A zinc-finger protein, PLAGL2, induces the expression of a proapoptotic protein Nip3, leading to cellular apoptosis.
Pleomorphic adenomas gene-like 2 (PLAGL2) protein containing seven C(2)H(2) zinc finger motifs exhibits DNA binding and transcriptional activation activity and is expressed in response to hypoxia or iron deficiency. To identify the target genes of PLAGL2, we transfected mouse PLAGL2 cDNA into Balb/c3T3 fibroblasts and neuroblastoma Neuro2a cells. Both cells were induced to undergo apoptosis by the expression of PLAGL2 as judged by assays of TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling), DNA fragmentation, propidium iodide staining, and the binding of annexin V to the cell surface. The treatment of the cells with an iron chelator, desferrioxamine, resulted in the induction of apoptosis with a concomitant accumulation of PLAGL2 in the nucleus. The expression of PLAGL2 in Balb/c3T3 cells led to the mRNA expression of a proapoptotic factor, Nip3, which can dimerize with Bcl-2. Nip3 mRNA was also induced in desferrioxamine-treated cells. Furthermore, the Nip3 promoter containing a hypoxia-responsive element was activated by PLAGL2, independent of hypoxia-inducible factor-1 (HIF-1). The transfection of antisense oligonucleotide to mouse Nip3 mRNA into PLAGL2-expressing cells led to a decrease in apoptotic cells compared with sense oligonucleotide-transfected cells. Despite the activation of DNA-HIF-1 binding activity under hypoxic conditions, neither an accumulation of HIF-1 alpha nor the activation of HIF-1 was observed following the expression of PLAGL2. These results indicate that PLAGL2 is located downstream of HIF-1 and suggest that PLAGL2 functions as a tumor suppressor in association with HIF-1.
Mizutani
Atsushi
A
Department of Biotechnology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
Furukawa
Takako
T
Adachi
Yasushi
Y
Ikehara
Susumu
S
Taketani
Shigeru
S
D016475:3T3 Cells; D000818:Animals; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015687:Cell Hypoxia / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003676:Deferoxamine / Q000494:pharmacology; D005786:Gene Expression Regulation; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020287:In Situ Nick-End Labeling; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D009447:Neuroblastoma; D009687:Nuclear Proteins / Q000378:metabolism; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D016335:Zinc Fingers
D017304:Annexin A5; C090121:BNIP3 protein, human; C116838:BNIP3L protein, human; D015342:DNA Probes; D004268:DNA-Binding Proteins; C497443:Hif1a protein, mouse; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D009687:Nuclear Proteins; D020319:Oligodeoxyribonucleotides, Antisense; C485426:Plagl2 protein, mouse; D011518:Proto-Oncogene Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D013873:Thionucleotides; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D003676:Deferoxamine