老鼠αl-酸性醣蛋白基因的結構和表現

Abstract

αl-acid glycoprotein是一種主要的急性狀態反應劑．我們己經從小老鼠肝臟選殖到兩種αl- AGP的CDNA，命名為AGP-1和AGP- 2．其中，AGP-l具有兩種不同的基因型態，在不同品系的老鼠中使限制的認知位置改變，這所謂的AGP-1A和AGP-1B的CDNA已經從(B10X AKR/J) F1的CDNA基因庫中篩選出，並完全定序，發現在編譯區一個核?酸的改變，使AGP-1A和AGP-1B所帶電荷不等，而造成在電泳中移動速率不一致． 以AGP-1 CDNA為探針篩選C57BL/6的基因，共找到4個可以雜化的純系，加以分析後，發覺其中包含三個AGP基因，AGP-1, AGP-2，和AGP-3．經過限制?圖的分析和部分的核酸定序，已分離出三個基因的?動子區．利用引子延伸的技術，我們決定了AGP-1轉錄的起始點，並且知道在正常肝臟狀況下，AGP-1能有效率的表現，發炎時，能大量增加其轉錄量，AGP-2則不能． 將AGP-1和AGP-2的?動子區分離出，進行DNA轉染(Transfection)實驗，藉此研究糖皮素(glucocorticoid)及巨噬細胞分必因數對AGP基因的調控，和AGP-1邊與AGP-2轉錄的差別．

α1-acid glycoprotein is a major acute phase reactant. We have cloned two mouse α1-Agp cDNAs, termed Agp-1 and Agp-2. Two alleles of Agp-1 have also been identified from inbred mice by restriction site polymorphism. cDNA of both Agp-1A and Agp-1B have been cloned from (Bl0×AKR/J)F1 mouse and sequenced. A single nucleotide substitution in the coding sequence of Agp-1 is probably responsible for the observed difference in electrophoretic mobilities of Agp-1A and Agp-1B. Four λ genomic clones containing Agp-1, Agp-2 and Agp-3 have been isolated from C57BL/6 genomic library. Restriction mapping and partial sequencing have been employed for isolation of promoter sequences. Primer extension experiment has been used to determine the transcription initiation site; only Agp-1 is efficiently expressed in normal liver and is induced substantially during inflammation. Promoters of Agp-1 and Agp-2 were used for functional assay by transfection. We intend to study the gene regulation, by glucocorticoid and macrophage screted factors, and the molecular basis of differential transcription of Agp-1 and Agp-2.