A Study on Exon 17 and 20 of the Insulin Receptor Gene Variations in Patients with Acanthosis Nigricans and Their Close Relatives

Objective: To explore the relationship between the insulin resistance and thedefects or mutations or mutations in insulin receptor (InsR)gene. Methods: Using the single-strandconformation polymorphism(SSCP), mutations and polymorphisms were detected in nine patients withacan-thosis nigricans (AN) and their first degree relatives in exon 17 and 20 of InsR gene. Thepolymorphisms and mutations were confirmed by DNA direct sequencing. Results: Fourteen variant SSCPpat-terns were detected. Direct sequencing revealed seven point mutations and six silentpolymorphisms. Five of the mutations appeared not to be mentioned in the previous literature. Thesemutations were all located within the domain of tyrokinase in InsR. Conclusion: It seem to us thatalmost all the AN patients with severe insulin resistance in this study have mutations in InsRtyrokinase domain.

融合肽抑制剂T20抵抗株包膜蛋白热变异位点547对人类免疫缺陷病毒-1生物学功能的影响

目的分析人类免疫缺陷病毒（HIV）的融合肽抑制剂T20抵抗突变株热变异位点547对病毒生物学功能的影响。方法采用PCR和定点突变方法构建HIV包膜蛋白（Env）突变体pSM-HXB2-DIV／DIM／SIM和PSM—LAI-DIV四种表达质粒，并构建了含有547D突变并置换HXB2或LAI株gp120部分的Env质粒，pSM-LAIgp120／HXB2gp41-DIV（L／H-DIV）和pSM-HXB2gp120／LAIsp4t—DIV（H／L-DIV）。假病毒感染实验和细胞融合实验分析Env的功能；Westernblot检测Env表达。圆二色谱（CD）分析6螺旋束（6HB）的稳定性；PyMOL软件分析含有547D的6HB结构。结果HXB2为骨架的547DIV、DIM及SIM和LAI为骨架的DIV假病毒的感染性低于其野生型（wt），前者的各变异Env的融合活性也明显降低；L／H—DIV假病毒感染性与HXB2wt相似，但融合活性明显低于wt；H／L—DIV假病毒的感染性低于两种野生型，融合活性与LAI叭相似，但低于HXB2wt。CD结果证明547D突变降低6HB的稳定性；结构分析显示，547D突变没有改变NHR中该位点与CHR中Q652位点之间的氢键，但可能通过增加NHR的负电荷从而减少病毒与T20的结合。结论547D突变降低LAI与HXB2株的感染性和HXB2株的融合活性；该突变通过降低6HB稳定性和增加gp41所带负电荷来减少病毒与T20的结合。