The Long Chain Acyl-CoA Synthetases 4, 5 and 6: Their Implication in the Skeletal Myoblast Response to Mono-(2 Ethyl Hexyl) Phthalate (MEHP)

Abstract

Background: Obesity is influenced by genetic and environmental factors, including environmental contaminants like mono(2-ethylhexyl) phthalate (MEHP), which disrupt lipid metabolism. While their effects on adipose tissue and liver are not entirely known, their impact on skeletal muscle remains even less studied. This study examines how MEHP affects acyl-CoA synthetases (ACSLs), key enzymes in lipid processing, in a cellular model of skeletal muscle.

Objectives: To assess the effect of MEHP on lipid accumulation in C2C12 myoblasts and to determine its impact on the expression of ACSL4, ACSL5, and ACSL6.

Methods: In C2C12 myoblasts exposed to MEHP, lipid quantification was assessed by fluorimetry. ACSL4, ACSL5 and ACSL6 expression was determined by RT-qPCR and Western blots and one-way ANOVA was used for analysis.

Results: Lipid accumulation increased in MEHP exposed C2C12 cells, particularly at the highest doses of MEHP.MEHP induced dose-dependent downregulation of ACSL4, ACSL5 along with decreased protein levels of both isoforms. Western blot analysis of ACSL6 revealed an isoform-specific response to MEHP exposure: the 76 kDa and 78 kDa isoforms were downregulated, whereas the 74 kDa isoform was upregulated. These findings were consistent with mRNA analysis, which showed reduced expression of both ACSL6 76 kDa and 78 kDa transcript variants.

Conclusion: In summary, MEHP exposure increased lipid accumulation in C2C12 cells, downregulated ACSL4 and ACSL5 expression, and induced an isoform-specific response of ACSL6.This study highlights the role of MEHP in disrupting fatty acid metabolism by impairing metabolic function and emphasizes skeletal muscle dysfunction as a contributing factor to obesity and related metabolic disorders.