PMID- 10409767
OWN - NLM
STAT- MEDLINE
DCOM- 19990819
LR  - 20190508
IS  - 0270-7306 (Print)
IS  - 0270-7306 (Linking)
VI  - 19
IP  - 8
DP  - 1999 Aug
TI  - Multiple roles of ligand in transforming the dioxin receptor to an active basic
      helix-loop-helix/PAS transcription factor complex with the nuclear protein Arnt.
PG  - 5811-22
AB  - The dioxin receptor is a ligand-activated transcription factor belonging to an
      emerging class of basic helix-loop-helix/PAS proteins which show interaction with
      the molecular chaperone hsp90 in their latent states and require
      heterodimerization with a general cofactor, Arnt, to form active DNA binding
      complexes. Upon binding of polycyclic aromatic hydrocarbons typified by dioxin,
      the dioxin receptor translocates from the cytoplasm to the nucleus to allow
      interaction with Arnt. Here we have bypassed the nuclear translocation step by
      creating a cell line which expresses a constitutively nuclear dioxin receptor,
      which we find remains in a latent form, demonstrating that ligand has functional 
      roles beyond initiating nuclear import of the receptor. Treatment of the nuclear 
      receptor with dioxin induces dimerization with Arnt to form an active
      transcription factor complex, while in stark contrast, treatment with the hsp90
      ligand geldanamycin results in rapid degradation of the receptor. Inhibition of
      degradation by a proteasome inhibitor allowed geldanamycin to transform the
      nuclear dioxin receptor to a heterodimer with Arnt (DR-Arnt). Our results
      indicate that unchaperoned dioxin receptor is extremely labile and is consistent 
      with a concerted nuclear mechanism for receptor activation whereby hsp90 is
      released from the ligand-bound dioxin receptor concomitant with Arnt
      dimerization. Strikingly, artificial transformation of the receptor by
      geldanamycin provided a DR-Arnt complex capable of binding DNA but incapable of
      stimulating transcription. Limited proteolysis of DR-Arnt heterodimers indicated 
      different conformations for dioxin versus geldanamycin-transformed receptors. Our
      studies of intracellular dioxin receptor transformation indicate that ligand
      plays multiple mechanistic roles during receptor activation, being important for 
      nuclear translocation, transformation to an Arnt heterodimer, and maintenance of 
      a structural integrity key for transcriptional activation.
FAU - Lees, M J
AU  - Lees MJ
AD  - Department of Biochemistry, University of Adelaide, Adelaide 5005, South
      Australia, Australia.
FAU - Whitelaw, M L
AU  - Whitelaw ML
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Mol Cell Biol
JT  - Molecular and cellular biology
JID - 8109087
RN  - 0 (ARNT protein, human)
RN  - 0 (Arnt protein, mouse)
RN  - 0 (Benzoquinones)
RN  - 0 (DNA-Binding Proteins)
RN  - 0 (HSP90 Heat-Shock Proteins)
RN  - 0 (Lactams, Macrocyclic)
RN  - 0 (Ligands)
RN  - 0 (Macromolecular Substances)
RN  - 0 (Quinones)
RN  - 0 (Receptors, Aryl Hydrocarbon)
RN  - 0 (Recombinant Fusion Proteins)
RN  - 0 (Transcription Factors)
RN  - 138391-32-9 (Aryl Hydrocarbon Receptor Nuclear Translocator)
RN  - Z3K3VJ16KU (geldanamycin)
SB  - IM
MH  - Adrenal Glands
MH  - Amino Acid Sequence
MH  - Animals
MH  - Aryl Hydrocarbon Receptor Nuclear Translocator
MH  - Benzoquinones
MH  - Cell Line, Transformed
MH  - Cell Nucleus/metabolism
MH  - *DNA-Binding Proteins
MH  - Dimerization
MH  - HSP90 Heat-Shock Proteins/physiology
MH  - *Helix-Loop-Helix Motifs
MH  - Humans
MH  - Kidney
MH  - Lactams, Macrocyclic
MH  - Ligands
MH  - Liver Neoplasms, Experimental
MH  - Macromolecular Substances
MH  - Mice
MH  - Models, Biological
MH  - Molecular Sequence Data
MH  - Quinones/pharmacology
MH  - Receptors, Aryl Hydrocarbon/drug effects/*physiology
MH  - Recombinant Fusion Proteins/metabolism
MH  - Transcription Factors/chemistry/*physiology
MH  - Transcription, Genetic
MH  - Transfection
MH  - Tumor Cells, Cultured
PMC - PMC84430
EDAT- 1999/07/20 00:00
MHDA- 1999/07/20 00:01
CRDT- 1999/07/20 00:00
PHST- 1999/07/20 00:00 [pubmed]
PHST- 1999/07/20 00:01 [medline]
PHST- 1999/07/20 00:00 [entrez]
AID - 10.1128/mcb.19.8.5811 [doi]
PST - ppublish
SO  - Mol Cell Biol. 1999 Aug;19(8):5811-22. doi: 10.1128/mcb.19.8.5811.