Anderson M K, Sun X, Miracle A L, Litman G W, Rothenberg E V
Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
Proc Natl Acad Sci U S A. 2001 Jan 16;98(2):553-8. doi: 10.1073/pnas.98.2.553. Epub 2001 Jan 9.
T lymphocytes and B lymphocytes are present in jawed vertebrates, including cartilaginous fishes, but not in jawless vertebrates or invertebrates. The origins of these lineages may be understood in terms of evolutionary changes in the structure and regulation of transcription factors that control lymphocyte development, such as PU.1. The identification and characterization of three members of the PU.1 family of transcription factors in a cartilaginous fish, Raja eglanteria, are described here. Two of these genes are orthologs of mammalian PU.1 and Spi-C, respectively, whereas the third gene, Spi-D, is a different family member. In addition, a PU.1-like gene has been identified in a jawless vertebrate, Petromyzon marinus (sea lamprey). Both DNA-binding and transactivation domains are highly conserved between mammalian and skate PU.1, in marked contrast to lamprey Spi, in which similarity is evident only in the DNA-binding domain. Phylogenetic analysis of sequence data suggests that the appearance of Spi-C may predate the divergence of the jawed and jawless vertebrates and that Spi-D arose before the divergence of the cartilaginous fish from the lineage leading to the mammals. The tissue-specific expression patterns of skate PU.1 and Spi-C suggest that these genes share regulatory as well as structural properties with their mammalian orthologs.
T淋巴细胞和B淋巴细胞存在于有颌脊椎动物中，包括软骨鱼类，但不存在于无颌脊椎动物或无脊椎动物中。这些谱系的起源可以从控制淋巴细胞发育的转录因子（如PU.1）的结构和调控的进化变化方面来理解。本文描述了软骨鱼类星鲨（Raja eglanteria）中PU.1转录因子家族的三个成员的鉴定和特征。其中两个基因分别是哺乳动物PU.1和Spi-C的直系同源基因，而第三个基因Spi-D是一个不同的家族成员。此外，在无颌脊椎动物海七鳃鳗（Petromyzon marinus）中鉴定出了一个类似PU.1的基因。哺乳动物和鳐鱼PU.1之间的DNA结合域和反式激活域都高度保守，这与七鳃鳗Spi形成了显著对比，七鳃鳗Spi仅在DNA结合域有明显的相似性。序列数据的系统发育分析表明，Spi-C的出现可能早于有颌和无颌脊椎动物的分化，而Spi-D则出现在软骨鱼类与导致哺乳动物的谱系分化之前。鳐鱼PU.1和Spi-C的组织特异性表达模式表明，这些基因与其哺乳动物直系同源基因共享调控和结构特性。
