Shear Stress Induces Change in Extracellular Signal-Regulated Kinase 5 Levels with Sustained Activation under...

Area of Science:

• Cardiovascular Biology
• Mechanobiology
• Cell Signaling

Background:

• Extracellular signal-regulated kinase 5 (ERK5) is known to maintain endothelial integrity and prevent vascular dysfunction under normal (laminar) blood flow.
• ERK5 activation under laminar flow promotes the production of atheroprotective molecules.
• However, the specific activation patterns and levels of ERK5 under various disturbed flow conditions remain uncharacterized.

Purpose of the Study:

• To investigate and characterize the activation patterns and levels of ERK5 in human umbilical vein endothelial cells (HUVECs) under different types of shear stress.
• To determine how continuous laminar flow (CLF), to-and-fro flow (TFF), and pulsatile forward flow (PFF) affect ERK5 activation.

Main Methods:

• Human umbilical vein endothelial cells (HUVECs) were cultured and exposed to CLF, TFF, or PFF in a parallel plate flow chamber.
• Cell lysates were collected after specific time points and analyzed using immunoblotting to detect phosphorylated ERK5 (p-ERK5) and total ERK5.
• ERK5 activation was quantified by measuring p-ERK5 levels, with statistical analysis performed using ANOVA.

Main Results:

• ERK5 levels decreased across all tested flow conditions, with the most significant reduction observed under TFF.
• Sustained ERK5 phosphorylation was observed in HUVECs under both TFF and CLF for up to 4 hours.
• Pulsatile forward flow (PFF) induced transient ERK5 phosphorylation at 2 hours, which diminished by 4 hours.

Conclusions:

• Different shear stress patterns induce distinct ERK5 activation profiles in endothelial cells.
• The observed ERK5 activation under TFF suggests a potential role for this pathway in the pathogenesis of atherosclerosis and vascular remodeling associated with disturbed flow.