Wada E, Way J, Lebacq-Verheyden A M, Battey J F
Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892.
J Neurosci. 1990 Sep;10(9):2917-30. doi: 10.1523/JNEUROSCI.10-09-02917.1990.
The bombesin-like peptides are a family of structurally related amidated peptide ligands that are known to have a variety of potent pharmacological actions on various cells, including neurons in the rat brain. Two mammalian representatives of the bombesin family of peptides have been identified, gastrin-releasing peptide (GRP) and neuromedin B (NMB). Previously, we cloned the rat preproGRP gene and determined the locations of neurons expressing this gene using in situ hybridization. In this study, we describe the structure and sequence of the rat preproNMB gene, and the first detailed cellular localization of preproNMB mRNA in rat brain using in situ hybridization. Nucleotide sequence analysis of cDNA and genomic clones reveals a 117 amino acid precursor whose overall structure is similar to that described for human preproNMB. Sequence similarity between the rat NMB and GRP genes is observed only over a limited 10 amino acid sequence encoding the carboxy termini of the GRP and NMB peptides, the region shown to be necessary and sufficient for high-affinity receptor binding. In situ hybridization studies performed with cRNA probes specific for NMB or GRP mRNA show that the distribution of cells expressing either mRNA in brain is very distinct. NMB mRNA is found most prominently in the olfactory bulb, dentate gyrus, and dorsal root ganglion. In contrast, the highest levels of GRP mRNA are observed in the forebrain (isocortex and hippocampal formation). This heterogeneity of mRNA distribution for these peptides suggests that these 2 structurally related peptides may have very distinct functions as neuropeptides in the rat nervous system.
蛙皮素样肽是一类结构相关的酰胺化肽配体家族，已知其对包括大鼠脑内神经元在内的各种细胞具有多种强效药理作用。已鉴定出蛙皮素肽家族的两种哺乳动物代表，即胃泌素释放肽（GRP）和神经介素B（NMB）。此前，我们克隆了大鼠前胃泌素释放肽原基因，并使用原位杂交确定了表达该基因的神经元位置。在本研究中，我们描述了大鼠前神经介素B原基因的结构和序列，并首次使用原位杂交详细定位了大鼠脑中前神经介素B原mRNA的细胞定位。对cDNA和基因组克隆的核苷酸序列分析揭示了一个117个氨基酸的前体，其整体结构与人类前神经介素B原的结构相似。仅在编码GRP和NMB肽羧基末端的有限10个氨基酸序列上观察到大鼠NMB和GRP基因之间的序列相似性，该区域显示对高亲和力受体结合是必要且充分的。用针对NMB或GRP mRNA的cRNA探针进行的原位杂交研究表明，脑中表达这两种mRNA的细胞分布非常不同。NMB mRNA最显著地存在于嗅球、齿状回和背根神经节中。相比之下，GRP mRNA的最高水平出现在前脑（同皮质和海马结构）。这些肽的mRNA分布的这种异质性表明，这两种结构相关的肽在大鼠神经系统中作为神经肽可能具有非常不同的功能。
