马氏珠母贝TLR2基因cDNA的分子特征及组织表达分析

TLR2（toll like receptor 2）是TLR模式识别受体家族的重要成员之一，参与有机体的免疫识别。本研究采用cDNA末端快速扩增（RACE）技术克隆获得了马氏珠母贝（Pinctada martensii）TLR2基因（PmTLR2）cDNA的全长序列并对其序列特征进行分析；同时检测了PmTLR2基因的mRNA在马氏珠母贝六个组织中的表达。结果表明：PmTLR2基因的cDNA全长2614 bp，包含41 bp的5'UTR，299 bp的3'UTR，27 bp的polyA，开放阅读框为2274 bp，编码758个氨基酸残基。多序列比对显示PmTLR2与牡蛎TLR2的序列相似性最高，为51%；Smart软件分析显示PmTLR2的蛋白序列中含有8个亮氨酸重复序列（Leucine rich repeats，LRRs）, 1个C端亮氨酸富集区（Leucine-rich repeat C-terminal，LRR-CT），1个N端亮氨酸富集区（Leucine-rich repeat N-terminal，LRR-NT），1个TIR（Toll/IL-1R）同源结构域（TIR）；荧光定量PCR分析表明PmTLR2在马氏珠母贝肝胰脏、性腺、血淋巴、鳃、外套膜和闭壳肌六个组织中均有表达，鳃中表达量最高。本研究为进一步阐述PmTLR2在马氏珠母贝免疫应答中的作用机制提供理论基础。

Molecular Characterization and Tissue Expression Analysis of PmTLR2 Gene from Pinctada martensii

Toll like receptor 2 (TLR2) is an important component in the TLRs family, which is one family of pathogen-associated molecular pattern recognization receptors (PRRs). In this study, using rapid amplification of cDNA ends technology (RACE), we obtained the full length of PmTLR2 gene cDNA from Pinctada martensii (PmTLR2). The full length of PmTLR2 cDNA was 2614 bp, containing a 5’untranslated region (UTR) of 41 bp and a 3’UTR of 299 bp with 27 bp polyA tail. The open reading frame (ORF) was 2274 bp encoding 758 amino acid residues. Multiple sequence alignment indicated PmTLR2 had 51% sequence identity with that from Crassostrea gigas. SMART program analysis indicated PmTLR2 contained eight Leucine rich repeats (LRRs), one Leucine-rich repeat C-terminal (LRR-CT), one Leucine-rich repeat N-terminal (LRR-NT) and one TIR (Toll/IL-1R). Real-time PCR analysis demonstrated that PmTLR2 was constitutively expressed in all studied tissues (aductor muscle, gonad, hepatopancreas, mantle, hemocytes and gill) in P.martensii with the most abundant mRNA in the gill. These studies provide the basis for the further study of PmTLR2 in the immune response in mollusk.