TRANSCRIPTION OF GERMLINE V-H GENE ELEMENTS BY NORMAL HUMAN FETAL LIVER

Transcription of the gene elements that form the variable region of im munoglobulin heavy chains has been proposed to represent the process t hat controls access for the recombination enzymes in their sequential steps of catalysis. Evidence for germline transcription of V-H gene el ements, as part of V-H to DJ(H) recombination, has been limited to tra nscripts of only a few gene elements. We have examined normal fetal li ver mRNA by Northern blotting and present evidence for germline transc ripts from six human V-H gene families. The candidate V(H)4 transcript s have been confirmed as germline transcripts by hybridization with 3' flanking sequences that would have been removed by recombination from mature V(H)DJ(H) genes. The candidate transcripts for V(H)1, V(H)3, V (H)4 and V(H)6 have been confirmed by polymerase chain reaction amplif ication with primers from the 3' flanking sequences of these gene fami lies and determination of the sequence of these products. Determinatio n of sequence from two clones of VH 1, VH3 and VH4 indicates chat more than one gene from each of these families is transcribed. PCR amplifi cation of VH4 and VH6 with primers specific for the leader sequence (e xon 1) and 3' flanking sequence indicate that these transcripts are sp liced, representing RNA processing. Germline transcripts from these fa milies are also present in normal human bone marrow. These results ind icate that transcriptional activation of germline V-H gene elements is a general phenomenon in tissues undergoing V to DJ recombination. (C) 1997 Published by Elsevier Science Ltd.