Basal metallothionein-I/II protects against NMDA-mediated oxidative injury in cortical neuron/astrocyte cultures

Network analysis of S-nitrosylated synaptic proteins demonstrates unique roles in health and disease

Nitric oxide can covalently modify cysteine thiols on target proteins to alter that protein's function in a process called S-nitrosylation (SNO). S-nitrosylation of synaptic proteins plays an integral part in neurotransmission. Here we review the function of the SNO-proteome at the synapse and whether clusters of SNO-modification may predict synaptic dysfunction associated with disease. We used a systematic search strategy to concatenate SNO-proteomic datasets from normal human or murine brain samples. Identified SNO-modified proteins were then filtered against proteins reported in the Synaptome Database, which provides a detailed and experimentally verified annotation of all known synaptic proteins. Subsequently, we performed an unbiased network analysis of all known SNO-synaptic proteins to identify clusters of SNO proteins commonly involved in biological processes or with known disease associations. The resulting SNO networks were significantly enriched in biological processes related to metabolism, whereas significant gene-disease associations were related to Schizophrenia, Alzheimer's, Parkinson's and Huntington's disease. Guided by an unbiased network analysis, the current review presents a thorough discussion of how clustered changes to the SNO-proteome influence health and disease.

The level of the zinc homeostasis regulating proteins in the brain of rats subjected to olfactory bulbectomy model of depression

BACKGROUND

Zinc transporters (ZnTs) and metallothioneins (MT) are important in maintaining Zn homeostasis in the brain. The present study was designed to find out whether alterations in ZnTs and MTs are associated with the pathophysiology of depression and the mechanism of antidepressant action.

METHODS

Messenger RNA and proteins of ZnT1, ZnT3, ZnT4, ZnT5, ZnT6 and MT1/2 were measured in the prefrontal cortex (PFC) and hippocampus (Hp) of rats subjected to olfactory bulbectomy (OB) (a model of depression) and chronic amitriptyline (AMI) treatment by Real Time PCR and Western Blot/Immunohistochemistry (IHP).

RESULTS

Results in the OB rats showed: increases in the protein levels of ZnT1 in the PFC and Hp and MT1/2 in the PFC; a decrease in ZnT3 protein level in the PFC; no changes in ZnT4, ZnT5 and ZnT6 in the PFC and Hp. IHP labeling revealed increases in the optical densities of ZnT1-IR in the PFC and Hp and decreases in ZnT3 and ZnT4-IR in the PFC of OB rats. Although OB had no effects on gene expression of ZnTs, mRNAs for MT1/2 were increased. Chronic AMI treatment did not influence protein levels of ZnTs and MT1/2 in Sham and OB rats; however decreased mRNA levels of ZnT4 and ZnT5 in PFC and ZnT1, ZnT3, ZnT4 and ZnT6 in Hp of Sham rats and normalized OB induced increase in MT1/2 gene expression.

CONCLUSIONS

Changes in ZnTs and MT1/2 suggest altered cortical distribution of Zn in the OB model which further supports the hypothesis that Zn dyshomeostasis may be involved in the pathophysiology of depression.

A PGC-1α-Mediated Transcriptional Network Maintains Mitochondrial Redox and Bioenergetic Homeostasis against Doxorubicin-Induced Toxicity in Human Cardiomyocytes: Implementation of TT21C

Chemical toxicity testing is fast moving in a direction that relies increasingly on cell-basedin vitroassays anchored on toxicity pathways according to the toxicity testing in the 21st century vision. Identifying points of departure (POD) via these assays and revealing their mechanistic underpinnings via computational modeling of the relevant pathways are critical and challenging steps. Here we used doxorubicin (DOX) as a prototype chemical to study mitochondrial toxicity in human AC16 cells. Mitochondrial toxicity has been linked to cardiovascular risk of DOX, which has limited its clinical use as an antitumor drug. Ourin vitrostudy revealed a well-defined POD concentration of DOX below which adaptive induction of proliferator-activated receptor-γ coactivator-1α (PGC-1α) -mediated mitochondrial genes, including NRF-1, MnSOD, UCP2, and COX1, concurred with negligible changes in mitochondrial superoxide and cytotoxicity. At higher DOX concentrations adversity became significant with elevated superoxide and suppressed ATP levels. A computational model was formulated to simulate the PGC-1α-mediated transcriptional network comprising multiple negative feedback loops that underlie redox and bioenergetics homeostasis in the mitochondrion. The model recapitulated the transition phase from adaptive to adverse responses, supporting the notion that saturated induction of PGC-1α-mediated gene network underpins POD. The model further predicts (follow-up experiments verified) that silencing PGC-1α compromises the adaptive function of the transcriptional network, leading to disruption of mitochondria and cytotoxicity at lower DOX concentrations. In summary, our study demonstrates that combining pathway-focusedin vitroassays and computational simulation of relevant biochemical network is synergistic for understanding dose-response behaviors in the low-dose region and identifying POD.

