Rearranged T Cell Receptor Sequences in the Germline Genome of Channel Catfish Are Preferentially Expressed in Response to Infection.

ABSTRACT: Rearranged V(D)J genes coding for T cell receptor ? and ? chains are integrated into the germline genome of channel catfish. Previous analysis of expressed TCR V?2 repertoires demonstrated that channel catfish express multiple public clonotypes, which were shared among all the fish, following infection with a common protozoan parasite. In each case a single DNA sequence was predominately used to code for a public clonotype. We show here that the rearranged VDJ genes coding for these expressed public V?2 clonotypes can be amplified by PCR from germline DNA isolated from oocytes and erythrocytes. Sequencing of the V?2 PCR products confirmed that these expressed public V?2 clonotypes are integrated into the germline. Moreover, sequencing of PCR products confirmed that all five V? gene families and V?1 have rearranged V(D)J genes with diverse CDR3 sequences integrated into the germline. Germline rearranged V?2 and V?4 genes retain the intron between the leader and V? sequence. This suggests that the germline rearranged TCR V? genes arose through VDJ rearrangement in T cells, and subsequently moved into the germline through DNA transposon mediated transposition. These results reveal a new dimension to the adaptive immune system of vertebrates, namely: the expression of evolutionarily conserved, rearranged V(D)J genes from the germline.

SUBMITTER: Findly RC 

PROVIDER: S-EPMC6170632 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature