Mitochondrial outer membrane voltage-dependent anion channel is involved in renal dysfunction in a spontaneously hypertensive rat carrying transfer RNA mutations

Study on the mechanism of Wuzi-Yanzong-Wan-medicated serum interfering with the mitochondrial permeability transition pore in the GC-2 cell induced by atractyloside

Wuzi-Yanzong-Wan (WZYZW) is a classic prescription for male infertility. Our previous investigation has demonstrated that it can inhibit sperm apoptosis via affecting mitochondria, but the underlying mechanisms are unclear. The purpose of the present study was to explore the actions of WZYZW on mitochondrial permeability transition pore (mPTP) in mouse spermatocyte cell line (GC-2 cells) opened by atractyloside (ATR). At first, WZYZW-medicated serum was prepared from rats following oral administration of WZYZW for 7 days. GC-2 cells were divided into control group, model group, positive group, as well as 5%, 10%, 15% WZYZW-medicated serum group. Cyclosporine A (CsA) was used as a positive control. 50 μmol·L-1 ATR was added after drugs incubation. Cell viability was assessed using CCK-8. Apoptosis was detected using flow cytometry and TUNEL method. The opening of mPTP and mitochondrial membrane potential (MMP) were detected by Calcein AM and JC-1 fluorescent probe respectively. The mRNA and protein levels of voltage-dependent anion channel 1 (VDAC1), cyclophilin D (CypD), adenine nucleotide translocator (ANT), cytochrome C (Cyt C), caspase 3, 9 were detected by RT-PCR (real time quantity PCR) and Western blotting respectively. The results demonstrated that mPTP of GC-2 cells was opened after 24 hours of ATR treatment, resulting in decreased MMP and increased apoptosis. Pre-protection with WZYZ-medicated serum and CsA inhibited the opening of mPTP of GC-2 cells induced by ATR associated with increased MMP and decreased apoptosis. Moreover, the results of RT-qPCR and WB suggested that WZYZW-medicated serum could significantly reduce the mRNA and protein levels of VDAC1 and CypD, Caspase-3, 9 and CytC, as well as a increased ratio of Bcl/Bax. However, ANT was not significantly affected. Therefore, these findings indicated that WZYZW inhibited mitochondrial mediated apoptosis by attenuating the opening of mPTP in GC-2 cells. WZYZW-medicated serum inhibited the expressions of VDAC1 and CypD and increased the expression of Bcl-2, which affected the opening of mPTP and exerted protective and anti-apoptotic effects on GC-2 cell induced by ATR.

Atractylodin inhibits fructose-induced human podocyte hypermotility via anti-oxidant to down-regulate TRPC6/p-CaMK4 signaling

High fructose has been reported to drive glomerular podocyte oxidative stress and then induce podocyte foot process effacement in vivo, which could be partly regarded as podocyte hypermotility in vitro. Atractylodin possesses anti-oxidative effect. The aim of this study was to explore whether atractylodin prevented against fructose-induced podocyte hypermotility via anti-oxidative property. In fructose-exposed conditionally immortalized human podocytes, we found that atractylodin inhibited podocyte hypermotility, and up-regulated slit diaphragm proteins podocin and nephrin, and cytoskeleton protein CD2-associated protein (CD2AP), α-Actinin-4 and synaptopodin expression, which were consistent with its anti-oxidative activity evidenced by up-regulation of catalase (CAT) and superoxide dismutase (SOD) 1 expression, and reduction of reactive oxygen species (ROS) production. Atractylodin also significantly suppressed expression of transient receptor potential channels 6 (TRPC6) and phosphorylated Ca²⁺/calmodulin-dependent protein kinase IV (CaMK4) in cultured podocytes with fructose exposure. Additionally, in fructose-exposed podocytes, CaMK4 siRNA up-regulated synaptopodin and reduced podocyte hypermotility, whereas, silencing of TRPC6 by siRNA decreased p-CaMK4 expression, inhibited podocyte hypermotility, showing TRPC6/p-CaMK4 signaling activation in podocyte hypermotility under fructose condition. Just like atractylodin, antioxidant N-acetyl-L-cysteine (NAC) could inhibit TRPC6/p-CaMK4 signaling activation to reduce fructose-induced podocytes hypermotility. These results first demonstrated that the anti-oxidative property of atractylodin may contribute to the suppression of podocyte hypermotility via inhibiting TRPC6/p-CaMK4 signaling and restoring synaptopodin expression abnormality.

Embryotoxicity evaluation of atractylodin and β-eudesmol using the zebrafish model

Atractylodin and β-eudesmol are the major active ingredients of Atractylodes lancea (Thunb) DC. (AL). Both compounds exhibit various pharmacological activities, including anticancer activity against cholangiocarcinoma. Despite the widespread use of this plant in traditional medicine in China, Japan, Korea, and Thailand, studies of their toxicological profiles are limited. The present study aimed to evaluate the embryotoxicity of atractylodin and β-eudesmol using the zebrafish model. Zebrafish embryos were exposed to a series of concentrations (6.3, 12.5, 25, 50, and 100 μM) of each compound up to 72 h post-fertilization (hpf). The results showed that atractylodin and β-eudesmol induced mortality of zebrafish embryos with the 50% lethal concentration (LC₅₀) of 36.8 and 53.0 μM, respectively. Both compounds also caused embryonic deformities, including pericardial edema, malformed head, yolk sac edema, and truncated body. Only β-eudesmol decreased the hatching rates, while atractylodin reduced the heart rates of the zebrafish embryos. Additionally, both compounds increased reactive oxygen species (ROS) production and altered the transcriptional expression levels of superoxide dismutase 1 (sod1), catalase (cat), and glutathione S-transferase pi 2 (gstp2) genes. In conclusion, atractylodin and β-eudesmol induce mortality, developmental toxicity, and oxidative stress in zebrafish embryos. These findings may imply similar toxicity of both compounds in humans.

Cysteine Oxidations in Mitochondrial Membrane Proteins: The Case of VDAC Isoforms in Mammals

Cysteine residues are reactive amino acids that can undergo several modifications driven by redox reagents. Mitochondria are the source of an abundant production of radical species, and it is surprising that such a large availability of highly reactive chemicals is compatible with viable and active organelles, needed for the cell functions. In this work, we review the results highlighting the modifications of cysteines in the most abundant proteins of the outer mitochondrial membrane (OMM), that is, the voltage-dependent anion selective channel (VDAC) isoforms. This interesting protein family carries several cysteines exposed to the oxidative intermembrane space (IMS). Through mass spectrometry (MS) analysis, cysteine posttranslational modifications (PTMs) were precisely determined, and it was discovered that such cysteines can be subject to several oxidization degrees, ranging from the disulfide bridge to the most oxidized, the sulfonic acid, one. The large spectra of VDAC cysteine oxidations, which is unique for OMM proteins, indicate that they have both a regulative function and a buffering capacity able to counteract excess of mitochondrial reactive oxygen species (ROS) load. The consequence of these peculiar cysteine PTMs is discussed.