This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: EC.00322-06v1 6/3/430    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Damer, C. K. Articles by Naliboff, L. C. Search for Related Content PubMed PubMed Citation Articles by Damer, C. K. Articles by Naliboff, L. C.

 Previous Article  |  Next Article 

Eukaryotic Cell, March 2007, p. 430-442, Vol. 6, No. 3
1535-9778/07/$08.00+0     doi:10.1128/EC.00322-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Copine A Is Required for Cytokinesis, Contractile Vacuole Function, and Development in Dictyostelium ^,

Biochemistry Program,¹ Chemistry,² Biology Departments, Vassar College, 124 Raymond Ave., Poughkeepsie, New York 12604³

Received 9 October 2006/ Accepted 17 January 2007

Copines make up a family of soluble, calcium-dependent, membrane binding proteins found in a variety of eukaryotic organisms. In an earlier study, we identified six copine genes in the Dictyostelium discoideum genome and focused our studies on cpnA. Our previous localization studies of green fluorescent protein-tagged CpnA in Dictyostelium suggested that CpnA may have roles in contractile vacuole function, endolysosomal trafficking, and development. To test these hypotheses, we created a cpnA^– knockout strain, and here we report the initial characterization of the mutant phenotype. The cpnA^– cells exhibited normal growth rates and a slight cytokinesis defect. When placed in starvation conditions, cpnA^– cells appeared to aggregate into mounds and form fingers with normal timing; however, they were delayed or arrested in the finger stage. When placed in water, cpnA^– cells formed unusually large contractile vacuoles, indicating a defect in contractile vacuole function, while endocytosis and phagocytosis rates for the cpnA^– cells were similar to those seen for wild-type cells. These studies indicate that CpnA plays a role in cytokinesis and contractile vacuole function and is required for normal development, specifically in the later stages prior to culmination. We also used real-time reverse transcription-PCR to determine the expression patterns of all six copine genes during development. The six copine genes were expressed in vegetative cells, with each gene exhibiting a distinct pattern of expression throughout development. All of the copine genes except cpnF showed an upregulation of mRNA expression at one or two developmental transitions, suggesting that copines may be important regulators of Dictyostelium development.

Published ahead of print on 26 January 2007.

Supplemental material for this article may be found at http://ec.asm.org/.