Srinivasan Dinesh, Ojo Opeolu O, Abdel-Wahab Yasser H A, Flatt Peter R, Guilhaudis Laure, Conlon J Michael
School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, Northern Ireland BT52 1SA, United Kingdom.
Normandie Université, COBRA, UMR 6014, IRIB et FR 3038; Université de Rouen; INSA de Rouen; CNRS, IRCOF, 76821 Mont-Saint-Aignan Cedex, France.
Peptides. 2014 May;55:23-31. doi: 10.1016/j.peptides.2014.02.002. Epub 2014 Feb 12.
The frog skin host-defense peptide tigerinin-1R (RVCSAIPLPICH.NH2) is insulinotropic both in vitro and in vivo. This study investigates the effects on insulin release and cytotoxicity of changes in cationicity and hydrophobicity produced by selected substitutions of amino acids by l-arginine, l-lysine and l-tryptophan. The [A5W], [L8W] and [I10W] analogs produced a significant (P<0.01) increase in the rate of insulin release from BRIN-BD11 rat clonal β cells at concentration of 0.01 nM compared with 0.1 nM for tigerinin-1R. The increase in the rate of insulin release produced by a 3 μM concentration of the [S4R], [H12K], and [I10W] analogs from both BRIN-BD11 cells and mouse islets was significantly greater (P<0.05) than that produced by tigerinin-1R. No peptide stimulated the release of lactate dehydrogenase at concentrations up to 3 μM indicating that plasma membrane integrity had been preserved. [A5W] tigerinin-1R was the only analog tested that showed cytotoxic activity against human erythrocytes (LC50=265 ± 16 μM) and inhibited growth of Escherichia coli (MIC=500 μM) and Staphylococcus aureus (MIC=250 μM). The circular dichroism spectra of tigerinin-1R and [A5W] tigerinin-1R indicate that the peptides adopt a mixture of β-sheet, random coil and reverse β-turn conformations in 50% trifluoroethanol/water and methanol/water. Administration of [S4R] tigerinin-1R (75 nmol/kg body weight) to high-fat fed mice with insulin resistance significantly (P<0.05) enhanced insulin release and improved glucose tolerance over a 60 min period following an intraperitoneal glucose load. The study supports the claim that tigerinin-1R shows potential for development into novel therapeutic agents for treatment of type 2 diabetes mellitus.
青蛙皮肤宿主防御肽虎纹蛙肽 -1R（RVCSAIPLPICH.NH2）在体外和体内均具有促胰岛素分泌作用。本研究探讨了用L - 精氨酸、L - 赖氨酸和L - 色氨酸对氨基酸进行特定取代所产生的阳离子性和疏水性变化对胰岛素释放及细胞毒性的影响。与浓度为0.1 nM的虎纹蛙肽 -1R相比，[A5W]、[L8W]和[I10W]类似物在浓度为0.01 nM时，可使BRIN - BD11大鼠克隆β细胞的胰岛素释放速率显著（P<0.01）增加。浓度为3 μM的[S4R]、[H12K]和[I10W]类似物对BRIN - BD11细胞和小鼠胰岛胰岛素释放速率的增加显著大于（P<0.05）虎纹蛙肽 -1R。在浓度高达3 μM时，没有肽刺激乳酸脱氢酶的释放，这表明细胞膜完整性得以保留。[A5W]虎纹蛙肽 -1R是唯一被测试的对人红细胞具有细胞毒性活性（LC50 = 265±16 μM）且抑制大肠杆菌生长（MIC = 500 μM）和金黄色葡萄球菌生长（MIC = 250 μM）的类似物。虎纹蛙肽 -1R和[A5W]虎纹蛙肽 -1R的圆二色光谱表明，这些肽在50%三氟乙醇/水和甲醇/水中呈现β - 折叠、无规卷曲和反向β - 转角构象的混合。给患有胰岛素抵抗的高脂喂养小鼠腹腔注射[S4R]虎纹蛙肽 -1R（75 nmol/kg体重），在腹腔注射葡萄糖负荷后的60分钟内，显著（P<0.05）增强了胰岛素释放并改善了葡萄糖耐量。该研究支持了虎纹蛙肽 -1R具有开发成为治疗2型糖尿病新型治疗药物潜力的说法。
