Mitochondria regulate intestinal stem cell proliferation and epithelial homeostasis through FOXO

Area of Science:

• Cell Biology
• Developmental Biology
• Metabolism

Background:

• Stem cell differentiation often involves a metabolic shift towards oxidative phosphorylation.
• The precise role of mitochondrial respiration in stem cell behavior remains unclear.
• Intestinal stem cells (ISCs) in *Drosophila* provide a model for studying stem cell dynamics.

Purpose of the Study:

• To investigate the necessity of mitochondrial respiration for *Drosophila* ISC proliferation and differentiation.
• To elucidate the molecular mechanisms linking mitochondrial function to ISC behavior.

Main Methods:

• Genetic disruption of electron transport chain (ETC) complexes in *Drosophila* ISCs.
• Analysis of ISC proliferation, enteroblast production, and enterocyte differentiation.
• Assessment of forkhead box O (FOXO) signaling pathway activity.
• Evaluation of reactive oxygen species (ROS) levels.

Main Results:

• Impaired ETC function in ISCs led to significantly reduced proliferation and enteroblast production.
• Failure of enteroblast differentiation into enterocytes was observed in ETC-deficient ISCs.
• Elevated FOXO signaling in ETC-deficient ISCs was identified as a key impediment.
• Suppression of FOXO signaling partially rescued enterocyte differentiation.
• Reactive oxygen species (ROS) accumulation did not mediate the observed phenotype.

Conclusions:

• Mitochondrial respiration is essential for *Drosophila* ISC proliferation and lineage specification *in vivo*.
• Mitochondrial respiration regulates ISC behavior, at least in part, by repressing FOXO signaling.
• The findings challenge the assumption that ROS accumulation is the primary mediator of mitochondrial dysfunction phenotypes in ISCs.