Journal article
In vivo and in vitro effects of two novel gamma-actin (ACTG1) mutations that cause DFNA20/26 hearing impairment
Human molecular genetics, Vol.18(16), pp.3075-3089
08/15/2009
DOI: 10.1093/hmg/ddp249
PMCID: PMC2714729
PMID: 19477959
Abstract
Here we report the functional assessment of two novel deafness-associated γ-actin mutants, K118N and E241K, in a spectrum of different situations with increasing biological complexity by combining biochemical and cell biological analysis in yeast and mammalian cells. Our in vivo experiments showed that while the K118N had a very mild effect on yeast behaviour, the phenotype caused by the E241K mutation was very severe and characterized by a highly compromised ability to grow on glycerol as a carbon source, an aberrant multi-vacuolar pattern and the deposition of thick F-actin bundles randomly in the cell. The latter feature is consistent with the highly unusual spontaneous tendency of the E241K mutant to form bundles in vitro, although this propensity to bundle was neutralized by tropomyosin and the E241K filament bundles were hypersensitive to severing in the presence of cofilin. In transiently transfected NIH3T3 cells both mutant actins were normally incorporated into cytoskeleton structures, although cytoplasmic aggregates were also observed indicating an element of abnormality caused by the mutations in vivo. Interestingly, gene-gun mediated expression of these mutants in cochlear hair cells results in no gross alteration in cytoskeletal structures or the morphology of stereocilia. Our results provide a more complete picture of the biological consequences of deafness-associated γ-actin mutants and support the hypothesis that the post-lingual and progressive nature of the DFNA20/26 hearing loss is the result of a progressive deterioration of the hair cell cytoskeleton over time.
Details
- Title: Subtitle
- In vivo and in vitro effects of two novel gamma-actin (ACTG1) mutations that cause DFNA20/26 hearing impairment
- Creators
- Matías Morín - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainKeith E Bryan - 3 Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USAFernando Mayo-Merino - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainRichard Goodyear - 4 School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UKÁngeles Mencía - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainSilvia Modamio-Høybjør - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainIgnacio del Castillo - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainJessica M Cabalka - 3 Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USAGuy Richardson - 4 School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UKFelipe Moreno - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, SpainPeter A Rubenstein - 3 Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USAMiguel Ángel Moreno-Pelayo - 1 Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, Spain
- Resource Type
- Journal article
- Publication Details
- Human molecular genetics, Vol.18(16), pp.3075-3089
- Publisher
- Oxford University Press
- DOI
- 10.1093/hmg/ddp249
- PMID
- 19477959
- PMCID
- PMC2714729
- ISSN
- 0964-6906
- eISSN
- 1460-2083
- Language
- English
- Date published
- 08/15/2009
- Academic Unit
- Stead Family Department of Pediatrics; Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9984024542302771
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