Acidosis and Deafness in Patients with Recessive Mutations in FOXI1

Maintenance of the composition of inner ear fluid and regulation of electrolytes and acid-base homeostasis in the collecting duct system of the kidney require an overlapping set of membrane transport proteins regulated by the forkhead transcription factor FOXI1. In two unrelated consanguineous families, we identified three patients with novel homozygous missense mutations in FOXI1 (p.L146F and p.R213P) predicted to affect the highly conserved DNA binding domain. Patients presented with early-onset sensorineural deafness and distal renal tubular acidosis. In cultured cells, the mutations reduced the DNA binding affinity of FOXI1, which hence, failed to adequately activate genes crucial for normal inner ear function and acidbase regulation in the kidney. A substantial proportion of patients with a clinical diagnosis of inherited distal renal tubular acidosis has no identified causative mutations in currently known disease genes. Our data suggest that recessive mutations in FOXI1 can explain the disease in a subset of these patients

Peroxisome Proliferator Activated Receptor Gamma Controls Mature Brown Adipocyte Inducibility through Glycerol Kinase.

Peroxisome proliferator-activated receptors (PPARs) have been suggested as the master regulators of adipose tissue formation. However, their role in regulating brown fat functionality has not been resolved. To address this question, we generated mice with inducible brown fat-specific deletions of PPARα, β/δ, and γ, respectively. We found that both PPARα and β/δδ are dispensable for brown fat function. In contrast, we could show that ablation of PPARγ in vitro and in vivo led to a reduced thermogenic capacity accompanied by a loss of inducibility by β-adrenergic signaling, as well as a shift from oxidative fatty acid metabolism to glucose utilization. We identified glycerol kinase (Gyk) as a partial mediator of PPARγ function and could show that Gyk expression correlates with brown fat thermogenic capacity in human brown fat biopsies. Thus, Gyk might constitute the link between PPARγ-mediated regulation of brown fat function and activation by β-adrenergic signaling

The Forkhead Transcription Factor Foxi1 Is a Master Regulator of Vacuolar H+-ATPase Proton Pump Subunits in the Inner Ear, Kidney and Epididymis

The vacuolar H+-ATPase dependent transport of protons across cytoplasmic membranes in FORE (forkhead related) cells of endolymphatic epithelium in the inner ear, intercalated cells of collecting ducts in the kidney and in narrow and clear cells of epididymis require expression of several subunits that assemble into a functional multimeric proton pump. We demonstrate that expression of four such subunits A1, B1, E2 and a4 all co-localize with the forkhead transcription factor Foxi1 in a subset of epithelial cells at these three locations. In cells, of such epithelia, that lack Foxi1 we fail to identify any expression of A1, B1, E2 and a4 demonstrating an important role for the transcription factor Foxi1 in regulating subunit availability. Promoter reporter experiments, electrophoretic mobility shift assays (EMSA) and site directed mutagenesis demonstrate that a Foxi1 expression vector can trans-activate an a4-promoter reporter construct in a dose dependent manner. Furthermore, we demonstrate using chromatin immunoprecipitation (ChIP) assays that Foxi1-dependent activation to a large extent depends on cis-elements at position −561/−547 in the a4 promoter. Thus, we provide evidence that Foxi1 is necessary for expression of at least four subunits in three different epithelia and most likely is a major determinant for proper assembly of a functional vacuolar H+-ATPase complex at these locations

MTH1 inhibitors for the treatment of psoriasis

Inflammatory diseases, including psoriasis, are characterized by changes in redox regulation. The MTH1 prevents the incorporation of oxidized nucleotides during DNA replication. Using MTH1 small-molecule inhibitors, we found induced apoptosis through 8-oxodeoxyguanosine triphosphate accumulation and DNA double-strand breaks after oxidative stress in normal and malignant keratinocytes. In psoriasis, we detected increased MTH1 expression in lesional skin and PBMCs compared with that in the controls. Using the imiquimod psoriasis mouse model, we found that MTH1 inhibition diminished psoriatic histological characteristics and normalized the levels of neutrophils and T cells in the skin and skin-draining lymph nodes. The inhibition abolished the expression of T helper type 17‒associated cytokines in the skin, which was in line with decreased levels of IL-17–producing γδ T cells in lymph nodes. In human keratinocytes, MTH1 inhibition prevented the upregulation of IL-17‒downstream genes, which was independent of ROS-induced apoptosis. In conclusion, our data support MTH1 inhibition using small molecules suitable for topical application as a promising therapeutic approach to psoriasis

S100A7 (Psoriasin), highly expressed in Ductal Carcinoma In Situ (DCIS), is regulated by IFN-gamma in mammary epithelial cells

