title: Lack of REDD1 reduces whole body glucose and insulin tolerance, and impairs skeletal muscle insulin signaling.
abstract: A lack of the REDD1 promotes dysregulated growth signaling, though little has been established with respect to the metabolic role of REDD1. Therefore, the goal of this study was to determine the role of REDD1 on glucose and insulin tolerance, as well as insulin stimulated growth signaling pathway activation in skeletal muscle. First, intraperitoneal (IP) injection of glucose or insulin were administered to REDD1 wildtype (WT) versus knockout (KO) mice to examine changes in blood glucose over time. Next, alterations in skeletal muscle insulin (IRS-1, Akt, ERK 1/2) and growth (4E-BP1, S6K1, REDD1) signaling intermediates were determined before and after IP insulin treatment (10min). REDD1 KO mice were both glucose and insulin intolerant when compared to WT mice, evident by higher circulating blood glucose concentrations and a greater area under the curve following IP injections of glucose or insulin. While the REDD1 KO exhibited significant though blunted insulin-stimulated increases (p<0.05) in Akt S473 and T308 phosphorylation versus the WT mice, acute insulin treatment has no effect (p<0.05) on REDD1 KO skeletal muscle 4E-BP1 T37/46, S6K1 T389, IRS-1 Y1222, and ERK 1/2 T202/Y204 phosphorylation versus the WT mice. Collectively, these novel data suggest that REDD1 has a more distinct role in whole body and skeletal muscle metabolism and insulin action than previously thought.
authors.affiliation: Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States.
authors.forename: Cory M
authors.initials: CM
authors.lastname: Dungan
authors.affiliation: Department of Human Health and Nutrition Sciences, University of Guelph, Guelph, ON, Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Wright
authors.affiliation: Department of Exercise and Nutrition Sciences, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States. Electronic address: davidwil@buffalo.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Williamson
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; C469992:Ddit4 protein, mouse; D007328:Insulin; D046912:Multiprotein Complexes; D014157:Transcription Factors; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D005947:Glucose
keywords: Akt; ERK1/2; Insulin action; RTP801; mTOR