Functional Study of Cell Cycle Regulated Protein Kinase

Hepatocellular carcinoma (HCC) is the laeading cause of cancer death among male Chinese. Identification of novel control mechanism for carcinogenesis of HCC is urgently needed for developing effective treatment. Recently, we have isolated a novel serine protein kinase, HsHPK, from cultured human hepatoma Huh7 cells. MQK overexpressed in hepatoma tissue compare to the adjacent normal tissue. The preliminary results showed that HsHPK has unique cellular localization and activity changes during cell cycle progression. However, overexpression of HsHPK cause a delay of mitosis suggests that HsHPK may be involved in mitotic checkpoint control. This hypothesis was further strengthened by the observation that the mutation of HsHPK in Arabidosis cause develppmental abnormalities in flower and leaves. Since the MQK is a revolutionary conserved kinase, the homologues gene can be identified in various model organisms from Arabidosis, C. elegans, Zebrafish to mouse. In this proposal, we will use different model organisms to explore the function of HsHPK in vivo and the project can be divided into 2 parts. Part 1(Chou): We will establish the tec inducible system in human hepatoma cell to overexpress MQK. The effect of HsHPK on hepatoma cells will be examined as follows: (1) cell cycle progression ; (2)phosphorylation pattern and activity changes during cell cycle progression;(3)microarray analysis of gene expression pattern. Using multiple round of yeast two hybrid approach, we will establish the protein linkage map of MQK inside the cell. Fission yeast will be used as a genetic screening system to identify suppressor gene that can prevent HsHPK induced mitotic catastrophe. Part 2(Tsai): Employing liver specific promoter, we will generate single copy transgenic mice with chosen site integration (Knock-in mice). Conventional and conditional knockout mice will also be make. The effect of HsHPK on embryonic development, liver regeneration and chemical induced carcinogenesis will be examined in those knock-in and knockout mice. The change of gene expression pattern of liver tissue in those mice will also be examine by microarray. The results from this study would reveal clues for novel control mechanism in human hepatoma. To establish a network of model organisms to study function of novel human genes is also essential for functional genomic study in post genome ear in Taiwan.

Project ID:PG9403-1338
External Project ID:NHRI-EX94-9001BL