Isolation and characterization of XKaiso, a transcriptional repressor that associates with the catenin Xp120(ctn) in Xenopus laevis.
The Armadillo family of catenin proteins function in multiple capacities including cadherin-mediated cell-cell adhesion and nuclear signaling. The newest catenin, p120(ctn), differs from the classical catenins and binds to the membrane-proximal domain of cadherins. Recently, a novel transcription factor Kaiso was found to interact with p120(ctn), suggesting that p120(ctn) also possesses a nuclear function. We isolated the Xenopus homolog of Kaiso, XKaiso, from a Xenopus stage 17 cDNA library. XKaiso contains an amino-terminal BTB/POZ domain and three carboxyl-terminal zinc fingers. The XKaiso transcript was present maternally and expressed throughout early embryonic development. XKaiso's spatial expression was defined via in situ hybridization and was found localized to the brain, eye, ear, branchial arches, and spinal cord. Co-immunoprecipitation of Xenopus p120(ctn) and XKaiso demonstrated their mutual association, whereas related experiments employing differentially epitope-tagged XKaiso constructs suggest that XKaiso additionally self-associates. Finally, reporter assays employing a chimera of XKaiso fused to the GAL4 DNA binding domain indicate that XKaiso is a transcriptional repressor. These data suggest that XKaiso functions throughout development and that its repressor functions may be most apparent in the context of neural tissues. The significance of the XKaiso-p120(ctn) interaction has yet to be determined, but it may include transducing information from cadherin-mediated cell-cell contacts to transcriptional processes within the nucleus.
Kim
Si Wan
SW
Department of Biochemistry and Molecular Biology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Fang
Xiang
X
Ji
Hong
H
Paulson
Alicia F
AF
Daniel
Juliet M
JM
Ciesiolka
Malgorzata
M
van Roy
Frans
F
McCrea
Pierre D
PD
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D051177:Catenins; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D000939:Epitopes / Q000378:metabolism; D015723:Gene Library; D017403:In Situ Hybridization; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic; D014981:Xenopus; D029867:Xenopus Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D014982:Xenopus laevis; D000095002:Delta Catenin
D051177:Catenins; D015815:Cell Adhesion Molecules; D018076:DNA, Complementary; D000939:Epitopes; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C451401:ZBTB33 protein, Xenopus; C118822:Zbtb33 protein, mouse; D008156:Luciferases; D000095002:Delta Catenin