT1, tumor necrosis factor receptor-associated factor 2 (TRAF2) and cellular inhibitor of apoptosis 2 (cIAP2) mRNA were measured using RT-qPCR, as previously described (13). Total RNA was extracted from cells at a density of 1.5x10 6 cells/well, using TRIzol ® reagent (Invitrogen; Thermo Fisher Scientific, Inc.).…”

Neutralization of CD95 ligand protects the liver against ischemia-reperfusion injury and prevents acute liver failure

“…In an effort to ameliorate the problem of the severe shortage of available organs for transplantation, grafts from extended criteria donors, which are often highly susceptible to IRI, are increasingly being used for transplantation. Thus, there is an urgent clinical need for protective strategies against IRI in order to promote better graft function [1][2][3][4][5] . IRI of the liver is mediated by a complex series of mechanisms, including the production of reactive oxygen species (ROS), as well as local and systemic inflammatory responses, which are mediated by the release of proinflammatory cytokines from innate immune cells (i.e.…”