Evidence that taurine modulates osmoregulation by modification of osmolarity sensor protein ENVZ--expression

Roles and occurrences of microbiota in the osmoregulatory organs, gills and gut, in marine medaka upon hypotonic stress

Gills and gut are the two primary osmoregulatory organs in fish. Recently, studies have expanded beyond the osmoregulatory mechanisms of these organs to explore the microbiota communities inhabiting them. It is now known that microbial communities in both organs shift in response to osmotic stress. However, there are limited studies identifying the major contributors and co-occurrence among these microbiota in both organs under seawater and freshwater transfer conditions. The current data mining report performed a bioinformatics analysis on two previous published datasets from our group, aiming to provide insights into host-bacteria relationships under osmotic stress. We divided the samples into four groups: control seawater gills (LSW); control seawater gut (TSW); freshwater transfer gills (LFW); and freshwater transfer gut (TFW). Our results showed that LSW had higher diversities, richness, and evenness compared to TSW. However, both the LFW and LSW did not show any significant differences after the freshwater transfer experiment. We further applied co-occurrence network analysis and, for the first time, reported on the interactions of taxa shaping the community structure in these two organs. Moreover, we identified enriched ectoine biosynthesis in seawater samples, suggesting its potential role in seawater environments. Increased mRNA expression levels of Na+/K+-atpase, and cftr, were observed in gills after 6 h of ectoine treatment. These findings provide a foundation for future studies on host-bacteria interactions under osmotic stress.

Comparative proteomic analysis of the protein profile in the cuttlefish Sepia pharaonis associated with skin ulceration syndrome

Skin ulceration syndrome (SUS) is becoming a severe problem in the breeding and culturing process of the cuttlefish Sepia pharaonis. However, limited knowledge is available about the occurrence of this devastating disease. In this study, proteomic analysis was used to identify the differentially expressed proteins (DEPs) and the biological pathways enriched in SUS-diseased S. pharaonis. Both the healthy group and diseased group were analyzed in triplicate, with 4 cuttlefish in each replicate. The results showed that 85 DEPs were identified between the two groups, including 36 upregulated proteins and 49 downregulated proteins in the diseased group compared to the healthy group. GO enrichment analysis revealed that the DEPs were mainly enriched in cellular component organization or biogenesis, nucleus and ion binding processes. The results of the KEGG pathway analysis indicated that extracellular matrix (ECM)-receptor interaction was the most enriched upregulated pathway. Real-time reverse transcriptase PCR was used to identify the expression of two differentially expressed matrix metalloproteinases (MMPs), and the results showed that the mRNA expression of MMP14 and MMP19 was significantly upregulated in the skin tissue of the diseased group. Furthermore, the protease activity of the diseased group was higher than that of the healthy group. Our results offer basic knowledge on the changes in protein profiles during the occurrence of SUS in the cuttlefish S. pharaonis.

Cell cycle checkpoints: the role and evaluation for early diagnosis of senescence, cardiovascular, cancer, and neurodegenerative diseases

Maintenance of genomic integrity is critical for prevention of a wide variety of adverse cellular effects including apoptosis, cellular senescence, and malignant cell transformation. Under stress conditions and even during an unperturbed cell cycle, checkpoint proteins play the key role in genome maintenance by and mediating cellular response to DNA damage, and represent an essential part of the "cellular stress response proteome". Intact checkpoint signal transduction cascades check the presence of genome damage, trigger cell cycle arrest, and forward the information to the protein core of cell cycle machinery, replication apparatus, repair, and/or apoptotic protein cores. Genetic checkpoint defects lead to syndromes that demonstrate chromosomal instability, increased sensitivity to genotoxic stress, tissue degeneration, developmental retardation, premature aging, and cancer predisposition that is most extensively studied for the ATM-checkpoint mutated in Ataxia telangiectasia. Tissue specific epigenetic control over the function of cell cycle checkpoints can be, further, misregulated by aberrant DNA methylation status. The consequent checkpoint dysregulation may result in tissue specific degenerative processes such as degeneration and calcification of heart aortic valves, diabetic cardiomyopathy, hyperhomocysteinemic cerebrovascular, peripheral vascular and coronary heart diseases, neurodegenerative disorders (Alzheimer and Parkinson diseases, amyotrophic lateral sclerosis, glaucoma), and accelerated aging frequently accompanied with cancer. This review focuses on the checkpoints shown to be crucial for unperturbed cell cycle regulation, dysregulation of which might be considered as a potential molecular marker for early diagnosis of and therapy efficiency in neurodegenerative, cardiovascular and cancer diseases. An application of the most potent detection technologies such as "Disease Proteomics and Transcriptomics" also considered here, allows a most specific selection of diagnostic markers.

