PDGFRβ Recognizes and Binds Bacteria to Activate Src/Stat Pathway in Oysters.

Area of Science:

• Marine biology
• Immunology
• Molecular biology

Background:

• The Stat signaling pathway is crucial for cytokine and growth factor secretion in vertebrates.
• This pathway is typically initiated by various cell surface receptors, including growth factor receptors.

Purpose of the Study:

• To identify and characterize a platelet-derived growth factor receptor (PDGFR) in the Pacific oyster, Crassostrea gigas.
• To elucidate the role of CgPDGFRβ in the oyster's immune response to bacterial challenge.

Main Methods:

• Identification and domain analysis of CgPDGFRβ in Crassostrea gigas.
• Bacterial binding assays using Gram-negative and Gram-positive bacteria, and their components (LPS, peptidoglycan).
• Investigation of CgPDGFRβ dimerization, interaction with CgSrc, and subsequent activation of the Src/Stat pathway in hemocytes.

Main Results:

• CgPDGFRβ possesses characteristic domains including Ig domains, a transmembrane domain, and a kinase domain.
• The N-terminal Ig domains of CgPDGFRβ exhibit higher binding affinity for Gram-negative bacteria and LPS.
• Upon bacterial binding, CgPDGFRβ dimerizes, activates CgSrc, leading to CgStat translocation and increased expression of CgBigdef1, CgIL17-4, and CgTNF1.

Conclusions:

• The Src/Stat signaling pathway is activated by CgPDGFRβ in response to bacterial stimuli in oysters.
• This signaling cascade plays a significant role in the innate immune defense of Crassostrea gigas by upregulating antimicrobial and inflammatory gene expression.