Heme metabolism enzymes are dynamically expressed during Xenopus embryonic development.

As the key component of many hemoproteins (home-containing proteins), heme is involved in a broad range of biological processes. Enzymes required for heme biosynthesis and degradation pathways are evolutionarily conserved. While home metabolism has been studied extensively, the expression of hen le metabolism enzymes during development has not been described. Here, we report that all heme biosynthases and two heme oxygenases, which initiate heme degradation, are dynamically expressed during Xenopus embryonic development. All heme synthases, with the exception of aminolevulinic acid synthase 2, are maternally expressed. At neurula stage, home synthases are expressed in the developing neural tissue and in migrating neural crest cells. At the swimming tadpole stage, expression of home synthases can be detected in multiple lineages, including eyes. neural crest cells, developing central nervous system, ventral blood island, pronephron, and pronephric tubule. Similar to heme synthases, heme oxygenases arc expressed maternally. Zygotic expression of home oxygenases is mainly restricted to the developing neural and neural crest lineages. Unlike heme synthases, heme oxygenases are not expressed in the ventral blood island and arc expressed at a very low level in the pronephron and pronephric tubule. This indicates that heme metabolism may play important roles during development.