Cloning Expression And Functional Studies Of PTX3 From Goldfish And Gibel Carp

Goldfish was originated from Chinese crucian carp. Oranda was one important kind of goldfish, which has a beautiful headgrowth on the head. The ornamental and economic value is influenced by the shape, size and color of the headgrowth, but the mechanism of wen development remained unknown. The present study generally considered that the headgrowth was abnormal hyperplasia. The latest study showed that the expression of PTX3(Pentraxin 3) was up-regulated, which proved that PTX3 may play an important role in the occurrence of headgrowth. PTX3 played an immune related role in mammals, such as antibody-like functions, binding pathogens, activating and regulating complement. So we speculate that PTX3 may act as an immune related factor in the abnormal proliferation of the headgrowth.. To verify this inference, we carried out the related research of PTX3 in fish. The results were as follows:1. PTX3 was conserved in gene structure and protein structure. Both of the PTX3 gene from goldfish and gibel carp were composed of 3 exons and 2 introns. The two introns of goldfish were respectively 945 bp, 1519 bp, and gibel carp 970 bp, 1513 bp. The full length of the PTX3 c DNA sequence was 1918 bp in goldfish, and 1560 bp in gibel carp, which both contained a 1362 bp open reading frame, encoding 453 aa protein. The predicted protein of PTX3 consists of three parts: a signal peptide(1-22aa), an N-terminal domain(23-240aa) and a PTX domain(241-453aa) with an atypical pentraxin signal(HICAVWSS). The amino acid sequences of PTX3 from goldfish and gibel were highly homologous, and only two amino acids were different.2. PTX3 is constitutively expressed in different organs with the higher expression in brain and muscle.The up-regulation expression of PTX3 in liver, spleen, head kidney, intestine and blood after Aeromonas hydrophila infection indicating its involvement in innate immune regulation during bacterial infections.3. The results of the function experiments with recombinant protein in vitro suggested that PTX3 had bacterial binding capacity, but no antibacterial activity; both of the N-terminal domain and PTX domain had bacterial binding capacity.