Differential expression, localization and activity of two alternatively spliced isoforms of human APC regulator CDH1.
The timely destruction of key regulators through ubiquitin-mediated proteolysis ensures the orderly progression of the cell cycle. The APC (anaphase-promoting complex) is a major component of this degradation machinery and its activation is required for the execution of critical events. Recent studies have just begun to reveal the complex control of the APC through a regulatory network involving WD40 repeat proteins CDC20 and CDH1. In the present paper, we report on the identification and characterization of human CDH1beta, a novel alternatively spliced isoform of CDH1. Both CDH1alpha and CDH1beta can bind to the APC and stimulate the degradation of cyclin B1, but they are differentially expressed in human tissues and cells. CDH1alpha contains a nuclear localization signal which is absent in CDH1beta. Intracellularly, CDH1alpha appears in the nucleus whereas CDH1beta is a predominantly cytoplasmic protein. The forced overexpression of CDH1alpha in cultured cells correlates with the reduction of nuclear cyclin A, but the steady-state amount of cyclin A does not change noticeably in CDH1beta-overexpressed cells. In Xenopus embryos, ectopic overexpression of human CDH1alpha, but not of CDH1beta, induces cell-cycle arrest during the first G(1) phase at the mid-blastula transition. Taken together, our findings document the differential expression, subcellular localization and cell-cycle-regulatory activity of human CDH1 isoforms.
Zhou
Yuan
Y
Institute of Molecular Biology, The University of Hong Kong, 8th Floor, Kadoorie Biological Sciences Building, Pokfulam Road, Hong Kong, People's Republic of China.
Ching
Yick-Pang
YP
Ng
Raymond W M
RW
Jin
Dong-Yan
DY
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D015703:Antigens, CD; D001921:Brain / Q000378:metabolism; D015820:Cadherins; D002874:Chromosome Mapping; D002888:Chromosomes, Human, Pair 19; D005260:Female; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008025:Ligases / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism; D009928:Organ Specificity / Q000235:genetics; D011485:Protein Binding; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D012689:Sequence Homology, Nucleic Acid; D013154:Spleen / Q000737:chemistry / Q000378:metabolism; D014407:Tumor Cells, Cultured; D043743:Ubiquitin-Protein Ligase Complexes; D014982:Xenopus laevis
D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D020033:Protein Isoforms; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D008025:Ligases