RUFY3 regulates endolysosomes perinuclear positioning, antigen presentation and migration in activated phagocytes

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Endo-lysosomal trafficking is essential for phagocyte function during microbial infections.
• The precise regulation of endo-lysosome positioning and dynamics is critical for effective immune cell activation.

Purpose of the Study:

• To investigate the role of RUN and FYVE domain-containing protein 3 (RUFY3) isoforms in immune cell function.
• To elucidate the specific functions of the FYVE domain-bearing isoform (iRUFY3) in endo-lysosomal trafficking and phagocyte responses.

Main Methods:

• Analysis of RUFY3 alternative splicing and isoform characterization.
• Immunofluorescence microscopy to assess endo-lysosome positioning (ARL8b+/LAMP1+).
• Macrophage migration assays, MHC II presentation analysis, and Interferon-gamma response evaluation.
• In vivo studies using mouse models of LPS injection and bacterial pneumonia.

Main Results:

• RUFY3 exists in two isoforms, with iRUFY3 possessing a FYVE domain and binding phosphatidylinositol 3-phosphate.
• iRUFY3 is preferentially expressed in immune cells and upregulated upon microbial and Interferon activation.
• iRUFY3 is essential for the perinuclear positioning of endo-lysosomes in activated macrophages.
• iRUFY3 regulates macrophage migration, MHC II presentation, Interferon-gamma responses, and intracellular Salmonella replication.
• Phagocyte-specific inactivation of rufy3 exacerbates pathologies in mouse models.

Conclusions:

• The iRUFY3 isoform plays a critical role in regulating endo-lysosomal dynamics and positioning within phagocytes.
• iRUFY3 is a key regulator of macrophage activation, migration, antigen presentation, and immune response.
• iRUFY3 is vital for host defense against bacterial infections and inflammatory conditions.