SIRT1 modulates miRNA processing defects in p53-mutated human keratinocytes

Herbert, K. J. , Cook, A. L. and Snow, E. T. (2014) SIRT1 modulates miRNA processing defects in p53-mutated human keratinocytes. Journal of Dermatological Science, 74(2), pp. 142-149. (doi: 10.1016/j.jdermsci.2014.01.008) (PMID:24548601)

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Abstract

Background: Together with p53, the NAD-dependent lysine deacetylase SIRT1 and the microRNA miR-34a form a feedback loop which self-regulates SIRT1 expression and modulates p53-dependent responses. In addition to its well-described role in mediating transcriptional responses to genotoxic stress, p53 may also regulate microRNA processing and maturation. Objective: This study explored the functional relationship among p53, SIRT1 and miR-34a, and the influence of p53 and SIRT1 on microRNA biogenesis and maturation in primary (NHEK) and p53-mutated (HaCaT) keratinocyte cell lines. Methods: RNAi, miRNA target site blocking oligonucleotides and small molecule inhibitors were used to modulate activity and expression of SIRT1 and p53. Changes in microRNA and mRNA were analysed by qRT-PCR and protein expression was determined by immunoblotting. Results: Mature miR-34a decreased in p53-suppressed NHEK cells, whereas ablation of SIRT1 reduced the primary transcript (pri-miR-34a). When either SIRT1 expression or activity was inhibited in combination with p53 ablation, pri-miR-34a levels increased and mature miR-34a levels decreased. Under these same conditions, additional p53-regulated microRNAs (miRs 16-1/15, 145 and 107) also failed to mature. In HaCaT cells, primary microRNA transcripts for miR-16-1/15, miR-145 miR200c/141 and miRNA-107, but not miR-34a, were approximately 8-fold higher than in NHEK cells. However, the levels of mature microRNA sequences in HaCaT cells were only 1.5–2 fold higher (miR-16-1, miR-145), unchanged (miR-107) or decreased (miR-200c/141, miR-34a) compared to NHEK cells. Conclusions: Our results suggest that p53 mutations interfere with efficient microRNA biogenesis in keratinocytes, and that SIRT1 functions in combination with p53 in this process.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Herbert, Dr Katharine
Authors: Herbert, K. J., Cook, A. L., and Snow, E. T.
College/School:College of Medical Veterinary and Life Sciences > School of Cancer Sciences
Journal Name:Journal of Dermatological Science
Publisher:Elsevier
ISSN:0923-1811
ISSN (Online):1873-569X
Published Online:30 January 2014

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