Smirnova I V, Ma J Y, Citron B A, Ratzlaff K T, Gregory E J, Akaaboune M, Festoff B W
Neurobiology Research Laboratory, Department of Veterans Affairs Medical Center, Kansas City, Missouri 64128, USA.
J Neurochem. 1996 Nov;67(5):2188-99. doi: 10.1046/j.1471-4159.1996.67052188.x.
We addressed the balance between thrombin and its serpin protease nexin I (PNI) after sciatic nerve injury in the mouse. Prothrombin levels increased twofold 24 h after nerve crush, as measured by a specific chromogenic assay, and peaked at day 3. Thrombin activity also increased 2-4 days after injury in distal sciatic nerve segments. Nerve RNA analysis using reverse transcriptase--polymerase chain reaction (RT-PCR) assay confirmed that prothrombin was synthesized locally. We also monitored PNI levels in these injured nerve samples by complex formation with an 125I-labeled target protease and found peak activity occurring later, 6-9 days after the thrombin induction. These data indicate that nerve injury first induces the synthesis of prothrombin, which is subsequently converted to active thrombin. Nerve crush-induced thrombin is followed by the generation of functionally active PNI and may be directly responsible for its induction. By immunocytochemistry with anti-PNI antibody, we found that activated Schwann cells were the source of induced PNI. These results support the concept that the balance between serine proteases and their serpins is dysregulated during nerve injury and suggests a role for its reestablishment in nerve damage repair.
我们研究了小鼠坐骨神经损伤后凝血酶与其丝氨酸蛋白酶抑制因子I（PNI）之间的平衡。通过特异性显色测定法测得，神经挤压后24小时凝血酶原水平增加了两倍，并在第3天达到峰值。损伤后2 - 4天，坐骨神经远端节段的凝血酶活性也有所增加。使用逆转录 - 聚合酶链反应（RT-PCR）分析进行的神经RNA分析证实，凝血酶原是在局部合成的。我们还通过与125I标记的靶蛋白酶形成复合物来监测这些受损神经样本中的PNI水平，发现其峰值活性出现较晚，在凝血酶诱导后6 - 9天。这些数据表明，神经损伤首先诱导凝血酶原的合成，随后其转化为活性凝血酶。神经挤压诱导的凝血酶之后是功能性活性PNI的产生，并且可能直接导致其诱导。通过用抗PNI抗体进行免疫细胞化学分析，我们发现活化的雪旺细胞是诱导产生的PNI的来源。这些结果支持了这样一种观点，即丝氨酸蛋白酶与其丝氨酸蛋白酶抑制因子之间的平衡在神经损伤期间失调，并表明其在神经损伤修复中的重新建立具有重要作用。
