Search for novel peptide hormones, which act on gastrointestinal stemcells, and its role on the regeneration of gastrointestinal epithelium

孤儿GPCR LGR5受体是胃肠道干细胞的标志物。然而，LGR5的内源性配体尚未被发现。我们建立了一个稳定表达LGR5的细胞系，并将其用于脑和胃肠道组织肽提取物的系统检测，以寻找配体。我们在大脑样本中检测到一个阳性信号，并将其纯化为一个肽。通过氨基酸序列分析，我们发现纯化的肽是CGRP，一种神经肽。我们认为CGRP应该与CHO细胞上的内源性CGRP受体发生反应。lgr5及其相关受体LGR4和LGR6的真正内源性配体仍然存在争议。

An orphan GPCR LGR5 receptor is a marker for gastrointestinal stem cells. However,the endogenous ligand for LGR5 has not been discovered. We established a cell line, whichstably expressed LGR5, and used it for a systematic assay on brain and gastrointestinaltissue peptide extracts to search for the ligands. We detected a positive signal in thebrain samples and purified it to a single peptide. By amino acid sequence analysis, wefound that the purified peptide is CGRP, a neuropeptide. We thought that CGRP should havereacted to endogenous CGRP receptors on CHO cells. The real endogenous ligands for LGR5and its relative receptors, LGR4 and LGR6, are still controversial.