Fluid Shear Stress Reduces 11ss-Hydroxysteroid Dehydrogenase Type 2

During pregnancy, trophoblasts line maternal spiral arteries and face altered mechanical forces. Elevated shear stress in hypertensive conditions may influence cellular hormone regulation. 11β-hydroxysteroid dehydrogenases (11β-HSDs) control cortisol availability, which affects fluid balance and vascular tone. Prior research has shown that 11β-HSD2 regulates cortisol conversion, but its response to shear stress remains unclear. This gap motivated a study to determine how shear stress affects 11β-HSD2 activity in trophoblast models. No prior work had resolved how mechanical forces interact with enzyme regulation in this context. The question of whether shear stress alters 11β-HSD2 expression or activity remained open. This uncertainty drove the investigation into JEG-3 cells, a model for trophoblast function. The study aimed to clarify the mechanisms linking mechanical stress to enzyme activity.

The study aimed to assess how shear stress influences 11β-HSD2 activity in trophoblast-like JEG-3 cells. Researchers focused on whether mechanical forces could modulate this enzyme’s function, which regulates cortisol availability. They used JEG-3 cells because they lack 11β-HSD1 but express 11β-HSD2, making them suitable for testing enzyme activity. The goal was to determine if shear stress alters enzyme activity and identify the underlying mechanisms. The study also aimed to explore whether signaling pathways like PKA or PKC mediate this effect. Researchers wanted to assess if focal adhesion signaling is involved in the response to shear stress. They sought to determine if tyrosine phosphorylation of focal adhesion kinase plays a role. The findings could clarify how mechanical forces impact hormone regulation in pregnancy.

The study used JEG-3 cells, a trophoblast model, to assess 11β-HSD2 activity under shear stress. Researchers applied controlled mechanical forces to simulate vascular conditions. Enzyme activity was measured by analyzing cortisol-to-cortisone conversion in cell lysates. RNA was extracted to measure 11β-HSD2 mRNA levels via qPCR. The effect of shear stress was tested at varying intensities and durations. Researchers used inhibitors like PD-098059 and cytochalasin D to probe signaling pathways. Tyrosine kinase inhibitors genistein and herbimycin A were tested for their effects. The study also assessed whether cAMP-dependent PKA activation influenced enzyme activity.

Shear stress significantly reduced 11β-HSD2 activity in JEG-3 cells. This reduction was dose-dependent and fully reversible after stress cessation. 11β-HSD2 mRNA levels also decreased under shear stress conditions. cAMP-dependent PKA activation increased enzyme activity but did not counteract shear stress effects. PKC inhibition had no impact on the shear stress response. The MAP kinase inhibitor PD-098059 partially reversed the effect of shear stress. Cytochalasin D, which disrupts focal adhesion signaling, prevented tyrosine phosphorylation of FA kinase. Tyrosine kinase inhibitors genistein and herbimycin A had differential effects on enzyme activity.

The study found that shear stress reduces 11β-HSD2 activity in JEG-3 cells. This effect is reversible and dose-dependent, suggesting a direct mechanical influence. The reduction involves transcriptional regulation and focal adhesion signaling. Focal adhesion kinase phosphorylation is required for the shear stress response. Tyrosine kinase inhibitors partially or fully restore enzyme activity. These findings suggest that mechanical forces modulate cortisol availability in trophoblasts. The authors propose that this mechanism may support vasoconstrictive vascular responses. The study highlights the role of focal adhesion signaling in enzyme regulation.