Identification and functional characterization of trans-acting factors involved in the post-transcriptional regulation of CDK5R1

CDK5R1 encodes p35, an activator of CDK5, a proline-directed serine/threonine kinase that phosphorylates proteins involved in CNS development and maintenance. CDK5 and p35 were found to show an important role in neuronal migration and differentiation during CNS development and were also implicated in some neurodegenerative and cognitive disorders. Both the CDK5R1 3’-UTR remarkable size and its conservation during the evolution are strongly indicative of an important function in post-transcriptional regulation. We recently reported that CDK5R1 3’-UTR contains regulatory elements affecting transcript stability. In particular, a 138 bp region, that does not contain known miRNA binding sites, has been identified as the most destabilizing portion of the 3’-UTR by luciferase assays. UV cross-linking and site directed mutagenesis experiments allowed us to delimit potential binding site for RNA binding proteins (RBPs), among which we identified the nELAVs, showing a stabilizing activity on CDK5R1 transcript after overexpression and silencing experiments. To search for putative destabilizing factors, pull-down experiments have been carried out, allowing us to identify further binding factors, among which hnRNPA2/B1. The validation of hnRNPA2/B1 binding and the study of its silencing/over-expression might help to disclose the possible role of this protein on CDK5R1 post-transcriptional regulation. This study will help to define the functional role of the gene, addressing studies on the CDK5R1 implication in the pathogenesis of neurodegenerative and cognitive diseases.