Glucose homeostasis and tissue transcript content of insulin signaling intermediates in four inbred strains of mice: C57BL/6, C57BLKS/6, DBA/2, and 129X1.
Transgenic mice phenotypes generally depend on the background strains used in their creation. To examine the effects of genetic background on insulin signaling, we analyzed glucose homeostasis in four inbred strains of mice [C57BL/6 (B6), C57BLKS/6 (KLS), DBA/2 (DBA), and 129X1] and quantitated mRNA content of insulin receptor (IR) and its substrates in insulin-responsive tissues. At 2 months, the male B6 mouse is the least glucose-tolerant despite exhibiting similar insulin sensitivity and first-phase insulin secretion as the other strains. The 129X1 male mouse islet contains less insulin and exhibits a higher threshold for glucose-stimulated first-phase insulin secretion than the other strains. Female mice generally manifest better glucose tolerance than males, which is likely due to greater insulin sensitivity in liver and adipose tissue, a robust first-phase insulin secretion in B6 and KLS females, and improved insulin sensitivity in muscle in DBA and 129X1 females. At 6 months, although males exhibit improved first-phase insulin secretion, their physiology was relatively unchanged, whereas female B6 and KLS mice became less insulin sensitive. Gene expression of insulin signaling intermediates in insulin-responsive tissues was generally not strain dependent with the cell content of IR mRNA being highest. IR substrate (IRS)-1 and IRS-2 mRNA are ubiquitously expressed and IRS-3 and IRS-4 mRNA were detected in significant amounts in fat and brain tissues, respectively. These data indicate strain-, gender-, and age-dependent tissue sensitivity to insulin that is generally not associated with transcript content of IR or its substrates and should be taken into consideration during phenotypic characterization of transgenic mice.
Goren
H Joseph
HJ
Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA.
Kulkarni
Rohit N
RN
Kahn
C Ronald
CR
D000273:Adipose Tissue / Q000502:physiology; D000375:Aging; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000235:genetics*; D007004:Hypoglycemic Agents / Q000378:metabolism* / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin / Q000097:blood; D008099:Liver / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000502:physiology; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D017526:Receptor, IGF Type 1 / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D013045:Species Specificity
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526295:Irs1 protein, mouse; C526298:Irs2 protein, mouse; C108872:Irs3 protein, mouse; D020738:Leptin; D010750:Phosphoproteins; D012333:RNA, Messenger; D017526:Receptor, IGF Type 1; D005947:Glucose