Epigenetic Effects of an Adenosine Derivative in a Wistar Rat Model of Liver Cirrhosis

Abstract

The pathological characteristic of cirrhosis is scarring which results in a structurally distorted and dysfunctional liver. Previously, we demonstrated that Col1a1 and Pparg genes are deregulated in CCl 4 -induced cirrhosis but their normal expression levels are recovered upon treatment with IFC-305, an adenosine derivative. We observed that adenosine was able to modulate S-adenosylmethionine-dependent transmethylation reactions, and recently, we found that IFC-305 modulates HDAC3 expression. Here, we investigated whether epigenetic mechanisms, involving DNA methylation processes and histone acetylation, could explain the re-establishment of gene expression mediated by IFC-305 in cirrhosis. Therefore, Wistar rats were CCl 4 treated and a sub-group received IFC-305 to reverse fibrosis. Global changes in DNA methylation, 5-hydroxymethylation, and histone H4 acetylation were observed after treatment with IFC-305. In particular, during cirrhosis, the Pparg gene promoter is depleted of histone H4 acetylation, whereas IFC-305 administration restores normal histone acetylation levels which correlates with an increase of Pparg transcript and protein levels. In contrast, the promoter of Col1a1 gene is hypomethylated during cirrhosis but gains DNA methylation upon treatment with IFC-305 which correlates with a reduction of Col1a1 transcript and protein levels. Our results suggest a model in which cirrhosis results in a general loss of permissive chromatin histone marks which triggers the repression of the Pparg gene and the upregulation of the Col1a1 gene. Treatment with IFC-305 restores epigenetic modifications globally and specifically at the promoters of Pparg and Col1a1 genes. These results reveal one of the mechanisms of action of IFC-305 and suggest a possible therapeutic function in cirrhosis.

5-Hydroxymethylcytosine (5hmC), or How to Identify Your Favorite Cell

“…During different stages of chronic liver injury, 5hmC was found reduced, while hepatic stellate cells became transdifferentiated [111]. Consistent with these data, global 5hmC was shown to be reduced in a rat model of CCl4-induced cirrhosis [112]. It is important to note the recent availability of liver methylome and hydroxymethylome data on Wistar and Sprague-Dawley rats, as well as the genome-wide distribution of enhancer related chromatin marks (i.e., H3K4me1 and H3K27ac), which could represent a baseline reference for future studies of liver pathology [113].…”

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

“…With these results and in order to assess DNA methylation dynamics, 5hmC levels were measured and a similar behavior to the one observed with 5mC, a reduction of 5hmC in cirrhosis in concordance with group of Mann findings, was found [89]. Treatment with IFC-305 triggers a regaining of both 5mC and 5hmC [16]. These results together suggest that there is a perturbation of DNA methylation dynamic during cirrhosis, while IFC-305 is able to modulate this dynamic, possibly reducing chromosome instability.…”

“…Rats are intraperitoneal treated with 0.04 g/kg body weight of CCl 4 three times per week, during 10 weeks. After this time it is possible to observe a liver distortion, the formation of nodules, bilirubin accumulation and hepatomegaly [16], the generation of a fibrotic area of 16% of the tissue, and a reduction in parenchyma surface to around 78%. As a consequence of these liver architecture changes, there are alterations of liver function: serum samples of cirrhotic rats display elevated AST, ALT, and bilirubin levels and albumin are relatively reduced [17].…”

“…IFC-305 is able to reduce the levels to healthy-like levels for three fibrogenic genes (Fn1, Col1a1,andTgfb1), C9, Apob1 and Hdac3; meanwhile, this compound generates the increasing expression of Pparg and Cps1 recovering the levels of the healthy liver and partially restoring the levels of Ass1 [17]. Analyzing proteins, we could identify an increment in collagen I and HDAC3 and a reduction of PPARγ during cirrhosis, and the treatment with IFC-305 resembles the healthy-like levels of these three proteins [16]. Thus, through this quantitative analysis of expression and protein levels, IFC-305 shows capabilities to modulate the gene expression of some important genes involved in liver fibrogenesis.…”

“…We have previously shown that adenosine can modulate trans-methylation reactions, like methylation of phospholipids, via regulation of S-adenosylmethionine (SAM) levels [87], so that we make an approach to SAM levels and found that during cirrhosis, the amount of this molecule is diminished, whereas IFC-305 treatment restored the physiological levels; this suggests that during cirrhosis, it could be an imbalance of methylation reactions, and IFC-305, like adenosine, could also regulate this process [16].…”