Mechanisms of myogenic tone of coronary arteriole: Role of down stream signaling of the EGFR tyrosine kinase.
OBJECTIVE
we previously showed that epidermal growth factor receptor tyrosine kinase (EGFRtk) is essential in the development of myogenic tone. GRB2-SOS, protein kinase B (Akt), Janus kinase (JAK), and Signal Transducer and Activator of Transcription 3 (STAT3) are activated by stretch. Thus, we hypothesized that GRB2-SOS, Akt, JAK and STAT3 are downstream signaling of the EGFR and play role in myogenic tone.


METHODS
myogenic tone was determined in freshly isolated coronary arterioles from C57/BL6 mice with and without inhibitors. Pressurized coronary arterioles under 25 and 75mm Hg were subjected to Western blot analysis to determine signaling phosphorylation. Smooth muscle cells (SMC) stimulated with EGF were used to determine the interaction between signaling.


RESULTS
coronary arteriole myogenic tone was significantly reduced under EGFRtk, GRB2-SOS, JAK, and STAT3 inhibition (53.6 ± 2 vs. 83.4 ± 1.3; 82.8 ± 1; 83.6 ± 1; 86.1 ± 1% of passive diameter at 75mm Hg, p<0.05, respectively). However, Akt inhibition had no effect on coronary arteriole myogenic tone. Western blot analysis showed increased EGFRtk, STAT3, JAK, and Akt phosphorylation at 75mm Hg, which was significantly inhibited under EGFRtk inhibition. Interestingly, immunoprecipitation/Western blot analysis showed two intracellular complexes (ERK1/2-JAK-STAT3) involved in myogenic tone and (Akt-JAK-STAT3) not involved in myogenic tone.


CONCLUSIONS
these findings demonstrate that ERK1/2-JAK-STAT3 complex and GRB2-SOS, down stream signaling of the EGFRtk, are critical in the development of myogenic tone, thereby highlighting these signaling events as potential therapeutic targets in cardiovascular disease states associated with altered myogenic tone.
Department of Physiology, Hypertension and Renal Center of Excellence, Tulane University, 1430 Tulane Ave, New Orleans, LA 70112, USA.
Ali H
AH
Amin
Zakaria Y
ZY
Abd Elmageed
Megan
M
Partyka
Khalid
K
Matrougui
D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051380:GRB2 Adaptor Protein / Q000037:antagonists & inhibitors; D053612:Janus Kinases / Q000037:antagonists & inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology; D011312:Pressure; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D050791:STAT Transcription Factors / Q000037:antagonists & inhibitors; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D020664:Son of Sevenless Proteins / Q000037:antagonists & inhibitors; D020032:Tyrphostins / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D051380:GRB2 Adaptor Protein; C495949:Grb2 protein, mouse; D018994:Myosin Light Chains; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D050791:STAT Transcription Factors; D050796:STAT3 Transcription Factor; D020664:Son of Sevenless Proteins; C494087:Stat3 protein, mouse; D020032:Tyrphostins; D009599:Nitroprusside; C101044:RTKI cpd; D004815:Epidermal Growth Factor; D011189:Potassium Chloride; D000069347:Erlotinib Hydrochloride; C541485:EGFR protein, mouse; D066246:ErbB Receptors; D053612:Janus Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases