草鱼自噬相关基因Beclin1的克隆及其在MC-LR胁迫下的表达特征

CLONING OF BECLIN1, AN AUTOPHAGY GENE, AND IT'S EXPRESSION UNDER MICROCYSTIN-LR STRESS IN GRASS CARP(CTENOPHARYNGODON IDELLA)

为评估微囊藻毒素-LR (MC-LR)对鱼类自噬的影响,根据转录组测序结果得到的EST序列,采用RACE技术获得了草鱼(Ctenopharygodon idella)自噬基因Beclin1 (CiBeclin1)的cDNA全长序列。该基因序列全长1590 bp,包括1344 bp的开放阅读框,编码447个氨基酸,分子量为51.2 kD,理论等电点为4.88。CiBeclin1包含1个BH3和1个ECD结构域。CiBeclin1氨基酸序列与其他物种的相似性为88%—98%,构建的进化树显示CiBeclin1与稀有鲫(Gobiocypris rarus)的Beclin1亲缘关系最近。实时荧光定量PCR (qRT-PCR)检测结果表明, CiBeclin1在肝、肾、脾等10种不同组织中均广泛表达,但在肝脏组织中的相对表达量最丰富,显著高于相对表达量最低的头肾组织(P<0.05)。在不同剂量(25和100μg MC-LR/kg BW) MC-LR胁迫24h、48h、72h和96h后,草鱼肝脏中CiBeclin1表达量均显著低于对照组的表达水平,研究结果表明, MC-LR能抑制草鱼CiBeclin1的表达,但MC-LR是否在该剂量下诱导了草鱼的自噬还有待于进一步研究。

To estimate the effects of Microcystin-LR (MC-LR) on the autophagy, we cloned Beclin1 CiBeclin1 gene from grass carp (Ctenopharygodon idella) using rapid amplification of cDNA ends (RACE) based on the EST se- quence. The deduced amino acid sequence of CiBeclin1 was comprised of 447 amino acids, and CiBeclin1 possessed a typical Bcl-2 homology domain 3 (BH3) and an evolutionarily conserved domain (ECD). The similarity of CiBeclin1 amino acid sequence with other species was 88% 98%, and phylogenetic analysis demonstrated that CiBeclin1 formed a clade with rare minnow Beclin1. CiBeclin1 was ubiquitously expressed in 10 tested tissues, including the liver, kid- ney, spleen and others, with the highest level in liver. MC-LR significantly decreased the expression of CiBeclin1 at 24, 48, 72 and 96h, indicating that CiBeclin1 gene might play a regulatory role against MC-LR toxicity. However, whether the used doses of MC-LR could induce liver autophagy needs further investigation.