A phosphatase-centric mechanism drives stress signaling response.

Changing environmental cues lead to the adjustment of cellular physiology by phosphorylation signaling networks that typically center around kinases as active effectors and phosphatases as antagonistic elements. Here, we report a signaling mechanism that reverses this principle. Using the hyperosmotic stress response in Saccharomyces cerevisiae as a model system, we find that a phosphatase-driven mechanism causes induction of phosphorylation. The key activating step that triggers this phospho-proteomic response is the Endosulfine-mediated inhibition of protein phosphatase 2A-Cdc55 (PP2ACdc55 ), while we do not observe concurrent kinase activation. In fact, many of the stress-induced phosphorylation sites appear to be direct substrates of the phosphatase, rendering PP2ACdc55 the main downstream effector of a signaling response that operates in parallel and independent of the well-established kinase-centric stress signaling pathways. This response affects multiple cellular processes and is required for stress survival. Our results demonstrate how a phosphatase can assume the role of active downstream effectors during signaling and allow re-evaluating the impact of phosphatases on shaping the phosphorylome.

Rifaximin on epigenetics and autophagy in animal model of hepatocellular carcinoma secondary to metabolic-dysfunction associated steatotic liver disease.

BACKGROUND: Prevalence of hepatocellular carcinoma (HCC) is increasing, especially in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). AIM: To investigate rifaximin (RIF) effects on epigenetic/autophagy markers in animals. METHODS: Adult Sprague-Dawley rats were randomly assigned (n = 8, each) and treated from 5-16 wk: Control [standard diet, water plus gavage with vehicle (Veh)], HCC [high-fat choline deficient diet (HFCD), diethylnitrosamine (DEN) in drinking water and Veh gavage], and RIF [HFCD, DEN and RIF (50 mg/kg/d) gavage]. Gene expression of epigenetic/autophagy markers and circulating miRNAs were obtained. RESULTS: All HCC and RIF animals developed metabolic-dysfunction associated steatohepatitis fibrosis, and cirrhosis, but three RIF-group did not develop HCC. Comparing animals who developed HCC with those who did not, miR-122, miR-34a, tubulin alpha-1c (Tuba-1c), metalloproteinases-2 (Mmp2), and metalloproteinases-9 (Mmp9) were significantly higher in the HCC-group. The opposite occurred with Becn1, coactivator associated arginine methyltransferase-1 (Carm1), enhancer of zeste homolog-2 (Ezh2), autophagy-related factor LC3A/B (Map1 Lc3b), and p62/sequestosome-1 (p62/SQSTM1)-protein. Comparing with controls, Map1 Lc3b, Becn1 and Ezh2 were lower in HCC and RIF-groups (P < 0.05). Carm1 was lower in HCC compared to RIF (P < 0.05). Hepatic expression of Mmp9 was higher in HCC in relation to the control; the opposite was observed for p62/Sqstm1 (P < 0.05). Expression of p62/SQSTM1 protein was lower in the RIF-group compared to the control (P = 0.024). There was no difference among groups for Tuba-1c, Aldolase-B, alpha-fetoprotein, and Mmp2 (P > 0.05). miR-122 was higher in HCC, and miR-34a in RIF compared to controls (P < 0.05). miR-26b was lower in HCC compared to RIF, and the inverse was observed for miR-224 (P < 0.05). There was no difference among groups regarding miR-33a, miR-143, miR-155, miR-375 and miR-21 (P > 0.05). CONCLUSION: RIF might have a possible beneficial effect on preventing/delaying liver carcinogenesis through epigenetic modulation in a rat model of MASLD-HCC.

Gut Dysbiosis and Increased Intestinal Permeability Drive microRNAs, NLRP-3 Inflammasome and Liver Fibrosis in a Nutritional Model of Non-Alcoholic Steatohepatitis in Adult Male Sprague Dawley Rats.

BACKGROUND/AIM: The interactions between the gut and liver have been described in the progression of non-alcoholic steatohepatitis (NASH). The aim of this study was to develop an experimental nutritional model of NASH simulating metabolic changes occurring in humans. MATERIALS AND METHODS: Adult male Sprague Dawley rats were randomized into two groups: controls (standard diet) and intervention (high-fat and choline-deficient diet) for 16 weeks, each experimental group with 10 animals. Biochemical analysis, hepatic lipid content, microRNAs, inflammatory, gut permeability markers and gut microbiota were measured. RESULTS: Animals in the intervention group showed significantly higher delta Lee index (p=0.017), abdominal circumference (p<0.001), abdominal adipose tissue (p<0.001) and fresh liver weight (p<0.001), as well as higher serum levels of alanine aminotransferase (p=0.010), glucose (p=0.013), total cholesterol (p=0.033), LDL cholesterol (p=0.011), and triglycerides (p=0.011), and lower HDL cholesterol (p=0.006) compared to the control group. Higher TLR4 (p=0.041), TLR9 (p=0.033), MyD88 (p=0.001), Casp1 (p<0.001), NLPR3 (p=0.019), liver inflammation index interleukin (IL)-1ß/IL10 (p<0.001), IL6/IL10 (p=0.002) and TNFα/IL10 (p=0.001) were observed in the intervention group, and also lower permeability markers Ocln (p=0.003) and F11r (p=0.041). Gene expression of miR-122 increased (p=0.041) and miR-145 (p=0.010) decreased in the intervention group. Liver steatosis, inflammation and fibrosis, along with collagen fiber deposition increment (p<0.001), were seen in the intervention group. Regarding gut microbiota, Bray-Curtis dissimilarity index and number of operational taxonomic units were significantly different (p<0.001) between the groups. Composition of the gut microbiota showed a significant correlation with histopathological score of NAFLD (r=0.694) and index IL-1ß/IL-10 (r=0.522). CONCLUSION: This experimental model mimicking human NASH demonstrated gut and liver interaction, with gut microbiota and intestinal permeability changes occurring in parallel with systemic and liver inflammation, miRNAs regulation and liver tissue damage.

