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Poster Full Abstracts - Regulation of Gene Expression
Poster board number is above title. The first author is the presenter
346
803B
Protein interacting with Ttk69 and Sin3A (Pits) acts as a mediator to repress
tailless
expression.
Gwo-Jen Liaw. Dept Life Sci, Natl Yang-Ming Univ,
Taipei, Taiwan.
Histone deacetylation plays an important role in transcriptional repression. Our previous data showed that Tramtrack69 (Ttk69) formed a repression
complex with GAF and Heat Shock Factor (HSF) and that the genetic interaction of
ttk
with
rpd3
, encoding a histone deacetylase, was involved in
tailless
(
tll
) repression. To reveal molecular mechanism of how the Sin3A/Rpd3 complex is recruited by Ttk69, proteins interacting Ttk69 were screened. A protein
was found that it interacted with both Ttk69 and Sin3A, called as Protein interacting with Ttk69 and Sin3A (Pits). Pits uniformly distributed in early stages
of
Drosophila
embryos. Embryos with reduced maternal
pits
,
sin3A
and
ttk
activities showed a greatly expanded
tll
expression patterns, indicating that these
three gene activities work together to repress
tll
expression.
804C
Functional analysis of Blimp-1during pupal developmental stage in
Drosophila
.
ABDEL-RAHMAN SAYED SULTAN
1
, HITOSHI UEDA
1,2
. 1) The
Graduate School of Natural Science and Technology, Okayama University, Japan; 2) Department of Biology Faculty of Science, Okayama University,
Japan.
Blimp-1, an ecdysone-inducible transcriptional repressor, has been identified as one of the factors that binds to the promoter region of the
ftz-f1
gene and
plays an important role in determining the expression timing of the
ftz-f1
gene. It has been shown that its temporally restricted expression is important for
embryonic and prepupal development of
Drosophila
. However, its expression pattern and function during pupal period have not been analyzed.
Blimp-1
mRNA was detected at pupal stage by RT-PCR. We found that the
Blimp-1
gene is expressed during the pupal stage and the expression in female is
advancing to that in male. On the other hand, the expression level of
Blimp-1
in male is high comparing to that in female. These results consistence with the
reported ecdysone level during pupal stage. To elucidate the functional expression of
Blimp-1
at pupal stage. We examined effects of
Blimp-1
knockdown by
using GAL4/UAS system, We found that
Blimp-1
knockdown exhibits morphological malformations in the eye, wing and leg. Interestingly,
Blimp-1
knockdown in the whole body using
Act5C-GAL4
line induces advancing of pupation, delaying of pupal development and inhibition of eclosion.
805A
Role of
Drosophila
retinoblastoma proteins in insulin signaling pathway regulation.
Yiliang Wei
1
, Pankaj Acharya
2
, Liang Zhang
3
, William Henry
1
,
David Arnosti
1
. 1) Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI; 2) Microbiology and Molecular Genetics, Michigan
State University, East Lansing, MI; 3) Cell and Molecular Biology Graduate Program, Michigan State University, East Lansing, MI.
Drosophila
retinoblastoma family members Rbf1 and Rb2 are orthologs of human retinoblastoma (RB) tumor suppressors, which function as
transcriptional co-repressors controlling cell cycle and developmentally regulated gene expression. Our lab has carried out the first ChIP-Seq analysis of
Rbf1 in the
Drosophila
embryo. Surprisingly, in addition to conserved cell cycle-regulated genes, Rbf1 was also found to associate with promoter-proximal
regions of genes in the insulin signaling pathway. This conserved pathway plays an essential role in controlling animal growth and maintaining cellular and
organismal homeostasis. In vitro reporter assays showed that Rbf1 can functionally repress the insulin receptor (InR) promoter, and this repression function
appears to be E2F-independent, consistent with the lack of E2F motifs in the promoter. To investigate the physical binding of Rbfs to the InR promoter, we
carried out ChIP for Rbf1 and Rbf2 in
Drosophila
S2 cells. Remarkably, these proteins stay associated with the promoter region even when transcription is
stimulated by ecdysone treatment or starvation.
rbf1
and
rbf2
knock-down in
Drosophila
S2 cells induced only modest changes in transcript levels of genes
in insulin signaling pathway, indicating that other factors, such as FOXO or ligand-bound ecdysone receptor might be required to fully activate the
transcription of insulin signaling genes. Altogether, these results show that Rbf proteins may play critical roles in integrating signaling from cell-cycle and
growth control inputs by setting sensitivity of the insulin signaling pathway.
806B
The Instability Element of Retinoblastoma Proteins in Drosophila: Functional Overlap between Protein Turnover and Activity.
Liang Zhang
1
, Nitin
Raj
2
, Yiliang Wei
3
, William Henry
3
, David Arnosti
1,3
. 1) Cell and Molecular Biology Program, Michigan State University, East Lansing, MI; 2) Genetics
Program, Michigan State University, East Lansing, MI; 3) Dept of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI.
Retinoblastoma (RB) proteins, frequently inactivated in different types of cancers, are pivotal transcriptional corepressors in regulating cell cycle
progression and development through their interactions with E2F family transcription factors. Activity and stability of RB proteins are precisely controlled
during cell cycle through CDK-mediated phosphorylation and proteasome-dependent degradation. However, the molecular mechanism for degradation of
RB family proteins is not well understood. We characterized mutant forms of the Rbf1 protein in Drosophila and identified an instability element (IE) in the
C-terminal region. Paradoxically, when the IE is deleted, increased protein levels do not cause enhanced repression activity. Rather, these mutations
diminish repression activity of Rbf1, indicating a linkage between Rbf1 activity and instability, similar to the “degron” model of transcriptional activators.
By assaying the Rbf1 IE in the context of chimeric GFP proteins, we find that the IE is an independent module which is able to direct the turnover of a
heterologous protein through ubiquitylation pathway. More importantly, the IE itself is a repression domain when directly tethered to the promoter,
suggesting that the IE may serve as an interaction domain for multiple cofactors linking protein turnover and transcriptional repression. By fusing a single
ubiquitin to the inactive Rbf1 mutant, we observed its repression activity being partially restored. We propose that the IE controls Rbf1 stability and activity
in a ubiquitylation-mediated pathway.
807C
dNIAM: A chromatin protein that negatively regulates cell proliferation.
Olivia E. Jones
1
, Diane E. Cryderman
1
, Kristen E. Syring
1
, Shannon R.
Mackey
1
, Sara Reed
2
, Dawn E. Quelle
2
, Lori L. Wallrath
1
. 1) Department of Biochemistry, University of Iowa, Iowa City, IA; 2) Department of
Pharmacology, University of Iowa, Iowa City, IA.
Regulation of cell proliferation is a key step in the initiation and management of cancer. In humans, the nuclear factor NIAM (Nuclear Interactor of ARF
and Mdm2) associates with chromatin, maintains chromosome stability, and inhibits cellular proliferation independent of the tumor suppressor ARF. We