Research progress in ferroptosis pathways and ubiquitination modification of ferroptosis-related molecules / 中国药理学通报

Ferroptosis is an iron-dependent cell death caused by phospholipid peroxidation damage of polyunsaturated fatty acids on cell membranes and involves several pathways, including the iron homeostasis regulatory pathway, the cystine glutamate reverse transporter (system Xc) pathway and the voltage-dependent anion channel (VDAC) pathway. Ferroptosis is involved in the development of several diseases (e. g. myocardial infarction, stroke, cancer and degenerative diseases). The ubiquitination is an important post-translational modification of various protein molecules in the organism. Studies have shown that regulating the ubiquitination of ferroptosis pathway-related molecules can control cellular ferroptosis. Targeting the ubiquitination of ferroptosis pathway-related molecules can effectively promote or inhibit ferroptosis, which is expected to be a new strategy for the treatment of cancer or cardiovascular diseases. In this paper we review the progress of the ferroptosis pathways and the ubiquitination modification of ferroptosis-related molecules.

Effect of intermittent fasting on the cognitive dysfunction induced by irradiation / 中华放射医学与防护杂志

Objective:To investigate the protective effect of intermittent fasting on radiation-induced cognitive impairment and the possible underlying mechanism.Methods:A total of 36 male 7-week old c57BL/6J mice were divided into Sham-irradiation and ad libitum (Sham-AL) group, irradiation and ad libitum (IR-AL) group, and irradiation add intermittent fasting (IR-IF) group according to the random number table method, with 12 mice in each group. The cognitive function of mice was assessed by novel object recognition task. The expressions of autophagy gene 5 (ATG5), microtubulesas sociated protein light chain II (LC3II), voltage dependent anion channel protein 1 (VDAC1), interleukin-1β (IL-1β), synaptophysin (SYP), synapsin I (SYN-1), and postsynaptic density 95 (PSD95) were tested by Western blot. The location of VDAC1 in mice hippocampus was detected by immunofluorescence.Results:The discrimination index (-22.45 ± 16.76) of IR-AL group was significantly ( t=3.032, P<0.05) lower than that of Sham-AL group (30.02 ± 9.05). Compared to Sham-AL group, IR-AL group had a decreased expressions of autophagy-related proteins (ATG5 and LC3II), mitochondrial marker (VDAC1), inflammatory factors (IL-1β) as well as synapse-associated proteins SYP, SYN-1 and PSD95 ( t=2.49, 2.19, 2.40, 3.47, 2.87, 2.25, 2.17, 2.31, P<0.05). Compared to IR-AL group, IR-IF group had an increased discrimination index (21.22 ± 5.62) and the increased expressions of ATG5, LC3II, VDAC1, IL-1β, SYP, SYN-1, and PSD95 ( t=2.70, 2.88, 2.71, 3.18, 3.18, 3.11, 3.30, 3.35, 2.53, P<0.05). The immunofluorescence assay revealed that VDAC1 was co-expressed with the markers of astrocytes (GFAP) and microglia (IBA-1), but not with neurons (NEUN). Conclusions:Intermittent fasting could greatly improve the cognitive function of irradiated mice possibly by upregulating VDAC1 expression, induce autophagy, and inhibit the release of inflammatory factors and protecting the synapticplasticity in the hippocampus.

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 / 中国天然药物

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.

N-Methyl-(2S, 4R)-trans-4-hydroxy-L-proline, the major bioactive compound from Sideroxylon obtusifolium, attenuates pilocarpine-induced injury in cultured astrocytes

