Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Dopamine. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

A fourth isoform of endothelin-converting enzyme (ECE-1) is generated from an additional promoter molecular cloning and characterization.

Abstract: Human endothelin-converting enzyme (ECE-1) has been shown to exist as three isoforms (ECE-1a, ECE-1b and ECE-1c) diverging in their N-terminal sequence and displaying different patterns of subcellular localization. We report here the cloning of ECE-1d, a novel isoform of 767 amino acids, which is generated from the same gene via the existence of an additional promoter located upstream from the third exon of the ECE-1 gene. ECE-1d converting activity is comparable to that of the other three isoenzymes. In contrast to ECE-1b, ECE-1d is expressed at the cell surface, although less strongly than ECE-1a. We have also shown, by identifying ECE-1b and ECE-1d in rat, that the ECE-1 diversity is conserved between human and rodent, suggesting its physiological relevance. The mRNA levels of the four isoforms were assessed in the two species in various cell types, revealing some differences. In particular, the ECE-1a isoform, strongly expressed at the plasma membrane, was found to be highly expressed in primary cultures of endothelial cells but absent from primary cultures of smooth muscle cells.

High-fat diet modifies the PPAR-γ pathway leading to disruption of microbial and physiological ecosystem in murine small intestine

Abstract: Diet is among the most important factors contributing to intestinal homeostasis, and basic functions performed by the small intestine need to be tightly preserved to maintain health. Little is known about the direct impact of high-fat (HF) diet on small-intestinal mucosal defenses and spatial distribution of the microbiota during the early phase of its administration. We observed that only 30 d after HF diet initiation, the intervillous zone of the ileum—which is usually described as free of bacteria—became occupied by a dense microbiota. In addition to affecting its spatial distribution, HF diet also drastically affected microbiota composition with a profile characterized by the expansion of Firmicutes (appearance of Erysipelotrichi), Proteobacteria (Desulfovibrionales) and Verrucomicrobia, and decrease of Bacteroidetes (family S24-7) and Candidatus arthromitus. A decrease in antimicrobial peptide expression was predominantly observed in the ileum where bacterial density appeared highest. In addition, HF diet increased intestinal permeability and decreased cystic fibrosis transmembrane conductance regulator (Cftr) and the Na-K-2Cl cotransporter 1 (Nkcc1) gene and protein expressions, leading to a decrease in ileal secretion of chloride, likely responsible for massive alteration in mucus phenotype. This complex phenotype triggered by HF diet at the interface between the microbiota and the mucosal surface was reversed when the diet was switched back to standard composition or when mice were treated for 1 wk with rosiglitazone, a specific agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ). Moreover, weaker expression of antimicrobial peptide-encoding genes and intervillous bacterial colonization were observed in Ppar-γ–deficient mice, highlighting the major role of lipids in modulation of mucosal immune defenses.