Crosstalk between planar cell polarity signaling and miR-8 control of NHERF1-mediated actin reorganization.

The response to osmotic stress in developing zebrafish embryos requires proper apical patterning and trafficking of transmembrane ion transporters in ionocytes, specialized cells of the epidermis. The miR-8 family of miRNAs plays a key role in this process by precisely regulating the activity of NHERF1, a regulator of sodium hydrogen exchange that also serves as an adaptor protein linked to the actin cytoskeleton. We have discovered that NHERF1 activity is also coupled to Planar Cell Polarity (PCP) signaling in the zebrafish epidermis. Loss of NHERF1 in wild type fish disrupts actin organization but the observed defects can be largely restored when combined with mutants in the PCP pathway. We propose that proper apical patterning depends on input and coordination between PCP signaling and the response to stress.