Inositol lipids and TRPC channel activation
1National Institute of Environmental Health Sciences, NIH, Department of Health and Human Services, Research Triangle Park, NC 27709 USA. putney@niehs.nih.gov
Biochemical Society Symposium
|January 20, 2007
Summary
Inositol lipid breakdown directly activates transient receptor potential canonical (TRPC) channels, confirming a 30-year-old hypothesis. These TRPC channels are key players in calcium signaling pathways.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Inositol lipid breakdown was hypothesized to activate plasma membrane calcium channels.
- Calcium (Ca2+) signaling involves inositol trisphosphate (Ins(1,4,5)P3)-mediated release from intracellular stores.
- Ca2+ entry was thought to be a secondary mechanism following store depletion.
Purpose of the Study:
- To investigate the role of inositol lipid breakdown in calcium channel activation.
- To explore novel non-store-operated mechanisms for Ca2+ entry.
- To elucidate the function of Transient Receptor Potential Canonical (TRPC) channels in calcium signaling.
Main Methods:
- Review of existing literature on calcium signaling and inositol lipid metabolism.
- Analysis of studies involving mammalian TRPC channel homologues.
- Examination of TRPC channel activation by phospholipase C activity and its products.
Main Results:
- Mammalian TRPC channels (TRPC1-TRPC7) are homologues of Drosophila TRP.
- TRPC channels can function as store-operated channels but often link directly to phospholipase C activity.
- TRPC3, TRPC6, and TRPC7 are activated by diacylglycerol; TRPC4 and TRPC5 are activated by phospholipase C activity.
Conclusions:
- TRPC channels represent a family of ion channels directly activated by inositol lipid breakdown.
- This finding validates Bob Michell's original hypothesis regarding inositol lipid breakdown and calcium channel activation.
- TRPC channels play a significant role in calcium influx, directly modulated by lipid signaling pathways.
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