Reis Marta I R, Nascimento Diana S, do Vale Ana, Silva Manuel T, dos Santos Nuno M S
Fish Immunology and Vaccinology, Institute for Molecular and Cell Biology, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
Mol Immunol. 2007 Feb;44(5):774-83. doi: 10.1016/j.molimm.2006.04.028. Epub 2006 Jun 15.
Caspase-3 is one of the major caspases operating in apoptosis, cleaving and inactivating a number of molecules and largely contributing to the apoptotic phenotype and the dismantling of the apoptoting cell. The opening reading frame of sea bass (Dicentrarchus labrax L.) caspase-3 has 281 amino acids. The complete sequence of caspase-3 shows a very close homology to the correspondent sequence from other vertebrates, in particularly with that of Takifugu rubripes and Oryzias latipes, with 87.7 and 87.9% of similarity, respectively. Furthermore, the sea bass caspase-3 sequence retains the motifs that are functionally important, such as the pentapeptide active-site motif (QACRG) and the putative cleavage sites at the aspartic acids. In the sea bass genome, the caspase-3 gene exists as a single copy gene and is organised in six exons and five introns. A very low expression of caspase-3 was detected by RT-PCR in various organs of non-stimulated sea bass, with slightly higher levels in thymus and heart and was increased in head kidneys of Photobacterium damselae ssp. piscicida infected sea bass. This increased expression was accompanied by the occurrence of high numbers of apoptoting cells with activated caspase-3.
半胱天冬酶-3是凋亡过程中起作用的主要半胱天冬酶之一，它切割并使多种分子失活，在很大程度上促成凋亡表型以及凋亡细胞的解体。海鲈（欧洲鲈）半胱天冬酶-3的开放阅读框有281个氨基酸。半胱天冬酶-3的完整序列与其他脊椎动物的相应序列显示出非常高的同源性，特别是与红鳍东方鲀和青鳉的序列，相似度分别为87.7%和87.9%。此外，海鲈半胱天冬酶-3序列保留了具有重要功能的基序，如五肽活性位点基序（QACRG）和天冬氨酸处的假定切割位点。在海鲈基因组中，半胱天冬酶-3基因作为单拷贝基因存在，由6个外显子和5个内含子组成。通过逆转录聚合酶链反应（RT-PCR）在未受刺激的海鲈的各种器官中检测到半胱天冬酶-3的表达非常低，在胸腺和心脏中的水平略高，而在感染美人鱼发光杆菌杀鱼亚种的海鲈的头肾中表达增加。这种表达增加伴随着大量具有激活的半胱天冬酶-3的凋亡细胞的出现。
