Planned Member


Hiroyuki Ishikawa
Department of Biology, Graduate School of Science, Chiba University

Investigation of phosphorylation zone within the Golgi

Research abstract

Recent studies revealed a new class of kinases that phosphorylate the extracellular domain of proteins within the secretory pathway. The Drosophila Golgi kinase Four-jointed (Fj) phosphorylates the extracellular cadherin domains of atypical cadherins Fat and Dachsous (Ds). Fj-mediated phosphorylations of Fat and Ds modulate the Fat-Ds binding, and this modification controls formation of the epithelial tissues in Drosophila development. Golgi complex of Drosophila cells is a stack of cis-, medial-, and trans-cisternae, and the cisternae are present as dispersed stacks. Fj is localized to a subset of the Golgi stacks (phosphorylation zone) within the cells of the Drosophila wing imaginal disc. Furthermore, change in proportion of phosphorylation zone in the cells of the wing imaginal discs is observed through developmental stages. In this project, my research aims to clarify the molecular mechanism of establishment for the phosphorylation zone in the Golgi of the Drosophila cells.

Original papers

  1. Ishikawa, H. O., Xu, A., Ogura, E., Manning, G., and Irvine, K. D. (2012) The Raine syndrome protein FAM20C is a Golgi kinase that phosphorylates bio-mineralization proteins. PLoS One 7, e42988.
  2. Simon, M. A., Xu, A., Ishikawa, H. O., and Irvine, K. D. (2010) Modulation of Fat:Dachsous binding by the cadherin domain kinase Four-jointed. Curr Biol. 20, 811-817.
  3. Ishikawa, H. O., Takeuchi, H., Haltiwanger, R. S., and Irvine, K. D. (2008) Four-jointed is a Golgi kinase that phosphorylates a subset of cadherin domains. Science 321, 401-404.


  1. Keira, Y., Wada, M., and Ishikawa, H. O. (2017) Regulation of Drosophila development by the Golgi kinase Four-jointed. Curr Top Dev Biol. 123, 143-179.