Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) activity is required for V(D)J recombination

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• V(D)J recombination is essential for adaptive immunity, generating diverse B and T cell receptors.
• Sarco/endoplasmic reticulum Ca2+-ATPases (SERCAs) regulate intracellular calcium (Ca2+) homeostasis.
• ATP2A2, encoding SERCA2, was identified as a key gene in V(D)J recombination.

Purpose of the Study:

• To investigate the role of SERCA proteins in V(D)J recombination.
• To elucidate the molecular mechanisms by which SERCA impacts B cell development.

Main Methods:

• Whole-genome CRISPR/Cas9 screening in preB cells.
• Analysis of V(D)J recombination kinetics and RAG-mediated DNA cleavage.
• Assessment of ER and cytosolic Ca2+ levels.
• Gene expression analysis of RAG1 and RAG2.
• Study of B cell development in SERCA-deficient mice and human Darier disease patients.

Main Results:

• Loss of SERCA2 reduced V(D)J recombination kinetics due to impaired RAG-mediated DNA cleavage.
• SERCA2 deficiency led to increased SERCA3 expression.
• Combined SERCA2 and SERCA3 deficiency decreased ER Ca2+ and increased cytosolic Ca2+.
• This resulted in reduced RAG1/RAG2 expression and a block in V(D)J recombination.
• SERCA2 deficiency in mice and ATP2A2 mutations in humans caused reduced mature B cell counts.

Conclusions:

• SERCA proteins regulate intracellular Ca2+ levels, which are critical for RAG1/RAG2 gene expression and V(D)J recombination.
• Defects in SERCA function lead to impaired B cell development and lymphopenia.
• SERCA proteins represent a novel therapeutic target for B cell-related disorders.