title: PAX5-PML acts as a dual dominant-negative form of both PAX5 and PML.
abstract: PAX5 is a transcription factor required for B-cell development and maintenance. PML is a tumor suppressor and a pro-apoptotic factor. A fusion gene, PAX5-PML, was found in acute lymphoblastic leukemia (ALL) with chromosomal translocation t(9;15)(p13;q24), but no functional analysis has been reported. Here, we demonstrate that PAX5-PML had a dominant-negative effect on both PAX5 and PML. PAX5-PML dominant negatively inhibited PAX5 transcriptional activity in the luciferase reporter assay and suppressed the expression of the PAX5 transcriptional targets in B-lymphoid cell line. Surprisingly, PAX5-PML hardly showed DNA-binding activity in vitro although it retained the DNA-binding domain of PAX5. Additional experiments, including chromatin immunoprecipitation (ChIP) assay, suggested that PAX5-PML bound to the promoter through the association with PAX5 on the promoter. On the other hand, coexpression of PAX5-PML inhibited PML sumoylation, disrupted PML nuclear bodies (NBs), and conferred apoptosis resistance on HeLa cells. Furthermore, treatment with arsenic trioxide (ATO) induced PML sumoylation and reconstitution of PML NBs, and overcame the anti-apoptotic effect of PAX5-PML in HeLa cells. These data suggest the possible involvement of this fusion protein in the leukemogenesis of B-ALL in a dual dominant-negative manner and the possibility that ALL with PAX5-PML can be treated with ATO.
authors.affiliation: Department of Hematology and Oncology, Nagoya University, Graduate School of Medicine, Nagoya, Aichi, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kurahashi
authors.forename: F
authors.initials: F
authors.lastname: Hayakawa
authors.forename: Y
authors.initials: Y
authors.lastname: Miyata
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: Y
authors.initials: Y
authors.lastname: Minami
authors.forename: S
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: A
authors.initials: A
authors.lastname: Abe
authors.forename: T
authors.initials: T
authors.lastname: Naoe
mesh_terms: D002460:Cell Line; D005799:Genes, Dominant; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D051757:PAX5 Transcription Factor / Q000235:genetics / Q000502:physiology*; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D009687:Nuclear Proteins; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D000071156:Promyelocytic Leukemia Protein; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C070576:PML protein, human