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KCNJ10 gene mutations causing EAST syndrome (epilepsy, ataxia, sensorineural deafness, and tubulopathy) disrupt channel function
- Source :
- Proceedings of the National Academy of Sciences. 107:14490-14495
- Publication Year :
- 2010
- Publisher :
- Proceedings of the National Academy of Sciences, 2010.
-
Abstract
- Mutations of the KCNJ10 ( Kir4.1 ) K + channel underlie autosomal recessive epilepsy, ataxia, sensorineural deafness, and (a salt-wasting) renal tubulopathy (EAST) syndrome. We investigated the localization of KCNJ10 and the homologous KCNJ16 in kidney and the functional consequences of KCNJ10 mutations found in our patients with EAST syndrome. Kcnj10 and Kcnj16 were found in the basolateral membrane of mouse distal convoluted tubules, connecting tubules, and cortical collecting ducts. In the human kidney, KCNJ10 staining was additionally observed in the basolateral membrane of the cortical thick ascending limb of Henle's loop. EM of distal tubular cells of a patient with EAST syndrome showed reduced basal infoldings in this nephron segment, which likely reflects the morphological consequences of the impaired salt reabsorption capacity. When expressed in CHO and HEK293 cells, the KCNJ10 mutations R65P, G77R, and R175Q caused a marked impairment of channel function. R199X showed complete loss of function. Single-channel analysis revealed a strongly reduced mean open time. Qualitatively similar results were obtained with coexpression of KCNJ10/KCNJ16, suggesting a dominance of KCNJ10 function in native renal KCNJ10/KCNJ16 heteromers. The decrease in the current of R65P and R175Q was mainly caused by a remarkable shift of pH sensitivity to the alkaline range. In summary, EAST mutations of KCNJ10 lead to impaired channel function and structural changes in distal convoluted tubules. Intriguingly, the metabolic alkalosis present in patients carrying the R65P mutation possibly improves residual function of KCNJ10, which shows higher activity at alkaline pH.
- Subjects :
- medicine.medical_specialty
Ataxia
Hearing Loss, Sensorineural
Mutation, Missense
Nephron
KCNJ10
Gene mutation
Transfection
Cell Line
Mice
Tubulopathy
Internal medicine
medicine
EAST syndrome
Animals
Humans
Abnormalities, Multiple
Potassium Channels, Inwardly Rectifying
Kidney Tubules, Distal
Kidney
Epilepsy
Multidisciplinary
biology
Reabsorption
Syndrome
Biological Sciences
medicine.disease
Mice, Inbred C57BL
medicine.anatomical_structure
Endocrinology
biology.protein
Kidney Diseases
medicine.symptom
Subjects
Details
- ISSN :
- 10916490 and 00278424
- Volume :
- 107
- Database :
- OpenAIRE
- Journal :
- Proceedings of the National Academy of Sciences
- Accession number :
- edsair.doi.dedup.....711a154877b277b54fc3174787023bc6