The transcription factor Chronophage/BCL11A/B promotes intestinal stem cell proliferation and endocrine differentiation in the Drosophila intestine

Tissue-resident Adult Stem Cells (ASCs) need to continuously adapt their rate of division and differentiation based on their tissue environment. However, the gene regulatory networks that govern these decisions in ASCs and how they respond to challenges such as infection are often not fully understood. We use the Intestinal Stem Cells (ISCs) that maintain the adult Drosophila intestine or midgut as a model to study how transcriptional regulators govern ASC behaviour. We identify a novel role for the transcription factor (TF) Chronophage (Cph) in ISC proliferation and entero-endocrine (EE) cell differentiation. Cph is a Z2H2 zinc TF orthologous to mammalian BCL11A/B and recent work in Drosophila has demonstrated a role in regulating differentiation of neural stem cells (NSCs). We show here that Cph is expressed in ISCs and EEs in the Drosophila intestine. Increased levels of Cph correlates with increased ISC proliferation and EE differentiation. cph loss-of-function leads to impaired ISC proliferation. Cph levels are elevated during tumourigenesis as well as in ageing and infection conditions. Knockdown of Cph in a Notch-mutant tumour model reduces tumour size and incidence and extends lifespan. Mechanistically, Cph overexpression leads to an increase in enteroendocrine (EE) cells and DamID DNA-binding and qRT-PCR analysis reveals that Cph directly regulates the levels of key EE regulatory genes such as Prospero ( pros ) and Phyllopod ( phyl ). In addition, Cph directly regulates core cell cycle regulators such as E2F1 as well as the TF Nerfin-1 that controls ISC proliferation and maintenance. Together, these data support a role for Cph in finetuning the balance between differentiation and proliferation during entero-endocrine differentiation.