Heterogeneous PrPC metabolism in skeletal muscle cells.

Recent reports have shown that prions, the causative agent of transmissible spongiform encephalopathies, accumulate in the skeletal muscle of diseased animals and man. In an attempt to characterise in this tissue the prion protein (PrP(C)), whose conformational rearrangement governs the generation of prions, we have analysed the protein in primary cultured murine myocytes and in different skeletal muscle types. Our results indicate that the expression and cellular processing of PrP(C) change during myogenesis, and in muscle fibres with different contractile properties. These findings imply a potential role for PrP(C) in the skeletal muscle physiology, but may also explain the different capability of muscles to sustain prion replication.

Polymorphisms in DNA polymerase γ affect the mtDNA stability and the NRTI-induced mitochondrial toxicity in Saccharomyces cerevisiae.

Several pathological mutations have been identified in human POLG gene, encoding for the catalytic subunit of Pol γ, the solely mitochondrial replicase in animals and fungi. However, little is known regarding non-pathological polymorphisms found in this gene. Here we studied, in the yeast model Saccharomyces cerevisiae, eight human polymorphisms. We found that most of them are not neutral but enhanced both mtDNA extended mutability and the accumulation of mtDNA point mutations, either alone or in combination with a pathological mutation. In addition, we found that the presence of some SNPs increased the stavudine and/or zalcitabine-induced mtDNA mutability and instability.

Multi-modal distraction: insights from children's limited attention.

How does the multi-sensory nature of stimuli influence information processing? Cognitive systems with limited selective attention can elucidate these processes. Six-year-olds, 11-year-olds and 20-year-olds engaged in a visual search task that required them to detect a pre-defined coloured shape under conditions of low or high visual perceptual load. On each trial, a peripheral distractor that could be either compatible or incompatible with the current target colour was presented either visually, auditorily or audiovisually. Unlike unimodal distractors, audiovisual distractors elicited reliable compatibility effects across the two levels of load in adults and in the older children, but high visual load significantly reduced distraction for all children, especially the youngest participants. This study provides the first demonstration that multi-sensory distraction has powerful effects on selective attention: Adults and older children alike allocate attention to potentially relevant information across multiple senses. However, poorer attentional resources can, paradoxically, shield the youngest children from the deleterious effects of multi-sensory distraction. Furthermore, we highlight how developmental research can enrich the understanding of distinct mechanisms controlling adult selective attention in multi-sensory environments.

Clinical and Molecular Characterization of Osteogenesis Imperfecta Type V.

Osteogenesis imperfecta type V (OI-V) has a wide clinical variability, with distinct clinical/radiological features, such as calcification of the interosseous membrane (CIM) between the radius-ulna and/or tibia-fibula, hyperplastic callus (HPC) formation, dislocation of the radial head (DRH), and absence of dentinogenesis imperfecta (DI). Recently, a single heterozygous mutation (c.-14C>T) in the 5'UTR of the IFITM5 gene was identified to be causative for OI-V. Here, we describe 7 individuals from 5 unrelated families that carry the c.-14C>T IFITM5 mutation. The clinical findings in these cases are: absence of DI in all patients, presence of blue sclera in 2 cases, and 4 patients with DRH. Radiographic findings revealed HPC in 3 cases. All patients presented CIM between the radius and ulna, while 4 patients presented additional CIM between the tibia and fibula. Spinal fractures by vertebral compression were observed in all individuals. The proportion of cases identified with this mutation represents 4% of OI cases at our institution. The clinical identification of OI-V is crucial, as this mutation has an autosomal dominant inheritance with variable expressivity.

Experimental model of hepatic steatosis by fructose in adult zebrafish: a pilot study

Introduction: The consumption of fructose has been questioned, since its increase has led to an associated increase in steatosis caused by nonalcoholic fatty liver disease. Despite the advantages presented by the zebrafish as an animal model, at present there are no models of steatosis by fructose in adult zebrafish. The aim of this study is to establish a model of hepatic steatosis by fructose in adult zebrafish. Methods: Firstly, adult zebrafish were daily exposed to 4% or 6% fructose. Then, animals were exposed to 6% fructose every 2 days. The hepatic lipid accumulation was analyzed by Nile Red and Oil Red O staining. Results: The daily exposure to 6% fructose showed increased accumulation of hepatic lipids when compared to 4% and control groups, but the same concentration showed no difference when the exposure happened every 2 days. Conclusion: We can suggest the daily exposure to a concentration of 6% fructose can be considered as a new experimental model of adult zebrafish. (AU)

Environmental risk factors associated with biliary atresia in Rio Grande do Sul, Brazil

Biliary atresia (BA) seems to be a multifactorial disorder in which environmental factors interact with the patient's genetic constitution. This study aimed to analyze information concerning environmental risk factors associated with BA in southern Brazil. A case-control study with mothers of patients with BA and mothers of patients with cystic fibrosis (CF) was conducted. Inquiry included questions related to exposition to environmental risk factors during the periconceptional and gestational (second and third trimesters) periods. Mothers of BA patients had smoked during pregnancy more frequently in comparison with the mothers of CF patients, but no significant difference was found in a multivariate analysis. There was no between group difference in terms of seasonality, but the multivariate analysis showed a significant difference within the BA group between date of conception in winter compared to other seasons. In conclusion, smoking during pregnancy seemed to increase the risk of BA while date of conception in winter decreased it (AU)