Endothelin-1 activates MAPKs and modulates cell cycle proteins in OKP cells

Area of Science:

• Renal physiology
• Molecular signaling
• Cell biology

Background:

• Mechanisms of endothelin-1 (ET-1) induced renal tubular hyperplasia are not fully understood.
• ET-1 plays a role in regulating kidney function and pathology.

Purpose of the Study:

• To elucidate the signaling pathways through which ET-1 stimulates renal tubular epithelial cell proliferation.
• To investigate the role of ETB receptors in ET-1 mediated hyperplasia.

Main Methods:

• Utilized ETB-overexpressing opossum kidney (OKP) cells as an in vitro model.
• Measured c-jun mRNA abundance, extracellular signal-regulated kinase (ERK) 1/2 and mitogen-activated protein kinase kinase (MEK) 1/2 activity.
• Assessed cyclin D1 expression and retinoblastoma (RB) gene product phosphorylation.

Main Results:

• ET-1 rapidly increased c-jun mRNA and ERK1/2, MEK1/2 activity.
• ET-1 treatment led to increased cyclin D1 expression and RB phosphorylation.
• These effects were blocked by ETB-receptor blockade or MEK inhibition.

Conclusions:

• ET-1 binding to ETB receptors initiates a signaling cascade promoting cell proliferation.
• The pathway involves rapid activation of MAPKs, increased c-jun, and modulation of cell cycle proteins (cyclin D1, RB).
• This study provides insights into the molecular basis of ET-1-induced renal tubular hyperplasia.