Comprehensive isolation and functional analysis of the genes whose expressions are specifically induced upon entry into the Go phase of cell cycle

点击翻译按钮获取中文摘要

Mammalian cells stops growth and enter into the static phase or G_0 phase when the concentration of fetal calf serum in the culture medium was reduced from 10% to 0.5%. It was believed that a certain proliferation inhibitory factors exist in the medium harboring the cells in the G_0 phase to maintain the static condition. However, very few studies have been reported on the genes and their gene products that define the G_0 phase. Thus, if a large scale isolation of the genes whose expression was induced is performed, it would be possible to isolate the gene that is required to maintain the static phase by growth-inhibitory function. To isolate such genes comprehensively, we used an improved cDNA library subtraction p as we described previously. Using this method, we have so far been able to isolate more than 60 genes whose expression is induced in growth arrest condition and termed the transcript induced in growth arrest, TIGA, genes. Transcription of some of the TIGA genes are also induced upon contact inhibition of the cell growth. One of the TIGA genes, TIGA1, encodes a small protein with a single transmembrane motif. Ecopically expressed Tiga1 potently inhibited cell growth. Functional analyses of these TIGA genes might shed light to understanding the molecular mechanisms of induction and maintenance of G_0 state of the cell cycle.