Abstract

The stem cell niche is a complex microenvironment which regulates stem cell behaviour through secreted, cell-cell contact and mechanical cues. An under-studied component of epithelial stem cell niches is the basement membrane, a thin, laminar structure to which cells adhere basally via adhesion receptors, including Integrins, Dystroglycan and Syndecan. Using the adult Drosophila midgut as a model system to investigate the role of adhesion receptors in directing progenitor cell behaviour in vivo, we identified the laminin receptor Syndecan as a regulator of tissue renewal. Syndecan knockdown causes progenitor cells to detach from the basement membrane and be lost from the intestinal epithelium. Interestingly, progenitor depletion does not lead to major tissue attrition over time but to retention of old differentiated cells for longer periods. Whilst this preserves tissue integrity in the short term, it could potentially have deleterious effects as old cells accumulate mutations or become damaged by local insults. To reveal how Syndecan contributes to progenitor maintenance and communication with neighbouring cells, our ongoing work investigates what subset of progenitors depend on Syndecan activity, and which signalling pathways become disrupted in its absence.