An essential role for the Zn²⁺ transporter ZIP7 in B cell development

Area of Science:

• Immunology
• Molecular Biology
• Genetics

Background:

• Zinc is crucial for human immunity, but its molecular functions are not fully understood.
• A novel autosomal recessive disease presents with absent B cells, agammaglobulinemia, and recurrent infections.

Purpose of the Study:

• To investigate the molecular basis of a novel immunodeficiency disease.
• To elucidate the role of zinc transporter ZIP7 in B cell development and immunity.

Main Methods:

• Studied five unrelated families with the novel immunodeficiency.
• Utilized CRISPR-Cas9 gene editing to create mouse models of ZIP7 deficiency.
• Analyzed B cell development, zinc concentrations, and signaling pathways in patient cells and mouse models.

Main Results:

• Hypomorphic mutations in SLC39A7 (encoding ZIP7) cause the immunodeficiency.
• ZIP7 deficiency leads to reduced cytoplasmic free zinc in B cells.
• Impaired B cell receptor signaling and defective B cell development were observed in mutant mice and patients.

Conclusions:

• Cytosolic zinc, regulated by ZIP7, is essential for B cell receptor signaling and positive selection.
• ZIP7 is critical for normal B cell development and humoral immunity.
• This research identifies a key molecular mechanism underlying zinc-dependent immune function.