Core Concepts
Hair follicle stem cells tightly regulate the clearance of apoptotic cells through a dual lipid and retinoid signaling mechanism to balance phagocytic duties with their primary function of preserving tissue integrity during homeostasis.
Abstract
The content explores the mechanisms by which non-motile, non-professional phagocytes, such as hair follicle stem cells, can sense and eliminate dying cells while maintaining their normal tissue functions.
Key highlights:
- Billions of cells are eliminated daily from our bodies, and many epithelial and mesenchymal tissue cells can digest nearby apoptotic corpses.
- The authors exploit the cyclical bouts of tissue regeneration and degeneration during hair cycling to study this process.
- Hair follicle stem cells transiently unleash phagocytosis at the correct time and place through local molecular triggers that depend on both lipids released by neighboring apoptotic corpses and retinoids released by healthy counterparts.
- The activation of the RARγ–RXRα nuclear receptor complex enables tight regulation of apoptotic cell clearance genes and provides an effective, tunable mechanism to offset phagocytic duties against the primary stem cell function of preserving tissue integrity during homeostasis.
- The authors provide functional evidence that hair follicle stem cell-mediated phagocytosis is not simply redundant with professional phagocytes but rather has clear benefits to tissue fitness.
- The findings have broad implications for other non-motile tissue stem or progenitor cells that encounter cell death in an immune-privileged niche.
Stats
Billions of cells are eliminated daily from our bodies.
Many epithelial and mesenchymal tissue cells can digest nearby apoptotic corpses.
Quotes
"How these non-motile, non-professional phagocytes sense and eliminate dying cells while maintaining their normal tissue functions is unclear."
"We trace the heart of this dual ligand requirement to RARγ–RXRα, whose activation enables tight regulation of apoptotic cell clearance genes and provides an effective, tunable mechanism to offset phagocytic duties against the primary stem cell function of preserving tissue integrity during homeostasis."