Meyer A, Chrétien P, Massicotte G, Sargent C, Chrétien M, Marcinkiewicz M
J.A. DeSève Laboratory of Molecular Neuroendocrinology, Clinical Research Institute of Montreal, Quebec, Canada.
Brain Res. 1996 Sep 2;732(1-2):121-32. doi: 10.1016/0006-8993(96)00502-1.
Prohormone convertases (PCs) belong to the mammalian family of subtilisin/kexin-like enzymes which have been implicated in the posttranslational processing of precursor proteins. Several PCs are produced in the central and peripheral nervous system, and only a few specific precursor-substrates have been identified in vivo. In the nervous system, PCs may be involved in intracellular processing of precursors for neuropeptides, hormones and neurotrophic factors, including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). To study the interrelationships between the convertases furin, PC1 and PC2, and the neurotrophins NGF, BDNF and NT-3, we compared their mRNA distribution in different tissues. We also examined their expression in the hippocampus of mice undergoing kainic acid-induced seizures. In this experiment, in situ hybridization (ISH) demonstrated that the levels of mRNA for furin, PC1 and BDNF increased maximally at 3 h after kainic acid administration, followed by a decline to normal levels by 96 h. NGF showed small changes, while NT-3 was downregulated with minimal expression levels between 3 to 12 h. Double ISH with radioactively-labeled riboprobes and digoxigenin-labeled riboprobes demonstrated colocalization of furin with NGF and BDNF in the mouse submaxillary gland, and of furin and PC1 with BDNF in the trigeminal ganglion. Based on colocalization studies and evidence of coordinate expression with NGF and BDNF, we suggest the involvement of furin in processing of proNGF, and of both furin and PC1 in processing of proBDNF.
激素原转化酶（PCs）属于枯草杆菌蛋白酶/克新样酶的哺乳动物家族，这些酶与前体蛋白的翻译后加工有关。几种PCs在中枢和外周神经系统中产生，并且在体内仅鉴定出少数特定的前体底物。在神经系统中，PCs可能参与神经肽、激素和神经营养因子（包括神经生长因子（NGF）和脑源性神经营养因子（BDNF））前体的细胞内加工。为了研究弗林蛋白酶、PC1和PC2转化酶与神经营养因子NGF、BDNF和NT-3之间的相互关系，我们比较了它们在不同组织中的mRNA分布。我们还检测了它们在 kainic 酸诱导癫痫发作的小鼠海马体中的表达。在这个实验中，原位杂交（ISH）表明，弗林蛋白酶、PC1和BDNF的mRNA水平在给予 kainic 酸后3小时达到最大值，随后在96小时下降至正常水平。NGF变化较小，而NT-3在3至12小时之间表达下调且水平最低。用放射性标记的核糖探针和地高辛标记的核糖探针进行的双重ISH表明，弗林蛋白酶与NGF和BDNF在小鼠颌下腺中共定位，弗林蛋白酶和PC1与BDNF在三叉神经节中共定位。基于共定位研究以及与NGF和BDNF协同表达的证据，我们认为弗林蛋白酶参与前体NGF的加工，弗林蛋白酶和PC1都参与前体BDNF的加工。
