Endothelin-1 expression in vascular adventitial fibroblasts.

Area of Science:

• Vascular Biology
• Cellular Signaling
• Biochemistry

Background:

• Endothelial cells are known producers of endothelin-1 (ET-1).
• The role of vascular adventitial fibroblasts in ET-1 production was previously unexplored.
• Extracellular matrix synthesis is crucial for vascular integrity.

Purpose of the Study:

• To investigate whether aortic adventitial fibroblasts can produce ET-1.
• To determine if ET-1 from fibroblasts contributes to extracellular matrix synthesis.
• To elucidate the signaling pathways involved in fibroblast ET-1 production.

Main Methods:

• Isolation and culture of mouse aortic adventitial fibroblasts.
• Stimulation with angiotensin II (ANG II) and receptor antagonists (losartan, PD-123319).
• Analysis of preproET-1 and procollagen mRNA via RT-PCR, ET-1 levels via ELISA, and procollagen protein via Western blotting.

Main Results:

• ANG II significantly increased preproET-1 mRNA and ET-1 release in a time- and concentration-dependent manner.
• ANG II's effects were blocked by an AT1 receptor antagonist (losartan) but not an AT2 antagonist.
• Inhibition of ET(A) receptors (BQ-123) reduced ANG II-induced procollagen synthesis, while ET(B) inhibition (BQ-788) did not.

Conclusions:

• Vascular adventitial fibroblasts synthesize and release ET-1 upon stimulation with ANG II.
• Fibroblast-derived ET-1 plays a role in regulating extracellular matrix synthesis, primarily through the ET(A) receptor.
• These findings highlight a novel source and function of ET-1 in vascular physiology.