Glial cells have been implicated in temporal lobe epilepsy in humans and in its models. Astrocytes are lost in several brain regions after acute seizures induced by pilocarpine and may suffer hyperplasia at subsequent time points. This study investigated the effect of N-methyl-(2S,4R)-trans-4-hydroxy-L-proline (NMP) on astrocytes exposed to cytotoxic concentrations of pilocarpine. Astrocytes were incubated with pilocarpine (half maximal inhibitory concentration (IC50)=31.86 mM) for 24 h. Afterwards, they were treated with NMP at concentrations ranging from 3.12 to 100 μg/mL for 24 h. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytoplasmic reactive oxygen species (ROS) and mitochondrial transmembrane potential (ΔΨm) were analyzed by flow cytometry using 2',7'-dichlorofluorescein diacetate (DCFH-DA) and rhodamine-123 (Rho123), respectively. Expression of glial fibrillary acidic protein (GFAP) and voltage-dependent anion channel-1 (VDAC-1) were measured by western blot. Pilocarpine significantly decreased cell viability and mitochondrial potential and increased ROS concentration significantly by 6.7 times compared to the control. NMP concentrations ≥25 µg/mL protected astrocytes against pilocarpine-induced injury in a concentration-dependent manner. Concomitantly, NMP reduced cytoplasmic ROS accumulation to 27.3, 24.8, and 12.3% in the groups treated with 25, 50, and 100 µg/mL NMP, respectively. NMP also protected mitochondria from pilocarpine-induced depolarization. These effects were associated with improvement of pilocarpine-induced GFAP and VDAC-1 overexpression, which are important biomarkers of astrocyte dysfunction. In conclusion, the improvement of ROS accumulation, VDAC-1 overexpression, and mitochondrial depolarization are possible mechanisms of the NMP protective action on reactive astrocytes.

Tweety-homolog (Ttyh) Family Encodes the Pore-forming Subunits of the Swelling-dependent Volume-regulated Anion Channel (VRAC(swell)) in the Brain

In the brain, a reduction in extracellular osmolality causes water-influx and swelling, which subsequently triggers Cl⁻- and osmolytes-efflux via volume-regulated anion channel (VRAC). Although LRRC8 family has been recently proposed as the pore-forming VRAC which is activated by low cytoplasmic ionic strength but not by swelling, the molecular identity of the pore-forming swelling-dependent VRAC (VRAC(swell)) remains unclear. Here we identify and characterize Tweety-homologs (TTYH1, TTYH2, TTYH3) as the major VRAC(swell) in astrocytes. Gene-silencing of all Ttyh1/2/3 eliminated hypo-osmotic-solution-induced Cl⁻ conductance (I(Cl,swell)) in cultured and hippocampal astrocytes. When heterologously expressed in HEK293T or CHO-K1 cells, each TTYH isoform showed a significant I(Cl,swell) with similar aquaporin-4 dependency, pharmacological properties and glutamate permeability as I(Cl,swell) observed in native astrocytes. Mutagenesis-based structure-activity analysis revealed that positively charged arginine residue at 165 in TTYH1 and 164 in TTYH2 is critical for the formation of the channel-pore. Our results demonstrate that TTYH family confers the bona fide VRAC(swell) in the brain.

Pharmacological Dissection of Intrinsic Optical Signal Reveals a Functional Coupling between Synaptic Activity and Astrocytic Volume Transient

The neuronal activity-dependent change in the manner in which light is absorbed or scattered in brain tissue is called the intrinsic optical signal (IOS), and provides label-free, minimally invasive, and high spatial (~100 µm) resolution imaging for visualizing neuronal activity patterns. IOS imaging in isolated brain slices measured at an infrared wavelength (>700 nm) has recently been attributed to the changes in light scattering and transmittance due to aquaporin-4 (AQP4)-dependent astrocytic swelling. The complexity of functional interactions between neurons and astrocytes, however, has prevented the elucidation of the series of molecular mechanisms leading to the generation of IOS. Here, we pharmacologically dissected the IOS in the acutely prepared brain slices of the stratum radiatum of the hippocampus, induced by 1 s/20 Hz electrical stimulation of Schaffer-collateral pathway with simultaneous measurement of the activity of the neuronal population by field potential recordings. We found that 55% of IOSs peak upon stimulation and originate from postsynaptic AMPA and NMDA receptors. The remaining originated from presynaptic action potentials and vesicle fusion. Mechanistically, the elevated extracellular glutamate and K⁺ during synaptic transmission were taken up by astrocytes via a glutamate transporter and quinine-sensitive K2P channel, followed by an influx of water via AQP-4. We also found that the decay of IOS is mediated by the DCPIB- and NPPB-sensitive anion channels in astrocytes. Altogether, our results demonstrate that the functional coupling between synaptic activity and astrocytic transient volume change during excitatory synaptic transmission is the major source of IOS.

