Cleavage of proBDNF to BDNF by a tolloid-like metalloproteinase is required for acquisition of in vitro eyeblink classical conditioning.
Cleavage of proBDNF to BDNF by a tolloid-like metalloproteinase is required for acquisition of in vitro eyeblink classical conditioning.
复制标题
DOI：
10.1523/jneurosci.3649-09.2009
复制
发表时间：
2009-11-25
期刊：
影响因子：
--
通讯作者：
Clark TG
中科院分区：
文献类型：
--
作者：
Keifer J;Sabirzhanov BE;Zheng Z;Li W;Clark TG
金属蛋白酶的 Tolloid/骨形态发生蛋白-1 (BMP-1) 家族在胚胎模式形成和组织形态发生的调节中具有重要作用。研究表明它们参与成人突触可塑性机制，但对其功能知之甚少。最近，我们分离出了 tolloid 基因家族的爬行动物直系同源物，命名为海龟 tolloid 样基因（tTll）。在这里，我们使用分离的脑干制剂检查了 tTLL 在眨眼经典条件反射体外模型中的作用，以评估其在条件反射过程中突触可塑性中的作用。实时 RT-PCR 分析表明，细胞外分泌形式的 tTLL（tTLL）在 CR 获取过程中的调节早期阶段短暂表达，而胞质形式 tTLLc 则不然。 siRNA 指导的基因敲低和 tTLL 表达的拯救表明它是条件调节所必需的。值得注意的是，我们在切割试验研究中表明，tTLL 将前体 proBDNF 切割成成熟 BDNF，并且单独将重组 tTLL 蛋白应用于制剂中会导致成熟 BDNF 表达的诱导。 BDNF 的成熟形式在用抗 tTLL siRNA 处理的制剂中表达量最低，并且含有 GluR1 和 GluR4 的 AMPAR 的突触掺入显着减少，从而导致条件反射的抑制。这是第一项证明细胞外分泌的类毒素金属蛋白酶的表达在经典调节的早期阶段受到调节的研究，并且在 proBDNF 向成熟 BDNF 的转化中发挥作用。 BDNF 的成熟形式是 AMPAR 的突触传递和条件反应的获得所必需的。
The tolloid/bone morphogenetic protein-1 (BMP-1) family of metalloproteinases have an important role in the regulation of embryonic pattern formation and tissue morphogenesis. Studies suggest they participate in mechanisms of synaptic plasticity in adults, but very little is known about their function. Recently, we isolated a reptilian orthologue of the tolloid gene family designated turtle tolloid-like gene (tTll). Here, we examined the role of tTLL in an in vitro model of eyeblink classical conditioning using an isolated brain stem preparation to assess its role in synaptic plasticity during conditioning. Analysis by real-time RT-PCR shows that an extracellularly secreted form of tTLL, tTLLs, is transiently expressed in the early stages of conditioning during CR acquisition while a cytosolic form, tTLLc, is not. siRNA-directed gene knockdown and rescue of tTLL expression demonstrate that it is required for conditioning. Significantly, we show that tTLLs cleaves the precursor proBDNF into mature BDNF in cleavage assay studies and application of recombinant tTLLs protein alone to preparations results in induction of mature BDNF expression. The mature form of BDNF is minimally expressed in preparations treated with anti-tTLL siRNA, and the synaptic incorporation of both GluR1- and GluR4-containing AMPARs is significantly reduced resulting in suppression of conditioning. This is the first study to demonstrate that expression of an extracellularly secreted tolloid-like metalloproteinase is regulated in the early stages of classical conditioning and functions in the conversion of proBDNF to mature BDNF. The mature form of BDNF is required for synaptic delivery of AMPARs and acquisition of conditioned responses.