How to make ends meet in V(D)J recombination

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Vertebrate adaptive immunity relies on diverse antigen receptors expressed by B and T lymphocytes.
• This diversity is primarily generated through a process called V(D)J recombination.
• V(D)J recombination involves the joining of variable (V), diversity (D), and joining (J) gene segments.

Purpose of the Study:

• To explain the mechanism of V(D)J recombination.
• To highlight the key molecular players involved in this process.
• To discuss the evolutionary origins and conservation of the machinery.

Main Methods:

• Analysis of V(D)J recombination in various vertebrate species.
• Identification of the roles of recombination-activating gene (RAG) proteins.
• Examination of the nonhomologous DNA end-joining (NHEJ) pathway.

Main Results:

• V(D)J recombination creates antigen-receptor diversity by randomly joining V, D, and J gene segments.
• Lymphocyte-specific RAG-1/2 proteins mediate the site-specific cleavage of DNA.
• The DNA double-strand breaks are repaired by the conserved NHEJ pathway.

Conclusions:

• V(D)J recombination is a fundamental process for generating immune receptor diversity in vertebrates.
• The RAG proteins, likely derived from a transposable element, are crucial for initiating recombination.
• The reliance on the conserved NHEJ pathway underscores the ancient origins and broad applicability of this DNA repair mechanism.