Empagliflozin-Enhanced Antioxidant Defense Attenuates Lipotoxicity and Protects Hepatocytes by Promoting FoxO3a- and Nrf2-Mediated Nuclear Translocation via the CAMKK2/AMPK Pathway

Abstract

Lipotoxicity is an important factor in the development and progression of nonalcoholic steatohepatitis. Excessive accumulation of saturated fatty acids can increase the substrates of the mitochondrial electron transport chain in hepatocytes and cause the generation of reactive oxygen species, resulting in oxidative stress, mitochondrial dysfunction, loss of mitochondrial membrane potential, impaired triphosphate (ATP) production, and fracture and fragmentation of mitochondria, which ultimately leads to hepatocellular inflammatory injuries, apoptosis, and necrosis. In this study, we systematically investigated the effects and molecular mechanisms of empagliflozin on lipotoxicity in palmitic acid-treated LO2 cell lines. We found that empagliflozin protected hepatocytes and inhibited palmitic acid-induced lipotoxicity by reducing oxidative stress, improving mitochondrial functions, and attenuating apoptosis and inflammation responses. The mechanistic study indicated that empagliflozin significantly activated adenosine 5’-monophosphate (AMP)-activated protein kinase alpha (AMPKα) through Calcium/Calmodulin dependent protein kinase kinase beta (CAMKK2) instead of liver kinase B1 (LKB1) or TGF-beta activated kinase (TAK1). The activation of empagliflozin on AMPKα not only promoted FoxO3a phosphorylation and thus forkhead box O 3a (FoxO3a) nuclear translocation, but also promoted Nrf2 nuclear translocation. Furthermore, empagliflozin significantly upregulated the expressions of antioxidant enzymes superoxide dismutase (SOD) and HO-1. In addition, empagliflozin did not attenuate lipid accumulation at all. These results indicated that empagliflozin mitigated lipotoxicity in saturated fatty acid-induced hepatocytes, likely by promoting antioxidant defense instead of attenuating lipid accumulation through enhanced FoxO3a and Nrf2 nuclear translocation dependent on the CAMKK2/AMPKα pathway. The CAMKK2/AMPKα pathway might serve as a promising target in treatment of lipotoxicity in nonalcoholic steatohepatitis.

Canagliflozin Delays Aging of HUVECs Induced by Palmitic Acid via the ROS/p38/JNK Pathway

“…Moreover, evolutionarily conserved JNK signaling is an important genetic determinant of lifespan control [ 50 ], and JNK can mediate glycolytic activation leading to aging spermatogonial stem cells [ 51 ]. Similar findings were obtained in our study, where empagliflozin, a similar SGLT2 inhibitor to CAN, was able to act on JNK to block its signaling [ 52 ].…”

Extracellular Superoxide Dismutase Attenuates Hepatic Oxidative Stress in Nonalcoholic Fatty Liver Disease through the Adenosine Monophosphate-Activated Protein Kinase Activation

“…AMPK is a critical protein involved in regulating cellular energy metabolism and becomes active when cellular energy levels decrease. In a recent study, Wang et al demonstrated that within the NAFLD model, CAMKKβ functions as the initiating kinase for the AMPK-mediated antioxidant defense mechanism, which protect hepatocytes from lipotoxicity [33]. In the current study, we observed a decrease in the expression of CAMKKβ in db/db mice, which was restored following hEC-SOD administration (Figure 3A,B).…”

OL-FS13 Alleviates Cerebral Ischemia-reperfusion Injury by Inhibiting miR-21-3p Expression

“…Previous studies on miR-21-3p have primarily been about cancer and diabetes [ 71 - 74 ]. In addition, CAMKK2/AMPK research has primarily concentrated on cancer, while I/R research has mainly focused on myocardial I/R therapy [ 46 , 65 , 69 , 75 ]. As such, we not only explored the possible role of miR-21-3p in the CI/R domain for the first time and provided support for its impact on neurological diseases but also provided further evidence for the important role of CAMKK2/AMPK in CI/R therapy.…”