Cyclovirobuxine D Attenuates Doxorubicin-Induced Cardiomyopathy by Suppression of Oxidative Damage and Mitochondrial Biogenesis Impairment

The clinical application of doxorubicin (DOX) is compromised by its cardiac toxic effect. Cyclovirobuxine D (CVB-D) is a steroid alkaloid extracted from a traditional Chinese medicine, Buxus microphylla. Our results showed that CVB-D pretreatment markedly attenuated DOX-induced cardiac contractile dysfunction and histological alterations. By using TUNEL assay and western blot analysis, we found that CVB-D pretreatment reduced DOX-induced apoptosis of myocardial cells and mitochondrial cytochrome c release to cytosol. CVB-D pretreatment ameliorated DOX-induced cardiac oxidative damage including lipid peroxidation and protein carbonylation and a decrease in the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG). Moreover, CVB-D was found to prevent DOX-induced mitochondrial biogenesis impairment as evidenced by preservation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and nuclear respiratory factor 1 (NRF1), as well as mitochondrial DNA copy number. These findings demonstrate that CVB-D protects against DOX-induced cardiomyopathy, at least in part, by suppression of oxidative damage and mitochondrial biogenesis impairment.

Comparison of the deleterious effects of binge drinking-like alcohol exposure in adolescent and adult mice

A major cause of alcohol toxicity is the production of reactive oxygen species generated during ethanol metabolism. The aim of this study was to compare the effect of binge drinking-like alcohol exposure on a panel of genes implicated in oxidative mechanisms in adolescent and adult mice. In adolescent animals, alcohol decreased the expression of genes involved in the repair and protection of oxidative DNA damage such as atr, gpx7, or nudt15 and increased the expression of proapoptotic genes such as casp3. In contrast, in the adult brain, genes activated by alcohol were mainly associated with protective mechanisms that prevent cells from oxidative damage. Whatever the age, iterative binge-like episodes provoked the same deleterious effects as those observed after a single binge episode. In adolescent mice, multiple binge ethanol exposure substantially reduced neurogenesis in the dentate gyrus and impaired short-term memory in the novel object and passive avoidance tests. Taken together, our results indicate that alcohol causes deleterious effects in the adolescent brain which are distinct from those observed in adults. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity. The effects of alcohol exposure were investigated on genes involved in oxidative mechanisms. In adolescent animals, alcohol decreased the expression of genes involved in DNA repair, a potential cause of the observed decrease of neurogenesis. In contrast, in the adult brain, alcohol increased the expression of genes associated with antioxidant mechanisms. Apoptosis was increase in all groups and converged with other biochemical alterations to enhance short-term memory impairment in the adolescent brain. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity.

Metallothioneins attenuate paraquat-induced acute lung injury in mice through the mechanisms of anti-oxidation and anti-apoptosis

Paraquat (PQ) is a widely used herbicide, and lung is the primary target of PQ poisoning. Metallothionein (MT) is a potent antioxidant and free radical scavenger, and has been shown to play a protective role in lung injury induced by different stressors. This study was undertaken to evaluate the protective potential of MT against PQ-induced acute lung injury using MT-I/II null (MT(-/-)) mice. Wild-type (MT(+/+)) mice and MT(-/-) mice were given one intragastric administration of 50mg/kg PQ for 24h, and it was revealed that MT(-/-) mice were more susceptible to PQ-induced acute lung injury than MT(+/+) mice evidenced by the following findings. As compared with MT(+/+) mice, MT(-/-) mice presented more severe histopathological lesions in the lung, higher pulmonary malondialdehyde content, and more reduced pulmonary antioxidative enzymes activities. PQ also induced more apoptosis in pneumocytes from MT(-/-) mice, and the expressions of apoptosis-related proteins Bax, Bcl-2, cleaved-caspase-3, and the ratio of Bax/Bcl-2 were all more significantly increased in PQ-treated MT(-/-) mice. Our results clearly demonstrate that endogenous MT can attenuate PQ-induced acute lung injury, possibly through the mechanisms of anti-oxidation and anti-apoptosis.

