Involvement of lysosomal degradation in VEGF-C-induced down-regulation of VEGFR-3

• VEGF-C specifically down-regulates VEGFR-3 mRNA and protein in lymphatic endothelial cells.
• Down-regulation is mediated by VEGF-C binding to VEGFR-3 and VEGFR-3 auto-phosphorylation.
• Down-regulation does not require MMP activity or Notch signaling.
• Lysosomal protease inhibitors decrease the down-regulatory effect on VEGFR-3 protein levels.
• Results indicate a ligand-induced receptor down-regulation mechanism via lysosomal activity.

The vascular endothelial growth factor (VEGF)-C-induced down-regulation of VEGF receptor (VEGFR)-3 is important in lymphangiogenesis. Here, we demonstrate that VEGF-C, -D, and -C156S, but not VEGF-A, down-regulate VEGFR-3. VEGF-C stimulates VEGFR-3 tyrosyl phosphorylation and transient phosphorylation of extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinases in lymphatic endothelial cells. VEGF-C-induced down-regulation of VEGFR-3 was blocked by a VEGF-C trap, tyrosine kinase inhibitor, and leupeptin, pepstatin, and E64 (LPE), but was unaffected by Notch 1 activator and γ-secretase inhibitors. Our findings indicate that VEGF-C down-regulates VEGFR-3 in lymphatic endothelial cells through VEGFR-3 kinase activation and, in part, via lysosomal degradation.