Tsuchiya Takashi, Iwakura Hiroshi, Minamino Naoto, Kangawa Kenji, Sasaki Kazuki
Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center, 565-8565 Osaka, Japan.
The First Department of Medicine, Wakayama Medical University, 641-8509 Wakayama, Japan.
Biochem Biophys Res Commun. 2017 Sep 2;490(4):1142-1146. doi: 10.1016/j.bbrc.2017.06.155. Epub 2017 Jun 27.
Ghrelin is an orexigenic peptide primarily produced by gastric endocrine cells. The biosynthetic cleavage site of ghrelin has been well documented, but how its downstream region undergoes proteolytic processing remains poorly explored. Here, we provide the first snapshot of endogenous peptides from the ghrelin precursor by profiling the secretopeptidome of cultured mouse ghrelin-producing cells during exocytosis. Mapping of MS/MS sequenced peptides to the precursor highlighted three atypical monobasic processing sites, including the established C-terminus of ghrelin and the N-terminal cleavage site for obestatin, a putative 23-amino-acid C-terminally amidated peptide. However, we found that mouse obestatin does not occur in the form originally reported, but that a different amidation site is used to generate a shorter peptide. These data can be extended to study and characterize the precursor-derived peptides located downstream of ghrelin in different biological contexts.
胃饥饿素是一种主要由胃内分泌细胞产生的促食欲肽。胃饥饿素的生物合成切割位点已有充分记载，但对其下游区域如何进行蛋白水解加工的研究仍很少。在这里，我们通过对培养的小鼠胃饥饿素分泌细胞在胞吐过程中的分泌肽组进行分析，首次展示了胃饥饿素前体的内源性肽。将串联质谱测序的肽段映射到前体上，突出了三个非典型单碱性加工位点，包括已确定的胃饥饿素C末端和肥胖抑制素（一种假定的23个氨基酸的C末端酰胺化肽）的N末端切割位点。然而，我们发现小鼠肥胖抑制素并非以最初报道的形式存在，而是使用了不同的酰胺化位点来生成一种较短的肽。这些数据可扩展用于研究和表征在不同生物学背景下位于胃饥饿素下游的前体衍生肽。
