Nkcc1 (Slc12a2) is required for the regulation of endolymph volume in the otic vesicle and swim bladder volume in the zebrafish larva
Author:
Abbas Leila1, Whitfield Tanya T.1
Affiliation:
1. MRC Centre for Developmental and Biomedical Genetics and Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK.
Abstract
Endolymph is the specialised extracellular fluid present inside the inner ear. In mammals, disruptions to endolymph homeostasis can result in either collapse or distension of the endolymphatic compartment in the cochlea, with concomitant hearing loss. The zebrafish little ears (lte)mutant shows a collapse of the otic vesicle in the larva, apparently owing to a loss of endolymphatic fluid in the ear, together with an over-inflation of the swim bladder. Mutant larvae display signs of abnormal vestibular function by circling and swimming upside down. The two available alleles of lte are homozygous lethal: mutant larvae fail to thrive beyond 6 days post-fertilisation. Patterning of the otic vesicle is apparently normal. However, the expression of several genes thought to play a role in endolymph production is downregulated, including the sodium-potassium-chloride cotransporter gene nkcc1 (slc12a2) and several Na+/K+-ATPase channel subunit genes. We show here that lte mutations correspond to lesions in nkcc1. Each allele has a point mutation that disrupts splicing, leading to frame shifts in the coding region that predict the generation of truncated products. Endolymph collapse in the lte/nkcc1 mutant shows distinct parallels to that seen in mouse Nkcc1 mutants, validating zebrafish as a model for the study of endolymph disorders. The collapse in ear volume can be ameliorated in the to27d allele of lte by injection of a morpholino that blocks splicing at an ectopic site introduced by the mutation. This exemplifies the use of morpholinos as potential therapeutic agents for genetic disease.
Publisher
The Company of Biologists
Subject
Developmental Biology,Molecular Biology
Reference89 articles.
1. Akiyama, K., Miyashita, T., Mori, T. and Mori, N.(2007). Expression of the Na+-K+-2Cl- cotransporter in the rat endolymphatic sac. Biochem. Biophys. Res. Commun.364,913-917. 2. Andrieu-Soler, C., Halhal, M., Boatright, J. H., Padove, S. A.,Nickerson, J. M., Stodulkova, E., Stewart, R. E., Ciavatta, V. T., Doat, M.,Jeanny, J. C. et al. (2007). Single-stranded oligonucleotide-mediated in vivo gene repair in the rd1 retina. Mol. Vis.13,692-706. 3. Blasiole, B., Degrave, A., Canfield, V., Boehmler, W., Thisse,C., Thisse, B., Mohideen, M. A. and Levenson, R. (2003). Differential expression of Na,K-ATPase alpha and beta subunit genes in the developing zebrafish inner ear. Dev. Dyn.228,386-392. 4. Blasiole, B., Canfield, V. A., Vollrath, M. A., Huss, D.,Mohideen, M. A., Dickman, J. D., Cheng, K. C., Fekete, D. M. and Levenson,R. (2006). Separate Na,K-ATPase genes are required for otolith formation and semicircular canal development in zebrafish. Dev. Biol.294,148-160. 5. Bourke, E. (1976). Frusemide, bumetanide, and ototoxicity. Lancet1,917-918.
Cited by
58 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|