METABOLITE CONTROL OF TRANSCRIPTION

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METABOLITE CONTROL OF TRANSCRIPTION IN
EUKARYOTIC CELLS
Michael S. Kilberg Department of Biochemistry
Molecular Biology R3-116 ARB 2-2711
mkilberg_at_ufl.edu
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CHARACTERIZING METABOLITE CONTROL REQUIRES IN
VITRO MODEL SYSTEMS
Deficient diet in vivo
Nutrient changes
Assay transcription
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CHARACTERIZING METABOLITE CONTROL REQUIRES IN
VITRO MODEL SYSTEMS
Nutrient deficient culture medium in vitro
Deficient diet in vivo
Nutrient changes
Hormonal changes
Assay transcription
Assay transcription
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ACTIVATION OF TRANSCRIPTION BY THE ABSENCE
OF CARBOHYDRATE
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THE YEAST UNFOLDED PROTEIN RESPONSE (UPR)
IS MEDIATED BY THE Hac1 TRANSCRIPTION FACTOR
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UPRE GENOMIC SEQUENCES RECOGNIZED BY THE
YEAST Hac1P TRANSCRIPTION FACTOR
Yeast UPRE Consensus CA n C n TG
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THE UPR IN MAMMALIAN CELLS IS MORE
COMPLICATED IS ALSO REFERRED TO AS
THE ER STRESS RESPONSE
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Identification of the endoplasmic reticulum
stress response element (ERSE)
Yoshida, H., Haze, K., Yanagi, H., Yura, T., and
Mori, K. J. Biol. Chem. (1998) 273 33741-33749
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Characterization of the endoplasmic reticulum
stress response element (ERSE)
Yoshida, H., Haze, K., Yanagi, H., Yura, T., and
Mori, K. J. Biol. Chem. (1998) 273 33741-33749
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Binding proteins for the endoplasmic reticulum
stress response element (ERSE)
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THE UNFOLDED PROTEIN RESPONSE IN MAMMLIAN
CELLS
But what about Ire1p ?
And, what about XBP-1?
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THE UNFOLDED PROTEIN RESPONSE IN MAMMLIAN
CELLS
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THERE ARE XBP1-RESPONSIVE MAMMALIAN GENES
THAT DO NOT CONTAIN THE ERSE CONSENSUS
SEQUENCE
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ACTIVATION OF TRANSCRIPTION BY THE PRESENCE
OF CARBOHYDRATE
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GENE TRANSCRIPTION INDUCED BY THE PRESENCE
OF CARBOHYDRATE
1. L-Type Pyruvate Kinase 2. Acetyl CoA
Carboxylase 3. Fatty Acid Synthase 4. ATP
Citrate Lyase
Carbohydrate-induced enzymes associated with
fatty acid biosynthesis
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TRANSCRIPTIONAL CONTROL OF L-Type PYRUVATE
KINASE BY CARBOHYDRATE
The E-box sequence is recognized by the
basic/helix-loop-helix/leucine zipper family of
transcription factors.
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GLUCOSE SENSING GENOMIC ELEMENTS IN MAMMALIAN
CELLS
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IDENTIFICATION OF A CARBOHYDRATE RESPONSE ELEMENT
BINDING PROTEIN (ChREBP) BY ELECTROPHORESIS
MOBILITY SHIFT ANALYSIS (EMSA)
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THE DNA BINDING ACTIVITY OF ChREBP IS
REGULATED BY PHOSPHORYLATION
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REGULATION OF ChREBP FUNCTION BY THE
PRESENCE OF CARBOHYDRATE
Hiromi Yamashita , Makoto Takenoshita, Masaharu
Sakurai, Richard K. Bruick, William J. Henzel ,
Wendy Shillinglaw , David Arnot , and Kosaku
Uyeda (2001) A glucose-responsive transcription
factor that regulates carbohydrate metabolism in
the liver. Proc. Natl. Acad. Sci. 98 9116-9121.
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SUMMARY 1) Specific genes are
transcriptionally regulated by metabolites so
that the cell can respond to changes in
nutritional variability. 2) Each class of
metabolites (amino acids, sugars, lipids, etc)
has its own signal transduction mechanisms and
modulate a different set of cellular genes. 3)
Even for a given metabolite, glucose for example,
the signal transduction pathway that detects an
increased level of the metabolite can be
different than the one that detects a limiting
amount. 4) The genomic cis-acting elements that
mediate the changes in transcription of the
target genes are different for each signal
transduction pathway. Even when the metabolite
is the same, e.g., glucose.