Deng Wenlin, Shuyu E, Tsukahara Ryoko, Valentine William J, Durgam Gangadhar, Gududuru Veeresa, Balazs Louisa, Manickam Venkatraman, Arsura Marcello, VanMiddlesworth Lester, Johnson Leonard R, Parrill Abby L, Miller Duane D, Tigyi Gabor
Department of Physiology, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
Gastroenterology. 2007 May;132(5):1834-51. doi: 10.1053/j.gastro.2007.03.038. Epub 2007 Mar 24.
BACKGROUND & AIMS: We recently identified lysophosphatidic acid (LPA) as a potent antiapoptotic agent for the intestinal epithelium. The objective of the present study was to evaluate the effect of octadecenyl thiophosphate (OTP), a novel rationally designed, metabolically stabilized LPA mimic, on radiation-induced apoptosis of intestinal epithelial cells in vitro and in vivo.
The receptors and signaling pathways activated by OTP were examined in IEC-6 and RH7777 cell lines and wild-type and LPA(1) and LPA(2) knockout mice exposed to different apoptotic stimuli.
OTP was more efficacious than LPA in reducing gamma irradiation-, camptothecin-, or tumor necrosis factor alpha/cycloheximide-induced apoptosis and caspase-3-8, and caspase-9 activity in the IEC-6 cell line. In RH7777 cells lacking LPA receptors, OTP selectively protected LPA(2) but not LPA(1) and LPA(3) transfectants. In C57BL/6 and LPA(1) knockout mice exposed to 15 Gy gamma irradiation, orally applied OTP reduced the number of apoptotic bodies and activated caspase-3-positive cells but was ineffective in LPA(2) knockout mice. OTP, with higher efficacy than LPA, enhanced intestinal crypt survival in C57BL/6 mice but was without any effect in LPA(2) knockout mice. Intraperitoneally administered OTP reduced death caused by lethal dose (LD)(100/30) radiation by 50%.
Our data indicate that OTP is a highly effective antiapoptotic agent that engages similar prosurvival pathways to LPA through the LPA(2) receptor subtype.
我们最近发现溶血磷脂酸（LPA）是一种对肠上皮具有强大抗凋亡作用的物质。本研究的目的是评估一种新的、经合理设计且代谢稳定的LPA模拟物——十八烯基硫代磷酸酯（OTP），在体外和体内对辐射诱导的肠上皮细胞凋亡的影响。
在IEC - 6和RH7777细胞系以及暴露于不同凋亡刺激的野生型、LPA(1)和LPA(2)基因敲除小鼠中，检测OTP激活的受体和信号通路。
在IEC - 6细胞系中，OTP在减少γ射线照射、喜树碱或肿瘤坏死因子α/放线菌酮诱导的凋亡以及半胱天冬酶-3 - 8和半胱天冬酶-9活性方面比LPA更有效。在缺乏LPA受体的RH7777细胞中，OTP选择性地保护LPA(2)转染细胞，而对LPA(1)和LPA(3)转染细胞无效。在接受15 Gy γ射线照射的C57BL/6和LPA(1)基因敲除小鼠中，口服给予OTP可减少凋亡小体数量并激活半胱天冬酶-3阳性细胞，但对LPA(2)基因敲除小鼠无效。OTP比LPA更有效，可提高C57BL/6小鼠肠道隐窝的存活率，但对LPA(2)基因敲除小鼠无任何影响。腹腔注射OTP可使致死剂量（LD）(100/30)辐射引起的死亡减少50%。
我们的数据表明，OTP是一种高效的抗凋亡剂，它通过LPA(2)受体亚型参与与LPA相似的促存活途径。
