Oncotarget

Research Papers:

GUCY2C maintains intestinal LGR5+ stem cells by opposing ER stress

Crystal L. Kraft, Jeffrey A. Rappaport, Adam E. Snook, Amanda M. Pattison, John P. Lynch and Scott A. Waldman _

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Oncotarget. 2017; 8:102923-102933. https://doi.org/10.18632/oncotarget.22084

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Abstract

Crystal L. Kraft1, Jeffrey A. Rappaport1, Adam E. Snook1, Amanda M. Pattison1, John P. Lynch2 and Scott A. Waldman1

1Department of Pharmacology and Experimental Therapeutics, Thomas Jefferson University, Philadelphia, United States of America, PA, USA

2Division of Gastroenterology, Department of Medicine, Abramson Cancer Center, University of Pennsylvania, Philadelphia, United States of America, PA, USA

Correspondence to:

Scott A. Waldman, email: Scott.Waldman@jefferson.edu

Keywords: intestinal stem cell; guanylate cyclase C; Lgr5; Bmi1; epithelial regeneration

Received: July 12, 2017     Accepted: October 11, 2017     Published: October 26, 2017

ABSTRACT

Long-lived multipotent stem cells (ISCs) at the base of intestinal crypts adjust their phenotypes to accommodate normal maintenance and post-injury regeneration of the epithelium. Their long life, lineage plasticity, and proliferative potential underlie the necessity for tight homeostatic regulation of the ISC compartment. In that context, the guanylate cyclase C (GUCY2C) receptor and its paracrine ligands regulate intestinal epithelial homeostasis, including proliferation, lineage commitment, and DNA damage repair. However, a role for this axis in maintaining ISCs remains unknown. Transgenic mice enabling analysis of ISCs (Lgr5-GFP) in the context of GUCY2C elimination (Gucy2c–/–) were combined with immunodetection techniques and pharmacological treatments to define the role of the GUCY2C signaling axis in supporting ISCs. ISCs were reduced in Gucy2c–/– mice, associated with loss of active Lgr5+ cells but a reciprocal increase in reserve Bmi1+ cells. GUCY2C was expressed in crypt base Lgr5+ cells in which it mediates canonical cyclic (c) GMP-dependent signaling. Endoplasmic reticulum (ER) stress, typically absent from ISCs, was elevated throughout the crypt base in Gucy2c–/– mice. The chemical chaperone tauroursodeoxycholic acid resolved this ER stress and restored the balance of ISCs, an effect mimicked by the GUCY2C effector 8Br-cGMP. Reduced ISCs in Gucy2c–/–mice was associated with greater epithelial injury and impaired regeneration following sub-lethal doses of irradiation. These observations suggest that GUCY2C provides homeostatic signals that modulate ER stress and cell vulnerability as part of the machinery contributing to the integrity of ISCs.


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