Cornwell R D, Gollahon K A, Hickstein D D
Medical Research Service, Seattle Veterans Affairs Medical Center, WA 98108.
Proc Natl Acad Sci U S A. 1993 May 1;90(9):4221-5. doi: 10.1073/pnas.90.9.4221.
The CD11a/CD18 (leukocyte function-associated antigen 1 or LFA-1) leukocyte integrin is expressed at high levels on the cell surface of T lymphocytes and macrophages, where it mediates homotypic and heterotypic adherence between leukocytes and other cell types by binding to intracellular adhesion molecules 1 and 2 on the conjugate cell. To initiate studies of the molecular regulation of expression of the CD11a molecule, we isolated genomic clones corresponding to the 5'-flanking region of CD11a, identified the transcriptional start sites for CD11a, and characterized the CD11a promoter sequence in transient expression assays. The CD11a promoter (1.7 kb) directed functional activity of a heterologous reporter gene in the T-lymphocyte cell line Jurkat and the myeloid cell line HL-60 but did not direct functional activity in three different nonleukocyte cell lines. Deletional analysis of the CD11a promoter sequence indicated the presence of distinct, cell-type-specific regulatory sequences with the region from -40 to -17 relative to the transcription start sites responsible for most of the in vitro activity of the CD11a promoter in the Jurkat T-cell line, and the promoter sequence located within the first 17 bp relative to the transcription start sites responsible for CD11a promoter activity in the HL-60 cell line. Identification of the CD11a promoter provides the opportunity to identify unique cis-acting elements and trans-acting factors responsible for the cell-type-specific expression of CD11a in human leukocytes. Further, the CD11a promoter may be useful in transgenic constructs and in retroviral vectors to direct expression of heterologous genes selectively in leukocytes.
CD11a/CD18（白细胞功能相关抗原1或LFA-1）白细胞整合素在T淋巴细胞和巨噬细胞的细胞表面高水平表达，在那里它通过与结合细胞上的细胞间黏附分子1和2结合，介导白细胞与其他细胞类型之间的同型和异型黏附。为了启动对CD11a分子表达的分子调控研究，我们分离了与CD11a 5'侧翼区域相对应的基因组克隆，确定了CD11a的转录起始位点，并在瞬时表达试验中对CD11a启动子序列进行了表征。CD11a启动子（1.7 kb）在T淋巴细胞系Jurkat和髓细胞系HL-60中指导异源报告基因的功能活性，但在三种不同的非白细胞细胞系中不指导功能活性。对CD11a启动子序列的缺失分析表明，存在不同的细胞类型特异性调控序列，相对于转录起始位点，-40至-17区域负责Jurkat T细胞系中CD11a启动子的大部分体外活性，而相对于转录起始位点位于前17 bp内的启动子序列负责HL-60细胞系中CD11a启动子的活性。CD11a启动子的鉴定为鉴定负责人类白细胞中CD11a细胞类型特异性表达的独特顺式作用元件和反式作用因子提供了机会。此外，CD11a启动子可能在转基因构建体和逆转录病毒载体中有用，以在白细胞中选择性地指导异源基因的表达。