Myo-inositol restores the inflammation-induced down-regulation of taurine transport by the murine macrophage cell line, RAW 264.7

The role of myo-inositol in the regulation of taurine transport in activated murine macrophage cell line, RAW 264.7, was studied. Challenge of RAW 264.7 murine macrophages for 24 hr with phorbol ester 12-myristate 13-acetate (PMA) (10 ng/ml), a PKC activator, resulted in a 62% decrease in taurine transport activity. Among the various monosaccharides (1 mM) tested in the presence of PMA, myo-inositol was most effective in restoring the PMA-induced down-regulation of taurine transport in murine macrophages (82% increase compared to the value for cells treated with PMA Alone, p < 0.01). The protective role of myo-inositol against stress-induced down-regulation of taurine transport by macrophages was further investigated in conditions mimicking bacterial infection, inflammation, and immune-suppressed circumstances. A challenge of murine macrophages with lipopolysaccharide (LPS) (0.1 and 10 microg/ml) resulted in a 60% decrease in taurine transport activity compared to the value for untreated control cells (p < 0.01). When cells were co-treated with myo-inositol (100 nM approximately 10 mM) in the presence of LPS for 24 hrs, taurine transport activity increased in a dose-dependent manner compared to the value for cells treated with LPS only. Taurine transport activity in cells treated with LPS (10 microg/ml) plus interferon-gamma (IFN-gamma) (150 unit/ml) for 24 hrs was 13% of the value for untreated control cells (p < 0.01). Again, this inflammation-induced down-regulation of taurine transport activity was completely antagonized with co-administration of 100 nM or higher levels of myo-inositol in the culture medium. Similarly, myo-inositol effectively restored the taurine transport activity suppressed by cyclosporin A (0.5 and 50 nM) in murine macrophages (p < 0.01). From these results, myo-inositol appears to be a common accelerator of taurine transport by murine macrophages in diverse conditions of down-regulated taurine transport.

DNA damage and expression of checkpoint genes p21(WAF1/CIP1) and 14-3-3 sigma in taurine-deficient cardiomyocytes

OBJECTIVE

Taurine depletion is associated with development of cardiomyopathy. Further, oxidative stress is advanced as a critical factor mediating the effect of taurine deficiency on target organs. However, the molecular mechanism(s) linking taurine deficiency with the development of cardiomyopathy remains elusive. Since transition between apoptotic degeneration and cell proliferation in stress conditions is regulated at cell cycle checkpoints, we determined the expression of two such genes, namely p21(WAF1/CIP1) and 14-3-3 sigma as well as p53 that are responsible for oxidative stress and DNA damage. We also carried out quantitative determination of DNA damage.

METHODS

Cardiomyocytes from beta-alanine-induced taurine-depleted (TD) rats were used for this investigation. Single- and double-stranded DNA damage was quantified using comet assay analysis. Western blot and two-dimensional polyacrylamide gel electrophoresis with immunoblotting analysis were applied for protein analysis.

RESULTS

Comet assay analysis indicated that the extent of double-stranded DNA damage was greater in TD than in control cardiomyocytes. Whereas only traces of both p53 and p21(WAF1/CIP1) and no detectable expression of 14-3-3 sigma were found in cardiomyocytes of control animals, the TD cardiomyocytes expressed all three genes.

CONCLUSIONS

DNA damage and the consequent up-regulation of checkpoint proteins observed in TD cardiomyocytes indicate the involvement of cell cycle control mechanisms in the effect of taurine deficiency on cardiomyocytes. Single- and double-stranded DNA damage and the consequent arrest of cell proliferation in both G(1) and G(2) phases of the cell cycle induced by checkpoint proteins may trigger the cardiomyopathy that is associated with taurine deficiency.

Taurine modulates induction of cytochrome P450 3A4 mRNA by rifampicin in the HepG2 cell line

Taurine is not only present in foods, tonics and nutrient drinks but is also used as a medicinal agent mainly for treatment of chronic heart failure and liver disease. However, little is known about its influence on drug-metabolizing enzymes, especially cytochrome P450 (CYP), in human. We examined whether taurine could affect the expression of CYP3A4 mRNA in the presence or absence of rifampicin (RFP), which is a potent inducer of CYPs, with HepG2 cells. Taurine enhanced twice the induction of CYP3A4 mRNA by RFP, but did not affect the expression by itself. This effect was both concentration- and time-dependent. On the other hand, taurine did not affect the induction by phenobarbital. Taurine did not increase intracellular uptake of RFP. Therefore, we conclude that taurine is an enhancer for the induction of CYP3A4 by RFP.