Overexpression of Kir2.3 in PC12 cells resists rotenone-induced neurotoxicity associated with PKC signaling pathway

Vitamin E protects dopaminergic neurons against manganese-induced neurotoxicity through stimulation of CHRM1 and KCNJ4

BACKGROUND

Manganese (Mn) overexposure can induce neurotoxicity and lead to manganism. Vitamin E (Vit E) has neuroprotective effects by acting as an ROS scavenger, preventing mitochondrial dysfunction and neuronal apoptosis. However, the effects of Vit E on Mn-induced nigrostriatal system lesions remains unknown.

OBJECTIVES

We aim to investigate whether Vit E has protective effects on Mn-induced nigrostriatal system lesions and mRNA expression profiles in the SN of mice.

METHODS

Sixty 8-week-old C57BL/6 male mice were randomly divided into the Control, MnCl2, MnCl2 +Vit E, and Vit E group. Twenty-four hours after the last injection, the behaviour test was performed. The numbers of dopaminergic neurons in Substantia nigra (SN), the contents of dopamine and its metabolite levels in striatium, and the morphology of mitochondria and nuclei in the dopaminergic neurons in SN were detected by immunofluorescence staining, high-performance liquid chromatography, and transmission electron microscopy. Transcriptome analysis was used to analyze the signaling pathways and RT-PCR was used to verify the mRNA levels.

RESULTS

Vit E ameliorates behavioral disorders and attenuates the loss of nigral dopaminergic neurons in the Mn-induced mouse model. In addition, Vit E antagonized Mn-induced toxicity by restoring mitochondrial function. The results of transcriptome sequencing and RTPCR show that the protective effect of Vit E was related to the upregulation of CHRM1 and KCNJ4 mRNA in the SN.

CONCLUSIONS

Vit E has neuroprotective effects on Mn-induced neurodegeneration in the nigrostriatal system. This effect may be related to the upregulation of CHRM1 and KCNJ4 mRNA stimulated by Vit E in the SN.

Exploration of the Shared Molecular Mechanisms between COVID-19 and Neurodegenerative Diseases through Bioinformatic Analysis

The COVID-19 pandemic has caused millions of deaths and remains a major public health burden worldwide. Previous studies found that a large number of COVID-19 patients and survivors developed neurological symptoms and might be at high risk of neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). We aimed to explore the shared pathways between COVID-19, AD, and PD by using bioinformatic analysis to reveal potential mechanisms, which may explain the neurological symptoms and degeneration of brain that occur in COVID-19 patients, and to provide early intervention. In this study, gene expression datasets of the frontal cortex were employed to detect common differentially expressed genes (DEGs) of COVID-19, AD, and PD. A total of 52 common DEGs were then examined using functional annotation, protein-protein interaction (PPI) construction, candidate drug identification, and regulatory network analysis. We found that the involvement of the synaptic vesicle cycle and down-regulation of synapses were shared by these three diseases, suggesting that synaptic dysfunction might contribute to the onset and progress of neurodegenerative diseases caused by COVID-19. Five hub genes and one key module were obtained from the PPI network. Moreover, 5 drugs and 42 transcription factors (TFs) were also identified on the datasets. In conclusion, the results of our study provide new insights and directions for follow-up studies of the relationship between COVID-19 and neurodegenerative diseases. The hub genes and potential drugs we identified may provide promising treatment strategies to prevent COVID-19 patients from developing these disorders.

