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dictyNews Volume 25 Number 04
Dicty News
Electronic Edition
Volume 25, number 4
August 12, 2005
Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to dicty@northwestern.edu
or by using the form at
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.
Back issues of Dicty-News, the Dicty Reference database and other
useful information is available at dictyBase - http://dictybase.org.
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Abstracts
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A secreted factor represses cell proliferation in Dictyostelium
Debra A. Brock and Richard H. Gomer
Howard Hughes Medical Institute and Department of Biochemistry and Cell
Biology, MS-140, Rice University, 6100 S. Main Street, Houston, TX 77005
Development, in press
Many cells appear to secrete factors called chalones that limit their
proliferation, but in most cases the factors have not been identified. We
found that growing Dictyostelium cells secrete a 60 kDa protein called
AprA for autocrine proliferation repressor. AprA has similarity to putative
bacterial proteins of unknown function. Compared to wild-type cells, aprA
null cells proliferate faster while AprA overexpressing cells proliferate
slower. Growing wild-type cells secrete a factor that inhibits the
proliferation of wild-type and aprAø cells; this activity is not secreted
by aprAø cells. AprA purified by immunoprecipitation also slows the
proliferation of wild-type and aprAø cells. Compared to wild-type, there
is a higher percentage of multinucleate cells in the aprAø population,
and when starved aprAø cells form abnormal structures that contain fewer
spores. AprA may thus decrease the number of multinucleate cells and
increase spore production. Together, the data suggest that AprA functions
as part of a Dictyostelium chalone.
Submitted by: Richard Gomer [richard@rice.edu>]
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[End Dicty News, volume 25, number 4] 