Research progress of mitochondrial anion channel as a potential drug target for Alzheimer's disease / 药学学报

Voltage-dependent anion channels (VDACs), which are located at the mitochondrial outer membrane, playing an important role in the regulation of mitochondrial energy metabolism and mitochondria- mediated apoptotic events, are considered as potential targets for tumor therapy. Studies have indicated that neurodegenerative diseases such as Alzheimer's disease (AD) generally lead to mitochondrial dysfunction. During this process, VDAC1, changing in expression, interacting with disease-related molecules, was involved in the occurrence and development of diseases. This review summarizes the characteristics and physiological functions of VDAC1, common important structural units and its role in apoptosis. The focus is on the research progress of VDAC1 in AD, as well as the effects in learning and memory related functions by modulating VDAC1 expression or function.

Effect of high-level spinal cord injury on expression of mitochondrial voltage-dependent anion channel 2 in rat cardiomyocytes / 中华麻醉学杂志

Objective To evaluate the effect of high-level spinal cord injury(SCI)on the expression of mitochondrial voltage-dependent anion channel 2(VDAC2)in rat cardiomyocytes.Methods Forty-eight pathogen-free healthy adult male Sprague-Dawley rats,weighing 200-250 g,were divided into 2 groups(n=24 each)using a random number table:sham operation group(group S)and high-level SCI group(group H).The animals were anesthetized with intraperitoneal chloral hydrate and subjected to SCI using the modified Allen weight-drop method in group H.The spinal cord was only exposed in group S.At 6,12,24 and 48 h after SCI(T1-4),6 rats in each group were randomly selected and sacrificed,and myocardial specimens were collected from the cardiac apex for microscopic examination of the cell morphology(with a transmission electron microscope) and for determination of cell apoptosis(by TUNEL assay),expression of Bax,Bcl-2 and VDAC2 protein and mRNA in cardiomyocytes(by Western blot and real-time polymerase chain reaction,respectively).The apoptosis rate and ratios of Bax/Bcl-2 protein and mRNA were calculated.Results Compared with group S,the apoptosis rate and ratios of Bax/Bcl-2 protein and mRNA were significantly increased at T1-4,the expression of VDAC2 protein and mRNA was significantly down-regulated at T2-4(P<0.05 or 0.01),and the pathologic changes of cardiomyocytes were aggravated in group H.Conclusion The mechanism of myocardial damage is related to down-regulation of mitochondrial VDAC2 expression in cardiomyocytes and promotion of cell apoptosis in rats with high-level SCI.

The cell model establishment through lentivirus transfecting fluorescent protein EYFP-H148Q/I152L / 西安交通大学学报(医学版)

Objective To establish the HeLa cell line that can stably express EYFP fluorescent protein as the model for anion channel blocker (halide ion) screening ,which lays the foundation for high throughput screening of anion channel blocker (halide ion) .Methods Through gene recombination technology ,a new lentivirus vector which can express mutant protein YFP (EYFP‐H148Q/I152L) and puromycin resistance ,was built .The mixture of lentivirus vector and packaging plasmid was transfected into 293T cells to produce lentivirus particles . After infection of HeLa cells by the lentivirus particles ,puromycin was used to screen the cells as YFP‐positive HeLa cell line .Then cell amplification was carried out after purification and efficiency of EYFP‐H148Q/I152L was further detected by Real‐time quantitative PCR (RT‐PCR) and Western blot .We then verified the activity of EYFP‐HeLa transfected cell line as a screening model of anion channel blocker .Results Gene sequencing verified that EYFP‐H148Q/I152L was successfully inserted into lentivirus vectors .RT‐PCR and Western blot results showed that the target gene was overexpressed in HeLa cells . The specific yellow fluorescence of EYFP of HeLa cells could be observed under fluorescence microscope with the efficiency of nearly 100% . I- (low permeability ) solution stimulated the opening of anion (halogen) channels ,and the yellow fluorescence was quenched by I - flow into cells . Conclusion The EYFP‐HeLa cell line can stably express EYFP yellow fluorescent protein and is sensitive to the internal flow of I - .Therefore ,it can be used as an ideal screening model of anion channel blocker (halide ion) .

