摘要
OBJECTIVE: To clone and study the polymorphism within interleukin-4 (IL-4) proximal promoter of asthmatic children. METHODS: The IL-4 proximal promoter segments were amplified and selected by polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) with genomic DNA from ten healthy children and forty patients with dominantly allergic familial histories as templates. The selected PCR segments were cloned into recombinant plasmids pIL-4-Jx2. The PCR inserts were sequenced by dideoxy chain termination method. RESULTS: Seven aberrant bands were found in SSCP analysis from forty asthmatic patients. The sequencing results showed that four variant sites were found within or adjacent to the known IL-4 regulatory element. A C to A transversion located at -229 position was just within the positive regulatory element-I (PRE-I) in one patient. A C to T transition adjacent to the negative regulatory element-II (NRE-II) and an extra G adjacent to TATA box were found in two patients. A five base nucleotide deletion was found near signal transducers and activators of transcription-6 responsive element (STAT-6 RE) in one patient. CONCLUSION: There were polymorphisms within the IL-4 proximal promoter of allergic asthmatic patients and these polymorphisms might result in aberrant expression of IL-4 gene and asthma.
目的 克隆和研究支气管哮喘患儿白细胞介素 4 (IL 4 )近侧启动子区DNA序列的多态性。方法 取 4 0名有明显家族及过敏史的哮喘患儿和 10名正常儿童 ,多聚酶链式反应 (PCR)结合单链构象多态性(SSCP )扩增、筛选IL 4近侧启动子片段 ,进一步构建正常对照和异常条带PCR产物的重组质粒pIL 4 Jx2 ,并用双脱氧链终止法对重组质粒进行序列测定。结果 在 4 0名患儿SSCP分析中发现了 7组异常条带。DNA测序结果显示有四处变异位点位于已知的调控元件之内或毗邻位点 :一名病人 - 2 2 9位C被A所替代 ,该变异恰好位于IL 4正性调节元件 Ⅰ (PRE Ⅰ )元件之内 ;两名病人负性调节元件 Ⅱ (NRE Ⅱ )元件毗邻C被T所替代 ,TATA框前增加一个G ;一名病人STAT 6元件附近缺少了ATTTT五碱基核苷酸。结论 过敏性哮喘患儿IL 4近侧启动子区DNA序列存在多态性 ,这可能与IL 4基因异常表达及哮喘的发病有关。
