Functional Importance of a Proteoglycan Coreceptor in Pathologic Lymphangiogenesis

Area of Science:

• Vascular Biology
• Glycobiology
• Cancer Biology

Background:

• Lymphatic vessel growth is regulated by factors like vascular endothelial growth factor (VEGF-C).
• Heparan sulfate (HS) is involved in angiogenesis, but its role in lymphatic remodeling is unclear.

Purpose of the Study:

• To investigate how heparan sulfate proteoglycans (HSPGs) mediate pathological lymphatic remodeling.
• To elucidate the genetic basis and mechanisms of HSPG involvement in lymphatic remodeling.

Main Methods:

• Examined mice with deficiencies in N-deacetylase/N-sulfotransferase-1 (Ndst1), a key HS biosynthetic enzyme, in lymphatic endothelial cells.
• Assessed the role of syndecan-4 (Sdc4), a major HSPG in lymphatic endothelium, using Sdc4 knockout mice.
• Analyzed VEGF receptor-3 (VEGFR-3) signaling, mitogen-activated protein kinase (MAPK) and Akt pathways, and apoptosis in deficient models.

Main Results:

• Ndst1 deficiency in lymphatic endothelium reduced lymphangiogenesis and impaired VEGF-C-mediated signaling and survival.
• HS deficiency reduced VEGFR-3 phosphorylation in response to VEGF-C.
• Syndecan-4 deficiency impaired pathological lymphangiogenesis, and VEGF-C induced syndecan-4 and VEGFR-3 association, crucial for signaling.

Conclusions:

• Heparan sulfate and syndecan-4 are genetically important for pathological lymphatic remodeling.
• These findings suggest novel strategies for modulating pathological lymphatic-vascular remodeling.