세포분열에 관여하는 인간의 CIP29/Hcc1 유전자와 상동성을 가지는 분열형 효모의 새로운 유전자 mas1+의 특성분석

Abstract

The regulation of gene expression plays an important role in cell cycle controls. In this study, a novel gene, the mas1?(mitosis associated protein) gene, a homolog of human CIP29/Hcc1, was isolated and characterized from fission yeast Schizosaccharomyces pombe (S. pombe) using a gene-specific polymerase chain reaction. The isolated gene contained a complete open reading frame capable of encoding 245 amino acid residues with a typical promoter, as judged by nucleotide sequence analysis. It was also found that a PCB (pombe cell cycle box) is located in the promoter region, which controls M-G1 specific transcription in S. pombe. The quantitative analysis of the mas1? transcript against adh1? showed that the pattern of expression is similar to that of the septation index. Cytokinesis of mas1 null mutant was greatly delayed at 25℃ and 36℃, and a large number of multi-septate cells were produced. The mas1 null mutant had 2C, 4C and 6C DNA contents, as determined by FACS analysis. In addition, the number of multi-septate cells significantly increased. When cells were cultured in nitrogen starvation medium to increase proliferation, the abnormal phenotypes of mas1 null mutant dramatically increased. These phenotypes could be rescued by an overexpression of the mas1+ gene. The mas1 protein localized in the nuclei of S. pombe and human HeLa cells, as evidenced by Mas1-EGFP signals. The abnormal growth pattern and the morphology of mas1 null mutant were complemented by a plasmid carrying human CIP29/Hcc-1cDNA. In addition, CIP29 /Hcc-1 transcript level increased in active cell proliferation stages in the developing mouse embryos. These results indicate that the mas1? ishomologous to the human CIP29/Hcc1 gene and is involved in cytokinesis and cell shape control.