Nuclear receptors
Reshma Taneja
Department of Molecular, Cell and Developmental Biology
Mount Sinai School of Medicine
Advanced Signal Transduction Course/ STKE
March 31st, 2005
Nuclear Receptors
I.
Introduction
-Types
-Domain Structure
-DNA binding specificities
II. Mechanisms of transcriptional regulation
-Interaction with coactivators and corepressors
III. Modulation of nuclear receptor activity by phosphorylation
-Estrogen receptor by MAPK -implications in breast cancer
-Retinoic acid receptors by proline-directed kinases - role in differentiation
of F9 cells
IV. Nuclear receptors in cancers
-Utility of retinoids in therapy and chemoprevention
-Acute Promyelocytic leukemia
The nuclear receptor superfamily
Mangelsdorf et al, (1995) Cell 83:835-839
Activation of steroid and non-steroid nuclear receptors
Steroid receptors
S
R
hsphsp
S
S
R
R
HRE
R
+
hsphsp
S
Target gene
H
Non-steroid
receptors
RX
R
Target gene
HRE
RX
R
HRE
H
Target gene
Adapted from: Weigel, N. (1996) Biochem J, 319: 657-667
Domain structure of nuclear hormone receptors
2
Gronemeyer et al, (2004) Nat Rev Drug Discov 3:950-964
DNA binding sites of retinoid receptors
Bastein and Rochette-Egly (2004) Gene 328, 1-16
Transcriptional repression and activation by nuclear
receptors
Corepressors complexes
HDAC
A
NCoR /SMRT
Repressed
Transcription
Histones
deacetylation
RAR/RXR
ligand
B
Coactivators complexes
Histones/Acetylation /
methylation /phosphorylation
P
CH3 Ac
Kinase HAT
HMT P300 /
(CARM-1) CBP
PCAF
P160
Ac
SWI/SNF
P
CH3
Ac
Ac
Ac
Ac
Ac Ac
C
Ac
Nucleosomes
Translocation
Recruitment of the mediator and
transcription machinery
Transcription
P
CH3 Ac
Ac
Ac
Ac
Ac
TAFs
RNA pol II
TBP
TATA TFIIF
TFIIB
TFIIH
TFIIA
TFIIE
Mediator
Bastein and Rochette-Egly (2004) Gene 328, 1-16
Alternative activation and repression functions of nuclear receptors
regulated by ligand (or signaling pathway) control of recruitment of
either coactivators or corepressors
Rosenfeld, M. et al. (2001) J. Biol. Chem. 276:36865-36868
Nuclear receptor coactivators
LXXLL
p160
coactivators
SRC-1
TIF2
p/CIP
AD1
AD2
Q
bHLH
PAS
CBP
RID
CARM1
P/CAF
HAT
LXXLL
CBP/
p300
CH/1
RID
KIX
Br
CH/2
CH/3
HAT
P/CAF
SRC-1
pCIP
Utilization of multiple coactivator complexes
Glass C et al. (2000) Genes Dev. 14: 121-141
Nuclear receptor corepressors
Glass C et al. (2000) Genes Dev. 14: 121-141
Integration of nuclear signaling events by coactivator and corepressor complexes
Glass C et al., (2000) Genes Dev. 14: 121-141
Regulation of nuclear receptor activity by phosphorylation
Bastein and Rochette-Egly (2004) Gene 328, 1-16
Phosphorylation of steroid nuclear receptors
Rochette-Egly Cell Signal. 15, 355-366 (2003)
Role of phosphorylation in
transcriptional activation of ER
(Kato et al, Science 1995; Bunone et al, EMBO J. 1996)
The transcriptional activity of ER can be induced by growth
factors (EGF, IGF) through the Ras-Raf-MAPK pathway.
hER is phosphorylated by mitogen-activated protein kinase
(MAPK) at Serine 118 located in AF-1.
Phosphorylation of Ser118 results in stimulation of AF-1 of ER
resulting in ligand-independent activation of ER.
Phosphorylation of non-steroid nuclear receptors
Rochette-Egly Cell Signal. 15, 355-366 (2003)
Phosphorylation of RARa and RARg is required for
differentiation of F9 cells into distinct cell types
(Taneja et al, EMBO J. 1997)
AF-1 of RARa1 and RARg2 are phosphorylated by proline
directed kinases
Phosphorylation of AF-1 in RARg2 is required for RAinduced differentiation into primitive endoderm, whereas
phosphorylation of AF-1 in RARa1 is required for
differentiation into parietal endoderm.
AF-2 of RARa1 and RARg2 are phosphorylated by PKA
Phosphorylation of AF-2 in RARa1, but not in RARg2, is
required for differentiation into parietal endodermal cells.
Ligand-independent activation of ER
by Cyclin D1
(Zwijsen et al, Cell 1997; Genes & Dev. 1998).
The transcriptional activity of ER is modulated in a ligandindependent manner by cyclin D1.
Cyclin D1 directly interacts with, and activates ERa in a CDKindependent manner.
Cyclin D1 also interacts with the co-activator SRC1 in a ligandindependent manner. By acting as a bridge between ERa and
SRC1, cyclin D1 recruits SRC1 to ERa in the absence of ligand.
The clinical use of retinoids in cancer therapies and
chemoprevention
Trade name
Retinoid
Activity
Some Therapeutic applications
Tretinoin
ATRA
Pan-RAR
Promyelocytic leukemia,
Leukoplakia (prevention), Actinic
keratosis (prevention)
Alitretinoin,
Panretin
9-cis retinoic acid
Pan-RAR
Pan-RXR
Kaposi's sarcoma
Breast cancer
Isotretinoin
and
13-cis retinoic acid
Pan-RAR
Oral leukoplakia, Skin cancer, Head
neck cancer (in combination with IFN),
Neuroblastoma
Bexarotene
LDG1069
RXR
Cutaneous T-cell lymphoma (stage IAIB, IIA), NSCLC
Fenretidine
4- HPR
4-hydroxy
-phenylretinamide
polyprenoic acid
RAR
Breast cancer
Leukoplakia
Ovarian cancer
Hepatocellular carcinoma (prevention)
Acyclic retinoid
RAR, RXR,
PPAR activities
Abbreviations: ATRA, all trans retinoic acid4-HRP, 4-hydroxy-phenylretinamide; APL, promyelocytic leukemia; IFN,
interferon; PPAR, peroxisome proliferator activated receptor; RAR, retinoic acid receptor; RXR, retinoid X receptor.
(Adapted from:Altucci and Gronemeyer, Nat. Rev Cancer, 2001 1:181)
Lin et al (1999) Trends in Genetics 15:179
Schematic representation of PML and PML-RARa fusion proteins
Altucci et al (2004) The International Journal of Bicochem & Cell Biol 36:178
Molecular basis of RA response in PML-RARa
and PLZF-RARa APL cells
Altucci et al (2004) The International Journal of Biochem & Cell Biol 36:178