PT  - JOURNAL ARTICLE
AU  - Margot L K Williams
AU  - Atsushi Sawada
AU  - Terin Budine
AU  - Chunyue Yin
AU  - Paul Gontarz
AU  - Lilianna Solnica- Krezel
TI  - The chromatin factor Gon4l regulates embryonic axis extension by promoting mediolateral cell polarity and notochord boundary formation through negative regulation of cell adhesion
AID  - 10.1101/154310
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 154310
4099  - http://biorxiv.org/content/early/2017/06/23/154310.short
4100  - http://biorxiv.org/content/early/2017/06/23/154310.full
AB  - Anteroposterior axis extension during vertebrate gastrulation requires cell proliferation, embryonic patterning, and morphogenesis to be spatiotemporally coordinated, but the underlying genetic mechanisms remain poorly understood. Here we define a role for the conserved chromatin factor Gon4l, encoded by ugly duckling (udu), in coordinating tissue patterning and axis extension during zebrafish gastrulation. Although identified as a recessive enhancer of short axis phenotypes in planar cell polarity (PCP) mutants, we found that Gon4l functions in a genetically independent, partially overlapping fashion with PCP signaling to regulate mediolateral cell polarity underlying axis extension in part by promoting notochord boundary formation. We identified direct genomic targets of Gon4l and found that it acts as both a positive and negative regulator of gene expression, including limiting expression of the cell-cell and cell-matrix adhesion molecules EpCAM and Integrinα3b. Excess epcam or itga3b in wild-type gastrulae phenocopied notochord boundary defects of udu mutants, while downregulation of itga3b suppressed them. By promoting formation of this anteroposteriorly aligned boundary and associated cell polarity, Gon4l cooperates with PCP signaling to coordinate morphogenesis with the anteroposterior embryonic axis.