Guanylyl cyclase C maintains integrity of intestinal stem cells through modulation of endoplasmic reticulum stress
Intestinal stem cells (ISCs) are a long-lived, dynamic cell population at the base of intestinal crypts that adjust their molecular phenotypes as necessary to meet the maintenance and regenerative needs of the epithelium. The long-life, plasticity and proliferative potential of ISCs underlie the necessity for tight regulation, as these cells have been implicated as initiators of colorectal tumorigenesis. In that context, guanylyl cyclase C (GCC) and its effector, cGMP, regulate intestinal epithelial proliferation, differentiation, and susceptibility to intestinal insult and tumor formation. However, the specific role of this signaling axis in ISCs remains undefined. Here, utilizing transgenic mouse models and immunodetection techniques, we reveal that GCC mediates ligand-dependent cGMP signal transduction in ISCs. Further, the absence of GCC alters expression of key ISC markers, decreasing the active ISC marker Lgr5 and increasing the reserve ISC marker Bmi1. Endoplasmic reticulum (ER) stress, which is typically absent from ISCs and has been associated with inflammation and tumorigenesis, is elevated throughout the crypt base in the absence of GCC. Conversely, administration of cGMP or the chemical chaperone tauroursodeoxycholic acid eliminates ER stress and restores the normal crypt ISC phenotype. Finally, ISCs exhibit an impaired regeneration response following irradiation in the absence of GCC, highlighting the importance of this signaling pathway in ISC survival and epithelial repair. Together, these observations suggest that GCC signaling modulates ER stress as part of the essential machinery defending the integrity of the ISC niche.
Kraft, Crystal L, "Guanylyl cyclase C maintains integrity of intestinal stem cells through modulation of endoplasmic reticulum stress" (2016). ETD Collection for Thomas Jefferson University. AAI10109324.