N-acetylcysteine modulates rotenone-induced mitochondrial Complex I dysfunction in THP-1 cells

Mitochondrial Complex I dysfunction and oxidative stress have been part of the pathophysiology of several diseases ranging from mitochondrial disease to chronic diseases such as diabetes, mood disorders and Parkinson's Disease. Nonetheless, to investigate the potential of mitochondria-targeted therapeutic strategies for these conditions, there is a need further our understanding on how cells respond and adapt in the presence of Complex I dysfunction. In this study, we used low doses of rotenone, a classical inhibitor of mitochondrial complex I, to mimic peripheral mitochondrial dysfunction in THP-1 cells, a human monocytic cell line, and explored the effects of N-acetylcysteine on preventing this rotenone-induced mitochondrial dysfunction. Our results show that in THP-1 cells, rotenone exposure led to increases in mitochondrial superoxide, levels of cell-free mitochondrial DNA, and protein levels of the NDUFS7 subunit. N-acetylcysteine (NAC) pre-treatment ameliorated the rotenone-induced increase of cell-free mitochondrial DNA and NDUFS7 protein levels, but not mitochondrial superoxide. Furthermore, rotenone exposure did not affect protein levels of the NDUFV1 subunit but induced NDUFV1 glutathionylation. In summary, NAC may help to mitigate the effects of rotenone on Complex I and preserve the normal function of mitochondria in THP-1 cells.