Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, Jiangsu 225009, China.
Mol Immunol. 2012 Oct;52(3-4):117-24. doi: 10.1016/j.molimm.2012.05.005. Epub 2012 Jun 4.
Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) that are vital to activation of the innate immune system in response to invading pathogens through their recognition of pathogen-associated molecular patterns (PAMPs). TLR5 is responsible for the recognition of bacterial flagellin in vertebrates. In this study, we cloned the goose TLR5 gene using rapid amplification of cDNA ends (RACE). The open reading frame (ORF) of goose TLR5 cDNA is 2583 bp in length and encodes an 860 amino acid protein. The entire coding region of the TLR5 gene was successfully amplified from genomic DNA and contained a single exon. The putative amino acid sequence of goose TLR5 consisted of a signal peptide sequence, 11 leucine-rich repeat (LRR) domains, a leucine-rich repeat C-terminal (LRR-CT) domain, a transmembrane domain and an intracellular Toll-interleukin-1 receptor (TIR) domain. The amino acid sequence of goose TLR5 shared 50.5% identity with human (Homo sapiens), 49.8% with mouse (Mus musculus) and 82.7% with chicken (Gallus gallus). The goose TLR5 gene was highly expressed in the spleen, liver and brain; moderately expressed in PBMCs, kidney, lung, heart, bone marrow, small intestine and large intestine; and minimally expressed in the cecum. HEK293 cells transfected with goose TLR5 and NF-κB-luciferase containing plasmids significantly responded to flagellin from Salmonella typhimurium indicating that it is a functional TLR5 homologue. In response to infection with S. enterica serovar Enteritidis (SE), the level of TLR5 mRNA significantly increased over the control in PBMCs at 1 d post infection (p.i.) and was slightly elevated in the spleen at 1 d or 3 d p.i. IL-6 was expressed below control levels in PBMCs but was upregulated in the spleen. In contrast to IL-6, an evident decrease in the expression level of IL-8 was observed in both PBMCs and spleens at 1 d or 3 d p.i. SE challenge also resulted in an increase in the mRNA expression of IL-18 and IFN-γ in PBMCs and the spleen. These results imply that the expression of goose TLR5 is differentially regulated in various tissues and may participate in the immune response against bacterial pathogens.
Toll 样受体（TLRs）是模式识别受体（PRRs），通过识别病原体相关分子模式（PAMPs），在脊椎动物中对细菌鞭毛蛋白的识别中负责识别。在这项研究中，我们使用快速扩增 cDNA 末端（RACE）克隆了鹅 TLR5 基因。鹅 TLR5 cDNA 的开放阅读框（ORF）长 2583bp，编码 860 个氨基酸的蛋白质。TLR5 基因的整个编码区从基因组 DNA 中成功扩增，包含一个单一的外显子。鹅 TLR5 的推定氨基酸序列由信号肽序列、11 个富含亮氨酸重复（LRR）结构域、富含亮氨酸重复 C 末端（LRR-CT）结构域、跨膜结构域和细胞内 Toll-白细胞介素-1 受体（TIR）结构域组成。鹅 TLR5 的氨基酸序列与人类（Homo sapiens）有 50.5%的同一性，与小鼠（Mus musculus）有 49.8%的同一性，与鸡（Gallus gallus）有 82.7%的同一性。鹅 TLR5 基因在脾脏、肝脏和大脑中高度表达；在 PBMCs、肾脏、肺、心脏、骨髓、小肠和大肠中中度表达；在盲肠中微量表达。用含有 flagellin 的 Salmonella typhimurium 转染的 HEK293 细胞显著响应 TLR5 和 NF-κB-荧光素酶表达质粒，表明它是一种功能性 TLR5 同源物。在感染肠炎沙门氏菌（SE）后，感染后 1 天（p.i.）PBMCs 中 TLR5 mRNA 的水平明显高于对照，感染后 1 天或 3 天脾脏中 TLR5 mRNA 的水平略有升高。IL-6 在 PBMCs 中的表达低于对照水平，但在脾脏中上调。与 IL-6 相反，在感染后 1 天或 3 天，PBMCs 和脾脏中 IL-8 的表达水平明显下降。SE 攻击也导致 PBMCs 和脾脏中 IL-18 和 IFN-γ 的 mRNA 表达增加。这些结果表明，鹅 TLR5 的表达在不同组织中受到差异调控，可能参与了对细菌病原体的免疫反应。
