Anti-TOMM20 (full length) polyclonal antibody

Reactive oxygen species (ROS) overproduction and renal tubular epithelial cell (TEC) apoptosis are key mechanisms of contrast-induced acute kidney injury (CI-AKI). Mitochondria are the main source of intracellular ROS. In the present study, the characteristics of mitophagy and the effects of rapamycin on contrast-induced abnormalities in oxidative stress, mitochondrial injury and mitophagy, TEC apoptosis and renal function were investigated in a CI-AKI rat model. Rats were divided into control group, CI-AKI group, and pretreatment groups (with rapamycin dose of 2 or 5 mg/kg). CI-AKI was induced by intraperitoneal injection of iohexol (12.25 g iodine/kg). Renal malondialdehyde (MDA) and catalase (CAT) were measured as oxidative markers. Light-chain 3 (LC3), P62, Beclin-1, PTEN-induced putative kinase (Pink1), and cytochrome c (Cyt c) expression were measured by Western blot. Mitochondrial membrane potential (Delta psi m) was determined by JC-1, colocalization of LC3-labeled autophagosomes with TOMM20-labeled mitochondria or LAMP2-labeled lysosomes was observed by fluorescence microscopy. Significantly increased serum creatinine (Scr), MDA and CAT, obvious mitochondrial injury including increase in cytosolic/mitochondrial Cyt c and decrease in Delta psi m, TEC apoptosis were induced by contrast administration. Contrast administration induced an increased expression of LC3II/I, Beclin-1, and Pink1 and decreased expression of P62. Rapamycin pretreatment induced overexpression of LC3II/I and Beclin-1. Moreover, LC3-labeled autophagosomes increasingly overlapped with TOMM20-labeled mitochondria and LAMP2-labeled lysosomes in CI-AKI, which was further enhanced by rapamycin administration. Contrast-induced Scr increase, oxidative stress, mitochondrial injury, TEC apoptosis, and necrosis were dose-dependently attenuated by rapamycin pretreatment. Rapamycin exerts renoprotective effects against CI-AKI by attenuating mitochondrial injury and oxidative stress, which might be associated with increasing mitophagy.

Intracellular accumulation of wild type tau is a hallmark of sporadic Alzheimer's disease (AD). However, the molecular mechanisms underlying tau toxicity is not fully understood. Here, we detected mitophagy deficits evidenced by the increased levels of mitophagy markers, including COX IV, TOMM20, and the ratio of mtDNA to genomic DNA indexed as mt-Atp6/Rpl13, in the AD brains and in the human wild type full-length tau (htau) transgenic mice. More interestingly, the mitophagy deficit was only shown in the AD patients who had an increased total tau level. Further studies demonstrated that overexpression of htau induced mitophagy deficits in HEK293 cells, the primary hippocampal neurons and in the brains of C57 mice. Upon overexpression of htau, the mitochondrial membrane potential was increased and the levels of PTEN-induced kinase 1 (PINK1) and Parkin decreased in the mitochondrial fraction, while upregulation of Parkin attenuated the htau-induced mitophagy deficits. Finally, we detected a dose-dependent allocation of tau proteins into the mitochondrial outer membrane fraction along with its cytoplasmic accumulation. These data suggest that intracellular accumulation of htau induces mitophagy deficits by direct inserting into the mitochondrial membrane and thus increasing the membrane potential, which impairs the mitochondrial residence of PINK1/Parkin. Our findings reveal a novel mechanism underlying the htau-induced neuronal toxicities in AD and other tauopathies.