Simultaneous Induction of Glycolysis and Oxidative Phosphorylation during Activation of Hepatic Stellate Cells Reveals Novel Mitochondrial Targets to Treat Liver Fibrosis

Abstract

Upon liver injury, hepatic stellate cells (HSCs) transdifferentiate to migratory, proliferative and extracellular matrix-producing myofibroblasts (e.g., activated HSCs; aHSCs) causing liver fibrosis. HSC activation is associated with increased glycolysis and glutaminolysis. Here, we compared the contribution of glycolysis, glutaminolysis and mitochondrial oxidative phosphorylation (OXPHOS) in rat and human HSC activation. Basal levels of glycolysis (extracellular acidification rate ~3-fold higher) and particularly mitochondrial respiration (oxygen consumption rate ~5-fold higher) were significantly increased in rat aHSCs, when compared to quiescent rat HSC. This was accompanied by extensive mitochondrial fusion in rat and human aHSCs, which occurred without increasing mitochondrial DNA content and electron transport chain (ETC) components. Inhibition of glycolysis (by 2-deoxy-D-glucose) and glutaminolysis (by CB-839) did not inhibit rat aHSC proliferation, but did reduce Acta2 (encoding α-SMA) expression slightly. In contrast, inhibiting mitochondrial OXPHOS (by rotenone) significantly suppressed rat aHSC proliferation, as well as Col1a1 and Acta2 expression. Other than that observed for rat aHSCs, human aHSC proliferation and expression of fibrosis markers were significantly suppressed by inhibiting either glycolysis, glutaminolysis or mitochondrial OXPHOS (by metformin). Activation of HSCs is marked by simultaneous induction of glycolysis and mitochondrial metabolism, extending the possibilities to suppress hepatic fibrogenesis by interfering with HSC metabolism.

Age-related susceptibility to insulin resistance arises from a combination of CPT1B decline and lipid overload

“…Hexokinase and pyruvate kinase activities were carried out using NAD(P)H-linked assays at 37 °C in a Synergy H4 plate reader (BioTek™) at 340 nm for 6 min as previously described [60]. Briefly, for both enzyme measurements, the assay buffer contained 100 mM Tris-HCl, 15 mM NaCl, 0.5 mM CaCl 2 , 140 mM KCl and 5 mM potassium phosphate buffer (pH 7.0).…”

Comprehensive Analysis of the Transcriptome-Wide m6A Methylation Modification Difference in Liver Fibrosis Mice by High-Throughput m6A Sequencing

“…Liver fibrosis (LF) is defined as excessive deposition of extracellular matrix (ECM) in response to various cases of liver injury, which is a reversible abnormal tissue response, and excessive activation of hepatic stellate cells (HSCs) is central to its pathogenesis ( Bataller and Brenner, 2005 ; Zhang et al, 2017 ; Smith-Cortinez et al, 2020 ). LF is the most common pathological consequence of liver diseases and may lead to liver cirrhosis and liver cancer, and even develop into liver failure in severe cases ( Wang Q. et al, 2020 ).…”

Sodium butyrate inhibits aerobic glycolysis of hepatocellular carcinoma cells via the c‐myc/hexokinase 2 pathway

“… 57 DeWaal et al reported that the upregulation of HK2 begins during liver cirrhosis, increases in dysplasia and reaches peaks in HCC. 56 Furthermore, the upregulation of HK2 and the enhancement of glycolysis have been reported to play pertinent roles in the activation of HSCs and liver fibrosis, 13 , 58 which is the main contributor to liver cirrhosis and HCC. 59 These findings show that targeting HK2 could be an excellent and safe strategy for treating HCC, even in the early phase of hepatocellular carcinogenesis.…”