The Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
PLoS One. 2010 Jan 15;5(1):e8743. doi: 10.1371/journal.pone.0008743.
We have identified a cytosine-adenosine (CA) repeat length polymorphism in the 5'-regulatory region of the human integrin alpha2 gene ITGA2 that begins at -605. Our objective was to establish the contribution of this polymorphism to the regulation of integrin alpha2beta1 expression, which is known to vary several-fold among normal individuals, and to investigate the underlying mechanism(s).
METHODOLOGY/PRINCIPAL FINDINGS: In combination with the SNP C-52T, previously identified by us as a binding site for the transcription factor Sp1, four ITGA2 haplotypes can be distinguished, in the order in which they enhance ITGA2 transcription: (CA)(12)/-52C>(CA)(11)/-52C>(CA)(11)/-52T>(CA)(10)/-52T. By DNA affinity chromatography and chromatin immunoprecipitation (ChIP) assays, we show that poly (ADP-ribose)polymerase-1 (PARP-1) and Ku80/70 bind specifically and with enhanced affinity to the longer (CA)(12) repeat alleles.
CONCLUSIONS/SIGNIFICANCE: The increased binding of PARP-1 and Ku80/70, known components of transcription co-activator complexes, to the longer (CA)(12) alleles of ITGA2 coincides with enhanced alpha2beta1 expression. The most likely explanation for these findings is that PARP-1 and Ku80/70 contribute to the transcriptional regulation of ITGA2. These observations provide new insight into the mechanisms(s) underlying haplotype-dependent variability in integrin alpha2beta1 expression in human platelets and other cells.
我们已经在人类整合素 alpha2 基因 ITGA2 的 5'调控区鉴定出一个胞嘧啶-腺嘌呤（CA）重复长度多态性，其起始于-605。我们的目的是确定该多态性对整合素 alpha2beta1 表达的调节作用，已知该表达在正常个体中存在几倍的变化，并研究潜在的机制。
方法/主要发现：结合我们先前鉴定的转录因子 Sp1 的结合位点 SNP C-52T，可区分 ITGA2 的四个单倍型，其按增强 ITGA2 转录的顺序排列：（CA）（12）/-52C>（CA）（11）/-52C>（CA）（11）/-52T>（CA）（10）/-52T。通过 DNA 亲和层析和染色质免疫沉淀（ChIP）实验，我们表明聚（ADP-核糖）聚合酶-1（PARP-1）和 Ku80/70 特异性地并以增强的亲和力结合到较长的（CA）（12）重复等位基因。
结论/意义：PARP-1 和 Ku80/70 的结合增加，已知是转录共激活复合物的组成部分，与 ITGA2 的较长（CA）（12）等位基因的 alpha2beta1 表达增强相一致。这些发现的最可能解释是 PARP-1 和 Ku80/70 有助于 ITGA2 的转录调节。这些观察结果为整合素 alpha2beta1 在人血小板和其他细胞中依赖单倍型的表达变异性的潜在机制提供了新的见解。
