FOXC1 negatively regulates BMP-SMAD activity and Id1 expression during osteoblast differentiation.

Bone morphogenetic proteins regulate a diverse range of biological processes through their activation of SMAD1, SMAD5, or SMAD8 proteins that, in turn, regulate gene expression. These SMAD transcription factors achieve a layer of functional specificity in different cell types largely through actions with additional transcriptional regulatory molecules. In this study, we demonstrate that the forkhead box C1 (FOXC1) transcription factor can modulate bone morphogenetic protein (BMP) signaling to impair the expression of BMP4-responsive genes and prevent the efficient osteoblast differentiation. We demonstrate that repression occurs downstream of BMP signaling and impacts the ability SMAD1 or SMAD5 to activate gene expression. Repression of SMAD activity requires FOXC1 DNA-binding capacity and the transcriptional inhibitory domain of FOXC1. We report that FOXC1 inhibits BMP4 induction of Id1 expression and identify a motif in the regulatory region of mouse Id1 gene that FOXC1 binds. We determine that this inhibition by FOXC1 binding does not affect SMAD1, SMAD5, or SMAD8 binding to its target sequence in the Id1 gene. Finally, we determine that the elevated expression of FOXC1 can reduces expression osteogenic differentiation genes in mouse embryonic stems directed to the osteoblast lineage through BMP4 treatment. Together, these findings indicate that FOXC1 can negatively regulate certain aspects of BMP4 signaling required for osteoblast differentiation. We propose that FOXC1 acts to attenuate the initial BMP-activated pathways that establish osteoblast differentiation and allow for terminal osteoblast differentiation to conclude.

Molecular analysis of NPAS3 functional domains and variants.

BACKGROUND: NPAS3 encodes a transcription factor which has been associated with multiple human psychiatric and neurodevelopmental disorders. In mice, deletion of Npas3 was found to cause alterations in neurodevelopment, as well as a marked reduction in neurogenesis in the adult mouse hippocampus. This neurogenic deficit, alongside the reduction in cortical interneuron number, likely contributes to the behavioral and cognitive alterations observed in Npas3 knockout mice. Although loss of Npas3 has been found to affect proliferation and apoptosis, the molecular function of NPAS3 is largely uncharacterized outside of predictions based on its high homology to bHLH-PAS transcription factors. Here we set out to characterize NPAS3 as a transcription factor, and to confirm whether NPAS3 acts as predicted for a Class 1 bHLH-PAS family member. RESULTS: Through these studies we have experimentally demonstrated that NPAS3 behaves as a true transcription factor, capable of gene regulation through direct association with DNA. NPAS3 and ARNT are confirmed to directly interact in human cells through both bHLH and PAS dimerization domains. The C-terminus of NPAS3 was found to contain a functional transactivation domain. Further, the NPAS3::ARNT heterodimer was shown to directly regulate the expression of VGF and TXNIP through binding of their proximal promoters. Finally, we assessed the effects of three human variants of NPAS3 on gene regulatory function and do not observe significant deficits. CONCLUSIONS: NPAS3 is a true transcription factor capable of regulating expression of target genes through their promoters by directly cooperating with ARNT. The tested human variants of NPAS3 require further characterization to identify their effects on NPAS3 expression and function in the individuals that carry them. These data enhance our understanding of the molecular function of NPAS3 and the mechanism by which it contributes to normal and abnormal neurodevelopment and neural function.

Functional analysis of mutations in the ATP loop of the Wilson disease copper transporter, ATP7B.

Wilson disease (WND) is an autosomal recessive disorder resulting from mutation of ATP7B. Transport of copper by ATP7B from the trans-Golgi of hepatocytes into apical membrane-trafficked vesicles for excretion in the bile is the major means of copper elimination from the body. Although copper is an essential nutrient, homeostasis must be carefully maintained. If homeostasis is disrupted, copper can accumulate within the liver, kidney, cornea, and/or brain. The range of organs affected leads to clinical heterogeneity and difficulty in WND diagnosis. Sequencing of ATP7B is an important adjunct for diagnosis but has led to the discovery of many novel missense variants. Although prediction programs are available, functional characterization is essential for determining the consequence of novel variants. We have tested 12 missense variants localized to the ATP loop of ATP7B and compared three predictive programs (SIFT, PolyPhen, and Align-GVGD). We found p.L1043P, p.G1000R, p.G1101R, p.I1102T, p.V1239G, and p.D1267V deleterious; p.G1176E and p.G1287S intermediate; p.E1173G temperature sensitive; p.T991M and p.I1148T mild; and p.R1228T functioning as wild type. We found that SIFT most often agreed with functional data (92%), compared with PolyPhen (83%) and Align-GVGD (67%). We conclude that variants found to negatively affect function likely contribute to the WND phenotype in patients.

Influence of Clinical Trials of Acute Coronary Syndrome Beyond the Primary Hypothesis: A Systematic Review.

Importance: Conducting a clinical trial involves significant risks, time, and resources. The return on investment for these trials, measured by advancing health care and contributions to the scientific literature, is often uncertain. Objective: To assess the long-term effects of major clinical trials of acute coronary syndromes contemporary to the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) trial, which did not achieve its primary objective. Evidence Review: The Cochrane Central Register of Controlled Trials database was screened for clinical trials of acute coronary syndromes (including unstable angina, ST-elevation myocardial infarction, and non-ST-elevation myocardial infarction) with more than 1000 participants and primary results published between January 1, 2005, and December 31, 2009, in Circulation, European Heart Journal, JAMA, Journal of the American College of Cardiology, The Lancet, and The New England Journal of Medicine. For identified trials, bibliographic information, citations, trial name, registration, inclusion diagnosis, intervention type, sample size, primary outcome result, sponsor information, and academic involvement were extracted. To identify secondary analyses, bibliographic information for citing articles, their citations, and their abstracts were extracted. Clinical practice guideline bibliographies for citations of trial publications were reviewed, and the class and level of evidence of resulting recommendations were extracted. Findings: Of 784 records screened, 30 were primary publications of 25 clinical trials. Through December 31, 2018, these trials were cited a median of 497 times (interquartile range [IQR], 424-931 citations). Trials that did not achieve their primary objective had fewer primary citations (the number of times that each published journal article with the primary [main] results of a trial was cited) (median, 443 [IQR, 396-468] vs 868 [IQR, 645-1774] citations, P = .006). The frequency of secondary analyses peaked within 5 years of the primary trial at 643. Trials that did not achieve the primary objective had fewer secondary analyses (median, 15 [IQR, 5-31] vs 18 [IQR, 10-43] analyses, P = .44) that were not cited significantly less often (median, 484 [IQR, 191-1299] vs 1124 [IQR, 410-4283] citations, P = .16). All trials were cited by at least 1 clinical practice guideline. Conclusions and Relevance: This review found that trials that achieved the primary objective were frequently cited. Secondary research activity did not differ by primary result, and the primary trials and secondary analyses contributed to clinical practice recommendations. These data show the long-term importance of clinical trials regardless of primary outcome result.