MiR-34/449 control apical actin network formation during multiciliogenesis through small GTPase pathways.

Benoît Chevalier,Andrea Pasini,Olivier Mercey,Diego R Revinski,Anna Adamiok,Pascal Barbry,Laurent Kodjabachian,Laure-Emmanuelle Zaragosi,Brice Marcet

doi:10.1038/ncomms9386

Abstract

Vertebrate multiciliated cells (MCCs) contribute to fluid propulsion in several biological processes. We previously showed that microRNAs of the miR-34/449 family trigger MCC differentiation by repressing cell cycle genes and the Notch pathway. Here, using human and Xenopus MCCs, we show that beyond this initial step, miR-34/449 later promote the assembly of an apical actin network, required for proper basal bodies anchoring. Identification of miR-34/449 targets related to small GTPase pathways led us to characterize R-Ras as a key regulator of this process. Protection of RRAS messenger RNA against miR-34/449 binding impairs actin cap formation and multiciliogenesis, despite a still active RhoA. We propose that miR-34/449 also promote relocalization of the actin binding protein Filamin-A, a known RRAS interactor, near basal bodies in MCCs. Our study illustrates the intricate role played by miR-34/449 in coordinating several steps of a complex differentiation programme by regulating distinct signalling pathways.

Highlights

Vertebrate multiciliated cells (MCCs) contribute to fluid propulsion in several biological processes
As the development of functional motile cilia appears exquisitely sensitive to the reorganization of the actin cytoskeleton, we reasoned that miR-34/449 may regulate one or more molecules associated with actin dynamics or small GTPase pathways
Apical actin cytoskeleton formation was examined at several time points during differentiation of primary cultures of human airway epithelial cells (HAECs) grown at an air–liquid interface (ALI) and in Xenopus embryonic epidermis[9]

Summary

Introduction

Vertebrate multiciliated cells (MCCs) contribute to fluid propulsion in several biological processes. In control embryos and in miR-34/449 morphants, almost all rGBD-GFPpositive cells expressed the early MCC differentiation marker a-tubulin (Fig. 3c).

Results

Conclusion