Related Experiment Video
Updated: Aug 3, 2026
09:49
Induction and Assessment of Class Switch Recombination in Purified Murine B Cells
Published on: August 14, 2010
Rad51 expression and localization in B cells carrying out class switch recombination
M J Li1, M C Peakman, E I Golub
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
Summary
Rad51 protein is highly induced in B cells during immunoglobulin class switch recombination. This suggests Rad51 may play a role in this DNA repair process, but not in somatic hypermutation or general cell proliferation.
Area of Science:
- Immunology
- Molecular Biology
- Genetics
Background:
- Rad51 is a conserved protein homologous to bacterial RecA, involved in DNA repair and meiotic recombination.
- B cells undergo heavy chain class switch recombination (CSR) to change antibody effector function.
- CSR involves DNA recombination and repair mechanisms within B lymphocytes.
Purpose of the Study:
- To investigate the role of Rad51 in B cell heavy chain class switch recombination.
- To determine if Rad51 expression correlates with CSR, somatic hypermutation, or cell proliferation.
- To explore the potential function of Rad51 in the CSR pathway.
Main Methods:
- Primary murine B cells were cultured with lipopolysaccharide (LPS) to induce CSR.
- Immunofluorescence microscopy was used to detect Rad51 foci within B cell nuclei.
- Immunohistochemistry was performed on splenic sections to analyze Rad51 expression in vivo.
Main Results:
- Rad51 protein levels were significantly increased in B cells undergoing CSR.
- Rad51 staining was observed in the nuclei of B cells switching from IgM to IgG expression.
- Rad51 expression was not detected in germinal center B cells, indicating it's not linked to somatic hypermutation or proliferation.
Conclusions:
- Rad51 expression is specifically associated with the process of class switch recombination in B cells.
- The data suggest that Rad51, or a related RecA family member, may function in CSR.
- Rad51's role appears distinct from its involvement in somatic hypermutation or general cell proliferation.
Related Concept Videos
00:57Viral Recombination
Cells are sometimes infected by more than one virus at once. When two viruses disassemble to expose their genomes for replication in the same cell, similar regions of their genomes can pair together and exchange sequences in a process called recombination. Alternatively, viruses with segmented genomes can swap segments in a process called reassortment.
02:31Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
02:08Gene Conversion
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
01:30Crossing Over
Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...