hnRNPA2/B1 and nELAV proteins bind to a specific U-rich element in CDK5R1 3'-UTR and oppositely regulate its expression.

Paola Zuccotti, Claudia Colombrita, Silvia Moncini, Andrea Barbieri, Marta Lunghi, Cecilia Gelfi, Sara De Palma, Angelo Nicolin, Antonia Ratti, Marco Venturin, Paola Riva

Biochimica et biophysica acta 2014 Jun

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Cyclin-dependent kinase 5 regulatory subunit 1 (CDK5R1) encodes p35, a specific activator of cyclin-dependent kinase 5 (CDK5). CDK5 and p35 have a fundamental role in neuronal migration and differentiation during CNS development. Both the CDK5R1 3'-UTR's remarkable size and its conservation during evolution strongly indicate an important role in post-transcriptional regulation. We previously validated different regulatory elements in the 3'-UTR of CDK5R1, which affect transcript stability, p35 levels and cellular migration through the binding with nELAV proteins and miR-103/7 miRNAs. Interestingly, a 138 bp-long region, named C2.1, was identified as the most mRNA destabilizing portion within CDK5R1 3'-UTR. This feature was maintained by a shorter region of 73 bp, characterized by two poly-U stretches. UV-CL experiments showed that this region interacts with protein factors. UV-CLIP assays and pull-down experiments followed by mass spectrometry analysis demonstrated that nELAV and hnRNPA2/B1 proteins bind to the same U-rich element. These RNA-binding proteins (RBPs) were shown to oppositely control CDK5R1 mRNA stability and p35 protein content at post-trascriptional level. While nELAV proteins have a positive regulatory effect, hnRNPA2/B1 has a negative action that is responsible for the mRNA destabilizing activity both of the C2.1 region and of the full-length 3'-UTR. In co-expression experiments of hnRNPA2/B1 and nELAV RBPs we observed an overall decrease of p35 content. We also demonstrated that hnRNPA2/B1 can downregulate nELAV protein content but not vice versa. This study, by providing new insights on the combined action of different regulatory factors, contributes to clarify the complex post-transcriptional control of CDK5R1 gene expression. Copyright © 2014 Elsevier B.V. All rights reserved.

Citation

Paola Zuccotti, Claudia Colombrita, Silvia Moncini, Andrea Barbieri, Marta Lunghi, Cecilia Gelfi, Sara De Palma, Angelo Nicolin, Antonia Ratti, Marco Venturin, Paola Riva. hnRNPA2/B1 and nELAV proteins bind to a specific U-rich element in CDK5R1 3'-UTR and oppositely regulate its expression. Biochimica et biophysica acta. 2014 Jun;1839(6):506-16