Transcriptome profiling of the newborn mouse brain after hypoxia-reoxygenation: hyperoxic reoxygenation induces inflammatory and energy failure responsive genes

BACKGROUND

Supplemental oxygen used during resuscitation can be detrimental to the newborn brain. The aim was to determine how different oxygen therapies affect gene transcription in a hypoxia-reoxygenation model.

METHODS

C57BL/6 mice (n = 56), postnatal day 7, were randomized either to 120 min of hypoxia 8% O2 followed by 30 min of reoxygenation with 21, 40, 60, or 100% O2, or to normoxia followed by 30 min of 21 or 100% O2. Affymetrix 750k expression array was applied with RT-PCR used for validation. Histopathology and immunohistochemistry 3 d after hypoxia-reoxygenation compared groups reoxygenated with 21 or 100% O2 with normoxic controls (n = 22).

RESULTS

In total, ~81% of the gene expression changes were altered in response to reoxygenation with 60 or 100% O2 and constituted many inflammatory-responsive genes (i.e., C5ar2, Stat3, and Ccl12). Oxidative phosphorylation was downregulated after 60 or 100% O2. Iba1(+) cells were significantly increased in the striatum and hippocampal CA1 after both 21 and 100% O2.

CONCLUSION

In the present model, hypoxia-reoxygenation induces microglial accumulation in subregions of the brain. The transcriptional changes dominating after applying hyperoxic reoxygenation regimes include upregulating genes related to inflammatory responses and suppressing the oxidative phosphorylation pathway.

Metallothionein-II inhibits lipid peroxidation and improves functional recovery after transient brain ischemia and reperfusion in rats

After transient cerebral ischemia and reperfusion (I/R), damaging mechanisms, such as excitotoxicity and oxidative stress, lead to irreversible neurological deficits. The induction of metallothionein-II (MT-II) protein is an endogenous mechanism after I/R. Our aim was to evaluate the neuroprotective effect of MT-II after I/R in rats. Male Wistar rats were transiently occluded at the middle cerebral artery for 2 h, followed by reperfusion. Rats received either MT (10 μg per rat i.p.) or vehicle after ischemia. Lipid peroxidation (LP) was measured 22 h after reperfusion in frontal cortex and hippocampus; also, neurological deficit was evaluated after ischemia, using the Longa scoring scale. Infarction area was analyzed 72 hours after ischemia. Results showed increased LP in frontal cortex (30.7%) and hippocampus (26.4%), as compared to control group; this effect was fully reversed by MT treatment. Likewise, we also observed a diminished neurological deficit assessed by the Longa scale in those animals treated with MT compared to control group values. The MT-treated group showed a significant (P < 0.05) reduction of 39.9% in the infarction area, only at the level of hippocampus, as compared to control group. Results suggest that MT-II may be a novel neuroprotective treatment to prevent ischemia injury.

Bone mineral density and polymorphisms in metallothionein 1A and 2A in a Chinese population exposed to cadmium

Cadmium (Cd) effect on bone varies between individuals. We investigated whether genetic variation in metallothionein (MT)1A and MT2A associated with Cd induced bone loss in this study. A total of 465 persons (311 women and 154 men), living in control, moderately and heavily polluted areas, participated. The participants completed a questionnaire and the bone mineral density (BMD) was measured by dual energy x-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of Cd in urine (UCd) and blood (BCd). Genotypes for polymorphisms in MT1A (rs11076161) and MT2A (rs10636) were determined by Taqman allelic discrimination assays. BCd had a weak association with variant alleles for MT1A (rs11076161) and MT2A (rs10636) in female living in the highly polluted group (p=0.08 and 0.05, respectively). A weak association was found between bone mineral density and MT2A polymorphisms variation (p=0.06) in female living in the highly polluted group. Only a weak association was found between bone mineral density and MT1A polymorphisms variation in female. Genetic variation in the MT1A and MT2A genes may not associate with bone loss caused by cadmium exposure.