Effects on differentiation by the promyelocytic leukemia PML/RARalpha protein depend on the fusion of the PML protein dimerization and RARalpha DNA binding domains.
The block of terminal differentiation is a prominent feature of acute promyelocytic leukemia (APL) and its release by retinoic acid correlates with disease remission. Expression of the APL-specific PML/RARalpha fusion protein in hematopoietic precursor cell lines blocks terminal differentiation, suggesting that PML/ RARalpha may have the same activity in APL blasts. We expressed different PML/RARalpha mutants in U937 and TF-1 cells and demonstrated that the integrity of the PML protein dimerization and RARalpha DNA binding domains is crucial for the differentiation block induced by PML/RARalpha, and that these domains exert their functions only within the context of the fusion protein. Analysis of the in vivo dimerization and cell localization properties of the PML/RARalpha mutants revealed that PML/RARalpha--PML and PML/RARalpha--RXR heterodimers are not necessary for PML/RARalpha activity on differentiation. We propose that a crucial mechanism underlying PML/RARalpha oncogenic activity is the deregulation of a transcription factor, RARalpha, through its fusion with the dimerization interface of another nuclear protein, PML.
Istituto di Clinica Medica I, Policlinico Monteluce, Perugia University, Italy.
F
F
Grignani
U
U
Testa
D
D
Rogaia
P F
PF
Ferrucci
P
P
Samoggia
A
A
Pinto
D
D
Aldinucci
V
V
Gelmetti
M
M
Fagioli
M
M
Alcalay
J
J
Seeler
F
F
Grignani
I
I
Nicoletti
C
C
Peschle
P G
PG
Pelicci
D001665:Binding Sites; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D004247:DNA / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D000071156:Promyelocytic Leukemia Protein; D011487:Protein Conformation; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D047488:Retinoid X Receptors; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism*; D014212:Tretinoin / Q000378:metabolism; D025521:Tumor Suppressor Proteins
D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D015514:Oncogene Proteins, Fusion; D000071156:Promyelocytic Leukemia Protein; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C093476:promyelocytic leukemia-retinoic acid receptor alpha fusion oncoprotein; C070576:PML protein, human; D014212:Tretinoin; D004247:DNA