dictyNews
Electronic Edition
Volume 42, number 10
April 1, 2016

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=========
Abstracts
=========


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]