Pazdrak Konrad, Shi Xuan-Zheng, Sarna Sushil K
Department of Internal Medicine, Enteric Neuromuscular Disorders and Visceral Pain Center, Division of Gastroenterology, The University of Texas Medical Branch at Galveston, 77555-1064, USA.
Gastroenterology. 2004 Oct;127(4):1096-109. doi: 10.1053/j.gastro.2004.07.008.
BACKGROUND & AIMS: Intercellular adhesion molecule 1 (ICAM-1) receptors are expressed at low levels on human colonic circular smooth muscle cells (HCCSMCs) and their expression is increased in patients with Crohn's disease. We investigated the roles of transcription factors Sp1 and nuclear factor kappa B (NF-kappaB) in the regulation of ICAM-1 expression on HCCSMCs and examined whether ICAM-1 expression mediates the suppression of contractility in response to TNFalpha.
Experiments were performed on primary cultures of HCCSMCs and fresh human colonic circular muscle strips.
TNFalpha treatment of HCCSMCs induced rapid and prolonged accumulation of ICAM-1 messenger RNA (mRNA) and protein. NF-kappaB inhibition before, but not after, 1 hour of TNFalpha-stimulation blocked the expression of ICAM-1. TNFalpha significantly enhanced Sp1/DNA binding. Sp1 bound to the 3' flanking region of a variant kappaB site in the -192/-172 region of ICAM-1 promoter. Mutation of this region abolished the response to TNFalpha. The treatment of HCCSMCs with Sp1 antisense oligonucleotides (ODNs) blocked the expression of ICAM-1, but sense ODNs had no effect. Protein kinase C zeta (PKCzeta) inhibition before or 3 hours after stimulation with TNFalpha also blocked the expression of ICAM-1. TNFalpha treatment of circular muscle strips pretreated with ICAM-1 sense ODNs or control medium significantly reduced their response to acetylcholine, whereas pretreatment with antisense ODNs blocked this effect.
The expression of ICAM-1 on HCCSMCs in response to TNFalpha is regulated by transcription factors Sp1 and NF-kappaB binding independently to the -192/-172 region of the ICAM-1 promoter. The expression of ICAM-1 plays a critical role in the suppression of cell contractility in response to TNFalpha.
细胞间黏附分子1（ICAM-1）受体在人结肠环形平滑肌细胞（HCCSMC）上低水平表达，且在克罗恩病患者中其表达增加。我们研究了转录因子Sp1和核因子κB（NF-κB）在调节HCCSMC上ICAM-1表达中的作用，并检测ICAM-1表达是否介导了对肿瘤坏死因子α（TNFα）反应性的收缩性抑制。
在HCCSMC原代培养物和新鲜人结肠环形肌条上进行实验。
TNFα处理HCCSMC可诱导ICAM-1信使核糖核酸（mRNA）和蛋白快速且持续的积累。在TNFα刺激1小时之前而非之后抑制NF-κB可阻断ICAM-1的表达。TNFα显著增强Sp1/DNA结合。Sp1结合至ICAM-1启动子-192 / -172区域中一个可变κB位点的3'侧翼区域。该区域的突变消除了对TNFα的反应。用Sp1反义寡核苷酸（ODN）处理HCCSMC可阻断ICAM-1的表达，但正义ODN无此作用。在TNFα刺激之前或刺激3小时后抑制蛋白激酶Cζ（PKCζ）也可阻断ICAM-1的表达。用ICAM-1正义ODN或对照培养基预处理的环形肌条经TNFα处理后，其对乙酰胆碱的反应显著降低，而用反义ODN预处理可阻断此效应。
HCCSMC上ICAM-1对TNFα的反应性表达受转录因子Sp1和NF-κB独立结合至ICAM-1启动子-192 / -172区域的调控。ICAM-1的表达在对TNFα反应性的细胞收缩性抑制中起关键作用。
