Ligand-inducible interaction of the DRIP/TRAP coactivator complex with retinoid receptors in retinoic acid-sensitive and -resistant acute promyelocytic leukemia cells.
Retinoic acid (RA) signaling is mediated by its nuclear receptors RXR and RAR, which bind to their cognate response elements as a heterodimer, RXR/RAR, and act in concert with coregulatory factors to regulate gene transcription on ligand binding. To identify specific cofactors that interact with the RXR/RAR heterodimer in acute promyelocytic leukemia (APL) cells, a double cistronic construct was used that allowed coexpression of the RXR LBD (ligand binding domain) with the RAR LBD as an affinity matrix to pull down interacting proteins from nuclear extracts prepared from a human APL cell line, NB4. A group of proteins was detected whose interaction with RXR/RAR is ligand inducible. The molecular weight pattern of these proteins is similar to that of a complex of proteins previously identified as DRIP or TRAP, which are ligand-dependent transcription activators of VDR and TR, respectively. The RXR/RAR-interacting proteins from NB4 were confirmed to be identical to the DRIP subunits by comparative electrophoresis, Western blot analysis, and in vitro protein interaction assay. In addition to RXR/RAR, the DRIP component can interact directly with the APL-specific PML-RARalpha fusion protein. The same DRIP complex is present in RA-resistant APL cells and in a variety of cancer cell lines, supporting its global role in transcriptional regulation.
Shao
W
W
Department of Medicine, Division of Experimental Medicine, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
Rosenauer
A
A
Mann
K
K
Chang
C P
CP
Rachez
C
C
Freedman
L P
LP
Miller
W H
WH
D000970:Antineoplastic Agents / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000378:metabolism*; D056892:Mediator Complex; D009687:Nuclear Proteins / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; C113182:DRIP, VDR interacting protein complex; C491863:MED4 protein, human; D056892:Mediator Complex; D009687:Nuclear Proteins; D018168:Receptors, Retinoic Acid; D015534:Trans-Activators; D014157:Transcription Factors; D014212:Tretinoin