Involvement of Pro-Phenoloxidase 3 in Lamellocyte-Meidated Spontaneous Melanization in Drosophila

  • Nam, Hyuck-Jin (Division of Life and Pharmaceutical Science, Department of Life Science, Ewha Womans University, and National Creative Research Initiative Center for Symbiosystem) ;
  • Jang, In-Hwan (Division of Life and Pharmaceutical Science, Department of Life Science, Ewha Womans University, and National Creative Research Initiative Center for Symbiosystem) ;
  • Asano, Tsunaki (Cellular Genetics Laboratory, Faculty of Biological Sciences, Tokyo Metropolitan University) ;
  • Lee, Won-Jae (Division of Life and Pharmaceutical Science, Department of Life Science, Ewha Womans University, and National Creative Research Initiative Center for Symbiosystem)
  • Received : 2008.09.24
  • Accepted : 2008.09.29
  • Published : 2008.12.31


Phenoloxidase (PO), a melanin-forming enzyme around the foreign bodies, is an important component of the host defense system in invertebrates. Pro-PO is the enzymatically inactive zymogen form of PO. In the Drosophila genome, three Pro-PO isoforms have been identified to date. These include Pro-PO1 and 2, which are primarily expressed in crystal cells, and Pro-PO3, which is predominantly found in the lamellocytes. In this study, we demonstrated that Drosophila Pro-PO3, but not Pro-PO1 or 2, is enzymatically active in its zymogen form. These findings were evidenced by spectacular melanin forming capacities of various cells and tissues that overexpressed these pro-enzymes. Furthermore, the melanization phenotype observed in the lamellocyte-enriched $hop^{Tum-l}$ mutant was drastically reduced in the absence of PPO3, indicating that PPO3 plays a major role in the lamellocyte-mediated spontaneous melanization process. Taken together, these findings indicate that the biochemical properties, activation mode and in vivo role of Pro-PO3 are likely distinct from those of the other two Pro-PO enzymes involved in Drosophila physiology.


Drosophila;innate immunity;lamellocyte;melanization;prophenoloxidase


Supported by : Korea Research Foundation


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