PDGF-D Prodomain Differentially Inhibits the Biological Activities of PDGF-D and PDGF-B

Area of Science:

• Molecular Biology
• Cell Signaling
• Protein Structure

Background:

• Platelet-derived growth factor-D (PDGF-D) is a growth factor involved in development and healing.
• Unlike other PDGF family members, PDGF-D possesses an N-terminal CUB domain, contributing to its latent state.
• The precise role of the CUB domain in PDGF-D latency and activation remains unclear.

Purpose of the Study:

• To model the dimeric structure of the PDGF-D pro-complex.
• To investigate the inhibitory mechanisms of the PDGF-D prodomain on PDGF-B and PDGF-D signaling.
• To elucidate the structural basis for PDGF-D latency and differential signaling inhibition.

Main Methods:

• Computational modeling of the dimeric PDGF-D pro-complex structure.
• Biochemical assays to assess PDGFR-β transphosphorylation inhibition.
• Cell proliferation assays using NIH 3T3 cells.

Main Results:

• The model revealed PDGF-D growth factor domains forming a VEGF-D-like dimer.
• The CUB and hinge domains were shown to sterically hinder PDGFR-β binding.
• PDGF-D prodomain demonstrated dose-dependent inhibition of PDGFR-β transphosphorylation for both PDGF-B and PDGF-D.
• The prodomain selectively inhibited PDGF-D-induced NIH 3T3 cell proliferation, not PDGF-B-induced proliferation.

Conclusions:

• The CUB domain and prodomain are crucial for PDGF-D latency by preventing receptor interaction.
• PDGF-D prodomain exhibits differential inhibitory effects on PDGF-B and PDGF-D signaling pathways.
• Structural insights into PDGF-D pro-complex provide a basis for understanding its regulation and biological functions.