Cloning and Characterization of the Human Integrin β6 Gene Promoter

The integrin β6 (ITGB6) gene, which encodes the limiting subunit of the integrin αvβ6 heterodimer, plays an important role in wound healing and carcinogenesis. The mechanism underlying ITGB6 regulation, including the identification of DNA elements and cognate transcription factors responsible for basic transcription of human ITGB6 gene, remains unknown. This report describes the cloning and characterization of the human ITGB6 promoter. Using 5′-RACE (rapid amplification of cDNA ends) analysis, the transcriptional initiation site was identified. Promoter deletion analysis identified and functionally validated a TATA box located in the region −24 to −18 base pairs upstream of the ITGB6 promoter. The regulatory elements for transcription of the ITGB6 gene were predominantly located −289 to −150 from the ITGB6 promoter and contained putative binding sites for transcription factors such as STAT3 and C/EBPα. Using chromatin immunoprecipitation assays, this study has demonstrated, for the first time, that transcription factors STAT3 and C/EBPα are involved in the positive regulation of ITGB6 transcription in oral squamous cell carcinoma cells. These findings have important implications for unraveling the mechanism of abnormal ITGB6 activation in tissue remodeling and tumorigenesis.整合素β6（integrin β6, ITGB6）基因编码整合素αvβ6异二聚体的限制性亚基，在伤口愈合与癌变进程中发挥关键作用。目前，有关ITGB6基因的调控机制——包括鉴定负责人类ITGB6基因基础转录的DNA元件及其同源转录因子——仍有待阐明。本研究报道了人类ITGB6启动子的克隆与特征分析。通过5'-RACE（cDNA末端快速扩增，rapid amplification of cDNA ends）分析，研究人员明确了该基因的转录起始位点。启动子缺失分析鉴定并功能验证了位于ITGB6启动子上游-24至-18碱基对区域的TATA盒。ITGB6基因转录的调控元件主要分布于该启动子上游-289至-150区间，其中包含STAT3与C/EBPα等转录因子的潜在结合位点。本研究通过染色质免疫沉淀（chromatin immunoprecipitation）实验，首次证实转录因子STAT3与C/EBPα可在口腔鳞状细胞癌细胞中正向调控ITGB6的转录。上述发现对于解析组织重塑与肿瘤发生过程中ITGB6异常激活的机制具有重要价值。