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dictyNews Volume 42 Number 10
dictyNews
Electronic Edition
Volume 42, number 10
April 1, 2016
Please submit abstracts of your papers as soon as they have been
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Abstracts
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Regulation of ecmF gene expression and genetic hierarchy among STATa,
CudA, and MybC on several prestalk A-specific gene expressions in
Dictyostelium
Yukika Saga 1, Tomoka Inamura 1, Nao Shimada 1, 2, and
Takefumi Kawata 1, *
1 Department of Biology, Faculty of Science, Toho University,
2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
2 Present Address: Graduate School of Arts and Sciences,
University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
Develop. Growth Diff., in press
STATa, a Dictyostelium homologue of metazoan signal transducer
and activator of transcription, is important for the organizer function
in the tip region of the migrating Dictyostelium slug. We previously
showed that ecmF gene expression depends on STATa in prestalk A
(pstA) cells, where STATa is activated. Deletion and site-directed
mutagenesis analysis of the ecmF/lacZ fusion gene in wild-type and
STATa null strains identified an imperfect inverted repeat sequence,
ACAAATANTATTTGT, as a STATa-responsive element. An upstream
sequence element was required for efficient expression in the rear region
of pstA zone; an element downstream of the inverted repeat was
necessary for sufficient prestalk expression during culmination. Band shift
analyses using purified STATa protein detected no sequence-specific
binding to those ecmF elements. The only verified upregulated target
gene of STATa is cudA gene; CudA directly activates expL7 gene
expression in prestalk cells. However, ecmF gene expression was almost
unaffected in a cudA null mutant. Several previously reported putative
STATa target genes were also expressed in cudA null mutant but were
downregulated in STATa null mutant. Moreover, mybC, which encodes
another transcription factor, belonged to this category, and ecmF
expression was downregulated in a mybC null mutant. These findings
demonstrate the existence of a genetic hierarchy for pstA-specific
genes, which can be classified into two distinct STATa downstream
pathways, CudA dependent and independent. The ecmF expression
is indirectly upregulated by STATa in a CudA-independent activation
manner but dependent on MybC, whose expression is positively
regulated by STATa.
submitted by: Takefumi Kawata [tkawata@bio.sci.toho-u.ac.jp]
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[End dictyNews, volume 42, number 10]
