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SIRT1 modulates miRNA processing defects in p53-mutated human keratinocytes

journal contribution
posted on 2023-05-17, 23:32 authored by Herbert, KJ, Anthony CookAnthony Cook, Elizabeth Snow

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.

Funding

Cancer Council of Tasmania

History

Publication title

Journal of Dermatological Science

Volume

74

Pagination

142-149

ISSN

0923-1811

Department/School

School of Health Sciences

Publisher

Elsevier Sci Ireland Ltd

Place of publication

Customer Relations Manager, Bay 15, Shannon Industrial Estate Co, Clare, Ireland

Rights statement

Copyright 2014 Elsevier

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the health sciences

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