Disruption of mitochondrial functions involving mitochondrial permeability transition pore opening caused by maleic acid in rat kidney

Mitochondrial Signaling, the Mechanisms of AKI-to-CKD Transition and Potential Treatment Targets

Acute kidney injury (AKI) is increasing in prevalence and causes a global health burden. AKI is associated with significant mortality and can subsequently develop into chronic kidney disease (CKD). The kidney is one of the most energy-demanding organs in the human body and has a role in active solute transport, maintenance of electrochemical gradients, and regulation of fluid balance. Renal proximal tubular cells (PTCs) are the primary segment to reabsorb and secrete various solutes and take part in AKI initiation. Mitochondria, which are enriched in PTCs, are the main source of adenosine triphosphate (ATP) in cells as generated through oxidative phosphorylation. Mitochondrial dysfunction may result in reactive oxygen species (ROS) production, impaired biogenesis, oxidative stress multiplication, and ultimately leading to cell death. Even though mitochondrial damage and malfunction have been observed in both human kidney disease and animal models of AKI and CKD, the mechanism of mitochondrial signaling in PTC for AKI-to-CKD transition remains unknown. We review the recent findings of the development of AKI-to-CKD transition with a focus on mitochondrial disorders in PTCs. We propose that mitochondrial signaling is a key mechanism of the progression of AKI to CKD and potential targeting for treatment.

Predicting molecular mechanism of silymarin-potentiated diclofenac toxicity: Insight from in silico molecular docking

Silymarin was shown to enhance diclofenac toxicity by inducing the loss of mitochondrial membrane permeability (MMP) in Caco-2 cells, independent of endoplasmic reticulum stress. This study employed in silico molecular docking to further investigate the potential interaction between silymarin and specific mitochondrial proteins involved in the loss of mitochondria integrity, aiming to elucidate the underlying mechanism of potentiation. The target proteins for our docking analysis included mitochondrial complex I and III, voltage-dependent anion-selective channel (VDAC), and cyclophilin D (CypD). Our results indicated that diclofenac could bind to both mitochondrial complex I and III. In contrast, silymarin exhibited a strong interaction with mitochondrial complex I with the binding energy (ΔG) -7.74 kcal/mol and the inhibition constant (Ki) 2.12 µM, while not showing significant interaction with mitochondrial complex III. Additionally, silymarin had the potential to induce the opening of mitochondrial permeability transition pore by binding with VDAC in the outer mitochondrial membrane with ΔG -6.08 kcal/mol and Ki 34.94 µM. However, silymarin did not exhibit significant interaction with CypD in the inner mitochondrial membrane. Therefore, mitochondrial complex I and VDAC could be the potentiation targets of silymarin, resulting in the disruption of mitochondria integrity and enhancing the toxicity of diclofenac.

Pathophysiological mechanisms of complications associated with propionic acidemia

Propionic acidemia (PA) is a genetic metabolic disorder caused by mutations in the mitochondrial enzyme, propionyl-CoA carboxylase (PCC), which is responsible for converting propionyl-CoA to methylmalonyl-CoA for further metabolism in the tricarboxylic acid cycle. When this process is disrupted, propionyl-CoA and its metabolites accumulate, leading to a variety of complications including life-threatening cardiac diseases and other metabolic strokes. While the clinical symptoms and diagnosis of PA are well established, the underlying pathophysiological mechanisms of PA-induced diseases are not fully understood. As a result, there are currently few effective therapies for PA beyond dietary restriction. This review focuses on the pathophysiological mechanisms of the various complications associated with PA, drawing on extensive research and clinical reports. Most research suggests that propionyl-CoA and its metabolites can impair mitochondrial energy metabolism and cause cellular damage by inducing oxidative stress. However, direct evidence from in vivo studies is still lacking. Additionally, elevated levels of ammonia can be toxic, although not all PA patients develop hyperammonemia. The discovery of pathophysiological mechanisms underlying various complications associated with PA can aid in the development of more effective therapeutic treatments. The consequences of elevated odd-chain fatty acids in lipid metabolism and potential gene expression changes mediated by histone propionylation also warrant further investigation.

Cadmium induced time-dependent kidney injury in common carp via mitochondrial pathway: Impaired mitochondrial energy metabolism and mitochondrion-dependent apoptosis

Toxic effect of heavy metal cadmium (Cd) on fish kidneys had been reported. Mitochondrion is an important organelle for maintaining kidney function, while its role in Cd-induced kidney injury in common carp remained unclarified. In this experiment, we established a poisoning model of common carp with Cd exposure (0.26 mg/L) for 15, 30, and 45 days. Serum biochemistry determination, histological observation, TUNEL assay, qRT-PCR, Western blot, and integrated biomarker response (IBR) were applied to assess the nephrotoxicity of Cd to common carp. Our results displayed that Cd exposure increased the levels of serum biochemical indexes (UREA, CRE, and UA), indicating kidney injury. We further revealed via histological observation that Cd damaged structural integrity of kidneys, as evidenced by renal glomerulus and renal tubular injury, hallmark phenotypes of apoptosis, and mitochondrial damage, suggesting that mitochondria damage and apoptosis were involved in Cd-induced kidney injury. Moreover, Cd exposure decreased ATPase (Na⁺/K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase, and Ca²⁺Mg²⁺-ATPase) activities as well as PGC-1a and Mfn2 levels, while increased Drp1 and PINK1 levels as well as LC3-II/LC3-I ratio, which indicated that Cd-impaired renal energy metabolism was related to mitochondrial dysfunction. Additionally, we found that Cd induced oxidative stress (abnormal levels of SOD, CAT, GPX, MDA, and H₂O₂) in kidneys, which was involved in triggering mitochondrial dysfunction and further impairing mitochondrial energy metabolism. Moreover, the occurrence of mitochondria-dependent apoptosis was found after Cd-exposure in common carp kidneys, as indicated by enhanced levels of Bax, CytC, APAF1, Caspase-9, and Caspase-3, while declined level of Bcl-2. Subsequently, we confirmed a time-dependent nephrotoxicity of Cd to common carp via IBR assessment. In conclusion, Cd induced time-dependent nephrotoxicity in common carp via mitochondrial pathway. This mitochondria-oriented study shed light on underlying mechanisms of Cd-induced renal pathologies and provided a theoretical basis for evaluating Cd toxicity to aquatic organisms.