# Autocrine Wingless constricts the Drosophila embryonic gut by Ca+2-mediated repolarisation of mesoderm cells

## TL;DR

This study shows how Wingless (Wg) signaling in fruit fly embryos helps shape the gut by changing the structure of mesoderm cells through calcium pulses.

## Contribution

The study reveals a novel mechanism by which autocrine Wg signaling induces gut constriction via Ca+2-mediated repolarization of mesodermal cells.

## Key findings

- Wg signaling induces ClC-a transcription in mesodermal cells, leading to Ca+2 pulses.
- Ca+2 pulses cause repolarization of mesodermal cells and microtubule reorganization.
- Mesodermal repolarization is essential for forming the middle constriction of the Drosophila gut.

## Abstract

Wg/Wnt signalling—a highly conserved transduction pathway—has most commonly been found to be involved in patterning, cell fate, or cell proliferation, but less so in shaping organs or body parts. A remarkable case of the latter is the role of Wg signalling in the midgut of the Drosophila embryo. The Drosophila embryonic midgut is divided into four chambers that arise by the formation of three constrictions at distinct sites along the midgut. In particular, Wg is responsible for the middle constriction, a role first described more than 30 years ago. However, while some partial data have been obtained regarding the formation of this gut constriction, an overall picture of the process is lacking. Here we unveil that Wg signalling leads to this constriction by inducing ClC-a transcription in a subset of mesodermal cells. ClC-a, encodes a chloride channel, which in turn prompts a Ca+2 pulse in these cells. Consequently, the mesoderm cells, which already showed some polarity, repolarise and in so doing so they reshape the microtubule organisation, therefore inducing the constriction of the cells.

Wg-dependent repolarization of mesodermal cells is required for the formation of the middle constriction of the Drosophila embryonic gut.

Besides the well-known role of Wg in patterning, cell fate, or cell proliferation, this study describes the role of Wg in shaping organs or body parts.An autocrine Wg signal constricts the mesoderm, which then shapes the neighbouring endoderm.Polarity of mesodermal cells is altered by Wg signalling via a Ca+2-mediated mechanism.

Besides the well-known role of Wg in patterning, cell fate, or cell proliferation, this study describes the role of Wg in shaping organs or body parts.

An autocrine Wg signal constricts the mesoderm, which then shapes the neighbouring endoderm.

Polarity of mesodermal cells is altered by Wg signalling via a Ca+2-mediated mechanism.

Wg-dependent repolarization of mesodermal cells is required for the formation of the middle constriction of the Drosophila embryonic gut.