The Co-activator-like Mediator Complex Forms a Molecular Bridge Between Activation Domains and Pol II

example of several upstream activators interacting with a single co-activator-like mediator complex

the general problem

Co-activator

Transcription Regulation And Gene Expression in Eukaryotes

FS 2016 Graduate Course G2

P. Matthias and RG Clerc Pharmazentrum Hörsaal 2 16h15-18h00

REGULATORY MECHANISMS OF TRANSCRIPTIONFACTOR FUNCTION

•Protein synthesized

•Protein phosphorylated

•Ligand binding

•Release inhibitor

•Change partner, etc

RG Clerc April 6. 2016Transcription factors as final effectors of the cellular signaling cascade

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

anterior early expression posterior late expression

high RA response low RA response

hindbrain trunk

Body plan is constructed through interactions of the developmentally regulated homeotic gene expression

Alexander T and Krumlauf R. Ann.Rev.Cell.Dev.Biol: 25_431 (2009)

Hoxb transcription factors mRNA distribution along the AP axis

A

staggered expression of the anterior border within somites is a property of the physical ordering along the chromosome: the colinearity

Alexander T and Krumlauf R. Ann.Rev.Cell.Dev.Biol: 25_431 (2009)

Transcription control of the Hox genes: insight into colinear activation

AP

a

WT MUT WT MUT WT MUT

Tarchini B and Duboule D. Dev.Cell 10_93 (2006)a aa ap pp pp pa

correlation between linear arrangement along the chromosome and spatial transcriptional regulation

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

Activation of TRX following G-Protein Coupled Receptor GPCR Ligand Binding

Structure of the CREB basic region/leucine zipper domain (amino acids 285–339) (bZIP) bound to the somatostatin CRE (TGACGTCA)

CREB (cyclic-AMP Responsive Elements Binding Protein)

Phosphorylation of CREB at Ser133 Induces Complex Formation With an α-Helical Domain in CBP

KIXCBP-CREB complex

Nuclear stress bodies are the main sites of accumulation of HSF1/2 in stressed cells

The Heat Shock Transcription Factor DBD (wHTH)

cgcctcGAAtgTTCgcGAAa -46 hsp70

cgcctcGAAtgTTCgcGAAa [-46 hsp70]

Canonical HSE (multiple adjacent pentanucleotide motifs)

The Heat Shock Factor Family Across Species

Regulation of the HS Response and the HSF Cycle

•Inert monomer in the cytoplasm and nucleus

•Stress induced DNA binding and TA potential (hyperphosphorylation)

•Trimerization

•HSF binding protein (HSBP1) negatively regulates trimer

•Dissociation of trimers

•Generation of unactive monomers upon binding of chaperones Hsp70 and Hdj-1

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

The Nuclear Pore Complex is the Gateway That Regulates the Two-Way Traffic Between the Nucleus and the Rest of the Cell

The Nuclear Pore Complex is the Gateway That Regulates the Two-Way Traffic Between the Nucleus and the Rest of the Cell

Nucleocytoplasmic Trafficking: Nucleopore Complex and Karyopherins

Regulation of FoxO by Nuclear Shuttling in Response to AKT Mediated Phosphorylation

Phosporylation stimulates nuclear export (NES) and prevents nuclear import (NLS)

Winged-helix family of trx factors are involved in

development, metabolism, cell differentiation

Fox=Forkhead box (100AA)

Regulation of FoxO by Nuclear Shuttling in Response to AKT Mediated Phosphorylation

The activity of FoxO is tightly regulated by post-translational modifications including phosphorylation, acetylation and ubiquitylation

Multiple Levels of Control of NFAT Signaling

TCR, IGF, EGF

CsA

induction

inhibition

Gwack Y. et al. Cell Calcium 42:145-156

IL2,IL3,IL4,GMCSF,TNF

TAD

Cooperative Binding of Two Unrelated Transcription Factors to Neighboring Sites

NF-AT (REL homology domain), AP-1 (Fos-Jun) cooperatively bind a composite DNA site (ARRE from IL-2 promoter)

Chen L. and Harrison SC. Nature 392:42-48

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

Hormone Dependent Gene Activation by a Homodimeric or Heterodimeric Nuclear Hormone Receptor

Conformational Change of the LBD of Two Related Nuclear Hormone Receptors Upon Ligand Binding

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

The NFκB Paradigm: Signal Induced Degradation of a Cytosolic Inhibitor Proteins Which Activates the TF

Phosphorylation dependent release by inhibitor (eg. iκB-α) upon polyubiquitination -proteasomal mediated degradation

Baltimore D. Nature Immunology 12: 683-686 (2011)

The NFκB/REL Family and IκB Proteins

NF-kappa B p50 homodimer bound to DNAMüller CW, Harrisson SG and Verdine GL. Nature 373:311-317

The NFκB Paradigm: Signal Induced Degradation of Cytosolic Inhibitor Proteins Which Activates the TF: 25 years on !

Oeckinghaus A. Hayden M. Ghosh S (2011) Nature Immunology 12:695-708

TRX factors such as NFκB are final effectors of various cellular signaling cascades

The NFκB patent

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

Helix-Loop-Helix Domains

E box TF 5’CANNTG3’

Structural Classes Helix-Loop-Helix Domains - the DBD is Separated by Nonhelical Loops from the Leu-Zipper Region (Coiled-Coil)

T. Kadesch Cell Growth and Diff.4:49 (1993)

bHLH Factors Activity is Modulated by Partner Exchange

bHLH dimers in which both subunits have a basic region can bind DNA; a dimer in which a subunit lacks the basic region (eg Id) cannot bind the promoter regulatory element

CREB

FOXONFAT

Regulatory Mechanisms of Transcription Factor Function

Genes X. Lewin B. editor

Cholesterol and Triglyceride Synthesis Pathways

Domain Structure of SREBP’s Membrane Bound TF(sterol regulatory element (SRE) binding protein - 5’PyCAPyNPyCAPy3’)

Sterol Dependent Two-Steps Proteolytic Cleavage of TF

The Sterol Response: Cleavage to Release the Active TF

Brown M. Goldstein JL. Cell 89 (1997)

The canonical Wnt–β-catenin pathway

W. Birchmeier. Nature Reviews 8:387-398 (2008)

LEF-1/TCF-1

L6

M13M10

E28

HELIX 2

HELIX 1

HELIX 3 BASIC C-TERM

5’

C

C

T

T

T

G

A

A

G

C

3’

Y76

Looking Beyond …

The Joy of Learning is as Indispensable in Study as Breathing is in LifeSimone Weil