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TGF-beta(1) downregulates PTHrP in coronary endothelial cells

S Wenzel1, K Schorr, H Degenhardt

  • 1Physiologisches Institut, Justus-Liebig-Universität Giessen, Germany.

Journal of Molecular and Cellular Cardiology
|July 11, 2001
PubMed

Insights

Transforming growth factor-beta(1) reduces parathyroid hormone-related peptide (PTHrP) expression in cardiac endothelial cells. This finding is relevant for understanding PTHrP

Area of Science:

  • Cardiovascular Biology
  • Endocrinology
  • Molecular Biology

Background:

  • Parathyroid hormone-related peptide (PTHrP) is present in the cardiovascular system, particularly in coronary endothelial cells.
  • The regulatory factors influencing cardiac PTHrP expression remain largely unexamined.
  • Transforming growth factor-beta(1) (TGF-β1) is implicated in various cardiovascular conditions.

Purpose of the Study:

  • To investigate the effect of TGF-β1 on ventricular PTHrP expression.
  • To explore the relationship between TGF-β1, PTHrP, and cardiac hypertrophy in different physiological and pathophysiological states.

Main Methods:

  • Isolation of rat coronary endothelial cells for in vitro analysis.
  • Immunoblotting and RT-PCR to quantify PTHrP protein and mRNA levels.
  • Studies in transgenic mice overexpressing TGF-β1 and in spontaneously hypertensive rats (SHR-SP).
  • Investigation of ventricular PTHrP in a rat model of pressure-induced cardiac hypertrophy (aortic banding).

Main Results:

  • TGF-β1 caused a concentration-dependent decrease in PTHrP protein in cultured coronary endothelial cells within 24 hours.
  • Transgenic mice overexpressing TGF-β1 exhibited reduced ventricular PTHrP protein and mRNA.
  • In aging SHR-SP rats, increased TGF-β1 correlated with downregulated ventricular PTHrP mRNA.
  • Pressure-induced cardiac hypertrophy without TGF-β1 induction led to transiently increased ventricular PTHrP.
  • PTHrP expression was reduced under all conditions involving TGF-β1 exposure to coronary endothelial cells.

Conclusions:

  • TGF-β1 downregulates PTHrP expression in ventricular coronary endothelial cells.
  • Cardiac PTHrP expression does not correlate with cardiac hypertrophy.
  • The downregulation of PTHrP by TGF-β1 is significant for the paracrine functions of PTHrP in the ventricle.

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