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[摘要]：Hemoglobin of bony fish and higher vertebrates is a tetrameric protein constructed by 2 alpha- and 2 beta-globins, which are expressed in a developmental stage-specific manner. The genomic organization of genes for embryonic and adult a- and p-globin varies from species to species. In fish, it is known that there is a unique genomic organization of globin genes, that is, alpha- and beta-globin genes are arranged in a bi-directional and head-to-head orientation with respect to transcription start sites. In medaka, we have demonstrated that 14 globin genes are located in 2 different clusters, and 5 pairs of the alpha- and beta-globin genes were found to be organized in a head-to-head orientation. The developmental expression patterns of the 11 globin genes were classified into 4 types. To clarify how their developmental stage-specific expressions are regulated, we produced 4 types of GFP- or RFP-transgenic medaka. Such transgenic medaka revealed that each of the 1-1.7 kbp 5' upstream sequences from respective globin genes possesses the ability to regulate the developmental stage-specific globin gene expression. In particular, the intervals between head-to-head alpha 3 and beta 3, and alpha 4 and beta 4 genes controlled the synchronized expression of the globin genes located at both sides of the intervals, which is significant to understand the mechanism by which equal amounts of a- and beta-globins are expressed in erythroid cells. We also demonstrated that the head-to-head intervals can control the expression of the globin genes located at both sides. These findings are significant to understand the mechanism by which alpha- and beta-globins are equally expressed in erythroid cells. (C) 2011 Elsevier B.V. All rights reserved. |
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