Nonlinear Responses Of Gene Expression In Local Gene Network Induced By Tup1 Gene Mutations

Using gene microarray to analyze characterization of the non-linearity of gene network is a basis for development of gene network technology. Tup1, a global transcriptional repressor of Saccharomyces cerevisiae, was used to build a four-layer, Tup1-centered local gene network (LGN) with 741 genes mainly by their protein-interactions. Expression changes of every gene in DNA microarray data based on Tup1 deletion and five point mutations were classified. The whole genes in the LGN have been analyzed statistically in accordance with the characteristics of gene network and the essential \ non-essential genes, the network level, network nodes, the gene locus. The non-linear relationship between the nodes' expression and the characteristics of the network was investigated.There are 225 genes repressed in the nomal state while significiantly up-regulated expression after mutation. (1)The average expression of the essential genes was lower than the non-essential genes in the mutation. The nodes numbers of the essential genes were grater in the network. The essential genes play more important role in controlling the network. (2)The inverse proportion between the level of the gene expression and nodes number in network was constructed during the smaller number of nodes in a certain extent. In the local network, gene expression was regulated at different network levels. (3)The gene expression changes in the near-centre layer were larger than the outer layers. (4)The genes with larger expression change ratios were found to scatter in the local network but focus on the endpoints to the chromosomes with unknown reason. (5)The genes in ChrXIII are significantly-down ragulated in Tup1 deleted-mutation. Tup1 might be an activator to genes in ChrXIII. This is in contrast with other genes.