Scientists have now shown that the obesity status of human fathers can dynamically alter the epigenome of their spermatozoa and such changes can be passed on to their children to have profound and lasting effects on the metabolism of future generations. In particular, in a multi-part study, the researchers first showed that spermatozoa from lean and from obese men differed significantly in the expression of many small non-coding RNA (sncRNA) molecules, a subtype of RNAs that is strongly implicated in epigenetic inheritance. More specifically, a particular subtype of sncRNAs, namely piwi-interacting RNAs (piRNAs), was found to be differentially expressed between lean and obese men. piRNAs are mainly expressed in the germline and are known to play a fundamental roles in maintaining genomic stability by repressing repetitive elements, and also in the regulating the expression of coding genes. A role for piRNAs in epigenetic inheritance has previously been demonstrated in Drosophila. In the current study, the scientists reported that target prediction of the piRNAs differentially expressed between lean and obese men retrieved genes with best enrichment scores for the terms ‘‘Chromosome’’ and ‘‘Chromatin’’ and the genetic annotation term ‘‘Chemdependancy.’’ Specifically, the cocaine and amphetamine regulated transcript (CART), a regulator of food intake involved in obesity, was differentially expressed in obese men.
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