Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama, 338-8570, Japan.
Faculty of Pharmaceutical Sciences, Department of Pharmaceutical and Health Sciences, Josai University, 1-1 Keiyaki dai, Sakado, Saitama, 350-0295, Japan.
Cell Tissue Res. 2019 Jun;376(3):401-412. doi: 10.1007/s00441-019-02991-2. Epub 2019 Jan 24.
Lysozyme is one of the most prominent antimicrobial peptides and has been identified from many mammalian species. However, this enzyme has not been studied in the order Insectivora, which includes the most primitive placental mammals. Here, we done the lysozyme cDNA from Suncus murinus (referred to as suncus, its laboratory name) and compare the predicted amino acid sequence to those from other mammalian species. Quantitative PCR analysis revealed a relatively higher expression of this gene in the spleen and gastrointestinal tract of suncus. The lysozyme-immunopositive (ip) cells were found mainly in the red pulp of the spleen and in the mucosa of the whole small intestine, including the follicle-associated epithelium and subepithelial dome of Peyer's patches. The lysozyme-ip cells in the small intestine were mostly distributed in the intestinal crypt, although lysozyme-expressing cells were found not only in the crypt but also in the villi. On the other hand, only a few lysozyme-ip cells were found in the villi and some granules showing intense fluorescence were located toward the lumen. As reported for other mammals, Ki67-ip cells were localized in the crypt and did not co-localize with the lysozyme-ip cells. Moreover, fasting induced a decrease in the mRNA levels of lysozyme in the intestine of suncus. In conclusion, we firstly identified the lysozyme mRNA sequence, clarified expression profile of lysozyme transcripts in suncus and found a unique distribution of lysozyme-producing cells in the suncus intestine.
溶菌酶是最显著的抗菌肽之一，已从许多哺乳动物物种中鉴定出来。然而，这种酶在包括最原始的胎盘哺乳动物的食虫目动物中尚未得到研究。在这里，我们从臭鼩鼱（Suncus murinus）（称为臭鼩鼱，其实验室名称）中获得了溶菌酶 cDNA，并将预测的氨基酸序列与其他哺乳动物物种的序列进行了比较。定量 PCR 分析显示，该基因在臭鼩鼱的脾脏和胃肠道中表达相对较高。溶菌酶免疫阳性（ip）细胞主要存在于脾脏的红髓和整个小肠的黏膜中，包括滤泡相关上皮和派尔氏斑的黏膜下穹窿。小肠中的溶菌酶-ip 细胞主要分布在肠隐窝中，尽管表达溶菌酶的细胞不仅存在于隐窝中，也存在于绒毛中。另一方面，仅在绒毛中发现少数溶菌酶-ip 细胞，并且一些显示强荧光的颗粒位于腔中。与其他哺乳动物一样，Ki67-ip 细胞定位于隐窝中，并且与溶菌酶-ip 细胞不共定位。此外，禁食诱导臭鼩鼱肠道中溶菌酶的 mRNA 水平降低。总之，我们首次鉴定了溶菌酶 mRNA 序列，阐明了溶菌酶转录本在臭鼩鼱中的表达谱，并发现了溶菌酶产生细胞在臭鼩鼱肠道中的独特分布。
