Owolabi Bosede O, Ojo Opeolu O, Srinivasan Dinesh K, Conlon J Michael, Flatt Peter R, Abdel-Wahab Yasser H A
SAAD Centre for Pharmacy and Diabetes, School of Biomedical Sciences, University of Ulster, Coleraine, BT52 1SA, Northern Ireland, UK.
School of Health, Sport and Bioscience, University of East London, Stratford, E15 4LZ, UK.
Amino Acids. 2016 Feb;48(2):535-47. doi: 10.1007/s00726-015-2107-x. Epub 2015 Oct 6.
Hymenochirin-1b (Hym-1B; IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH2) is a cationic, α-helical amphibian host-defense peptide with antimicrobial, anticancer, and immunomodulatory properties. This study investigates the abilities of the peptide and nine analogues containing substitutions of Pro(5), Glu(6), and Asp(9) by either L-lysine or D-lysine to stimulate insulin release in vitro using BRIN-BD11 clonal β cells or isolated mouse islets and in vivo using mice fed a high-fat diet to produce obesity and insulin resistance. Hym-1B produced a significant and concentration-dependent increase in the rate of insulin release from BRIN-BD11 cells without cytotoxicity at concentrations up to 1 µM with a threshold concentration of 1 nM. The threshold concentrations for the analogues were: [P5K], [E6K], [D9K], [P5K, E6K] and [E6K, D9k] 0.003 nM, [E6K, D9K] and [D9k] 0.01 nM, [P5K, D9K] 0.1 nM and [E6k] 0.3 nM. All peptides displayed cytotoxicity at concentrations ≥1 µM except the [P5K] and [D9k] analogues which were non-toxic at 3 µM. The potency and maximum rate of insulin release from mouse islets produced by the [P5K] peptide were significantly greater than produced by Hym-1B. Neither Hym-1B nor the [P5K] analogue at 1 µM concentration had an effect on membrane depolarization or intracellular Ca(2+). The [P5K] analogue (1 µM) produced a significant increase in cAMP concentration in BRIN-BD11 cells and stimulated GLP-1 secretion from GLUTag cells. Down-regulation of the protein kinase A pathway by overnight incubation with forskolin completely abolished the insulin-releasing effects of [P5K]hym-1B. Intraperitoneal administration of the [P5K] and [D9k] analogues (75 nmol/kg body weight) to high-fat-fed mice with insulin resistance significantly enhanced glucose tolerance with a concomitant increase in insulin secretion. We conclude that [P5K]hym-1B and [D9k]hym-1B show potential for development into anti-diabetic agents.
人膜翅目抗菌肽-1b（Hym-1B；IKLSPETKDNLKKVLKGAIKGAIAVAKMV.NH2）是一种阳离子α螺旋两栖类宿主防御肽，具有抗菌、抗癌和免疫调节特性。本研究调查了该肽及其九个分别用L-赖氨酸或D-赖氨酸取代Pro(5)、Glu(6)和Asp(9)的类似物，在体外使用BRIN-BD11克隆β细胞或分离的小鼠胰岛，以及在体内使用喂食高脂饮食以诱导肥胖和胰岛素抵抗的小鼠来刺激胰岛素释放的能力。Hym-1B在浓度高达1μM时对BRIN-BD11细胞的胰岛素释放速率产生显著的浓度依赖性增加，且在浓度高达1μM时无细胞毒性，阈值浓度为1 nM。类似物的阈值浓度分别为：[P5K]、[E6K]、[D9K]、[P5K, E6K]和[E6K, D9k]为0.003 nM，[E6K, D9K]和[D9k]为0.01 nM，[P5K, D9K]为0.1 nM，[E6k]为0.3 nM。除[P5K]和[D9k]类似物在3μM时无毒性外，所有肽在浓度≥1μM时均表现出细胞毒性。[P5K]肽从小鼠胰岛释放胰岛素的效力和最大速率显著高于Hym-1B。1μM浓度的Hym-1B和[P5K]类似物对膜去极化或细胞内Ca(2+)均无影响。[P5K]类似物（1μM）使BRIN-BD11细胞中的cAMP浓度显著增加，并刺激GLUTag细胞分泌GLP-1。用福司可林过夜孵育下调蛋白激酶A途径可完全消除[P5K]hym-1B的胰岛素释放作用。对胰岛素抵抗的高脂喂养小鼠腹腔注射[P5K]和[D9k]类似物（75 nmol/kg体重）可显著增强葡萄糖耐量，并伴随胰岛素分泌增加。我们得出结论，[P5K]hym-1B和[D9k]hym-1B显示出开发成抗糖尿病药物的潜力。
