Molecular and Cellular Aspects of Cirrhosis and How an Adenosine Derivative Could Revert Fibrosis

Hepatic fibrosis occurs in response to persistent liver damage and is characterized by an excessive accumulation of extracellular matrix. When the damage is prolonged, there is a chronic inflammation and persistent hepatic fibrosis eventually leads to cirrhosis, where in addition to the scar, there is an important vascular remodeling associated with portal hypertension and, if decompensated, leads to death or can develop hepatocellular carcinoma. We have been studying the pharmacologic functions of adenosine, finding that a derivative of this nucleoside, IFC-305, shows hepatoprotective effects in a CCl4-induced rat cirrhosis model where it reverses liver fibrosis through modulation of fibrosis-related genes and by ameliorating hepatic function. Furthermore, this compound has the property to rescue cell cycle inhibition in vivo, prevents hepatic stellate cell activation, modulates anti-inflammatory macrophage polarization, and favors a chromatin context that could decrease the genomic instability and characteristics of cirrhosis, enabling the recovery of gene expression profile. Here we show results that contribute to the comprehension of molecular and cellular mechanism of cirrhosis, give the opportunity to suggest biomarkers to the early diagnostic of this pathology, and constitute the fundaments to suggest IFC-305 as a coadjuvant for treatment of this disease

Genome-wide 5-hydroxymethylcytosine (5hmC) emerges at early stage of in vitro differentiation of a putative hepatocyte progenitor

International audienceA basic question linked to differential patterns of gene expression is how cells reach different fates despite using the same DNA template. Since 5-hydroxymethylcytosine (5hmC) emerged as an intermediate metabolite in active DNA demethylation, there have been increasing efforts to elucidate its function as a stable modification of the genome, including a role in establishing such tissue-specific patterns of expression. Recently we described TET1-mediated enrichment of 5hmC on the promoter region of the master regulator of hepatocyte identity, HNF4A, which precedes differentiation of liver adult progenitor cells in vitro. Here, we studied the genome-wide distribution of 5hmC at early in vitro differentiation of human hepatocyte-like cells. We found a global increase in 5hmC as well as a drop in 5-methylcytosine after one week of in vitro differentiation from bipotent progenitors, at a time when the liver transcript program is already established. 5hmC was overall higher at the bodies of overexpressed genes. Furthermore, by modifying the metabolic environment, an adenosine derivative prevents 5hmC enrichment and impairs the acquisition of hepatic identity markers. These results suggest that 5hmC could be a marker of cell identity, as well as a useful biomarker in conditions associated with cell de-differentiation such as liver malignancies

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field