VH gene expression and regulation in the mutant Alicia rabbit. Rescue of VHa2 allotype expression
Chen, H.T.; Alexander, C.B.; Young-Cooper, G.O.; Mage, R.G.
Journal of Immunology 150(7): 2783-2793
1993
ISSN/ISBN: 0022-1767 PMID: 8454855 Document Number: 417522
Rabbits of the Alicia strain, derived from rabbits expressing the V-Ha2 allotype, have a mutation in the H chain locus that has a cis effect upon the expression of V-Ha2 and V-Ha- genes. A small deletion at the most J-proximal (3') end of the V-H locus leads to low expression of all the genes on the entire chromosome in heterozygous ali mutants and altered relative expression of V-H genes in homozygotes. To study V-H gene expression and regulation, we used the polymerase chain reaction to amplify the V-H genes expressed in spleens of young and adult wild-type and mutant Alicia rabbits. The cDNA from reverse transcription of splenic mRNA was amplified and polymerase chain reaction libraries were constructed and screened with oligonucleotides from framework regions 1 and 3, as well as J-H. Thirty-three V-H-positive clones were sequenced and analyzed. We found that in mutant Alicia rabbits, products of the first functional V-H gene (V-H4a2), (or V-H4a2-like genes) were expressed in 2- to 8-wk-olds. Expression of both the V-Hx and V-Hy types of V-Ha- genes was also elevated but the relative proportions of V-Hx and V-Hy, especially V-Hx, decreased whereas the relative levels of expression of V-H4a2 or V-H4a2-like genes increased with age. Our results suggest that the appearance of sequences resembling that of the V-H1a2, which is deleted in the mutant ali rabbits, could be caused by alterations of the sequences of the rearranged V-H4a2 genes by gene conversions and/or rearrangement of upstream V-H1a2-like genes later in development.