title: The role of miR-103 and miR-107 in regulation of CDK5R1 expression and in cellular migration.
abstract: CDK5R1 encodes p35, a specific activator of the serine/threonine kinase CDK5, which plays crucial roles in CNS development and maintenance. CDK5 activity strongly depends on p35 levels and p35/CDK5 misregulation is deleterious for correct CNS function, suggesting that a tightly controlled regulation of CDK5R1 expression is needed for proper CDK5 activity. Accordingly, CDK5R1 expression was demonstrated to be controlled at both transcriptional and post-transcriptional levels, but a possible regulation through microRNAs (miRNAs) has never been investigated. We predicted, within the large CDK5R1 3'UTR several miRNA target sites. Among them, we selected for functional studies miR-103 and miR-107, whose expression has shown a strong inverse correlation with p35 levels in different cell lines. A significant reduction of CDK5R1 mRNA and p35 levels was observed after transfection of SK-N-BE neuroblastoma cells with the miR-103 or miR-107 precursor (pre-miR-103 or pre-miR-107). Conversely, p35 levels significantly increased following transfection of the corresponding antagonists (anti-miR-103 or anti-miR-107). Moreover, the level of CDK5R1 transcript shifts from the polysomal to the subpolysomal mRNA fraction after transfection with pre-miR-107 and, conversely, from the subpolysomal to the polysolmal mRNA fraction after transfection with anti-miR-107, suggesting a direct action on translation efficiency. We demonstrate, by means of luciferase assays, that miR-103 and miR-107 are able to directly interact with the CDK5R1 3'-UTR, in correspondence of a specific target site. Finally, miR-103 and miR-107 overexpression, as well as CDK5R1 silencing, caused a reduction in SK-N-BE migration ability, indicating that these miRNAs affect neuronal migration by modulating CDK5R1 expression. These findings indicate that miR-103 and miR-107 regulate CDK5R1 expression, allowing us to hypothesize that a miRNA-mediated mechanism may influence CDK5 activity and the associated molecular pathways.
authors.affiliation: Department of Biology and Genetics for Medical Sciences, University of Milan, Milan, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Moncini
authors.forename: Alessandro
authors.initials: A
authors.lastname: Salvi
authors.forename: Paola
authors.initials: P
authors.lastname: Zuccotti
authors.forename: Gabriella
authors.initials: G
authors.lastname: Viero
authors.forename: Alessandro
authors.initials: A
authors.lastname: Quattrone
authors.forename: Sergio
authors.initials: S
authors.lastname: Barlati
authors.forename: Giuseppina
authors.initials: G
authors.lastname: De Petro
authors.forename: Marco
authors.initials: M
authors.lastname: Venturin
authors.forename: Paola
authors.initials: P
authors.lastname: Riva
mesh_terms: D020413:3' Untranslated Regions; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D006801:Humans; D035683:MicroRNAs / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020413:3' Untranslated Regions; C544749:MIRN103 microRNA, human; C549045:MIRN107 microRNA, human; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C089495:neuronal Cdk5 activator (p25-p35)