N-acetylcysteine inhibits kinase phosphorylation during 3T3-L1 adipocyte differentiation

Objectives: Reports investigating the effects of antioxidants on obesity have provided contradictory results. We have previously demonstrated that treatment with the antioxidant N-acetylcysteine (NAC) inhibits cellular triglyceride (Tg) accumulation as well as total cellular monoamine oxidase A (MAOA) expression in 3T3-L1 mature adipocytes (Calzadilla et al., Redox Rep. 2013;210-218). Here we analyzed the role of NAC on adipogenic differentiation pathway. Methods: Assays were conducted using 3T3-L1 preadipocytes (undifferentiated cells: CC), which are capable of differentiating into mature adipocytes (differentiated cells: DC). We studied the effects of different doses of NAC (0.01 or 1mM) on DC, to evaluate cellular expression of phospho-JNK1/2 (pJNK1/2), phospho-ERK1/2 (pERK1/2) and, mitochondrial expression of citrate synthase, fumarate hydratase and MAOA. Results: Following the differentiation of preadipocytes, an increase in the expression levels of pJNK1/2 and pERK1/2 was observed, together with mitotic clonal expansion (MCE). We found that both doses of NAC decreased the expression of pJNK1/2 and pERK1/2. Consistent with these results, NAC significantly inhibited MCE and modified the expression of different mitochondrial proteins. Discussion: Our results suggested that NAC could inhibit Tg and mitochondrial protein expression by preventing both MCE and kinase phosphorylation.