栉孔扇贝(Chlamys farreri)过氧化物酶体增殖物激活受体基因的鉴定与表达分析

IDENTIFICATION AND EXPRESSION PROFILING OF THE PPAR GENE IN CHLAMYS FARRERI

过氧化物酶体增殖物激活受体(peroxisome-proliferator-activated receptors,PPARs)是核激素受体超家族成员,在脂肪代谢过程中发挥重要的调控作用,目前贝类过氧化物酶体增殖物激活受体仍未见报道。本文利用已发表的栉孔扇贝(Chlamys farreri)基因组和转录组,获得其PPAR基因,命名为CfPPAR-like,基因开放阅读框全长1572 bp,编码486个氨基酸,预测蛋白质分子量MW为54305.3 Da,等电点pI为8.3,二、三级结构以转角和卷曲为主,无信号肽和跨膜区域,属于胞内蛋白。与脊椎动物PPARs蛋白序列比对表明CfPPAR-like包含DBD和LDB结构域,其中DBD区域保守性较高,而LBD的保守性较低。进化分析显示,栉孔扇贝等软体动物的PPARs聚为单独一支,仿刺参等棘皮动物的PPARs聚为单独一支,果蝇和线虫的PPARs基因同源物在进化树的最外端,脊椎动物的三种PPARs亚型分别聚类后,再与无脊椎动物PPARs聚类,结果支持核激素受体超家族在脊椎动物进化早期出现了各亚型这一假说。CfPPAR-like在幼虫发育过程中呈现普遍性表达,暗示其参与扇贝幼虫早期的分裂,贝壳的形成以及幼贝的变态过程;在成体各组织中,CfPPAR-like在栉孔扇贝的性腺、肾脏以及消化腺中表达量较高,表明其参与扇贝性腺分化、脂肪代谢等过程的调控。研究结果对于揭示贝类脂质代谢调控机制以及优良扇贝品种的培育具有重要意义。

Peroxisome proliferator-activated receptor(PPAR),an important member of the nuclear hormone receptor family,plays important roles in regulating lipid metabolism.However,research about PPARs of invertebrates is scarce.In present study,a PPAR gene named CfPPAR-like was firstly identified from Zhikong scallop(Chlamys farreri)genome.The open reading frame of CfPPAR-like was 1572 bp,encoding 486 amino acids,the predicted molecular weight of the protein was 54305.3 Da and the isoelectric point was 8.3.The predicted protein structure indicated that the CfPPAR-like protein was mainly composed of turns and coils.In addition,signal peptide and transmembrane structure were not found,which suggested that it was an intracellular protein.After comparing the protein sequences of CfPPAR-like with PPARs of vertebrate,domains DBD and LBD were identified in the CfPPAR-like,and DBD was highly conserved but LBD was highly diverse.Phylogenetic analysis showed that the CfPPAR-like protein clustered with other Mollusca PPARs,PPARs of Echinoderms clustered together,and PPAR homologues of Drosophila melanogaster and Caenorhabditis elegans clustered outside.Three subtypes of PPARs of vertebrates clustered separately and then clustered with PPARs of invertebrate.The phylogenetic analysis supported the hypothesis that the subtypes of nuclear receptor superfamily were produced in early vertebrates.The transcriptome database showed that CfPPAR-like gene was continuously expressed in the whole developmental stages and all adult tissues,which indicated CfPPAR-like gene was involved in the early cell division,shell formation,and metamorphosis of the scallop.In tissues,CfPPAR-like was highly expressed in the gonads,kidneys,and digestive glands,suggesting that it might be involved in the regulation of gonad differentiation and metabolic activities of scallop.Our research will promote a better understanding of lipid metabolism and breeding of shellfish.