Leukemic transformation by the APL fusion protein PRKAR1A-RAR{alpha} critically depends on recruitment of RXR{alpha}.
PRKAR1A (R1A)-retinoic acid receptor-alpha (R1A-RARalpha) is the sixth RARalpha-containing fusion protein in acute promyelocytic leukemia (APL). Using the murine bone-marrow retroviral transduction/transformation assay, we showed that R1A-RARalpha fusion protein could transform bone-marrow progenitor/stem cells. In gel-shift assays, R1A-RARalpha was able to bind to a panel of retinoic acid response elements both as a homodimer and as a heterodimer with RXRalpha, and demonstrated distinct DNA-binding characteristics compared with wild-type RARalpha/RXRalpha or other X-RARalpha chimeric proteins. The ratio of R1A-RARalpha to RXRalpha proteins affected the retinoic acid response element interaction pattern of R1A-RARalpha/RXRalpha complexes. Studies comparing R1A-RARalpha with R1A-RARalpha(DeltaRIIa) demonstrated that the RIIa protein interaction domain located within R1A was responsible for R1A-RARalpha homodimeric DNA binding and interaction with wild-type R1A protein. However, the RIIa domain was not required for R1A-RARalpha-mediated transformation because its deletion in R1A-RARalpha(DeltaRIIa) did not compromise its transformation capability. In contrast, introduction of point mutations within the RARalpha portion of either R1A-RARalpha or R1A-RARalpha(DeltaRIIa), previously demonstrated to eliminate RXRalpha interaction or treatment of transduced cells with RXRalpha shRNA or a RXRalpha agonist, reduced transformation capability. Thus, leukemic transformation by APL fusion protein PRKAR1A-RARalpha is critically dependent on RXRalpha, which suggests RXRalpha is a promising target for APL.
Qiu
Jihui J
JJ
Department of Medicine, Baylor College of Medicine, Houston, TX, USA.
Lu
Xiaoxi
X
Zeisig
Bernd B
BB
Ma
Zhigui
Z
Cai
Xun
X
Chen
Saijuan
S
Gronemeyer
Hinrich
H
Tweardy
David J
DJ
So
Chi Wai Eric
CW
Dong
Shuo
S
D000818:Animals; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / Q000235:genetics / Q000378:metabolism*; D015973:Gene Expression Regulation, Leukemic; D006367:HeLa Cells; D006412:Hematopoietic Stem Cells / Q000473:pathology; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D000072482:Retinoic Acid Receptor alpha; D047490:Retinoid X Receptor alpha / Q000378:metabolism* / Q000502:physiology
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D015514:Oncogene Proteins, Fusion; C517834:PRKAR1A protein, human; C000607071:RARA protein, human; C000607072:Rara protein, mouse; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D047490:Retinoid X Receptor alpha