PgmNr D181: Motile stem cells exhibit tissue-level spatial order during homeostasis but not growth of the adult Drosophila midgut.

Authors:
X. Du; J. Martin (co-first); S. Balachandra; I. Riedel-Kruse; L. O'Brien


Institutes
Stanford University, Stanford, CA.


Keyword: intestinal stem cells

Abstract:

Many self-renewing, solid organs contain stem cell populations that are dispersed throughout the expanse of the tissue. Spatial dispersal ensures that each tissue field contains stem cells.  How dispersed stem cells maintain proper spacing during organ renewal is unknown.  Here we combine quantitative spatial analyses with long-term live imaging to investigate the underlying basis of stem cell spacing.  Comprehensive statistical maps of stem cell-stem cell distances reveal that stem cells are spatially ordered during steady-state organ renewal, but not during adaptive organ growth.  Overnight imaging of midguts within living animals, together with tissue-wide cell tracking and spatio-temporal analysis of individual cell displacements, shows that stem cells are autonomously motile.  Individual cells, propelled by actin-rich protrusions, flatten and slither beneath the basal epithelium.  At the population level, stem cell motility appears stochastic in frequency and direction.  Progenitor-specific depletion of motility factors disrupts the spatial ordering of stem cells, implying that motility is needed for tissue-level dispersal.  Our findings show that spatial order is a hallmark of steady-state but not expanding stem cell populations and suggest that autonomous motility is involved in stem cell distribution during tissue homeostasis.