Hepatic effects of tartrazine (E 102) after systemic exposure are independent of oestrogen receptor interactions in the mouse

Tartrazine is a food colour that activates the transcriptional function of the human oestrogen receptor alpha in an in vitro cell model. Since oestrogens are cholestatic, we hypothesised tartrazine will cause periportal injury to the liver in vivo. To test this hypothesis, tartrazine was initially administered systemically to mice resulting in a periportal recruitment of inflammatory cells, increased serum alkaline phosphatase activity and mild periportal fibrosis. To determine whether an oestrogenic effect may be a key event in this response, tartrazine, sulphonated metabolites and a food additive contaminant were screened for their ability to interact with murine oestrogen receptors. In all cases, there were no interactions as agonists or antagonists and further, no oestrogenicity was observed with tartrazine in an in vivo uterine growth assay. To examine the relevance of the hepatic effects of tartrazine to its use as a food additive, tartrazine was orally administered to transgenic NF-κB-Luc mice. Pre- and concurrent oral treatment with alcohol was incorporated given its potential to promote gut permeability and hepatic inflammation. Tartrazine alone induced NF- κB activities in the colon and liver but there was no periportal recruitment of inflammatory cells or fibrosis. Tartrazine, its sulphonated metabolites and the contaminant inhibited sulphotransferase activities in murine hepatic S9 extracts. Given the role of sulfotransferases in bile acid excretion, the initiating event giving rise to periportal inflammation and subsequent hepatic pathology through systemic tartrazine exposure is therefore potentially associated an inhibition of bile acid sulphation and excretion and not on oestrogen receptor-mediated transcriptional function. However, these effects were restricted to systemic exposures to tartrazine and did not occur to any significant effect after oral exposure

Displacement of PKA catalytic subunit from AKAP signaling islands drives pathology in Cushing’s syndrome

Abstract Mutations in the catalytic subunit of protein kinase A (PKAc) drive the stress hormone disorder adrenal Cushing’s syndrome. Here we define mechanisms of action for the PKAc-L205R and W196R variants. Both Cushing’s mutants are excluded from A kinase anchoring protein (AKAP) signaling islands and consequently diffuse throughout the cell. Kinase-dead experiments show that PKA activity is required for cortisol hypersecretion. However, kinase activation is not sufficient, as only cAMP analog drugs that displace native PKAc from AKAPs enhance cortisol release. Rescue experiments that incorporate mutant PKAc into AKAP signaling islands abolish cortisol overproduction, indicating that kinase anchoring restores normal endocrine function. Phosphoproteomics show that PKAc-L205R and W196R engage different mitogenic signaling pathways. ERK activity is elevated in adrenal-specific PKAc-W196R knock-in mice. Conversely, PKAc-L205R attenuates Hippo signaling, thereby upregulating the YAP/TAZ transcriptional co-activators. Thus, aberrant localization of each Cushing’s variant promotes the transmission of a distinct downstream pathogenic signal

Identification of a xenobiotic as a potential environmental trigger in primary biliary cholangitis

Background and Aims: Primary biliary cholangitis (PBC) is an autoimmune-associated chronic liver disease triggered by environmental factors - such as exposure to xenobiotics - leading to a loss of tolerance to the lipoic acid conjugated regions of the mitochondrial branched-chain α-ketoacid dehydrogenase complex, typically to the E2 component (PDC-E2). Methods: Urban landfill and control soil samples from a region with high PBC incidence were screened for xenobiotic activities using analytical, cell-based xenobiotic receptor activation assays and toxicity screens. Results: A variety of potential xenobiotic classes were ubiquitously present, as identified by their interaction with xenobiotic receptors - aryl hydrocarbon (AhR), androgen (AR) and peroxisome proliferator activated receptor alpha (PPARα) receptors - in cell-based screens. In contrast, xenoestrogen – estrogen receptor (ERα) - interacting chemicals were present at higher levels in soil extracts from around an urban landfill. Furthermore, two landfill sampling sites contained a chemical(s) that inhibited mitochondrial oxidative phosphorylation and induced the apoptosis of an hepatic progenitor cell. The mitochondrial effect was also demonstrated in human liver cholangiocytes from 3 separate donors. The chemical was identified as the ionic liquid [3-methyl-1-octyl-1H-imidazol-3-ium]+ (M8OI) and the toxic effects were recapitulated using authentic pure chemical. A carboxylate-containing human hepatocyte metabolite of M8OI - bearing structural similarity to lipoic acid - was also enzymatically incorporated into the E2 component of pyruvate dehydrogenase via the exogenous lipoylation pathway in vitro. Conclusions: These results identify for the first time, a xenobiotic in the environment that may be related to and/or potentially be a component of an environmental trigger for PBC. Lay summary: PBC is a liver disease in which most patients have antibodies to mitochondrial proteins containing lipoic acid binding site(s). This paper identified a man-made chemical present in soils around a waste site and shows that it is metabolised to a product having structural similarity to lipoic acid and is capable of replacing lipoic acid in mitochondrial proteins

Mislocalization of protein kinase A drives pathology in Cushing's syndrome.

Mutations in the catalytic subunit of protein kinase A (PKAc) drive the stress hormone disorder adrenal Cushing's syndrome. We define mechanisms of action for the PKAc-L205R and W196R variants. Proximity proteomic techniques demonstrate that both Cushing's mutants are excluded from A kinase-anchoring protein (AKAP)-signaling islands, whereas live-cell photoactivation microscopy reveals that these kinase mutants indiscriminately diffuse throughout the cell. Only cAMP analog drugs that displace native PKAc from AKAPs enhance cortisol release. Rescue experiments that incorporate PKAc mutants into AKAP complexes abolish cortisol overproduction, indicating that kinase anchoring restores normal endocrine function. Analyses of adrenal-specific PKAc-W196R knockin mice and Cushing's syndrome patient tissue reveal defective signaling mechanisms of the disease. Surprisingly each Cushing's mutant engages a different mitogenic-signaling pathway, with upregulation of YAP/TAZ by PKAc-L205R and ERK kinase activation by PKAc-W196R. Thus, aberrant spatiotemporal regulation of each Cushing's variant promotes the transmission of distinct downstream pathogenic signals

Stimulating healthy tissue regeneration by targeting the 5-HT(2B) receptor in chronic liver disease

LettersTissue homeostasis requires an effective, limited wound-healing response to injury. In chronic disease, failure to regenerate parenchymal tissue leads to the replacement of lost cellular mass with a fibrotic matrix. The mechanisms that dictate the balance of cell regeneration and fibrogenesis are not well understood1. Here we report that fibrogenic hepatic stellate cells (HSCs) in the liver are negative regulators of hepatocyte regeneration. This negative regulatory function requires stimulation of the 5-hydroxytryptamine 2B receptor (5-HT2B) on HSCs by serotonin, which activates expression of transforming growth factor β1 (TGF-β1), a powerful suppressor of hepatocyte proliferation, through signaling by mitogen-activated protein kinase 1 (ERK) and the transcription factor JunD. Selective antagonism of 5-HT2B enhanced hepatocyte growth in models of acute and chronic liver injury. We also observed similar effects in mice lacking 5-HT2B or JunD or upon selective depletion of HSCs in wild-type mice. Antagonism of 5-HT2B attenuated fibrogenesis and improved liver function in disease models in which fibrosis was pre-established and progressive. Pharmacological targeting of 5-HT2B is clinically safe in humans and may be therapeutic in chronic liver disease.Mohammad R Ebrahimkhani, Fiona Oakley, Lindsay B Murphy, Jelena Mann, Anna Moles, Maria J Perugorria, Elizabeth Ellis, Anne F Lakey, Alastair D Burt, Angela Douglass, Matthew C Wright, Steven A White, Fabrice Jaffré, Luc Maroteaux & Derek A Man

Religiousness and Social Support: A Study in Secular Norway

Previous research has shown that religiousness is related to social support, but most studies on this subject have been conducted in highly religious contexts. In the secular culture of Norway, we investigated the level of perceived social support among religious and non-religious individuals using the scale from the Medical Outcomes Study Social Support Survey. Of the 3,000 randomly selected persons aged 18–75 years, 653 (22 %) participated in this cross-sectional postal questionnaire study in 2009. The results showed that the association between religiousness and social support differed by age, and was moderated by gender and by one’s view of life enrichment. Among older adults (60–75 years), non-religious people reported higher levels on all five dimensions of social support compared to religious people, and for affectionate support, positive social interaction and tangible support this relationship depended on high view of life enrichment. In contrast, no differences in social support were seen among middle aged adults (40–59 years). Gender differences in social support were found in the younger adults (18–39 years), as religious men reported more tangible and emotional support compared to non-religious men, while the opposite was found for women. Results are discussed based on previous empirical findings on religiousness and social support, as well as the role of religiousness in society

HNRNPC haploinsufficiency affects alternative splicing of intellectual disability-associated genes and causes a neurodevelopmental disorder

Heterogeneous nuclear ribonucleoprotein C (HNRNPC) is an essential, ubiquitously abundant protein involved in mRNA processing. Genetic variants in other members of the HNRNP family have been associated with neurodevelopmental disorders. Here, we describe 13 individuals with global developmental delay, intellectual disability, behavioral abnormalities, and subtle facial dysmorphology with heterozygous HNRNPC germline variants. Five of them bear an identical in-frame deletion of nine amino acids in the extreme C terminus. To study the effect of this recurrent variant as well as HNRNPC haploinsufficiency, we used induced pluripotent stem cells (iPSCs) and fibroblasts obtained from affected individuals. While protein localization and oligomerization were unaffected by the recurrent C-terminal deletion variant, total HNRNPC levels were decreased. Previously, reduced HNRNPC levels have been associated with changes in alternative splicing. Therefore, we performed a meta-analysis on published RNA-seq datasets of three different cell lines to identify a ubiquitous HNRNPC-dependent signature of alternative spliced exons. The identified signature was not only confirmed in fibroblasts obtained from an affected individual but also showed a significant enrichment for genes associated with intellectual disability. Hence, we assessed the effect of decreased and increased levels of HNRNPC on neuronal arborization and neuronal migration and found that either condition affects neuronal function. Taken together, our data indicate that HNRNPC haploinsufficiency affects alternative splicing of multiple intellectual disability-associated genes and that the developing brain is sensitive to aberrant levels of HNRNPC. Hence, our data strongly support the inclusion of HNRNPC to the family of HNRNP-related neurodevelopmental disorders. [Display omitted] We identified genetic variants of HNRNPC in 13 individuals with intellectual disability and global developmental delay. Through a meta-analysis of multiple cell types, we found that loss of HNRNPC affects alternative splicing, in particular of intellectual disability-associated genes. In vivo assays confirmed that neurodevelopment was affected by aberrant HNRNPC levels