Distinct vitellogenin domains differentially regulate immunological outcomes in invertebrates

Area of Science:

• Invertebrate immunology
• Molecular biology
• Crustacean research

Background:

• Vitellogenin (Vg) traditionally provides embryonic nutrition.
• Vg's role in host immune defense is increasingly recognized.
• Vg immunological functions are domain-dependent and poorly understood.

Purpose of the Study:

• Investigate distinct immunological functions of Vitellogenin (Vg) domains in the Chinese mitten crab (Eriocheir sinensis).
• Determine interactions between Vg domains and polymeric immunoglobulin receptor (pIgR).
• Elucidate Vg's contribution to innate immunity in invertebrates.

Main Methods:

• Confirmed conserved Vg domains (LPD_N, DUF1943, VWD) in Eriocheir sinensis.
• Assessed bacterial binding and antibacterial activity of individual Vg domains.
• Utilized co-immunoprecipitation assays to study Vg-pIgR interactions.
• Investigated Vg's effect on hemocyte phagocytosis.

Main Results:

• DUF1943 and VWD domains exhibited bacterial binding activity; LPD_N did not.
• Only the VWD domain demonstrated antibacterial activity, inhibiting bacterial proliferation.
• The DUF1943 domain specifically interacted with polymeric immunoglobulin receptor (pIgR).
• EsVg binding to EspIgR via DUF1943 enhanced hemocyte phagocytosis and bacterial clearance.

Conclusions:

• Distinct Vg domains mediate different immunological outcomes in invertebrates.
• The VWD domain possesses direct antibacterial properties.
• The DUF1943 domain mediates immune function through interaction with pIgR, enhancing host defense.
• This study provides novel insights into Vg's multifaceted role in invertebrate immunity and identifies pIgR as a key mediator in Vg-regulated phagocytosis.