Reeceheide7513

Clostridioides difficileis a spore-forming bacterial pathogen that is the leading cause of hospital-acquired gastroenteritis. C. difficileinfections begin when its spore form germinates in the gut upon sensing bile acids. These germinants induce a proteolytic signaling cascade controlled by three members of the subtilisin-like serine protease family, CspA, CspB, and CspC. Notably, even though CspC and CspA are both pseudoproteases, they are nevertheless required to sense germinants and activate the protease, CspB. Thus, CspC and CspA are part of a growing list of pseudoenzymes that play important roles in regulating cellular processes. ZD1839 solubility dmso However, despite their importance, the structural properties of pseudoenzymes that allow them to function as regulators remain poorly understood. Our recently solved crystal structure of CspC revealed that its pseudoactive site residues align closely with the catalytic triad of CspB, suggesting that it might be possible to "resurrect" the ancestral protease activity of the CspC and CspA pseudoproteases. Here, we demonstrate that restoring the catalytic triad to these pseudoproteases fails to resurrect their protease activity. We further show that the pseudoactive site substitutions differentially affect the stability and function of the CspC and CspA pseudoproteases the substitutions destabilized CspC and impaired spore germination without affecting CspA stability or function. Thus, our results surprisingly reveal that the presence of a catalytic triad does not necessarily predict protease activity. Since homologs of C. difficile CspA occasionally carry an intact catalytic triad, our results indicate that bioinformatic predictions of enzyme activity may underestimate pseudoenzymes in rare cases. Copyright 2020 The Author(s).Cadmium is ovarian toxic in animal studies, but its association with diminished ovarian reserve in women is not established. We investigated urinary cadmium, a biomarker of long-term exposure, in relation to diminished ovarian reserve, as indicated by elevated serum follicle stimulating hormone concentrations (≥10 IU/L), in women ages 35-49 (unweighted n=1,681). Using data from the Third National Health and Nutrition Examination Survey, 1988-94, we conducted Poisson regression to estimate adjusted relative risks (RR) and 95% confidence intervals (CI). Because the best approach to correct for urinary dilution in spot samples with creatinine remains controversial, we employed three approaches standardization, covariate adjustment, and covariate-adjusted standardization. Our data suggested a modest association with standardization (highest vs. lowest quartile RR 1.3, 95% CI 0.8, 1.9; Ptrend=0.06) and covariate-adjusted standardization (highest vs. lowest quartile RR 1.3, 95% CI 0.9, 1.9; Ptrend=0.05), and a stronger association with covariate adjustment (highest vs. lowest quartile RR 1.8, 95% CI 1.2, 2.9; Ptrend=0.01). The stronger association with covariate adjustment may reflect bias from conditioning on urinary creatinine, a collider in the hypothesized causal pathway. We conclude that cadmium may contribute to ovarian aging in women and that careful consideration of the creatinine-adjustment approach is needed to minimize bias. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2020.Research in the social and health sciences has linked job insecurity to poorer mental health, but relies on observational data and faces challenges of causal inference. In this issue of the Journal, LaMontagne et al. (Am J Epidemiol. XXXX;XXX(XX)XXXX-XXXX)) innovate by using both within-person fixed effects (FE) and random effects (RE) regression to analyze data from 14 annual waves spanning 2002 to 2015. Using this more rigorous design, they find that improvements in perceived job insecurity were associated with improvements in MHI-5 mental health scores in a large, nationally representative panel study of Australians. By using each respondent as their own control, fixed effects models remove the influence of time-invariant confounders. Innovative new approaches are still needed to address the causal directionality of the association and to capture both those whose exposure changes as well as those for whom it persists. Future work should also consider potential modifying factors including societal conditions, macroeconomic and other period effects, and characteristics of individuals, as well as drawing on multidisciplinary approaches that consider jobs as a combination of multiple health relevant exposures and embed individual workers in families and communities to assess the full reach and consequences of perceived job insecurity. © The Author(s) 2020. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.Estrogen insensitivity syndrome (EIS) arises from rare mutations in estrogen receptor α (ERα, encoded by ESR1 gene) resulting in the inability of estrogen to exert its biological effects. Due to the rarity, mutations in ESR1 gene and the underlying molecular mechanisms of EIS have not been thoroughly studied. Here, we investigate known ESR1 mutants, Q375H and R394H, associated with EIS patients using in vitro and in vivo systems. Comparison of the transcriptome and DNA methylome from stable cell lines of both Q375H and R394H clinical mutants show a differential profile compared to WT ERα resulting in loss of estrogen-responsiveness. Molecular dynamic simulation shows that both ESR1 mutations change the ERα conformation of the ligand receptor complexes. Furthermore, we generated a mouse model Esr1-Q, harboring the human mutation using CRISPR/Cas9 genome editing. Female and male Esr1-Q mice are infertile and have similar phenotypes to αERKO mice. Overall phenotypes of the Esr1-Q mice correspond to those observed in the Q375H patient. Finally, we explore the effects of a synthetic progestogen and a GnRH inhibitor in the Esr1-Q mice for potentially reversing the impaired female reproductive tract function. These findings provide an important basis for understanding the molecular mechanistic consequences associated with EIS. Published by Oxford University Press on behalf of the Endocrine Society 2020. This work is written by (a) US Government employee(s) and is in the public domain in the US.