Biology subjects

Wafer, R.

Publications and source records attributed to Wafer, R..

3 recordsLinked to original sources

bioRxiv2025

Recognition of pathogenic bacteria by intestinal progenitors promotes adult Drosophila midgut regeneration via PGRP-MKK3-p38 signalling.

When enteropathogenic bacteria breach the intestinal epithelium, they are recognized by epithelial and immune cells that elicit an intestinal regenerative response. However, less is known about whether and how intestinal progenitors directly detect invading pathogenic bacteria and couple this to their proliferation. Here we show that adult Drosophila midgut progenitors recognise peptidoglycan from pathogenic bacteria through the peptidoglycan recognition proteins, PGRP-LC and PGRP-LE, and translate this to ISC proliferation by stimulating MKK3-p38 signalling. Moreover, we find that PGRP-LC/LE-MKK3-p38 signalling in progenitors regulates p38 activation throughout the midgut epithelium after infection, indicating that progenitors can influence the regenerative niche in a non-cell autonomous manner. Whilst it was previously thought that ISC proliferation in both mammals and flies is driven solely by damage-induced signals after infection, our work reveals that progenitors can directly recognise pathogenic bacteria and mount a strong parallel regenerative response that spreads throughout the midgut epithelium. Increased ISC proliferation after bacterial recognition may also serve as a strategy to repopulate the epithelium with uninfected cells.

developmental biology↗

bioRxiv2025

In vivo CRISPR screening identifies regulators of hyperplastic and hypertrophic adipose remodelling in zebrafish

Adipose tissues exhibit a remarkable capacity to expand, regress, and remodel in response to energy status. The cellular mechanisms underlying adipose remodelling are central to metabolic health. Hypertrophic remodelling - characterised by the enlargement of existing adipocytes - is associated with insulin resistance, type 2 diabetes, and cardiovascular disease. In contrast, hyperplastic remodelling - in which new adipocytes are generated - is linked to improved metabolic outcomes. Despite its clinical importance, the regulation of hypertrophic and hyperplastic adipose morphology remains poorly understood. Here, we integrate human transcriptomic data with a quantitative CRISPR-imaging platform in zebrafish to identify regulators of adipose morphology. We developed an image-based phenotyping pipeline that captures lipid droplet size, number, and spatial patterning, and applied generalised additive modelling to quantify hyperplastic versus hypertrophic morphology signatures. Using this platform, we conducted an F0 CRISPR screen targeting 25 candidate genes and identified three that induced hypertrophic morphology (txnipa, mmp14b and foxp1b) and an additional candidate that altered total adiposity (kazna). For functional validation, we generated stable loss-of-function alleles for both zebrafish foxp1 paralogues. Spatial analysis along the anterior-posterior axis revealed that foxp1b mutants display developmental hypertrophy but profoundly blunted adaptive responses to high-fat diet ([~]68% reduction across all spatial zones), while foxp1a mutants show normal baseline morphology but disrupted spatial patterning of diet-induced hypertrophy. Together, these findings establish a scalable CRISPR-imaging platform for in vivo genetic screening of adipose morphology, and reveal distinct roles for Foxp1 paralogues in developmental patterning and adaptive responses to dietary challenge in adipose tissue.

developmental biology↗

bioRxiv2025

Damage recognition by intestinal stem cells via Draper-Src-Shark-STAT signalling promotes adult Drosophila midgut regeneration.

Regeneration after injury is crucial for maintaining epithelial structure and function. In order to facilitate this, a regenerative niche forms upon damage that produces cues to induce stem cell proliferation to replace damaged or lost cells. Whereas much is known about this process, less is understood about how stem cells themselves sense damage, translate this into their proliferation and shape the regenerative niche. In the adult Drosophila midgut, the non-receptor tyrosine kinase Src42A is required in progenitors to promote ISC proliferation after pathogenic bacterial infection. Although STAT is necessary for Src42A-driven ISC proliferation, the mechanism by which Src42A activates STAT in progenitors remains unclear. Here we show that Draper-Src-Shark signalling acts in ISCs to recognise midgut damage and is required for full STAT activation in ISCs to promote their proliferation. Unlike its role in phagocytes, we find that the engulfment receptor Draper in ISCs does not promote the engulfment of dying midgut epithelial cells but rather is required for ISC proliferation only in the presence of apoptotic enterocytes. Moreover, we uncover that Draper-Src-Shark signalling in progenitors regulates STAT activity non-cell autonomously in the visceral muscle, indicating that progenitors can shape the regenerative niche. As both Src and Stat are activated in the mammalian intestinal epithelium after damage and tumour formation, our work likely extends to mammalian organisms and may aid in developing therapies for tissue regeneration, inflammatory diseases and cancer.

cell biology↗