Inhibition of the BNIP3/NIX‐dependent mitophagy aggravates copper‐induced mitochondrial dysfunction in duck renal tubular epithelial cells

Abstract

The accumulation of copper (Cu) in the organisms could lead to kidney damage by causing mitochondrial dysfunction. Given that mitochondria are one of the targets of Cu poisoning, this study aimed to investigate the role of mitophagy in Cu‐induced mitochondrial dysfunction in renal tubular epithelial cells to understand the mechanism of Cu nephrotoxicity. Hence, the cells were treated with different concentrations of Cu sulfate (CuSO4) (0, 100, and 200 μM), and mitophagy inhibitor (Cyclosporine A, 0.5 μM) and/or 200 μM CuSO4 in the combination for 12 h. Results showed that Cu caused mitochondrial swelling, vacuoles, and cristae fracture; increased the number of mitochondrial and lysosome fluorescent aggregation points; upregulated the mRNA levels of mitophagy‐associated genes (LC3A, LC3B, P62, BNIP3, NIX, OPTN, NDP52, Cyp D LAMP1, and LAMP2) and protein levels of LC3II/LC3I, BNIP3, and NIX, downregulated the mRNA and protein levels of P62; reduced the mitochondrial membrane potential (MMP), ATP content, mitochondrial respiratory control rate (RCR), mitochondrial respiratory control rate (OPR), and the mRNA and protein levels of PGC‐1α, TOMM20, and Mfn2, but increased the mRNA and protein levels of Drp1. Besides, cotreatment with Cu and CsA dramatically decreased the level of mitophagy, but increased mitochondrial division, further reduced MMP, ATP content, RCR, and OPR, mitochondrial fusion and thereby reduced mitochondrial biogenesis. Taken together, these data indicated that Cu exposure induced BNIP3/NIX‐dependent mitophagy in duck renal tubular epithelial cells, and inhibition of mitophagy aggravated Cu‐induced mitochondrial dysfunction.

The role of mitophagy in metabolic diseases and its exercise intervention

“…Studies have demonstrated that various types of mitophagy-related receptors in mammalian cells can mediate this process. Mitochondrial swelling, vesicle formation, and somatic cristae breakage were observed in the CuSO4-induced kidney injury model, nip3-like protein (NIX)/BNIP3 mRNA and protein levels were significantly upregulated, and the number of mitochondrial and lysosomal fluorescent aggregation sites was increased, suggesting that CuSO4 treatment promotes the onset of BNIP3/NIX-mediated mitophagy, and that co-treatment with CuSO4 and an inhibitor of mitophagy significantly exacerbates mitochondrial dysfunction ( Bai et al, 2023 ). Focused low-intensity pulsed ultrasound (FLIPUS) treatment significantly enhanced the protein level of phosphoglycerate mutase 5 (PGAM5) in interleukin-1β (IL-1β)-induced primary mouse chondrocytes of knee joints, promoted Ser13 dephosphorylation containing FUN14 do domain protein 1 (FUNDC1), activated mitophagy in chondrocytes, significantly upregulated the expression of collagen II (Col II) and B-cell lymphoma/leukemia-2 (Bcl-2), downregulated matrix metalloproteinase 13 (MMP13), Bcl-2 associated X protein (Bax), and cleaved caspase-3 expression, and attenuated extracellular matrix (ECM) degradation and apoptosis.…”