RESUMO
Using a large-scale genotyping analysis of gene-based single nucleotide polymorphisms (SNPs) in Japanese type 2 diabetic patients, we have identified a gene encoding neurocalcin delta (NCALD) as a candidate for a susceptibility gene to diabetic nephropathy; the landmark SNP was found in the 3' UTR of NCALD (rs1131863: exon 4 +1340 A vs. G, P = 0.00004, odds ratio = 1.59, 95% CI 1.27-1.98). We also discovered two other SNPs in exon 4 of this gene (+999 T/A, +1307 A/G) that showed absolute linkage disequilibrium to the landmark SNP. Subsequent in vitro functional analysis revealed that synthetic mRNA corresponding to the disease susceptible haplotype (exon 4 +1340 G, +1307 G, +999 A) was degraded faster than mRNA corresponding to the major haplotype (exon 4 +1340 A, +1307 A, +999 T), and allelic mRNA expression of the disease susceptibility allele was significantly lower than that of the major allele in normal kidney tissues. In an experiment using a short interfering RNA targeting NCALD, we found that silencing of the NCALD led to a considerable enhancement of cell migration, accompanied by a significant reduction in E-cadherin expression, and by an elevation of alpha smooth muscle actin expression in cultured renal proximal tubular epithelial cells. We also identified the association of the landmark SNP with the progression of diabetic nephropathy in a 8-year prospective study (A vs. G, P = 0.03, odds ratio = 1.91, 95% CI 1.07-3.42). These results suggest that the NCALD gene is a likely candidate for conferring susceptibility to diabetic nephropathy.
Assuntos
Neuropatias Diabéticas/genética , Neurocalcina/genética , Polimorfismo de Nucleotídeo Único , Estabilidade de RNA/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Regiões 3' não Traduzidas , Alelos , Sequência de Bases , Estudos de Casos e Controles , Células Cultivadas , Estudos de Coortes , Primers do DNA/genética , Proteínas de Ligação a DNA/genética , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Perfilação da Expressão Gênica , Predisposição Genética para Doença , Humanos , Técnicas In Vitro , Desequilíbrio de Ligação , Estudos Prospectivos , Interferência de RNA , Fatores de Transcrição/genéticaRESUMO
To search for a gene(s) conferring susceptibility to diabetic nephropathy (DN), we genotyped over 80,000 gene-based single nucleotide polymorphisms (SNPs) in Japanese patients and identified that the engulfment and cell motility 1 gene (ELMO1) was a likely candidate for conferring susceptibility to DN, in view of the significant association of an SNP in this gene with the disease (intron 18+9170, GG vs. GA+AA, chi(2) = 19.9, P = 0.000008; odds ratio 2.67, 95% CI 1.71-4.16). In situ hybridization (ISH) using the kidney of normal and diabetic mice revealed that ELMO1 expression was weakly detectable mainly in tubular and glomerular epithelial cells in normal mouse kidney and was clearly elevated in the kidney of diabetic mice. Subsequent in vitro analysis revealed that ELMO1 expression was elevated in cells cultured under high glucose conditions (25 mmol/l) compared with cells cultured under normal glucose conditions (5.5 mmol/l). Furthermore, we identified that the expression of extracellular matrix protein genes, such as type 1 collagen and fibronectin, were increased in cells that overexpress ELMO1, whereas the expression of matrix metalloproteinases was decreased. These results indicate that ELMO1 is a novel candidate gene that both confers susceptibility to DN and plays an important role in the development and progression of this disease.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Diabetes Mellitus Tipo 2/genética , Nefropatias Diabéticas/genética , Proteínas Adaptadoras de Transdução de Sinal/biossíntese , Alelos , Animais , Sequência de Bases , Células COS , Proteínas da Matriz Extracelular/metabolismo , Expressão Gênica , Predisposição Genética para Doença , Variação Genética , Humanos , Hibridização In Situ , Rim/metabolismo , Metaloproteinases da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos NOD , Polimorfismo de Nucleotídeo Único , Fator de Crescimento Transformador beta/metabolismo , Fator de Crescimento Transformador beta1RESUMO
To identify genetic elements that might confer susceptibility to diabetic nephropathy, we performed a genome-wide analysis of gene-based single nucleotide polymorphisms (SNPs) in a large cohort of Japanese patients with diabetes. In case-control association studies, patients with type 2 diabetes were divided into two groups, one having retinopathy as well as overt nephropathy and the other (the control group) having diabetic retinopathy but with no signs of renal involvement. Genotyping of these patients at >55,000 SNP loci indicated a gene encoding solute carrier family 12 member 3 (SLC12A3) to be a good candidate for the susceptibility to diabetic nephropathy, in view of a significant association of one landmark SNP located in the 24th intron (chi(2) = 15.4, P = 0.000087, odds ratio = 2.53 [95% CI 1.57-4.09]). Subsequent analysis of additional genetic variations in this gene identified several SNPs that were significantly associated with nephropathy, especially one in exon 23 (+78 G to A: Arg913Gln, chi(2) = 18.5, P = 0.00002, odds ratio = 2.53 [95% CI 1.64-3.90]). The results implicated that substitution of Arg913 to Gln in the SLC12A3 gene might reduce the risk to develop diabetic nephropathy and suggested that the gene product might be a potential target for the prevention or treatment of this disease.
