Role of long non-coding RNA in cells: Example of the H19/IGF2 locus

In the past decade, studies of non-coding RNAs increase. Non-coding RNAs are divided in two classes: small and long non-coding RNA. It was shown that long non-coding RNAs regulate expression of 70% of genes. Long non-coding RNAs are involved in several cellular processes like epigenetic regulation, dosage compensation, alternative splicing and stem cells maintenance for example. Misregulations of their expression induce diseases such as developmental syndrome or cancer. In this review, we describe some functions of long non-coding RNA in cells. Furthermore, we study the H19/IGF2 cluster: an imprinted genomic locus located on chromosome 11p15.5. Genomic imprinting allows gene expression from a single allele in a parent-origin-dependent manner. This cluster encode for the first long non-coding RNA identified: H19. In 1990, it was established that H19 functions as a riboregulator. Recently, it was shown that H19 is a precursor of microRNA (hsa-miR-675), and several news transcripts were identified at the H19/IGF2 locus. So, the complexity of this locus increasing, in this review, we summarize our current understanding about the H19/IGF2 cluster both in terms of transcription as well as in terms of functions in cells. We highlight the involvement of H19, its new antisense transcript 91H and its microRNA, in the regulation of IGF receptor function and in cell cycle progression.