Wang Aili, Chao Tianle, Ji Zhibin, Xuan Rong, Liu Shuang, Guo Maosen, Wang Guizhi, Wang Jianmin
Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Taian, P.R. China.
PeerJ. 2020 Oct 7;8:e9947. doi: 10.7717/peerj.9947. eCollection 2020.
The submandibular glands, as major salivary glands, participate in rumen digestion in goats. Sialic acid, lysozyme, immunoglobulin A (IgA), lactoferrin and other biologically active substances secreted in the submandibular glands were reported in succession, which suggests that the submandibular gland may have immune functions in addition to participating in digestion. The aim of this study was to map the expression profile of differentially expressed genes (DEGs) at three different stages by transcriptome sequencing, screen immune-related genes and pathways by bioinformatics methods, and predict the immune function of submandibular glands at different developmental stages.
Nine submandibular gland tissue samples were collected from groups of 1-month-old kids, 12-month-old adolescent goats and 24-month-old adult goats (3 samples from each group), and high-throughput transcriptome sequencing was conducted on these samples. The DEGs among the three stages were screened and analysed. Key genes and signalling pathways were selected via protein-protein interaction (PPI) network analysis.
The results revealed 2,706, 2,525 and 52 DEGs between 1-month-old and 12-month-old goats, between 1-month-old and 24-month-old goats, and between 12-month-old and 24-month-old goats, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that most of the DEGs were enriched in immune- related GO terms and pathways. Based on functional enrichment analysis and network analysis, 10 genes ( and ), two signalling pathways (the T cell receptor signalling pathway and the NF-κβ signalling pathway) and eight GO terms (T cell receptor signalling pathway, neutrophil mediated immunity, B cell mediated immunity, regulation of alpha-beta T cell activation, positive regulation of T cell proliferation, regulation of leukocyte differentiation, positive regulation of antigen receptor-mediated signalling pathway, positive regulation of lymphocyte proliferation) that may play key roles in the immune functions of the goat submandibular glands at different developmental stages were identified. Moreover, we found that eight antibacterial peptide-encoding genes were downregulated in the tuberculosis and salivary secretion pathways, while all immunoglobulins were upregulated in 10 immune system pathways. These findings indicate that the submandibular glands may be important immunological organs during the growth process of goats and that the immune function of these glands gradually weakens with age up to 12 months but remains relatively stable after 12 months of age. Overall, this study will improve our understanding of transcriptional regulation related to goat submandibular gland immune function.
下颌下腺作为主要的唾液腺，参与山羊的瘤胃消化。下颌下腺分泌的唾液酸、溶菌酶、免疫球蛋白A（IgA）、乳铁蛋白等生物活性物质相继被报道，这表明下颌下腺除参与消化外可能还具有免疫功能。本研究的目的是通过转录组测序绘制三个不同阶段差异表达基因（DEG）的表达谱，通过生物信息学方法筛选免疫相关基因和通路，并预测不同发育阶段下颌下腺的免疫功能。
从1月龄羔羊、12月龄青年山羊和24月龄成年山羊组中收集9个下颌下腺组织样本（每组3个样本），并对这些样本进行高通量转录组测序。筛选并分析三个阶段之间的差异表达基因。通过蛋白质-蛋白质相互作用（PPI）网络分析选择关键基因和信号通路。
结果显示，1月龄和12月龄山羊之间、1月龄和24月龄山羊之间以及12月龄和24月龄山羊之间分别有2706、2525和52个差异表达基因。基因本体论（GO）和京都基因与基因组百科全书（KEGG）分析表明，大多数差异表达基因富集在免疫相关的GO术语和通路中。基于功能富集分析和网络分析，确定了10个基因（和）、两条信号通路（T细胞受体信号通路和NF-κβ信号通路）以及八个GO术语（T细胞受体信号通路、中性粒细胞介导的免疫、B细胞介导的免疫、α-βT细胞活化的调节、T细胞增殖的正调节、白细胞分化的调节、抗原受体介导的信号通路的正调节、淋巴细胞增殖的正调节），它们可能在山羊下颌下腺不同发育阶段的免疫功能中起关键作用。此外，我们发现8个抗菌肽编码基因在结核病和唾液分泌途径中下调，而所有免疫球蛋白在10个免疫系统途径中上调。这些发现表明，下颌下腺可能是山羊生长过程中的重要免疫器官，并且这些腺体的免疫功能在12个月龄前随年龄增长逐渐减弱，但在12个月龄后保持相对稳定。总体而言，本研究将增进我们对山羊下颌下腺免疫功能相关转录调控的理解。
