Vitamin K2 Attenuates Mitochondrial Damage in Renal Proximal Tubular Cells

Excessive reactive oxygen species (ROS) levels cause oxidative stress, which can lead to various diseases. Renal failure is associated with oxidative stress and mitochondrial dysfunction. Vitamin K1 (phylloquinone) and K2 (menaquinone) are essential for blood coagulation and bone formation. Vitamin K has been shown to have anti-inflammation, glucose metabolism regulation, and antiferroptosis functions. We investigated the impact of menaquinone-4 (MK-4) on oxidative stress and mitochondrial dysfunction in human renal proximal tubular cells. MK-4 protected cells from oxidative damage induced by l-buthionine-(<i>S</i>,<i>R</i>)-sulfoximine (BSO), a selective inhibitor of glutathione metabolism, by inhibiting cell death, mitochondrial ROS production, and lipid peroxidation. MK-4 also reduced lactate production, prevented mitochondrial fragmentation, and improved mitochondrial respiratory function, indicating cytoprotective effects. Moreover, it enhanced intracellular ATP production and respiratory capacity, even in the absence of oxidative stress. Thus, MK-4 plays an important role in mitochondrial function in renal proximal tubular cells.