Brown A M, Barr C L, Ting J P
Lineberger Cancer Research Center, University of North Carolina, Chapel Hill 27599-7295.
J Immunol. 1991 May 1;146(9):3183-9.
Invariant chain (Ii) is intracellularly associated with MHC class II molecules, is implicated in class II function, and is coordinately regulated with the alpha- and beta-chains of MHC class II genes at the transcriptional level. Included among the various cis-acting elements of transcriptional control in MHC class II genes are the class II boxes, X and Y, and sequences 5' of X in the W (Z, H, S) region of class II genes. The Ii promoter region contains homologues of these elements, designated here as X, Y', and "W". This study utilized transient transfection and chloramphenicol acetyltransferase analysis to investigate the role of these elements in basal and inducible Ii gene expression. Invariant chain X, Y', and "W" all contribute to gene expression in B lymphoblastoid cell lines, making them likely candidates to mediate coordinate control of class II and Ii genes. IFN-gamma-inducible expression of the Ii gene in a glioblastoma cell line is also regulated through X, Y', and "W". Thus, the Ii class II boxes and "W" have dual roles in basal and inducible gene transcription.
恒定链（Ii）在细胞内与MHC II类分子相关联，参与II类功能，并在转录水平上与MHC II类基因的α链和β链协同调节。MHC II类基因转录控制的各种顺式作用元件包括II类盒、X和Y，以及II类基因W（Z、H、S）区域中X的5'端序列。Ii启动子区域包含这些元件的同源物，在此处命名为X、Y'和“W”。本研究利用瞬时转染和氯霉素乙酰转移酶分析来研究这些元件在基础和诱导性Ii基因表达中的作用。恒定链X、Y'和“W”均有助于B淋巴母细胞系中的基因表达，使其可能成为介导II类和Ii基因协同控制的候选元件。胶质母细胞瘤细胞系中Ii基因的IFN-γ诱导性表达也通过X、Y'和“W”进行调节。因此，Ii II类盒和“W”在基础和诱导性基因转录中具有双重作用。
