Aldosterone signaling modifies capillary formation by human bone marrow endothelial cells

Area of Science:

• Endocrinology
• Cell Biology
• Vascular Biology

Background:

• The epithelial sodium channel (ENaC) plays a crucial role in sodium transport and is regulated by mineralocorticoid hormones.
• Human bone marrow endothelial cells (HBMEC) are key components of the vasculature and may be targets for mineralocorticoid signaling.

Purpose of the Study:

• To investigate the expression and regulation of the mineralocorticoid receptor (MCR) and ENaC alpha subunit in HBMEC.
• To determine the effects of aldosterone on HBMEC capillary formation and morphology.
• To elucidate the role of ENaC in mediating aldosterone's effects on endothelial cells.

Main Methods:

• Quantitative PCR to detect MCR and ENaC alpha subunit mRNA expression.
• Western blotting to analyze MCR and ENaC protein levels and localization.
• Confocal microscopy to visualize MCR and ENaC localization and colocalization with tubulin.
• In vitro angiogenesis assays using Matrigel and fibrin matrices to assess capillary formation and morphology.

Main Results:

• HBMEC express mRNA for MCR and ENaC alpha subunit.
• Aldosterone treatment increased MCR nuclear translocation and alphaENaC abundance in HBMEC.
• Aldosterone alone did not affect capillary formation but increased capillary diameter on fibrin; amiloride inhibited capillary elongation and reversed aldosterone-induced swelling.
• Aldosterone exacerbated amiloride's inhibitory effect on capillary organization on Matrigel.

Conclusions:

• Mineralocorticoid signaling via MCR and ENaC occurs in HBMEC, similar to epithelial cells.
• Aldosterone induces endothelial cell swelling, potentially contributing to hypertension.
• ENaC plays a role in mediating aldosterone's effects on endothelial cell volume and angiogenesis.