Document Detail

Cell-specific differences in the processing of the R14W CAIV mutant associated with retinitis pigmentosa 17.
MedLine Citation:
PMID:  20626030     Owner:  NLM     Status:  MEDLINE    
Retinitis pigmentosa is a highly heterogeneous form of inherited blindness which affects more than 1.3 million individuals worldwide. The RP17 form of the disease is caused by an arginine to tryptophan (R14W) mutation in the signal sequence of carbonic anhydrase IV (CAIV). While CAIV is expressed in the choriocapillaries of the eye and renal epithelium, the R14W mutation results in an exclusively ocular phenotype in affected individuals. In order to investigate the mechanism of disease in RP17 and the lack of kidney phenotype, we compared the subcellular localization and post-translational processing of wild-type (WT)- and mutant-CAIV in three cell types. We show using immunocytochemistry that unlike WT CAIV which is transported to the plasma membrane of transfected COS-7 and HT-1080 cells, the R14W mutant CAIV is retained in the endoplasmic reticulum. Western blot analyses further reveal that whereas the WT CAIV is processed to its mature form in both these cell lines, significant levels of the R14W mutant protein remain in its immature form. Importantly, flow cytometry experiments demonstrate that compared to WT CAIV protein, expression of specifically the R14W CAIV results in an S and G2/M cell-cycle block, followed by apoptosis. Interestingly, when the above experiments were repeated in the human embryonic kidney cell line, HEK-293, strikingly different results were obtained. These cells were unaffected by the expression of the R14W mutant CAIV and were able to process the mutant and WT protein equally effectively. This study has important implications for our understanding of the RP17 phenotype.
Aisha Pandor; Rajkumar Ramesar; Sharon Prince
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of cellular biochemistry     Volume:  111     ISSN:  1097-4644     ISO Abbreviation:  J. Cell. Biochem.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-09-27     Completed Date:  2011-01-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8205768     Medline TA:  J Cell Biochem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  735-41     Citation Subset:  IM    
Copyright Information:
© 2010 Wiley-Liss, Inc.
Division of Human Genetics, Department of Clinical and Laboratory Sciences, University of Cape Town, Cape Town, South Africa.
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MeSH Terms
COS Cells
Carbonic Anhydrase IV / genetics*
Cell Cycle
Cell Line
Cercopithecus aethiops
Mutant Proteins
Mutation, Missense*
Retinitis Pigmentosa / genetics*
Species Specificity
Reg. No./Substance:
0/Mutant Proteins; EC 4.2.1.-/Carbonic Anhydrase IV

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