Role of ion transport in control of apoptotic cell death

Cell shrinkage is a hallmark and contributes to signaling of apoptosis. Apoptotic cell shrinkage requires ion transport across the cell membrane involving K(+) channels, Cl(-) or anion channels, Na(+)/H(+) exchange, Na(+),K(+),Cl(-) cotransport, and Na(+)/K(+)ATPase. Activation of K(+) channels fosters K(+) exit with decrease of cytosolic K(+) concentration, activation of anion channels triggers exit of Cl(-), organic osmolytes, and HCO3(-). Cellular loss of K(+) and organic osmolytes as well as cytosolic acidification favor apoptosis. Ca(2+) entry through Ca(2+)-permeable cation channels may result in apoptosis by affecting mitochondrial integrity, stimulating proteinases, inducing cell shrinkage due to activation of Ca(2+)-sensitive K(+) channels, and triggering cell-membrane scrambling. Signaling involved in the modification of cell-volume regulatory ion transport during apoptosis include mitogen-activated kinases p38, JNK, ERK1/2, MEKK1, MKK4, the small G proteins Cdc42, and/or Rac and the transcription factor p53. Osmosensing involves integrin receptors, focal adhesion kinases, and tyrosine kinase receptors. Hyperosmotic shock leads to vesicular acidification followed by activation of acid sphingomyelinase, ceramide formation, release of reactive oxygen species, activation of the tyrosine kinase Yes with subsequent stimulation of CD95 trafficking to the cell membrane. Apoptosis is counteracted by mechanisms involved in regulatory volume increase (RVI), by organic osmolytes, by focal adhesion kinase, and by heat-shock proteins. Clearly, our knowledge on the interplay between cell-volume regulatory mechanisms and suicidal cell death is still far from complete and substantial additional experimental effort is needed to elucidate the role of cell-volume regulatory mechanisms in suicidal cell death.

The evidence of HeLa cell apoptosis induced with tetraethylammonium using proteomics and various analytical methods

Tetraethylammonium (TEA) is a potassium channel (KCh) blocker applied in the functional and pharmacological studies of the KChs. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, a colorimetric assay to quantitatively measure living cells, demonstrated that TEA reduced the HeLa cell viability dose-dependently. Flow cytometry analysis indicated an increased apoptosis rate of the HeLa cell after exposing to TEA. The patch clamp technique revealed that the K(+) current of the HeLa cell was inhibited up to 80% when exposed to TEA. In addition, quantitative real-time PCR approach set up cross-talk among the cytotoxicity of TEA, 4-aminopyridine, and anti-cancer drug such as cisplatin. Using comparative proteomics combined with MALDI-TOF MS/MS, 33 significantly changed proteins were found from TEA treatment group; among these proteins, 12 were up-regulated, and 21 were down-regulated. Here we indicated that these proteins were closely connected with many biological functions such as oxidative stress response, signal transduction, metabolism, protein synthesis, and degradation. Both Western blotting and quantitative real-time PCR approaches further verified these differential proteins. Ingenuity Pathways Analysis software, a tool to analyze "omics" data and model biological system, was applied to analyze the interaction pathways of these proteins. The subcellular locations of the differential proteins are also predicted from Uniprot. All results above can help in our understanding of the mechanism of TEA-induced cytotoxicity and provide potential cancer biomarkers. Various experimental results in this study (like those for cisplatin) indicated that TEA is not only a KCh blocker but also a potential anti-cancer drug.

Alternative splicing and transcriptome profiling of experimental autoimmune encephalomyelitis using genome-wide exon arrays

Background

Multiple Sclerosis (MS) is a chronic inflammatory disease causing demyelination and nerve loss in the central nervous system. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS that is widely used to investigate complex pathogenic mechanisms. Transcriptional control through isoform selection and mRNA levels determines pathway activation and ultimately susceptibility to disease.

Methodology/Principal Findings

We have studied the role of alternative splicing and differential expression in lymph node cells from EAE-susceptible Dark Agouti (DA) and EAE-resistant Piebald Virol Glaxo.AV1 (PVG) inbred rat strains using Affymetrix Gene Chip Rat Exon 1.0 ST Arrays. Comparing the two strains, we identified 11 differentially spliced and 206 differentially expressed genes at day 7 post-immunization, as well as 9 differentially spliced and 144 differentially expressed genes upon autoantigen re-stimulation. Functional clustering and pathway analysis implicate genes for glycosylation, lymphocyte activation, potassium channel activity and cellular differentiation in EAE susceptibility.

Conclusions/Significance

Our results demonstrate that alternative splicing occurs during complex disease and may govern EAE susceptibility. Additionally, transcriptome analysis not only identified previously defined EAE pathways regulating the immune system, but also novel mechanisms. Furthermore, several identified genes overlap known quantitative trait loci, providing novel causative candidate targets governing EAE.