Cloning and expression of zebrafish genes encoding the heme synthesis enzymes uroporphyrinogen III synthase (UROS) and protoporphyrinogen oxidase (PPO)

Abstract

Heme is synthesized from glycine and succinyl CoA by eight heme synthesis enzymes. Although genetic defects in any of these enzymes are known to cause severe human blood diseases, their developmental expression in mammals is unknown. In this paper, we report two zebrafish heme synthesis enzymes, uroporphyrinogen III synthase (UROS) and protoporphyrinogen oxidase (PPO) that are well conserved in comparison to their human counterparts. Both UROS and PPO formed pairs of bilateral stripes in the lateral plate mesoderm at the 15-somite stage. At 24 h post-fertilization (hpf), UROS and PPO were predominantly expressed in the intermediate cell mass (ICM) that is the major site of primitive hematopoiesis. The expression of UROS and PPO was drastically suppressed in the bloodless mutants cloche and vlad tepes/gata 1 from 15-somite to 24hpf stages, indicating that both cloche and vlad tepes/gata 1 are required for the induction and maintenance of UROS and PPO expression in the ICM.

• Heme synthesis
• UROS
• PPO
• zebrafish

Acknowledgements

The authors thank M. Kawahara, K. Hoshino, S. Endo and Y. Shioyama for fish maintenance and technical assistance; B.M. Weinstein and M. Hibi for fish mutants; Y. Kaziro for suggestions and encouragement. This work was supported by the Special Coordination Funds for Promoting Science and Technology of Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, by NBRP of Japan, by Kato Memorial Bioscience Foundation, and by the Intramural Program, NICHD, NIH.