Gap junctions in human umbilical cord endothelial cells contain multiple connexins

Area of Science:

• Cardiovascular Biology
• Cellular Physiology
• Molecular Medicine

Background:

• Gap junctional proteins, known as connexins (Cx), are crucial for intercellular communication in endothelial cells.
• Understanding connexin expression and function in distinct vascular beds is vital for comprehending endothelial cell behavior.

Purpose of the Study:

• To investigate the expression patterns and functional characteristics of connexins (Cx37, Cx40, Cx43) in human umbilical vein endothelial cells (HUVEC) and human umbilical artery endothelial cells (HUAEC).
• To compare the in situ and in vitro expression and functional differences of gap junctions between arterial and venous endothelial cells.

Main Methods:

• In situ and in vitro analysis of connexin expression (Cx37, Cx40, Cx43) in HUVEC and HUAEC.
• Lucifer yellow CH dye-coupling experiments to assess functional intercellular communication.
• Dual voltage-clamp electrophysiology to determine gap junctional electrical conductance and single-channel conductances.

Main Results:

• Cx37, Cx40, and Cx43 were detected in both HUVEC and HUAEC, with heterogeneous expression patterns observed in vitro, particularly for Cx37.
• Cx40 was more abundant in cultured arterial endothelium than venous endothelium.
• While HUVEC exhibited extensive dye coupling, HUAEC showed restricted dye spread but significantly larger macroscopic electrical conductance, with unique single-channel conductances possibly linked to Cx40.

Conclusions:

• Differential expression and functional properties of connexins exist between human umbilical artery and vein endothelial cells.
• Higher Cx40 abundance and electrical conductance in HUAEC suggest specialized roles in arterial endothelial function.
• These findings highlight distinct gap junctional communication mechanisms in arterial versus venous endothelial cells.