title: Clock is important for food and circadian regulation of macronutrient absorption in mice.
abstract: Clock genes respond to external stimuli and exhibit circadian rhythms. This study investigated the expression of clock genes in the small intestine and their contribution in the regulation of nutrient absorption by enterocytes. We examined expression of clock genes and macronutrient transport proteins in the small intestines of wild-type and Clock mutant (Clk(mt/mt)) mice with free or limited access to food. In addition, we studied absorption of macronutrients in these mice. Intestinal clock genes show circadian expression and respond to food entrainment in wild-type mice. Dominant negative Clock in Clk(mt/mt) mice disrupts circadian expression and food entrainment of clock genes. The absorption of lipids and monosaccharides was high in Clk(mt/mt) mice whereas peptide absorption was reduced. Molecular studies revealed that Clock regulates several transport proteins involved in nutrient absorption. Clock plays an important role in light and food entrainment of intestinal functions by regulating nutrient transport proteins. Disruptions in intestinal circadian activity may contribute to hyperlipidemia and hyperglycemia.
authors.affiliation: Departments of Anatomy and Cell Biology, and Pediatrics, State University of New York Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Pan
authors.forename: M Mahmood
authors.initials: MM
authors.lastname: Hussain
mesh_terms: D000818:Animals; D056926:CLOCK Proteins / Q000235:genetics / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects*; D005502:Food; D005786:Gene Expression Regulation / Q000528:radiation effects; D005947:Glucose / Q000378:metabolism; D007408:Intestinal Absorption / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects*; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D050356:Lipid Metabolism / Q000528:radiation effects; D008297:Male; D051379:Mice; D010455:Peptides / Q000378:metabolism
chemical_list: D010455:Peptides; D056926:CLOCK Proteins; D005947:Glucose