<p>Abstract</p> <p>Background</p> <p>The aim of the present work was to explore signal transduction pathways used in the regulation of S100A7 (psoriasin). Members of the S100 gene family participate in many important cellular functions. Psoriasin, S100A8 (calgranulin A) and S100A9 (calgranulin B) are expressed in ductal carcinoma <it>in situ </it>(DCIS), as well as in the hyperproliferative skin disease, psoriasis. In the latter condition, a disturbance in the STAT pathway has recently been reported. This pathway is implicated in the regulation of IFN-gamma, widely recognized as a key cytokine in psoriasis. IFN-gamma also exerts anti-tumor action in a number of tumor cell types, including breast cancer. We therefore examined the effect of IFN-gamma and STAT-signaling on the psoriasin expression.</p> <p>Methods</p> <p>We established a TAC2 mouse mammary epithelial cell line with tetracycline-inducible psoriasin expression (Tet-Off). Viability in cell culture was estimated using MTS assay. Protein and gene expression were evaluated by Western blotting and quantitative real-time PCR. Statistical analyses were assessed using a one-tailed, paired t-test.</p> <p>Results</p> <p>We report the downregulation of psoriasin by IFN-gamma in the MDA-MB-468 breast cancer cell line, as well as the downregulation of psoriasin induced by anoikis in cell lines derived from different epithelial tissues. In contrast, IFN-gamma had no suppressive effect on calgranulin A or calgranulin B. IFN-gamma is an important activator of the STAT1 pathway and we confirmed an active signaling pathway in the cell lines that responded to IFN-gamma treatment. In contrast, in the SUM190 breast carcinoma cell line, IFN-gamma did not suppress the expression of endogenous psoriasin. Moreover, a reduced phosphorylation of the STAT1 protein was observed. We showed that IFN-gamma treatment and the inhibition of the transcription factor NFkappaB had a synergistic effect on psoriasin levels. Finally, in TAC2 cells with tetracycline-induced psoriasin expression, we observed the increased viability of psoriasin-expressing cells after IFN-gamma treatment.</p> <p>Conclusion</p> <p>Our data support the possibility that psoriasin expression is transcriptionally suppressed by IFN-gamma and that this effect is likely to be mediated by the activation of the STAT1 signaling pathway. The increased viability of psoriasin-expressing cells after IFN-gamma exposure suggests that psoriasin expression leads to the development of an apoptosis-resistant phenotype.</p

A Genetic Risk Score Combining Ten Psoriasis Risk Loci Improves Disease Prediction

Psoriasis is a chronic, immune-mediated skin disease affecting 2–3% of Caucasians. Recent genetic association studies have identified multiple psoriasis risk loci; however, most of these loci contribute only modestly to disease risk. In this study, we investigated whether a genetic risk score (GRS) combining multiple loci could improve psoriasis prediction. Two approaches were used: a simple risk alleles count (cGRS) and a weighted (wGRS) approach. Ten psoriasis risk SNPs were genotyped in 2815 case-control samples and 858 family samples. We found that the total number of risk alleles in the cases was significantly higher than in controls, mean 13.16 (SD 1.7) versus 12.09 (SD 1.8), p = 4.577×10−40. The wGRS captured considerably more risk than any SNP considered alone, with a psoriasis OR for high-low wGRS quartiles of 10.55 (95% CI 7.63–14.57), p = 2.010×10−65. To compare the discriminatory ability of the GRS models, receiver operating characteristic curves were used to calculate the area under the curve (AUC). The AUC for wGRS was significantly greater than for cGRS (72.0% versus 66.5%, p = 2.13×10−8). Additionally, the AUC for HLA-C alone (rs10484554) was equivalent to the AUC for all nine other risk loci combined (66.2% versus 63.8%, p = 0.18), highlighting the dominance of HLA-C as a risk locus. Logistic regression revealed that the wGRS was significantly associated with two subphenotypes of psoriasis, age of onset (p = 4.91×10−6) and family history (p = 0.020). Using a liability threshold model, we estimated that the 10 risk loci account for only11.6% of the genetic variance in psoriasis. In summary, we found that a GRS combining 10 psoriasis risk loci captured significantly more risk than any individual SNP and was associated with early onset of disease and a positive family history. Notably, only a small fraction of psoriasis heritability is captured by the common risk variants identified to date

UCP1 Induction during Recruitment of Brown Adipocytes in White Adipose Tissue Is Dependent on Cyclooxygenase Activity

Background The uncoupling protein 1 (UCP1) is a hallmark of brown adipocytes and pivotal for cold- and diet-induced thermogenesis. Methodology/Principal Findings Here we report that cyclooxygenase (COX) activity and prostaglandin E2 (PGE2) are crucially involved in induction of UCP1 expression in inguinal white adipocytes, but not in classic interscapular brown adipocytes. Cold-induced expression of UCP1 in inguinal white adipocytes was repressed in COX2 knockout (KO) mice and by administration of the COX inhibitor indomethacin in wild-type mice. Indomethacin repressed β-adrenergic induction of UCP1 expression in primary inguinal adipocytes. The use of PGE2 receptor antagonists implicated EP4 as a main PGE2 receptor, and injection of the stable PGE2 analog (EP3/4 agonist) 16,16 dm PGE2 induced UCP1 expression in inguinal white adipose tissue. Inhibition of COX activity attenuated diet-induced UCP1 expression and increased energy efficiency and adipose tissue mass in obesity-resistant mice kept at thermoneutrality. Conclusions/Significance Our findings provide evidence that induction of UCP1 expression in white adipose tissue, but not in classic interscapular brown adipose tissue is dependent on cyclooxygenase activity. Our results indicate that cyclooxygenase-dependent induction of UCP1 expression in white adipose tissues is important for diet-induced thermogenesis providing support for a surprising role of COX activity in the control of energy balance and obesity development

Large scale meta-analysis characterizes genetic architecture for common psoriasis associated variants

Psoriasis is a complex disease of skin with a prevalence of about 2%. We conducted the largest meta-analysis of genome-wide association studies (GWAS) for psoriasis to date, including data from eight different Caucasian cohorts, with a combined effective sample size >39,000 individuals. We identified 16 additional psoriasis susceptibility loci achieving genome-wide significance, increasing the number of identified loci to 63 for European-origin individuals. Functional analysis highlighted the roles of interferon signalling and the NFκB cascade, and we showed that the psoriasis signals are enriched in regulatory elements from different T cells (CD8+ T-cells and CD4+ T-cells including TH0, TH1 and TH17). The identified loci explain ∼28% of the genetic heritability and generate a discriminatory genetic risk score (AUC=0.76 in our sample) that is significantly correlated with age at onset (p=2 × 10−89). This study provides a comprehensive layout for the genetic architecture of common variants for psoriasis