Protective effect of melatonin on mitochondria in diabetic rats / 中华老年医学杂志

Objective To explore the effect of melatonin on mitochondria in streptozotocin (STZ)-induced diabetic rats and its potential mechanism. Methods The diabetic rat models were induced by intraperitoneal injection of STZ, and the diabetic rats were randomly divided into two groups: diabetes mellitus group (DM group) and melatonin-treated group (DM± MT group). The normal non-diabetic rats were served as control group. Mitochondrial membrane potential and mitochondrial swelling were measured, the expression of voltage-dependent anion channel (VDAC)was assayed by immunohistochemistry in the heart, liver and kidney among the different groups after 8 weeks. Results (1)Compared with DM group, mitochondrial membrane potential in the heart,liver and kidney were significantly elevated in DM± MT group (553.6± 193.5 vs. 311.4 ± 133.7;745.7±115.8 vs. 358.9±158.7; 951.6±246.1 vs. 425.8±177.9, all P＜0.05). (2)Compared with DM group, mitochondrial swelling in the heart, liver and kidney was reinforced in DM ± MT group. (3)Compared with DM group, the expressions of VDAC in the heart, liver and kidney were significantly up-regulated in DM± MT group (76.93 ± 8.263 vs. 58.59 ± 7.62, 50.69 ± 6.33 vs.40.11±6.30, 77.86±8.59 vs. 61.44± 12.86, all P＜0.05). Conclusions Melatonin has protective effect on the activity of mitochondria in the heart, liver and kidney in diabetic rats possibly by up-regulating the expression of VDAC.

Acidic pH-activated Cl- Current and Intracellular Ca2+ Response in Human Keratinocytes

The layers of keratinocytes form an acid mantle on the surface of the skin. Herein, we investigated the effects of acidic pH on the membrane current and [Ca2+](c) of human primary keratinocytes from foreskins and human keratinocyte cell line (HaCaT). Acidic extracellular pH (pHe< or =5.5) activated outwardly rectifying Cl- current (I(Cl,pH)) with slow kinetics of voltage-dependent activation. I(Cl,pH) was potently inhibited by an anion channel blocker 4,4`-diisothiocyanostilbene-2,2`-disulphonic acid (DIDS, 73.5% inhibition at 1micrometer). I(Cl,pH) became more sensitive to pHe by raising temperature from 24degrees C to 37degrees C. HaCaT cells also expressed Ca2+ -activated Cl- current (I(Cl,Ca)), and the amplitude of I(Cl,Ca) was increased by relatively weak acidic pHe (7.0 and 6.8). Interestingly, the acidic pHe (5.0) also induced a sharp increase in the intracellular [Ca2+] (delta[Ca2+](acid)) of HaCaT cells. The delta[Ca2+](acid) was independent of extracellular Ca2+, and was abolished by the pretreatment with PLC inhibitor, U73122. In primary human keratinocytes, 5 out of 28 tested cells showed delta[Ca2+](acid). In summary, we found I(Cl,pH) and delta[Ca2+](acid) in human keratinocytes, and these ionic signals might have implication in pathophysiological responses and differentiation of epidermal keratinocytes.

CFTR, a rectifying, non-rectifying anion channel?

No abstract available.