Funkelstein Lydiane, Hook Vivian
Department of Neuroscience, Pharmacology, and Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA 93093, USA.
Methods Mol Biol. 2011;768:107-25. doi: 10.1007/978-1-61779-204-5_5.
Neuropeptides are essential for cell-cell communication in the nervous and endocrine systems. Production of active neuropeptides requires proteolytic processing of proneuropeptide precursors in secretory vesicles that produce, store, and release neuropeptides that regulate physiological functions. This review describes research strategies utilizing chemical biology combined with protease gene knockout and expression to demonstrate the key role of cathepsin L for production of neuropeptides in secretory vesicles. Cathepsin L was discovered using activity-based probes and mass spectrometry to identify proenkephalin cleaving activity as cathepsin L. Significantly, in vivo protease gene knockout and expression approaches illustrate the key role of cathepsin L for neuropeptide production. Notably, cathepsin L is colocalized with neuropeptide secretory vesicles, the major site of proteolytic processing of proneuropeptides to generate active neuropeptides. Cathepsin L participates in producing opioid neuropeptides consisting of enkephalin, β-endorphin, and dynorphin, as well as in generating the POMC-derived peptide hormones ACTH and α-MSH. In addition, NPY, CCK, and catestatin neuropeptides utilize cathepsin L for their biosynthesis. The role of cathepsin L for neuropeptide production indicates its unique biological role in secretory vesicles, which contrasts with its role in lysosomes for protein degradation. Interesting evaluations of protease gene knockout studies in mice that lack cathepsin L compared to the PC1/3 and PC2 (PC, prohormone convertase) indicate the significant role of cathepsin L in neuropeptide production. Thus, dual cathepsin L and prohormone convertase protease pathways participate in neuropeptide production. These recent new findings indicate cathepsin L as a novel 'proprotein convertase' for production of neuropeptides that mediate cell-cell communication in health and disease.
神经肽对于神经和内分泌系统中的细胞间通讯至关重要。活性神经肽的产生需要在分泌小泡中对前神经肽前体进行蛋白水解加工，这些分泌小泡产生、储存并释放调节生理功能的神经肽。本综述描述了利用化学生物学结合蛋白酶基因敲除和表达的研究策略，以证明组织蛋白酶L在分泌小泡中神经肽产生中的关键作用。通过基于活性的探针和质谱法发现组织蛋白酶L，将脑啡肽原切割活性鉴定为组织蛋白酶L。重要的是，体内蛋白酶基因敲除和表达方法说明了组织蛋白酶L在神经肽产生中的关键作用。值得注意的是，组织蛋白酶L与神经肽分泌小泡共定位，神经肽分泌小泡是将前神经肽蛋白水解加工以产生活性神经肽的主要部位。组织蛋白酶L参与产生由脑啡肽、β-内啡肽和强啡肽组成的阿片类神经肽，以及产生源自阿黑皮素原的肽激素促肾上腺皮质激素（ACTH）和α-促黑素（α-MSH）。此外，神经肽Y（NPY）、胆囊收缩素（CCK）和抑制素神经肽利用组织蛋白酶L进行生物合成。组织蛋白酶L在神经肽产生中的作用表明其在分泌小泡中具有独特的生物学作用，这与其在溶酶体中进行蛋白质降解的作用形成对比。与PC1/3和PC2（PC，激素原转化酶）相比，对缺乏组织蛋白酶L的小鼠进行蛋白酶基因敲除研究的有趣评估表明组织蛋白酶L在神经肽产生中的重要作用。因此，组织蛋白酶L和激素原转化酶双重蛋白酶途径参与神经肽的产生。这些最新的新发现表明组织蛋白酶L是一种新型的“前体蛋白转化酶”，用于产生在健康和疾病中介导细胞间通讯的神经肽。
