Overexpression of salusin‑β downregulates adipoR1 expression to prevent fatty acid oxidation in HepG2 cells

Abstract

Salusin-β and adiponectin receptor 1 (adipoR1) serve important roles in the development of certain cardiovascular diseases and lipid metabolism. However, to the best of our knowledge, the relationship between salusin-β and adipoR1, and their underlying mechanisms of action, currently remain unclear. In the present study, lentiviral vectors designed to overexpress salusin-β or knock down salusin-β expression were used in 293T and HepG2 cells. Semi-quantitative PCR was performed to investigate the relationship between salusin-β and adipoR1 mRNA expression in 293T cells. Western blotting was used to assess the protein expression levels of adipoR1, adenosine monophosphate-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC) and carnitine palmitoyl transferase 1A (CPT-1A) in transfected HepG2 cells. Simultaneously, HepG2 cells were treated with an adipoR1 inhibitor (thapsigargin) or agonist (AdipoRon) and the resultant changes in the expression levels of the aforementioned proteins were observed. Oil Red O staining and measurements of cellular triglyceride levels were performed to assess the extent of lipid accumulation in HepG2 cells. The results demonstrated that salusin-β overexpression downregulated adipoR1 expression and inhibited the phosphorylation of AMPK and ACC, which led to decreased CPT-1A protein expression. By contrast, salusin-β knockdown increased adipoR1 expression and promoted the phosphorylation of AMPK and ACC, which conversely enhanced CPT-1A protein expression. Treatment with adipoR1 agonist, AdipoRon, reversed the effects of salusin-β overexpression. In addition, salusin-β overexpression enhanced intracellular lipid accumulation in HepG2 cells induced by free fatty acid treatment. These findings highlighted the potential regulatory role of salusin-β in adipoR1-mediated signaling pathways. To conclude, the present study provided insights into the regulation of fatty acid metabolism by the liver. In particular, salusin-β may serve as a potential target for the therapeutic intervention of metabolic disorders of lipids.

Salusin‑α alleviates lipid metabolism disorders via regulation of the downstream lipogenesis genes through the LKB1/AMPK pathway

“…Previous studies have shown that both Salusin-α and -β are important cardiovascular regulatory peptides and may have opposite effects on lipid metabolism; and there are relatively few studies on the direction of lipid metabolism of Salusin-β, which needs further confirmation. The authors' research group previously found that overexpression of Salusin-β would decrease the expression of AdipoR1 and thus increase lipid accumulation ( 19 ). Salusin-α may serve as a therapeutic target for the management of atherosclerosis, hypertension and other coronary artery diseases by reducing lipid accumulation, reducing vascular endothelial inflammation, and reducing foam cell formation ( 13 - 15 , 21 ).…”

“…According to a recent study by the authors ( 19 ), the free fatty acid (FFA) group used 200 µ M FFAs to construct the cellular steatosis model. First, a 10 mM oleic acid (OA) stock solution (Shanghai Macklin Biochemical Co., Ltd.) was prepared by fully dissolving OA with NaOH.…”