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.

The MicroRNA miR-199a-5p Down-regulation Switches on Wound Angiogenesis by Derepressing the v-ets Erythroblastosis Virus E26 Oncogene Homolog 1-Matrix Metalloproteinase-1 Pathway

“…miR-27b, a miR facilitating breast cancer cell invasiveness (35), promotes angiogenesis in endothelial cells by targeting angiostatic protein semaphorin 6A (36). miR-107, a miR down-regulated by hypoxia, attenuates cell migration (37,38) and blocks VEGF-dependent angiogenesis by targeting hypoxia-inducing factor (HIF)-1␤ (39). The current study, together with findings from previous reports, reinforces the concept that miR-199a-5p not only inhibits cell migration (9,13,16) but also exerts potent angiostatic effect on endothelial cells by targeting a discrete subset of gene(s).…”

Cdk5 activity in the brain – multiple paths of regulation

“…For example, several miRNA species, such as miR-101, miR-153 and miR-339-5p are dysregulated in AD (Long and Lahiri, 2011a;Long and Lahiri, 2011b;Long et al, 2014). In this context, p35 expression can be post-transcriptionally suppressed by miRNAs 103 and 107 (miR-103 and miR-107, respectively) (Moncini et al, 2011). miR-103 and miR-107 directly bind to 39UTR of p35 and repress its translation (Fig.…”

p39, the Primary Activator for Cyclin-dependent Kinase 5 (Cdk5) in Oligodendroglia, Is Essential for Oligodendroglia Differentiation and Myelin Repair

“…The transacting factors that suppress p35 translation in OLs still remain unknown. Nonetheless, it is worth mentioning that a number of microRNAs are predicted to target the lengthy 3Ј-UTR of p35 mRNA specifically but not the p39 mRNA (53). Which of these microRNAs are expressed in OLs and responsible for translational suppression of p35 is a challenging question to be addressed by future studies.…”