Document Detail

In vivo and in vitro effects of two novel gamma-actin (ACTG1) mutations that cause DFNA20/26 hearing impairment.
MedLine Citation:
PMID:  19477959     Owner:  NLM     Status:  MEDLINE    
Here we report the functional assessment of two novel deafness-associated gamma-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 gamma-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.
Matías Morín; Keith E Bryan; Fernando Mayo-Merino; Richard Goodyear; Angeles Mencía; Silvia Modamio-Høybjør; Ignacio del Castillo; Jessica M Cabalka; Guy Richardson; Felipe Moreno; Peter A Rubenstein; Miguel Angel Moreno-Pelayo
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-05-28
Journal Detail:
Title:  Human molecular genetics     Volume:  18     ISSN:  1460-2083     ISO Abbreviation:  Hum. Mol. Genet.     Publication Date:  2009 Aug 
Date Detail:
Created Date:  2009-07-24     Completed Date:  2009-10-27     Revised Date:  2010-09-27    
Medline Journal Info:
Nlm Unique ID:  9208958     Medline TA:  Hum Mol Genet     Country:  England    
Other Details:
Languages:  eng     Pagination:  3075-89     Citation Subset:  IM    
Unidad de Genética Molecular, Hospital Ramón y Cajal, 28034 Madrid, Spain.
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MeSH Terms
Actins / chemistry,  genetics*,  metabolism
Base Sequence
Cells, Cultured
Cytoskeleton / metabolism
Hair Cells, Auditory / metabolism
Hearing Loss / genetics*,  metabolism
Molecular Conformation
Molecular Sequence Data
Mutation, Missense*
NIH 3T3 Cells
Yeasts / genetics,  metabolism
Grant Support
Reg. No./Substance:

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