Effects of Muclin (Dmbt1) deficiency on the gastrointestinal system.
The Dmbt1 gene encodes alternatively spliced glycoproteins that are either membrane-associated or secreted epithelial products. Functions proposed for Dmbt1 include it being a tumor suppressor, having roles in innate immune defense and inflammation, and being a Golgi-sorting receptor in the exocrine pancreas. The heavily sulfated membrane glycoprotein mucin-like glycoprotein (Muclin) is a Dmbt1 product that is strongly expressed in organs of the gastrointestinal (GI) system. To explore Muclin's functions in the GI system, the Dmbt1 gene was targeted to produce Muclin-deficient mice. Muclin-deficient mice have normal body weight gain and are fertile. The Muclin-deficient mice did not develop GI tumors, even when crossed with mice lacking the known tumor suppressor p53. When colitis was induced by dextran sulfate sodium, there was no significant difference in disease severity in Muclin-deficient mice. Also, when acute pancreatitis was induced with supraphysiological caerulein, there was no difference in disease severity in the Muclin-deficient mice. Exocrine pancreatic function was impaired, as measured by attenuated neurohormonal-stimulated amylase release from Muclin-deficient acinar cells. Also, by [(35)S]Met/Cys pulse-chase analysis, traffic of newly synthesized protein to the stimulus-releasable pool was significantly retarded in Muclin-deficient cells compared with wild type. Thus Muclin deficiency impairs trafficking of regulated proteins to a stimulus-releasable pool in the exocrine pancreas.
De Lisle
Robert C
RC
Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, KS 66160, USA. rdelisle@kumc.edu
Xu
Weihong
W
Roe
Bruce A
BA
Ziemer
Donna
D
D000681:Amylases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins; D002108:Ceruletide; D003092:Colitis / Q000139:chemically induced / Q000235:genetics / Q000473:pathology; D004268:DNA-Binding Proteins; D016264:Dextran Sulfate; D004591:Electrophoresis, Polyacrylamide Gel; D005770:Gastrointestinal Neoplasms / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D041981:Gastrointestinal Tract / Q000502:physiology*; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009077:Mucins / Q000172:deficiency* / Q000235:genetics; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010195:Pancreatitis / Q000139:chemically induced / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D025521:Tumor Suppressor Proteins
D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; C114202:Dmbt1 protein, mouse; D009077:Mucins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D002108:Ceruletide; D016264:Dextran Sulfate; D000681:Amylases