Lennard Mara L, Wilson Melanie R, Miller Norman W, Clem L William, Warr Gregory W, Hikima Jun-ichi
Marine Biomedicine and Environmental Sciences Center and Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.
Fish Shellfish Immunol. 2006 Feb;20(2):227-38. doi: 10.1016/j.fsi.2005.01.011.
The Oct2 transcription factor is important in driving expression of the IgH locus of the channel catfish, Ictalurus punctatus. Two isoforms, catfish Oct2alpha and Oct2beta, have been characterized at the level of expression and function, but little is known of the structure of the Oct2 gene in catfish. To gain insight into the diversity of Oct2 gene structure and expression in the teleost fish, a comparative genomic analysis of Oct2 was undertaken in the pufferfish (Fugu rubripes) and the zebrafish (Danio rerio). The orthologues of zebrafish and Fugu Oct2 were identified, and share with catfish Oct2 the expression of a limited number (two in zebrafish, three in Fugu) of isotypes produced by alternative pathways of RNA processing. The alternatively spliced variants of catfish Oct2 showed a different pattern of exon use from those of Fugu and zebrafish. The analysis also identified a novel homologue of Oct2 in both zebrafish and Fugu. This homologue, termed Oct2x, shares similarities to both Oct1 and Oct2. A phylogenetic analysis of the relationships of Oct2x gave an unexpected result, with Oct2x occupying a position basal to the Oct gene families of both vertebrates and Drosophila.
Oct2转录因子在驱动斑点叉尾鮰（Ictalurus punctatus）免疫球蛋白重链（IgH）基因座的表达中起重要作用。已经在表达和功能水平上鉴定了两种异构体，即鲶鱼Oct2α和Oct2β，但对鲶鱼Oct2基因的结构了解甚少。为了深入了解硬骨鱼中Oct2基因结构和表达的多样性，对河豚（Fugu rubripes）和斑马鱼（Danio rerio）进行了Oct2的比较基因组分析。鉴定出了斑马鱼和河豚Oct2的直系同源物，它们与鲶鱼Oct2一样，通过RNA加工的替代途径产生有限数量（斑马鱼中为两种，河豚中为三种）的同种型。鲶鱼Oct2的可变剪接变体显示出与河豚和斑马鱼不同的外显子使用模式。该分析还在斑马鱼和河豚中鉴定出一种新的Oct2同源物。这种同源物称为Oct2x，与Oct1和Oct2都有相似之处。对Oct2x关系的系统发育分析得出了一个意想不到的结果，即Oct2x占据了脊椎动物和果蝇Oct基因家族基部的位置。
