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Open Biol. 2017 Jun;7(6). pii: 170024. doi: 10.1098/rsob.170024.

SUMOylation pathway alteration coupled with downregulation of SUMO E2 enzyme at mucosal epithelium modulates inflammation in inflammatory bowel disease.

Author information

1
Laboratory of gut inflammation and infection biology (LGIIB), Regional Centre for Biotechnology, 3rd milestone Gurgaon Faridabad Expressway, Faridabad, India.
2
Department of Gastroenterology, Manipal University, Manipal, Karnataka, India.
3
Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha, India.
4
Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Boston, MA, USA.
5
Functional interactomics laboratory, Bose Institute Kolkata, P 1/12, C.I.T Road, Scheme VII M, Kolkata 700054, India.
6
All India Institute of Medical Sciences, Ansari Nagar East, New Delhi, India.
7
National Institute of Immunology, New Delhi, India.
8
All India Institute of Medical Sciences, Ansari Nagar East, New Delhi, India vineet.aiims@gmail.com.
9
Laboratory of gut inflammation and infection biology (LGIIB), Regional Centre for Biotechnology, 3rd milestone Gurgaon Faridabad Expressway, Faridabad, India cvsrikanth@rcb.res.in.

Abstract

Post-translational modification pathways such as SUMOylation are integral to all cellular processes and tissue homeostasis. We investigated the possible involvement of SUMOylation in the epithelial signalling in Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel disease (IBD). Initially in a murine model of IBD, induced by dextran-sulfate-sodium (DSS mice), we observed inflammation accompanied by a lowering of global SUMOylation of colonic epithelium. The observed SUMOylation alteration was due to a decrease in the sole SUMO E2 enzyme (Ubc9). Mass-spectrometric analysis revealed the existence of a distinct SUMOylome (SUMO-conjugated proteome) in DSS mice with alteration of key cellular regulators, including master kinase Akt1. Knocking-down of Ubc9 in epithelial cells resulted in dramatic activation of inflammatory gene expression, a phenomenon that acted via reduction in Akt1 and its SUMOylated form. Importantly, a strong decrease in Ubc9 and Akt1 was also seen in endoscopic biopsy samples (N = 66) of human CD and UC patients. Furthermore, patients with maximum disease indices were always accompanied by severely lowered Ubc9 or SUMOylated-Akt1. Mucosal tissues with severely compromised Ubc9 function displayed higher levels of pro-inflammatory cytokines and compromised wound-healing markers. Thus, our results reveal an important and previously undescribed role for the SUMOylation pathway involving Ubc9 and Akt1 in modulation of epithelial inflammatory signalling in IBD.

KEYWORDS:

SUMOylation; colitis; epithelial signalling; inflammation; post-translational modification

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