Germline transcription and switch recombination of a transgene containing the entire H chain constant region locus: effect of a mutation in a STAT6 binding site in the gamma 1 promoter.
The switch (S) in H chain class is preceded by germline transcription and then mediated by a DNA recombination event. One of the impediments toward understanding the mechanism is the lack of a system in which a recombinant DNA molecule undergoes cytokine-regulated class S recombination. To study class S recombination, we used transgenic mice with a 230-kb bacterial artificial chromosome that included a rearranged VDJ gene and the entire murine H chain constant region locus. We found that both germline transcription and S recombination to the transgenic gamma1 H chain gene were regulated by IL-4 like that of the endogenous genes. In mice with two or more copies of the H chain locus transgene, both germline transcripts and S recombination took place at levels comparable to those from the endogenous loci. We also prepared a version of the transgene with a 4-bp mutation in a STAT6 binding site in the gamma1 promoter region. On the average, this mutation reduced germline transcription by 80%, but did not change the amount of S recombination in vitro. Among both the wild-type and mutant transgenes, we found no significant correlation between the amount of germline transcripts and the amount of S recombination. We infer that the physiologic level of germline transcription of the gamma1 gene is in excess over the amount required for efficient S recombination.
Dunnick
Wesley A
WA
Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA. wesadunn@umich.edu
Shi
Jian
J
Graves
Kevin A
KA
Collins
John T
JT
D000818:Animals; D001149:Arsenates / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D015326:Gene Rearrangement, B-Lymphocyte, Heavy Chain; D005819:Genetic Markers / Q000276:immunology; D018095:Germ-Line Mutation; D017578:Immunoglobulin Class Switching / Q000235:genetics*; D007127:Immunoglobulin Constant Regions / Q000235:genetics* / Q000378:metabolism; D007143:Immunoglobulin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D007142:Immunoglobulin gamma-Chains / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic / Q000276:immunology*; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D019076:Transgenes / Q000276:immunology
D001149:Arsenates; D005819:Genetic Markers; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007142:Immunoglobulin gamma-Chains; D050800:STAT6 Transcription Factor; C494100:Stat6 protein, mouse; D015534:Trans-Activators; C025657:arsenic acid