Kennedy M, Denenberg A G, Szabó C, Salzman A L
Division of Gastroenterology, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
Gastroenterology. 1998 Mar;114(3):510-8. doi: 10.1016/s0016-5085(98)70534-7.
BACKGROUND & AIMS: Peroxynitrite induces cytotoxicity by generating DNA single-strand breaks and activating poly(ADP-ribose) synthetase (PARS), a nuclear enzyme that consumes oxidized nicotinamide adenine dinucleotide (NAD+) and depletes cellular adenosine triphosphate (ATP). The aim of this study was to examine this mechanism of injury in an intestinal epithelial cell model after exposure to exogenous peroxynitrite (ONOO-) and nitric oxide (NO).
Caco-2BBe cell monolayers exposed to donors of peroxynitrite (3-morpholino-sydnonimine [SIN-1], 3 mmol/L) or NO (S-nitroso-N-acetyl penicillamine [SNAP]; 3 mmol/L) were analyzed for DNA strand breaks, [NAD+], [ATP], and transepithelial flux of fluorescein sulfonic acid.
SIN-1 but not SNAP induced DNA single-strand breakage. Both SIN-1 and SNAP reduced [ATP], but only SIN-1 reduced [NAD+]. Inhibition of PARS activity by the PARS inhibitors 5-iodo-6-amino 1,2-benzopyrone or 3-aminobenzamide prevented the SIN-1-induced reduction in [NAD+] and [ATP] but had no effect on the SNAP-induced reduction in [ATP]. PARS inhibition reduced SIN-1-but not SNAP-induced hyperpermeability.
Peroxynitrite but not NO increases transepithelial permeability by inducing DNA strand breaks that activate the PARS pathway and cause the depletion of intracellular energy stores. Inhibition of PARS activity may represent a novel strategy in ameliorating peroxynitrite-mediated epithelial injury during intestinal inflammation.
过氧亚硝酸盐通过产生DNA单链断裂并激活聚（ADP - 核糖）合成酶（PARS）诱导细胞毒性，PARS是一种核酶，可消耗氧化型烟酰胺腺嘌呤二核苷酸（NAD +）并耗尽细胞三磷酸腺苷（ATP）。本研究的目的是在暴露于外源性过氧亚硝酸盐（ONOO -）和一氧化氮（NO）后的肠上皮细胞模型中研究这种损伤机制。
分析暴露于过氧亚硝酸盐供体（3 - 吗啉代 - 西多福明[SIN - 1]，3 mmol/L）或NO供体（S - 亚硝基 - N - 乙酰青霉胺[SNAP]；3 mmol/L）的Caco - 2BBe细胞单层的DNA链断裂、[NAD +]、[ATP]以及荧光素磺酸的跨上皮通量。
SIN - 1而非SNAP诱导DNA单链断裂。SIN - 1和SNAP均降低了[ATP]，但只有SIN - 1降低了[NAD +]。PARS抑制剂5 - 碘 - 6 - 氨基 - 1,2 - 苯并吡喃或3 - 氨基苯甲酰胺对PARS活性的抑制可防止SIN - 1诱导的[NAD +]和[ATP]降低，但对SNAP诱导的[ATP]降低没有影响。PARS抑制降低了SIN - 1诱导的而非SNAP诱导的高通透性。
过氧亚硝酸盐而非NO通过诱导DNA链断裂激活PARS途径并导致细胞内能量储备耗竭，从而增加跨上皮通透性。抑制PARS活性可能是改善肠道炎症期间过氧亚硝酸盐介导的上皮损伤的一种新策略。
