Genome-wide Analysis of the Binding Sites of the JIL-1 H3S10 Kinase and its Contribution to Modulation of Gene Expression.

Genome-wide Analysis of the Binding Sites of the JIL-1 H3S10 Kinase and its Contribution to Modulation of Gene Expression. Kristen M. Johansen¹, Weili Cai¹, Chao Wang¹, Lu Shen¹, Yeran Li¹, Sanzhen Liu², Changfu Yao¹, Xiaomin Bao¹, Patrick S. Schnable^2,3, Jack Girton¹, Jørgen Johansen¹. 1) Biochem, Biophys & Molec Biol, Iowa State Univ, Ames, IA; 2) Agronomy, Iowa State Univ, Ames, IA; 3) Data2Bio LLC, Ames, IA.

JIL-1 kinase localizes to euchromatic regions and is responsible for H3S10 phosphorylation at interphase. Genetic interaction assays show that JIL-1 can counterbalance the gene-silencing effect of the three major heterochromatin components Su(var)3-9, Su(var)3-7, and HP1a. In this study we have determined the genome-wide relationship of JIL-1 kinase mediated H3S10 phosphorylation with gene expression and the distribution of the epigenetic H3K9me2 mark. We show in wild-type salivary gland cells that the H3S10ph mark is predominantly enriched at active genes whereas the H3K9me2 mark largely is associated with inactive genes. Comparison of global transcription profiles in salivary glands from wild-type and JIL-1 null mutant larvae revealed that the expression levels of 1,737 genes changed at least two-fold in the mutant and that a substantial number (39%) of these genes were upregulated whereas 61% were downregulated. Interestingly, salivary gland specific pathways were particularly affected by downregulation in the JIL-1 mutant background suggesting that H3S10 phosphorylation may serve to keep genes transcriptionally active in a tissue and/or developmentally stage specific context. Furthermore, the results showed that downregulation of genes in the mutant was correlated with higher levels or acquisition of the H3K9me2 mark whereas upregulation of a gene was correlated with loss of or diminished H3K9 dimethylation. These results are compatible with a model where gene expression levels are modulated by the levels of the H3K9me2 mark independent of the state of the H3S10ph mark, which is not required for either transcription or gene activation to occur. Rather, H3S10 phosphorylation functions to indirectly maintain active transcription by counteracting H3K9 dimethylation and gene silencing. Supported by NIH grant GM62916.