Expression Analysis Of Transcription Factor Blimp-1 In B Cell Differentiation Of Cyprinus Carpio L.

The transcription factor Blimp-1(B lymphocyte maturation protein-1)is a transcription inhibitor encoded by the prdm1 gene.At present,the prdm1 homologous protein has been found in insects,worms,echinoderms,amphibians,birds,mammals and several common teleosts.As a switch of B cell differentiation,Blimp-1 is the main regulator of differentiation of mature B cells into plasma cells.The expression of Blimp-1 inhibits the expression of B cell genes pax5 and bcl6,and promotes their terminal differentiation into plasma cells.Currently,it is known that Blimp-1 is expressed in several types of bony fishes and chondrichthyes,but there are differences in the localization of Blimp-1 expression in B cells,especially in the differentiation process of fish B cells into plasma cells.In this study,the expression of transcription factor Blimp-1 in B cell differentiation was explored in common economic cultured fish(Cyprinus carpio L.).First of all,this study tested the carp immunoglobulin molecules known as IgM,IgZ1,IgZ2,IgZ3 and IgD gene expression in different development stage by RT-PCR.The results showed that IgM was the immunoglobulin with the highest basal expression level during the whole development period of carp.In the novel immunoglobulin IgZ,the expression of the three IgZ subclasses is significantly different and the high expression level of IgZ3 appears in the hindgut at several development stages,in which IgZ3~+cells distribute in the mucosa lamina propria and between epithelial cells.Secondly,the gene expression of transcription factor Blimp-1 at different developmental stages was detected in this study,and the expression localization of Blimp-1~+B cells in the head kidney,liver,gut and spleen tissues of carp was detected by Blimp-1 polyclonal antibody.The results showed that the expression level of Blimp-1 was high in the early development stage of carp,and in the subsequent development stage,the expression of Blimp-1 was detected in both the lamina propria and the epithelial cells of gut tissue,and the transcription factor was positive in both the nuclear region and the cytoplasm region.Thirdly,this study isolated lymphocytes from different tissue sources and detected the basic expression levels of Ig genes and transcription factors.The results showed that there were differences in gene expression under different selecting conditions,which indicated that the acquisition of B cells at different differentiation stages would be affected by selecting conditions.At the same time,cells co-expressing Blimp-1 and Ig in peripheral blood were detected by immunofluorescence and flow cytometry.Fourthly,in this study,LPS immune-stimulated carp model was also established to explore the expression patterns of Ig gene and transcription factor Blimp-1 in peripheral blood lymphocytes and splenic lymphocytes of carp,as well as gene expression patterns in different tissues under the condition of LPS immune-stimulated activation.The results showed that the expression of Blimp-1 was upregulated in both peripheral blood lymphocytes and splenic lymphocytes at 3 days post stimulation(dps),and the upregulated ratio in spleen was much higher than that in peripheral blood.However,IgM was 10.5-fold upregulated in peripheral blood lymphocytes 8 dps,while immunofluorescence revealed the presence of Blimp-1~+IgM~+cells in spleen tissue at 5 dps.Bony fish is the first vertebrate developing adaptive immunity.The study of gene expression in B cell differentiation of carp is conducive to the study of the molecular mechanism of immune response in bony fish,and is of great significance to the study of the evolution of immunity.In addition,as an important economic cultured fish in China,the study of B cell differentiation of carp can provide a theoretical basis for immune protection measures in production and culture.