The mouse oviduct-specific glycoprotein gene : Genomic organization and structure of the 5'-flanking regulatory region

输卵管特异性糖蛋白（OGP）是几丁质酶蛋白家族的一员，在输卵管中可直接与配子或早期胚胎结合。虽然糖蛋白广泛分布于哺乳动物物种中，并且有间接证据表明该分子参与受精过程，但其生理功能远未完全了解。为了了解指导基因表达的基本机制以及了解OGP的生理意义，我们分离并鉴定了小鼠OGP基因（mogp-1）。该基因全长13.4kb，包括11个外显子和10个内含子。与几丁质酶家族的其他成员相比，mogp-1的基因组结构非常保守。两个转录起始位点被发现在位置18和14上游的第一个ATG密码子。荧光原位杂交分析表明，mogp-1位于小鼠3号染色体的R-阳性F3带。mogp-1的启动子区缺乏典型的TATA、CAAT或GC盒序列，但含有多个转录因子结合位点的基序序列，包括10个半回文的雌激素反应元件（ERE）和一个不完全的ERE。瞬时转染实验表明，启动子活性可以由5 '侧翼区的2.2-kb内的各种序列调节，并且mogp-1启动子在雌激素受体阳性细胞系MCF-7中通过加入17 β-雌二醇（E2）被反式激活。此外，E2反应性的相关启动子活性位于mogp-1上游的前270 bp内。这些发现将有助于我们理解OGP基因表达的调控，并可能有助于设计实验来阐明OGP在哺乳动物受精过程中的作用。

A member of the chitinase protein family, oviduct-specific glycoprotein (OGP), can directly associate with gametes or the early embryo in the oviduct. Although the glycoprotein is widely distributed among mammalian species and there is indirect evidence concerning the involvement of the molecule for fertilization process, its physiological functions are far from completely understood. To understand the fundamental mechanisms that direct gene expression as well as to know the physiological significance of OGP, we have isolated and characterized a mouse OGP gene(mogp-1). The gene was found to span 13.4-kilo bases (kb) including 11 exons and 10 introns. The genomic organization of mogp-1 is well conserved compared to the other members of the chitinase family. Two transcription initiation sites were found at positions 18 and 14 upstream from the first ATG codon. Fluorescence in situ hybridization analysis demonstrated that the mogp-1 was located the on R-positive F3 band of mouse chromosome 3. Although the putative promoter region of mogp-1 lacked typical TATA, CAAT or GC box sequences, the region contained several motif sequences of transcription factor binding sites including 10 half-palindromic estrogen responsive elements (ERE) and an imperfect ERE. Transient transfection experiments demonstrated that promoter activity could be modulated by various sequences within the 2.2-kb of the 5'-flanking region, and that the mogp-1 promoter was transactivated in an estrogen receptor positive cell line, MCF-7, by the addition of 17beta-estradiol (E2). In addition, a relevant promoter activity for E2 responsiveness resides within the first 270 bp upstream of the mogp-1. These findings should facilitate our understanding of the regulation of OGP gene expression and they may be helpful for designing experiments to unravel the role of OGP in the process of mammalian fertilization.