Alternative splicing of the imprinted candidate tumor suppressor gene ZAC regulates its antiproliferative and DNA binding activities.
ZAC encodes a zinc finger protein with antiproliferative activity, is maternally imprinted and is a candidate for the tumor suppressor gene on 6q24. ZAC expression is frequently lost in breast and ovary tumor-derived cell lines and down-regulated in breast primary tumors. In this report, we describe ZACDelta2, an alternatively spliced variant of ZAC lacking the sequence encoding the two N-terminal zinc fingers. Messenger RNAs encoding ZAC or ZACDelta2 were equally abundant and both proteins were nuclear. ZACDelta2 displayed an improved transactivation activity and an enhanced affinity for a ZAC binding site, suggesting that the two N-terminal zinc fingers negatively regulated ZAC binding to its target DNA sequences. Both proteins were equally efficient in preventing colony formation, indicating similar overall antiproliferative activities. However, these activities resulted from a differential regulation of apoptosis vs cell cycle progression since ZACDelta2 was more efficient at induction of cell cycle arrest than ZAC, whereas it was the reverse for apoptosis induction. Hence, these data further underline that ZAC gene is critically controlled, both at the transcriptional level through imprinting and at the functional level through alternative splicing.
Bilanges
B
B
Mécanismes Moléculaires des Communications Cellulaires, UPR 9023 CNRS, 141 rue de la Cardonille, F-34094 Montpellier Cedex 05, France.
Varrault
A
A
Mazumdar
A
A
Pantaloni
C
C
Hoffmann
A
A
Bockaert
J
J
Spengler
D
D
Journot
L
L
D017398:Alternative Splicing / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D004587:Electrophoresis, Agar Gel; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D020862:GC Rich Sequence / Q000235:genetics; D017353:Gene Deletion; D016147:Genes, Tumor Suppressor / Q000502:physiology*; D006801:Humans; D007124:Immunoenzyme Techniques; D007668:Kidney / Q000378:metabolism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D025521:Tumor Suppressor Proteins; D016335:Zinc Fingers / Q000502:physiology*
D018797:Cell Cycle Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C106464:PLAGL1 protein, human; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D015500:Chloramphenicol O-Acetyltransferase