Extracellular regulation of BMP signalling by Short Gastrulation in Drosophila embryogenesis.

Abstract

Bone Morphogenetic Protein (BMP) signalling is essential throughout vertebrate and invertebrate life, with BMP misregulation leading to a number of human diseases. During early Drosophila embryogenesis, graded BMP signalling patterns the dorsal-ventral axis. The BMP gradient is established through regulation of BMP ligand activity and distribution by a network of extracellular proteins including Short Gastrulation (Sog). This project aims to use a multidisciplinary approach to understand how Sog regulates BMP signalling. Negative stain and cryo-electron microscopy data show that Sog has a curved shape similar to Chordin, the vertebrate homologue, which is consistent with current models of Sog-BMP-Tsg (Twisted Gastrulation) complex formation. To examine Sog function in vivo, CRISPR genome engineering was used to modify the sog locus such that sog sequence variants have been introduced and are expressed under the endogenous promoter. These sequences encode a mNeonGreen, HaloTag, or GFP Nanobody tag to facilitate visualisation of Sog live during development. It was found that although Sog could not be detected during dorsal-ventral patterning, for the first time, Sog could be visualised live from embryonic stage 6 onwards. In addition, the sog coding sequence carrying mutations at two putative palmitoylation sites was expressed in vivo. Interestingly, the C27,28S mutation results in only a minor impact on Sog function, indicating that these residues are not critical for Sog secretion as previously suggested. Increasing our understanding of how Sog regulates BMP signalling in vivo could lead to innovative strategies for influencing cellular behaviour (e.g. regenerative medicine applications) and disease outcomes.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Clair Baldock (Supervisor), Hilary Ashe (Supervisor) & Karel Dorey (Supervisor)