ABSTRACT
Objective: To clarify the molecular basis of patients with Bartter syndrome type I and explore the therapeutic effect of trafficking-defective variations by chemical chaperone 4-Phenylbutyric acid(4-PBA). Methods: The clinical characteristics, laboratory findings and genetic data of 3 patients diagnosed with Bartter syndrome type I who were admitted to Department of Nephrology, Children's Hospital of Nanjing Medical University from 2017 to 2018 were retrospectively analyzed. Wild type and variant SLC12A1 gene constructs were transiently overexpressed in HEK293 cells. Western blotting was used to detect the expression levels of Na+-K+-2Cl-cotransporter(NKCC2) protein. Immunofluorescent staining was applied to investigate the subcellular localization of NKCC2 protein. In addition, the effect of the chemical chaperone 4-PBA on the expression and localization of the SLC12A1 gene variants was investigated. Unpaired t test was used for statistical analysis of 4-PBA treatment. Results: All the 3 patients (2 males and 1 female), aged 3.0, 4.0 and 1.2 years, respectively. All patients had antenatal onset with polyhydramnios and were born prematurely. After birth, all patients presented with hypochlorine alkalosis accompanied by hypokalemia and hyponatremia. Sequencing analysis revealed that the 3 patients were homozygotes or compound heterozygotes for variants in the SLC12A1 gene. In HEK293 cells, the surface expression of NKCC2 in 3 variants (p.L463S, p.L479V, p.507-510del) are all lower than in wild type (0.718±0.039, 0.287±0.081, 0.025±0.156 vs. 1.001±0.028, t=5.92, 8.35, 30.49, all P<0.01). Moreover, the total protein expression of p.L479V and p.507-510del group were all lower than that in wild type group (0.630±0.032, 0.043±0.003 vs. 1.000±0.111, t=3.21, 8.65, all P<0.05). 4-PBA treatment increased the mature protein expression level of the p.L463S and p. L479V group in 4-PBA treatment group are all higher than the untreated group (0.459±0.018 vs. 1.123±0.024, 0.053±0.012 vs. 1.256±0.037, t=2.75, 18.35, all P<0.05). Cytoplasmic retention of the L479V and 507-510del variants were observed by immunofluorescent staining. 4-PBA treatment could rescue a number of NKCC2 L479V variants to the membrane. Conclusions: The 3 SLC12A1 variants cause expression or subcellular localization defects of the protein. The findings that plasma membrane expression and activity can be rescued by 4PBA might help to develop novel therapeutic strategy for Bartter syndrome type Ⅰ.
Subject(s)
Child, Preschool , Female , Humans , Infant , Male , Pregnancy , Bartter Syndrome/genetics , HEK293 Cells , Homozygote , Retrospective Studies , Solute Carrier Family 12, Member 1/geneticsABSTRACT
Objective To observe the abnormal Minnesota code (MC) distribution and interrelated characteristic on electrocardiograms (ECGs) of the adult Kazakh population.Methods Resting ECGs and blood press of randomly sampled 30 000 adult Kazakh people in three Northern regions of Xinjiang were continuously examined and analyzed,using Minnesota code recommended by WHO as the classification of ECG.Results The overall rate of abnormal ECG findings was 248.60‰,and the main abnormality in males was 146.83‰,compared to 157.71‰ in females.The prevalence rates of abnormal ST-T changes,the total arrhythmia and atrial fibrillation (AF) were 100.03‰,71.17‰ and 2.83‰ respectively.There were statistically significant differences among the main abnormities from the three regions.Conclusion The ECGs abnormalities of adult Kazakh people were high.There was significant relation found between the main abnormalities and hypertension.The prevalence of AF was different from the domestically reported literature that calls for further study.