A switch region inversion contributes to the aberrant rearrangement of a μ. immnnoglobulin heavy chain gene in MPC-11 cells

摘要

We describe the unique features of an aberrantly rearranged μ immunoglobulin heavy chain gene isolated from MPC-11 cells (a Y _2b producing Balb/c plasmacytana). A novel rearrangement has occurred 1.5 Kb 5′ of the MPC-11 μ gene (denoted 18bμ) resulting in the deletion of the majority of the repetitive switch region (S_μ) and 5′ flanking DNA including the Joining (J_H ) sequences. The remainder (275 bp) of the S_μ repeat has undergone a carplete sequence inversion. DNA sequences 5′ of the inverted S_μ sequence do not resemble Variable (V_H ), Diversity (D), J_H, or their conserved flanking sequences. A DNA sequence localized 5′ or the inverted Sy sequence, (p18bμ -1.4) detects a small family of homologous sequences in Balb/c DNA. The 18bμ-1.4 like sequences lack homology to S_μ , exhibit flanking sequence polymorphisms in 5 out of 6 inbred mouse strains and undergo partial or complete deletion in 5 out of 10 plasmacytomas tested. Two 18bμ-1.4 homologous sequences display a higher copy number in C57B1/6, AL/N and CAL9 mouse strains.