title: Immunoglobulin heavy chain switch region recombination within a retroviral vector in murine pre-B cells.
abstract: We have employed a retroviral vector, ZN(Smu/S gamma 2b)tk1, as a substrate for detecting the presence of immunoglobulin heavy chain constant region (CH) gene switch (S) recombination activity in murine pre-B cells. ZN(Smu/S gamma 2b)tk1 contains a neomycin (neo) resistance gene in addition to the herpes simplex virus thymidine kinase (Htk) gene which is positioned between murine Smu and S gamma 2b sequences. Stable acquisition of the ZN(Smu/S gamma 2b)tk1 vector was selected in G-418 and switch region recombination within these proviruses was selected by resistance to the drug bromodeoxyuridine (BUdR). Fluctuation analyses of ZN(Smu/S gamma 2b)tk1 infected 18-8tk- and 38B9tk- pre-B lines revealed Htk gene inactivations with apparent frequencies of 5 X 10(-5) and 1 X 10(-5) events/cell/generation, respectively, while G-418 resistant Ltk- fibroblasts lost the HTK phenotype at an apparent rate of 4 X 10(-8). Southern blot analysis demonstrated that switch recombination caused the deletion of the Htk gene in all pre-B clones examined while the loss of Htk in Ltk- clones was not mediated by S region recombination. In 21 out of 24 pre-B clones, the recombinations involved the tandemly repetitive portions of the Smu and S gamma 2b sequences. These results demonstrate that the CH gene S region segments inserted into ZN(Smu/S gamma 2b)tk1 are sufficient for B-cell-specific recombination/deletion within the S region tandem repeats.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002460:Cell Line; D004351:Drug Resistance; D005796:Genes; D005814:Genes, Viral; D005822:Genetic Vectors; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007142:Immunoglobulin gamma-Chains / Q000235:genetics; D007148:Immunoglobulin mu-Chains / Q000235:genetics; D051379:Mice; D011995:Recombination, Genetic; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics*; D013937:Thymidine Kinase / Q000235:genetics
chemical_list: D007143:Immunoglobulin Heavy Chains; D007142:Immunoglobulin gamma-Chains; D007148:Immunoglobulin mu-Chains; D013937:Thymidine Kinase; D001973:Bromodeoxyuridine