Ross, K. | bioRxiv Science

bioRxiv2018

MICRORNA-184 AND ITS LNCRNA SPONGE UCA1 ARE INDUCED IN WOUNDED KERATINOCYTES IN A STORE-OPERATED CALCIUM ENTRY-DEPENDENT MANNER

Emerging evidence implicates microRNAs (miRNA) in the regulation of keratinocyte migration. However, the putative roles of microRNA-184 (miR-184) in keratinocyte migration have not been examined. Here, we show that miR-184 expression was elevated following wounding of human keratinocyte monolayers. The induction of miR-184 was dependent on store-operated calcium entry (SOCE) as it was abolished by pharmacologic SOCE blockers. The long non-coding RNA urothelial cancer associated 1 (UCA1), which is thought to acts as a sponge or competing endogenous RNA (ceRNA) against miR-184 was also induced in scratched monolayers. Induction of UCA1 was impaired, but not abolished, by SOCE inhibition. Transfection of keratinocytes with a miR-184 mimic stimulated migration in scratch assays, whereas inhibition of miR-184 dampened the ability of keratinocytes to migrate. Together, our data suggest, for the first time, that SOCE promotes miR-184 induction in wounded monolayers to support keratinocyte migration while also increasing lncRNA UCA1 expression, which may in turn regulate miR-184 activity in keratinocytes.

cell biology↗

bioRxiv2018

MicroRNA-184 Is Induced By Store-Operated Calcium Entry And Regulates Early Keratinocyte Differentiation

Extracellular calcium (Ca2+) and store-operated Ca2+ entry (SOCE) govern homeostasis in the mammalian epidermis. Multiple microRNAs (miRNA) also regulate epidermal differentiation, and raised external Ca2+ modulates the expression of several such miRNAs in keratinocytes. However, little is known about the regulation of miR-184 in keratinocytes or the roles of miR-184 in keratinocyte differentiation. Here we report exogenous Ca2+ stimulates miR-184 expression in primary epidermal keratinocytes and that this occurs in a SOCE-dependent manner. Levels of miR-184 were raised by about 30-fold after exposure to 1.5 mM Ca2+ for 5 days. In contrast, neither phorbol ester nor 1, 25-dihydroxyvitamin D3 had any effect on miR-184 levels. Pharmacologic and genetic inhibitors of SOCE abrogated Ca2+-dependent miR-184 induction by 70% or more. Ectopic miR-184 inhibited keratinocyte proliferation and led to a 4-fold increase in the expression of involucrin, a marker of early keratinocyte differentiation. Exogenous miR-184 also triggered a 3-fold rise in levels of cyclin E and doubled the levels of {gamma}H2AX, a marker of DNA double strand breaks. The p21 cyclin-dependent kinase (CDK) inhibitor, which supports keratinocyte growth arrest, was also induced by miR-184. Together our findings point to a SOCE:miR-184 pathway that targets a cyclin E/DNA damage regulatory node to facilitate keratinocyte differentiation.

molecular biology↗