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LR1, a lipopolysaccharide-responsive factor with binding sites in the immunoglobulin switch regions and heavy-chain

M Williams1, N Maizels

  • 1Department of Molecular Biophysics and Biochemistry, Yale Medical School, New Haven, Connecticut 06510.

Genes & Development
|December 1, 1991
PubMed

Insights

Researchers discovered a new protein, LPS-responsive factor 1 (LR1), that regulates B-cell isotype switching. This factor

Area of Science:

  • Immunology
  • Molecular Biology
  • Genetics

Background:

  • B-cell differentiation involves isotype-switch recombination, a crucial process for antibody diversity.
  • The molecular mechanisms regulating isotype switching are not fully understood.

Purpose of the Study:

  • To identify and characterize novel regulatory factors involved in B-cell isotype-switch recombination.
  • To investigate the role of LPS-responsive factor 1 (LR1) in this process.

Main Methods:

  • Nuclear extracts from primary murine B lymphocytes cultured with LPS were analyzed.
  • DNA-binding assays were performed to identify and characterize LR1.
  • Kinetic studies and binding site analysis were conducted.

Main Results:

  • An inducible DNA-binding activity, termed LR1, was identified in LPS-stimulated B lymphocytes.
  • LR1 binds to conserved sequences in murine immunoglobulin switch regions and the heavy-chain enhancer.
  • LR1 activity is induced with kinetics parallel to isotype switching and depends on phosphorylation.

Conclusions:

  • LR1 is a candidate regulator of isotype-switch recombination in B cells.
  • Its induction and phosphorylation dependence suggest LR1 integrates kinase-dependent signaling pathways.
  • LR1 may play a critical role in communicating cellular signals to the chromosome to regulate antibody class switching.

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