Kapoor P, Raj V S, Saxena S, Balaraman S, Madhubala R
School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
J Parasitol. 2001 Oct;87(5):1071-6. doi: 10.1645/0022-3395(2001)087[1071:EOLDLO]2.0.CO;2.
Lipophosphoglycan (LPG), a major surface molecule from Leishmania donovani, stimulated ornithine decarboxylase (ODC) activity in macrophages in a dose- and time-dependent manner. LPG stimulated the rapid increase in ODC activity within 30 min after exposure, suggesting that the interaction of LPG with its receptor stimulated a specific signal transduction pathway. However, LPG-induced ODC activity was a transient event because 3 hr after exposure to LPG, no stimulation of ODC activity was detectable. ODC activity appeared to be coupled to the activation of protein kinase C (PKC) in macrophages, as activators of PKC caused a rapid increase in the ODC activity. Macrophages pretreated with LPG for 1 hr became unresponsive to subsequent stimulation by the PKC activators 1-oleoyl-2-acetyl-glycerol and the calcium ionophore A23187. In contrast, the ability of macrophages to express ODC activity in response to the cyclic AMP analogue dibutyryl cyclic AMP was not impaired by LPG.
脂磷壁酸聚糖（LPG）是杜氏利什曼原虫的一种主要表面分子，它能以剂量和时间依赖的方式刺激巨噬细胞中的鸟氨酸脱羧酶（ODC）活性。LPG在暴露后30分钟内刺激ODC活性迅速增加，这表明LPG与其受体的相互作用刺激了特定的信号转导途径。然而，LPG诱导的ODC活性是一个短暂的事件，因为在暴露于LPG 3小时后，未检测到对ODC活性的刺激。ODC活性似乎与巨噬细胞中蛋白激酶C（PKC）的激活相关，因为PKC激活剂会导致ODC活性迅速增加。用LPG预处理1小时的巨噬细胞对随后PKC激活剂1-油酰基-2-乙酰基甘油和钙离子载体A23187的刺激不再有反应。相反，LPG不会损害巨噬细胞对环磷酸腺苷类似物二丁酰环磷腺苷作出反应而表达ODC活性的能力。
