The scale of zebrafish pectoral fin buds is determined by intercellular K < sup > + < /sup > levels and consequent Ca < sup > 2+ < /sup > -mediated signaling via retinoic acid regulation of Rcan2 and Kcnk5b

by Xiaowen Jiang, Kun Zhao, Yi Sun, Xinyue Song, Chao Yi, Tianlong Xiong, Sen Wang, Yi Yu, Xiduo Chen, Run Liu, Xin Yan, Christopher L. Antos

K+ channels regulate morphogens to scale adult fins, but little is known about what regulates the channels and how they control morphogen expression. Using the zebrafish pectoral fin bud as a model for early vertebrate fin/limb development, we found that K+ channels also scale this anatomical structure, and we determined how one K+-leak channel, Kcnk5b, integrates into its developmental program. From FLIM measurements of a FRET-based K+ sensor, we observed coordinated decreases in intracellular K+ levels during bud growth, and overexpression of K+-leak channels in vivo coordinately increased bud proportions. Retinoic acid, which can enhance fin/limb bud growth, decreased K+ in bud tissues and up-regulatedregulator of calcineurin (rcan2).rcan2 overexpression increased bud growth and decreased K+, while CRISPR-Cas9 targeting ofrcan2 decreased growth and increased K+. We observed similar results in the adult caudal fins. Moreover, CRISPR targeting of Kcnk5b revealed that Rcan2-mediated growth was dependent on the Kcnk5b. We also found that Kcnk5b enhanced depolarization in fin bud cells via Na+ channels and that this enhanced depolarization was required for Kcnk5b-enhanced growth. Lastly, Kcnk5b-inducedshha transcription and bud growth required IP3R-mediated Ca2+ release and CaMKK activity. Thus, we provide a mechanism for how retinoic ac...

Source: PLoS Biology: Archived Table of Contents - March 25, 2024 Category: Biology Authors: Xiaowen Jiang Source Type: research