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Phospholipase C-gamma is required for agonist-induced Ca2+ entry
Randen L Patterson1, Damian B van Rossum, Diana L Ford
1Department of Neuroscience, Department of Pharmacology and Molecular Sciences, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Cell
|November 20, 2002
Summary
Phospholipase C-gamma (PLC-gamma) isoforms are crucial for agonist-induced calcium entry (ACE). This study reveals a lipase-independent function for PLC-gamma in regulating this vital cellular process.
Area of Science:
- Cell Biology
- Molecular Biology
- Physiology
Background:
- Agonist-induced calcium entry (ACE) is a critical cellular process.
- The precise molecular mechanisms regulating ACE are not fully understood.
- Phospholipase C-gamma (PLC-gamma) is implicated in calcium signaling pathways.
Purpose of the Study:
- To investigate the role of PLC-gamma isoforms in agonist-induced calcium entry (ACE).
- To determine if the enzymatic activity of PLC-gamma is necessary for ACE.
- To elucidate the specific domains of PLC-gamma involved in regulating ACE.
Main Methods:
- Overexpression of wild-type and mutant PLC-gamma isoforms in PC12 cells.
- RNA interference (RNAi) to deplete PLC-gamma1 and PLC-gamma2 in PC12 and A7r5 cells.
- Studies in DT40 B lymphocytes, including knockout cells and receptor stimulation.
- Assessment of calcium entry and endoplasmic reticulum (ER) calcium store release.
Main Results:
- Overexpression of wild-type and lipase-inactive PLC-gamma1 augmented ACE.
- A PLC-gamma1 deletion mutant lacking the SH3 domain was ineffective in augmenting ACE.
- RNAi-mediated depletion of PLC-gamma1 or PLC-gamma2 inhibited ACE.
- In DT40 cells, M5 receptor stimulation activated ACE, which was abolished in PLC-gamma2 knockout cells.
- ER calcium store release was unaffected by PLC-gamma2 depletion, but ACE was abolished.
- ACE was restored by expressing wild-type or lipase-inactive PLC-gamma2.
Conclusions:
- PLC-gamma isoforms play an essential, lipase-independent role in agonist-induced calcium entry.
- The SH3 domain of PLC-gamma1 appears critical for its function in ACE.
- These findings highlight a novel non-enzymatic function of PLC-gamma in calcium signaling regulation.
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