The WT1-like transcription factor Klumpfuss maintains lineage commitment in the intestine

Stem cell (SC) lineages in barrier epithelia exhibit a high degree of plasticity. Mechanisms that govern the precise specification of SC daughter cells during regenerative episodes are therefore critical to maintain homeostasis. One such common mechanism is the transient activation of the Notch (N) signaling pathway. N controls the choice between absorptive and entero-endocrine cell fates in both the mammalian small intestine and the Drosophila midgut, yet how precisely N signaling promotes lineage restriction in progenitor cells remains unclear. Here, we describe a role for the WT1-like transcription factor Klumpfuss (Klu) in restricting the fate of Drosophila enteroblasts (EBs) downstream of N activation. Klu is transiently induced in Notch-positive EBs and its transient activity restricts cell fate towards the enterocyte (EC) lineage. Transcriptomics and DamID profiling show that Klu suppresses enteroendocrine (EE) cell fates by repressing E(Spl)m8-HLH and Phyllopod, both negative regulators of the proneural gene Scute, which is essential for EE differentiation. At the same time, Klu suppresses cell cycle genes, committing EBs to differentiation. Klu-mediated repression of its own transcription further sets up a negative feedback loop that ensures temporal restriction of Klu-mediated gene regulation, and is essential for subsequent differentiation of ECs. Our findings define a transient cell state in which EC lineage restriction is cemented, and establish a hierarchy of transcriptional programs critical in executing a differentiation program downstream of initial induction events governed by N signaling.