The JIL-1 kinase regulates the structure of Drosophila polytene chromosomes

Huai Deng, Weiguo Zhang, Xiaomin Bao, Janine N. Martin, Jack Girton, Jørgen Johansen, Kristen M. Johansen

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


The JIL-1 kinase localizes to interband regions of Drosophila polytene chromosomes and phosphorylates histone H3 Ser10. Analysis of JIL-1 hypomorphic alleles demonstrated that reduced levels of JIL-1 protein lead to global changes in polytene chromatin structure. Here we have performed a detailed ultrastructural and cytological analysis of the defects in JIL-1 mutant chromosomes. We show that all autosomes and the female X chromosome are similarly affected, whereas the defects in the male X chromosome are qualitatively different. In polytene autosomes, loss of JIL-1 leads to misalignment of interband chromatin fibrils and to increased ectopic contacts between nonhomologous regions. Furthermore, there is an abnormal coiling of the chromosomes with an intermixing of euchromatic regions and the compacted chromatin characteristic of banded regions. In contrast, coiling of the male X polytene chromosome was not observed. Instead, the shortening of the male X chromosome appeared to be caused by increased dispersal of the chromatin into a diffuse network without any discernable banded regions. To account for the observed phenotypes we propose a model in which JIL-1 functions to establish or maintain the parallel alignment of interband chromosome fibrils as well as to repress the formation of contacts and intermingling of nonhomologous chromatid regions.

Original languageEnglish (US)
Pages (from-to)173-182
Number of pages10
Issue number3
StatePublished - Aug 2005

Bibliographical note

Funding Information:
Acknowledgements We thank members of the laboratory for discussion, advice, and critical reading of the manuscript. We also wish to acknowledge Ms. V. Lephart for maintenance of fly stocks, Mr. Laurence Woodruff for technical assistance, and Ms. Mary Sue Mayes and Dr. Ted Huiatt for assistance with the EM. We especially thank Dr. L. Wallrath for providing the GFP–lacI transgenic stock 128.1 and the lac operator repeats transgenic stock 4D5 and Dr. S. Heidmann for the generous gift of the H2AvDmRFP1 transgenic stock. We also wish to thank Dr. R. Tsien for making the mRFP1 construct available for these studies. This work was supported by NIH grant GM62916 (K.M.J.).


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