Related Experiment Videos
Fibroblast growth factor-2 stimulates phospholipase Cbeta in adult cardiomyocytes
P S Tappia1, R R Padua, V Panagia
1Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Human Anatomy & Cell Science, University of Manitoba, Winnipeg, Canada.
Abstract:
Although fibroblast growth factor-2 (FGF-2) plays an important role in cardioprotection and growth, little is known about the signals triggered by it in the adult heart. We therefore examined FGF-2-induced effects on phosphoinositide-specific phospholipase C (PI-PLC) isozymes, which produce second messengers linked to the inotropic and hypertrophic response of the myocardium. FGF-2, administered by retrograde perfusion to the isolated heart, induced an increase in inositol-1,4,5-trisphosphate levels in the cytosol, as well as an increase in total PI-PLC activity associated with sarcolemmal and cytosolic fractions. Furthermore FGF-2 induced a time-dependent elevation in cardiomyocyte membrane-associated PLC gamma1 and PLC beta1 activities, assayed in immunoprecipitated fractions, and moreover, increased the membrane levels of PLC beta1 and PLC beta3. Activation of PLC beta is suggestive of FGF-2-induced cross-talk between FGF-receptor tyrosine kinase and G-protein-coupled signaling in adult cardiomyocytes and underscores the importance of FGF-2 in cardiac physiology.
Insights
Fibroblast growth factor-2 (FGF-2) activates phosphoinositide-specific phospholipase C (PI-PLC) signaling pathways in adult cardiomyocytes. This research highlights FGF-2
Area of Science:
- Cardiovascular Physiology
- Molecular Cardiology
- Cell Signaling
Background:
- Fibroblast growth factor-2 (FGF-2) is recognized for its roles in cardiac protection and growth.
- The specific signaling cascades initiated by FGF-2 in the adult heart remain incompletely understood.
- Phosphoinositide-specific phospholipase C (PI-PLC) isozymes generate second messengers crucial for myocardial contractility and growth.
Purpose of the Study:
- To investigate the effects of FGF-2 on PI-PLC isozyme activity in the adult heart.
- To elucidate the signaling mechanisms underlying FGF-2's influence on cardiac cells.
Main Methods:
- Isolated adult hearts were perfused with FGF-2.
- Cytosolic inositol-1,4,5-trisphosphate levels and total PI-PLC activity were measured.
- Membrane-associated PI-PLC isozyme activities (PLCγ1, PLCβ1) were assessed via immunoprecipitation.
- Membrane levels of PLCβ1 and PLCβ3 were quantified.
Main Results:
- FGF-2 administration increased cytosolic inositol-1,4,5-trisphosphate levels.
- Total PI-PLC activity in sarcolemmal and cytosolic fractions was elevated by FGF-2.
- FGF-2 induced a time-dependent increase in cardiomyocyte membrane-associated PLCγ1 and PLCβ1 activities.
- Membrane levels of PLCβ1 and PLCβ3 were augmented following FGF-2 treatment.
Conclusions:
- FGF-2 activates PI-PLC signaling pathways in adult cardiomyocytes.
- The activation of PLCβ suggests crosstalk between FGF-receptor tyrosine kinase and G-protein-coupled signaling.
- These findings underscore the significant role of FGF-2 in adult cardiac physiology.