Koyasu S, Hussey R E, Clayton L K, Lerner A, Pedersen R, Delany-Heiken P, Chau F, Reinherz E L
Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA.
EMBO J. 1994 Feb 15;13(4):784-97. doi: 10.1002/j.1460-2075.1994.tb06321.x.
To elucidate the role of the CD3 eta subunit of the T cell receptor (TCR) in thymic development, a CD3 eta -/- mouse was generated by gene targeting. Insertion of a neomycin resistance gene into exon 9 of the CD3 zeta/eta/phi locus disrupted expression of CD3 eta and CD3 phi without affecting the expression of CD3 zeta. Little difference was observed between wild type and CD3 eta -/- mice with regard to cellularity or subset composition in thymus and peripheral lymphoid organs. Furthermore, neither alloproliferative responses nor cytotoxic T lymphocyte generation and effector function was affected by the mutation. The effect of the CD3 eta -/- mutation on thymic selection was examined by crossing the CD3 eta knockout animals with anti-HY TCR transgenic animals: the absence of the CD3 eta subunit altered neither positive nor negative selection. Thus, CD3 eta is not required for thymic selection. Of note, the birth rate of the CD3 eta -/- animals was significantly lower than that of wild type or heterozygous animals (P = 0.041-0.002). This unexpected result is probably the consequence of an alteration in mRNA expression of the Oct-1 nuclear transcription factor in CD3 eta -/- animals. The CD3 zeta/eta/phi locus partially overlaps the gene encoding Oct-1 whose transcription is dysregulated by the CD3 eta -/- mutation. Our results clearly underscore the value of characterizing all products of a genetic locus disrupted by gene targeting.
为阐明T细胞受体（TCR）的CD3 η亚基在胸腺发育中的作用，通过基因打靶构建了CD3 η基因敲除小鼠。将新霉素抗性基因插入CD3 ζ/η/φ基因座的外显子9中，破坏了CD3 η和CD3 φ的表达，而不影响CD3 ζ的表达。在胸腺和外周淋巴器官的细胞数量或亚群组成方面，野生型和CD3 η基因敲除小鼠之间未观察到明显差异。此外，同种异体增殖反应、细胞毒性T淋巴细胞的产生及效应功能均未受该突变影响。通过将CD3 η基因敲除动物与抗HY TCR转基因动物杂交，研究了CD3 η基因敲除对胸腺选择的影响：CD3 η亚基的缺失既未改变阳性选择也未改变阴性选择。因此，胸腺选择不需要CD3 η。值得注意的是，CD3 η基因敲除动物的出生率显著低于野生型或杂合子动物（P = 0.041 - 0.002）。这一意外结果可能是由于CD3 η基因敲除动物中Oct-1核转录因子mRNA表达改变所致。CD3 ζ/η/φ基因座与编码Oct-1的基因部分重叠，其转录因CD3 η基因敲除突变而失调。我们的结果清楚地强调了对基因打靶破坏的遗传位点的所有产物进行表征的价值。
