Abnormal expression and dysfunction of novel SGLT2 mutations identified in familial renal glucosuria patients
Abnormal expression and dysfunction of novel SGLT2 mutations identified in familial renal glucosuria patients
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家族性肾性糖尿患者中新发现的 SGLT2 突变的异常表达和功能障碍
DOI：
10.1007/s00439-010-0927-z
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发表时间：
2011-03-01
期刊：
影响因子：
5.3
通讯作者：
Zhang, Hong
中科院分区：
文献类型：
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作者：
Yu, Lei;Lv, Ji-Cheng;Zhang, Hong
家族性肾性葡萄糖尿症(FRG)的特征是，尽管血糖正常，但无明显的肾小管功能障碍，但仍持续糖尿。钠/葡萄糖共转运蛋白2(SGLT2)的突变已被发现，并最近被报道与FRG有关。然而，这种突变的功能和病理后果仍不清楚。在本研究中，我们收集了四个FRG家系。对SGLT2编码区、内含子片段和cDNA进行测序，发现3个错义突变(294C>；A：F98L；1388T>；G：L463R；1435C>；G：R479G)和两个剪接突变(IVS 1-16C>；A：Delexon3；IVS11+11G>；C：DelExon11)。先证者为SGLT2突变杂合子或复合杂合子，血糖定量为6-27微克/天。将构建的重组真核表达载体导入人293细胞，体外研究SGLT2突变体的表达和功能。使用绿色荧光蛋白(GFP)的共聚焦显微镜显示，除了294C>；A突变体外，突变导致了野生型SGLT2典型的点状膜模式的丢失。所有突变体的转运能力均显著低于野生型对照(26.49-71.48%)。一名同意的先证者的肾脏活检显示，与健康对照组和疾病对照组(微小病变病和糖尿病肾病)相比，近曲小管顶侧SGLT2的表达显著降低。目前的研究提供了有关SGLT2分子在FRG家族中从基因型到表型的功能线索。
Familial renal glucosuria (FRG) is characterized by persistent glucosuria despite normal serum glucose and in the absence of overt tubular dysfunction. Mutation of sodium/glucose co-transporter 2 (SGLT2) has been identified and was recently reported to be involved in FRG. However, the functional and pathological consequences of such mutations remain unknown. In the current study, we collected four families with FRG. Sequencing of the SGLT2 coding region, intronic segments and cDNA revealed three missense mutations (294C>A: F98L; 1388T>G: L463R; 1435C>G: R479G) and two splice mutations (IVS 1-16 C>A: Del exon3; IVS 11 + 1 G>C: Del exon11). The probands were either heterozygous or compound heterozygous for SGLT2 mutations, and had glucosuria quantified at 6–27 g/day. Human 293 cells were transfected with the plasmid constructs to study the expression and function of SGLT2 mutants in vitro. Confocal microscopy using green fluorescent protein (GFP) revealed that the mutation results in a loss of punctate membrane pattern typical of the wild-type SGLT2 except in the 294C>A mutant. All mutants had significantly lower transport capacity in comparison to the wild-type control (26.49–71.48%). Renal biopsy in one consenting proband revealed significantly lower SGLT2 expression in the apical side of the proximal convoluted tubule in comparison to both healthy and disease controls (minimal change disease and diabetic nephropathy). The current study provides functional clues regarding the SGLT2 molecule from genotype to phenotype in FRG families.