Multimerin-2 maintains vascular stability and permeability.

Area of Science:

• Biochemistry
• Molecular Biology
• Vascular Biology

Background:

• Multimerin-2, an ECM glycoprotein in the EMILIN family, regulates angiogenesis via the VEGFA/VEGFR2 axis.
• Its role in vascular homeostasis is largely unknown.

Purpose of the Study:

• To investigate Multimerin-2's function in maintaining vascular stability and homeostasis.
• To elucidate the molecular mechanisms underlying Multimerin-2's effects on endothelial cell junctions.

Main Methods:

• RNAi knockdown of Multimerin-2 in endothelial cells.
• Generation and analysis of Multimerin-2 knockout (Mmrn2-/-) mice.
• Assessment of vascular integrity, permeability, and pericyte coverage in vitro and in vivo.
• Evaluation of tumor vascularization, hypoxia, and chemotherapy efficacy in Mmrn2-/- mice.

Main Results:

• Multimerin-2 knockdown caused endothelial cell junction instability and increased permeability.
• Defects involved VEGFR2 phosphorylation, Src activation, and VE-cadherin phosphorylation.
• Mice lacking Multimerin-2 exhibited vascular leakage, impaired pericyte recruitment, and defective tumor vasculature.
• Tumor-associated vessels in Mmrn2-/- mice were leaky, hypoxic, and poorly perfused, reducing chemotherapy efficacy.

Conclusions:

• Multimerin-2 is essential for vascular homeostasis and stabilization.
• It plays a critical role in maintaining endothelial cell-cell junctions.
• Multimerin-2 levels may predict chemotherapy efficacy due to its impact on drug delivery.