A peptide from a ras effector-domain blocks ras-dependent cardiac hypertrophy in myocytes.
PNC-2 is a peptide corresponding to an effector domain (residues 96-110) of ras-p21 that strongly and specifically blocks mitogenic signal transduction by oncogenic but not activated, normally-expressed wild-type ras-p21 protein. Since myocardial hypertrophy can be induced both by oncogenic and overexpressed wild-type ras-p21, we investigated whether PNC-2 can block norepinephrine (NE)-induced, ras-dependent myocardial hypertrophy in cardiac myocytes. Since PNC-2 blocks oncogenic ras-p21-induced activation of JNK and ERK, we further determined whether this peptide blocks activation of these kinases in NE-treated myocytes. Using cultured neonatal rat ventricular myocytes (NRVM), we found that NE alone significantly increased NRVM surface area, (3)H-leucine uptake, protein/DNA ratio, and atrial nartiuretic factor (ANF) mRNA levels in these cells. However, pretreatment of the NRVM with PNC-2 linked on its carboxyl terminal end to a transmembrane-penetrating leader sequence (PNC-2-leader) resulted in strong inhibition of NE-mediated cell growth and (3)H-leucine uptake and in significantly lower protein/DNA ratios. Induction of ANF mRNA levels was likewise inhibited by PNC-2-leader. In contrast, no inhibition of any of these NE-induced events was observed with a negative control peptide, X13-leader. Western blot analysis showed that JNK and ERK1/2 activity, but not p38 activity, was increased in NRVM within 5 min of exposure to NE (2 microM). Pretreatment with PNC-2-leader decreased ERK1/2 and JNK activity to basal levels. We conclude that a synthetic peptide designed to block oncogenic ras can also counter the effects of NE-induced hypertrophy associated with overexpression of ras p21 by blocking JNK/ jun and ERK activation. PNC-2 may provide a prototype for novel therapy in cardiac conditions associated with activation of NE.
Deng
Lili
L
Molecular Cardiology Program, NY Harbor VA Medical Center, Brooklyn, New York 11209, USA.
Boujdir
Mohamed
M
Tremontano
Anthony
A
Pincus
Matthew R
MR
El-Sherif
Nabil
N
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D006332:Cardiomegaly / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D004247:DNA / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D009638:Norepinephrine / Q000494:pharmacology; D015689:Oncogene Protein p21(ras) / Q000737:chemistry*; D010455:Peptides / Q000494:pharmacology / Q000627:therapeutic use*; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D010455:Peptides; D021382:Protein Sorting Signals; D009320:Atrial Natriuretic Factor; D004247:DNA; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D015689:Oncogene Protein p21(ras); D009638:Norepinephrine