Identification of murine B cell lines that undergo somatic hypermutation focused to A:T and G:C residues.
Activation-induced deaminase (AID) is the master regulator of class switch recombination (CSR) and somatic hypermutation (SHM), but the mechanisms regulating AID function are obscure. The differential pattern of switch plasmid activity in three IgM(+)/AID(+) and two IgG(+)/AID(+) B cell lines prompted an analysis of global gene expression to discover the origin of these cells. Gene profiling suggested that the IgG(+)/AID(+) B cell lines derived from germinal center B cells. Analysis of SHM potential demonstrates that the IgVkappa domains are inducibly diversified at high rate during in vitro culture. The mutation spectra focused to A:T base pairs, revealing a component of the hypermutation program that occurs preferentially during phase 2 of SHM. The A:T error spectra were analyzed and were not characteristic of polymerase eta activity. A differential pattern of three consensus motifs used for A:T base substitutions was observed in WT and Poleta-, Msh2- and Msh6-deficient B cells. Strikingly, mutations in our B cell lines recapitulated the mutable motif profile for Poleta and Msh2 deficiency, respectively, and suggest that an additional pathway for the generation of A:T mutations in SHM is conserved in mouse and human.
Bhattacharya
Palash
P
Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, IL 60612-7344, USA.
Grigera
Fernando
F
Rogozin
Igor B
IB
McCarty
Thomas
T
Morse
Herbert C
HC
Kenter
Amy L
AL
D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D015870:Gene Expression; D020869:Gene Expression Profiling; D005803:Genes, Immunoglobulin; D018858:Germinal Center / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027041:Somatic Hypermutation, Immunoglobulin / Q000235:genetics*
D007135:Immunoglobulin Variable Region; D007145:Immunoglobulin kappa-Chains