Improved insulin sensitivity and resistance to weight gain in mice null for the Ahsg gene.
Fetuin inhibits insulin-induced insulin receptor (IR) autophosphorylation and tyrosine kinase activity in vitro, in intact cells, and in vivo. The fetuin gene (AHSG) is located on human chromosome 3q27, recently identified as a susceptibility locus for type 2 diabetes and the metabolic syndrome. Here, we explore insulin signaling, glucose homeostasis, and the effect of a high-fat diet on weight gain, body fat composition, and glucose disposal in mice carrying two null alleles for the gene encoding fetuin, Ahsg (B6, 129-Ahsg(tm1Mbl)). Fetuin knockout (KO) mice demonstrate increased basal and insulin-stimulated phosphorylation of IR and the downstream signaling molecules mitogen-activated protein kinase (MAPK) and Akt in liver and skeletal muscle. Glucose and insulin tolerance tests in fetuin KO mice indicate significantly enhanced glucose clearance and insulin sensitivity. Fetuin KO mice subjected to euglycemic-hyperinsulinemic clamp show augmented sensitivity to insulin, evidenced by increased glucose infusion rate (P = 0.077) and significantly increased skeletal muscle glycogen content (P < 0.05). When fed a high-fat diet, fetuin KO mice are resistant to weight gain, demonstrate significantly decreased body fat, and remain insulin sensitive. These data suggest that fetuin may play a significant role in regulating postprandial glucose disposal, insulin sensitivity, weight gain, and fat accumulation and may be a novel therapeutic target in the treatment of type 2 diabetes, obesity, and other insulin-resistant conditions.
Mathews
Suresh T
ST
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Singh
Gurmant P
GP
Ranalletta
Mollie
M
Cintron
Vivian J
VJ
Qiang
Xiaoling
X
Goustin
Anton Scott
AS
Jen
Kai-Lin Catherine
KL
Charron
Maureen J
MJ
Jahnen-Dechent
Willi
W
Grunberger
George
G
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001798:Blood Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018752:Diet, Fat-Restricted; D004041:Dietary Fats; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin / Q000378:metabolism; D012016:Reference Values; D015430:Weight Gain / Q000187:drug effects / Q000235:genetics*; D060749:alpha-2-HS-Glycoprotein; D000509:alpha-Fetoproteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology
C556354:AHSG protein, human; C556357:Ahsg protein, mouse; D001786:Blood Glucose; D001798:Blood Proteins; D004041:Dietary Fats; D007328:Insulin; D011518:Proto-Oncogene Proteins; D060749:alpha-2-HS-Glycoprotein; D000509:alpha-Fetoproteins; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt