miR-203 represses ‘stemness’ by repressing ΔNp63

Abstract

The epidermis, the outer layer of the skin composed of keratinocytes, is a stratified epithelium that functions as a barrier to protect the organism from dehydration and external insults. The epidermis develops depending on the transcription factor p63, a member of the p53 family of transcription factors. p63 is strongly expressed in the innermost basal layer where epithelial cells with high clonogenic and proliferative capacity reside. Deletion of p63 in mice results in a dramatic loss of all keratinocytes and loss of stratified epithelia, probably due to a premature proliferative rundown of the stem and transient amplifying cells. Here we report that microRNA (miR)-203 is induced in vitro in primary keratinocytes in parallel with differentiation. We found that miR-203 specifically targets human and mouse p63 3 0 -UTRs and not SOCS-3, despite bioinformatics alignment between miR-203 and SOCS-3 3 0 -UTR. We also show that miR-203 overexpression in proliferating keratinocytes is not sufficient to induce full epidermal differentiation in vitro. In addition, we demonstrate that miR-203 is downregulated during the epithelial commitment of embryonic stem cells, and that overexpression of miR-203 in rapidly proliferating human primary keratinocytes significantly reduces their clonogenic capacity. The results suggest that miR-203, by regulating the DNp63 expression level, is a key molecule controlling the p63-dependent proliferative potential of epithelial precursor cells both during keratinocyte differentiation and in epithelial development. In addition, we have shown that miR-203 can regulate DNp63 levels upon genotoxic damage in head and neck squamous cell carcinoma cells, thus controlling cell survival.

Regulation of lung endoderm progenitor cell behavior by miR302/367

“…1243 RESEARCH ARTICLE miR302/367 and lung endoderm development Little is known about the ability of miRNAs to regulate tissuespecific progenitor populations. In the skin, miR203 promotes differentiation of skin basal progenitor cells by repressing the important skin progenitor maintenance factor p63 (Lena et al, 2008;Yi et al, 2008;Wei et al, 2010). However, less is known in the lung.…”

Phospho-ΔNp63α is a key regulator of the cisplatin-induced microRNAome in cancer cells

“…[16][17][18][19] Certain miRNAs were shown to mediate the induction of cell death, cell cycle arrest, and senescence and contribute to epithelial stem cell maturation. [18][19][20] We previously observed that the head and neck squamous cell carcinoma (HNSCC) cells exposed to CIS displayed a dramatic downregulation of DNp63a through an ATMdependent phosphorylation mechanism. 21,22 We also showed that phospho (p)-DNp63a is critical for the transcriptional regulation of downstream mRNAs in HNSCC cells.…”

p63-microRNA feedback in keratinocyte senescence

“…PCR primers used to obtain them are available on request. Luciferase assays were performed as described in Lena et al (16). Cells were transfected with 100 ng of pGL3 vectors, 12 pmol of pre-miRNA or a scrambled sequence (Ambion), and 10 ng of Renilla luciferase pRL-CMV vector (Promega).…”

“…p63 KO mice completely lack skin and skin derivatives and die within a few hours after birth due to dehydration (13,14). The most abundant p63 isoform in the epidermis is ΔNp63, which is highly expressed only in the basal compartment of proliferating keratinocytes (13), and its expression is tightly regulated by miR-203 during keratinocyte differentiation (15,16). Studies have shown that p63 is involved in senescence pathways, as its absence in conditional knockout mice induces premature aging (17)(18)(19).…”