Theses Doctoral

Identification of a Homeostatic Stem Cell Population in the Intestinal Upper Crypt

Capdevila Castillo, Claudia

In the prevailing model, R-spondin (Rspo)-dependent 𝘓𝘨𝘳5+ crypt base columnar (CBC) cells are the only dedicated intestinal stem cells (ISCs) that sustain epithelial regeneration during homeostasis by upward migration of their progeny through an elusive transit-amplifying (TA) intermediate in the upper crypt. Paradoxically, the intestinal epithelium is resilient to 𝘓𝘨𝘳5+ CBC cell loss.

Elicited by intriguing R-spondin (Rspo) gain- and loss-of-function phenotypes that suggest regeneration emerges from a subset of 𝘓𝘨𝘳5- cells, here we combine single-cell RNA-sequencing (scRNA-seq) with time-resolved fate mapping to identify a proliferative population of multi-potent upper crypt cells in the putative location of TA cells. Distinct from the 𝘓𝘨𝘳5+ CBC cells and marked by expression of 𝘍𝘨𝘧𝘣𝘱1 - a gene which we demonstrate is essential for regeneration - these cells generate progeny that migrate bi-directionally along the crypt-villus axis and, unexpectedly, also serve as a source for the 𝘓𝘨𝘳5+ cells at the base. 𝘍𝘨𝘧𝘣𝘱1+ cells are resilient to Rspo signaling blockade and sustain epithelial homeostasis in the context of 𝘓𝘨𝘳5+ cell loss, suggesting functional independence. Consistent with their stem rather than TA cell function, our results point to the existence of a novel cellular hierarchy in the intestinal epithelium, contesting the regenerative capabilities of the 𝘓𝘨𝘳5+ CBC cell and helping reconcile many of the 𝘓𝘨𝘳5+ CBC model inconsistencies.


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More About This Work

Academic Units
Genetics and Development
Thesis Advisors
Yan, Kelley
Ph.D., Columbia University
Published Here
July 10, 2024