Evidence for protein phosphatase inhibitor‐1 playing an amplifier role in β‐adrenergic signaling in cardiac myocytes

Abstract
SPECIFIC AIMSIn vitro, the protein phosphatase inhibitor-1 (PPI-1) is a highly specific and potent inhibitor of type 1 phosphatases (PP1) that is active only in its PKA-phosphorylated form, and so could play a positive feedback role in cAMP-dependent signaling. The present study used an adenovirus approach and two cardiac cell models to test the hypothesis that overexpression of PPI-1 sensitizes cardiac myocytes to β-adrenergic stimulation. A potential role in human pathophysiology was studied by determining PPI-1 expression in ventricular samples from failing and nonfailing human hearts.PRINICIPAL FINDINGS1. The sequence of rat heart PPI-1 differs from published sequences in one codonPPI-1 was cloned from rat heart by RT-PCR and sequenced by two standard methods from both sides. Compared with published sequences of rat skeletal, rabbit, or human PPI-1, a single nucleotide exchange results in an amino acid exchange at position 27 (lysine instead of glutamine) near the regulatory threonine-35 phosphorylati...
Funding Information
  • Deutsche Forschungsgemeinschaft (Es 88/8-2, SFB556 B2)

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