Ancient BCMA-like Genes Herald B Cell Regulation in Lampreys.

Area of Science:

• Immunology
• Evolutionary Biology
• Comparative Genomics

Background:

• The TNF superfamily ligands BAFF and APRIL are crucial for B cell selection and homeostasis in mammals, interacting with receptors BAFFR, BCMA, and TACI.
• Lampreys, jawless vertebrates, possess B-like and T-like lymphocytes, indicating a conserved immune system structure.

Purpose of the Study:

• To investigate the roles of BCMA-like genes in lamprey lymphocyte regulation.
• To understand the evolutionary origins of BAFF-mediated B cell regulation.

Main Methods:

• Phylogenetic analysis to identify BCMA-like genes in lampreys.
• Quantitative PCR to assess gene expression in B-like lymphocytes.
• In vitro binding assays to test interactions between lamprey BAFF-like protein and BCMA-like receptors.

Main Results:

• Two BCMA-like genes, BCMAL1 and BCMAL2, were identified in lampreys and preferentially expressed by B-like lymphocytes.
• Lamprey BAFF-like protein demonstrated binding to a BCMA-like receptor and to both BCMAL1- and BCMAL2-transfected cells.
• Differential expression patterns of BCMAL1 and BCMAL2 suggest distinct regulatory roles in B-like lymphocyte activation.

Conclusions:

• The findings imply that BAFF-based mechanisms for B cell regulation predate the divergence of jawed and jawless vertebrates.
• This study provides insights into the evolution of immune regulation in early vertebrates.