Circadian regulation of uroguanylin and guanylin in the rat intestine.
Uroguanylin (UGN) and guanylin (GN) are the endogenous intestinal ligands for guanylyl cyclase C (GC-C). We examined the circadian expression of UGN, GN, and GC-C in the jejunum, ileum, and proximal colon of young adult rats by Northern blot analyses. These assays revealed that UGN is more abundant in the proximal small intestine, whereas GN and GC-C are more abundant in the proximal colon. mRNA levels showed significant circadian variation for UGN (3- to 18-fold peak/trough difference), GN (2.1- to 2.8-fold peak/trough difference), and GC-C (3- to 5-fold peak/trough difference). The maximal abundance occurred in the dark period for all three mRNAs, although peak UGN and GN expression occurred later in the dark period in the jejunum relative to the ileum and colon. Immunoblot analyses using monospecific polyclonal antibodies against UGN and GN prohormones confirmed the regional and circadian variation detected by Northern assays. Thus the expression of these genes is regulated not only by histological position but also by circadian time.
Scheving
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Division of Gastroenterology and Nutrition, Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. larry.scheving@mcmail.vanderbilt.edu
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D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D015152:Blotting, Northern; D015153:Blotting, Western; D002940:Circadian Rhythm / Q000502:physiology*; D003106:Colon / Q000737:chemistry / Q000201:enzymology; D020536:Enzyme Activators / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D005768:Gastrointestinal Hormones; D015870:Gene Expression / Q000502:physiology; D006162:Guanylate Cyclase / Q000032:analysis / Q000235:genetics / Q000276:immunology; D007082:Ileum / Q000737:chemistry / Q000201:enzymology; D007422:Intestines / Q000737:chemistry / Q000201:enzymology*; D007583:Jejunum / Q000737:chemistry / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D045265:Natriuretic Peptides; D010455:Peptides / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D011498:Protein Precursors / Q000032:analysis / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D018000:Receptors, Peptide / Q000032:analysis / Q000235:genetics / Q000276:immunology
D000911:Antibodies, Monoclonal; D020536:Enzyme Activators; D005768:Gastrointestinal Hormones; D045265:Natriuretic Peptides; D010455:Peptides; D011498:Protein Precursors; D012333:RNA, Messenger; D018000:Receptors, Peptide; C072685:guanylin; C084362:uroguanylin; D006162:Guanylate Cyclase; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled