A sensitized screen of N-ethyl-N-nitrosourea-mutagenized mice identifies dominant mutants predisposed to diabetic nephropathy.
Diabetic nephropathy (DN) is a late diabetic complication that comprises progressively increasing albuminuria, declining GFR, and increased cardiovascular risk. Only a minority of patients with diabetes (25 to 40%) develop nephropathy, and there is evidence that heritable genetic factors predispose these "at-risk" individuals to DN. Comparing variability among inbred mouse strains with respect to a specific phenotype can model interhuman variability, and each strain represents a genetically homogeneous system with a defined risk for nephropathy. C57BL/6 mice, which are relatively resistant to DN, were mutagenized using N-ethyl-N-nitrosourea and screened for mutants that developed excess albuminuria on a sensitizing type 1 diabetic background contributed by the dominant Akita mutation in insulin-2 gene (Ins2(Akita)). Two of 375 diabetic G1 founders were found to exhibit albumin excretion rates persistently 10-fold greater than albumin excretion rates in nonmutagenized Ins2(Akita) controls. This albuminuria trait was heritable and transmitted to approximately 50% of Ins2(Akita) G2 and G3 progeny, consistent with a simple, dominantly inherited trait, but was never observed in nondiabetic offspring. During the course of 1 yr, albuminuric Ins2(Akita) G2 and G3 progeny developed reduced inulin clearance with elevated blood urea nitrogen and plasma creatinine. Glomerular histology revealed mesangial expansion, and glomerular basement membrane thickening as determined by electron microscopy was enhanced in diabetic mutant kidneys. Hereditary albuminuric N-ethyl-N-nitrosourea-induced mutants were redesignated as Nphrp1 (nephropathy1) and Nphrp2 (nephropathy2) mice for two generated lines. These novel mutants provide new, robust mouse models of DN and should help to elucidate the underlying genetic basis of predisposition to DN.
Tchekneva
Elena E
EE
Division of Nephrology and Hypertension, Vanderbilt University Medical Center, 21st Avenue S. at Garland, Nashville, TN 37232, USA. elena.tchekneva@vanderbilt.edu
Rinchik
Eugene M
EM
Polosukhina
Dina
D
Davis
Linda S
LS
Kadkina
Veronika
V
Mohamed
Yassir
Y
Dunn
Steve R
SR
Sharma
Kumar
K
Qi
Zhonghua
Z
Fogo
Agnes B
AB
Breyer
Matthew D
MD
D000419:Albuminuria / Q000235:genetics; D000818:Animals; D003928:Diabetic Nephropathies / Q000209:etiology / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D005038:Ethylnitrosourea / Q000633:toxicity*; D005260:Female; D005799:Genes, Dominant; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D007328:Insulin / Q000235:genetics; D007668:Kidney / Q000473:pathology / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009153:Mutagens / Q000633:toxicity*; D009154:Mutation; D010641:Phenotype; D012680:Sensitivity and Specificity
D007328:Insulin; D009153:Mutagens; D005038:Ethylnitrosourea