SCGN deficiency results in colitis susceptibility.

Area of Science:

• Genetics and Molecular Biology
• Gastroenterology
• Neuroendocrinology

Background:

• Inflammatory bowel disease (IBD) has a significant genetic component, but much of the genetic predisposition remains unexplained.
• The SCGN gene encodes a calcium sensor protein crucial for vesicle fusion in neuroendocrine cells.

Purpose of the Study:

• To identify novel genetic factors contributing to unexplained IBD.
• To investigate the role of the SCGN gene in the pathogenesis of early-onset ulcerative colitis.

Main Methods:

• Identification and characterization of an ultrarare missense variant in the SCGN gene.
• Assessment of the variant's impact on SCGN protein function, including SNARE complex interaction and hormone release.
• Evaluation of Scgn-deficient mouse models for intestinal inflammation and hormone release defects.

Main Results:

• An ultrarare SCGN missense variant (p.Arg77His) was identified as a cause of Mendelian early-onset ulcerative colitis.
• The identified SCGN mutation disrupted SNAP25 localization, leading to impaired hormone release.
• Scgn deficiency in mice mimicked impaired hormone release and increased susceptibility to colitis.

Conclusions:

• Functional deficiency in SCGN can lead to intestinal inflammation, specifically ulcerative colitis.
• The neuroendocrine cellular compartment plays a significant role in IBD pathogenesis.
• SCGN is a novel genetic factor implicated in inflammatory bowel disease.