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The second messenger linking receptor activation to internal Ca release in liver
Nature
|May 3, 1984
Summary
Hormone activation of liver cells causes breakdown of phosphatidylinositol 4,5-bisphosphate, producing inositol trisphosphate (InsP3). This inositol trisphosphate then signals the release of calcium from intracellular stores.
Area of Science:
- Biochemistry
- Cell Biology
- Hepatology
Background:
- Hormone-induced increases in liver cytosolic calcium primarily result from intracellular calcium release.
- A plasma membrane-derived messenger is required to signal calcium release from intracellular stores.
Purpose of the Study:
- To investigate the role of inositol phosphates as second messengers in hormone-induced calcium release in hepatocytes.
- To identify the specific inositol phosphate involved in mediating calcium release.
Main Methods:
- Hormone activation of isolated hepatocytes.
- Measurement of polyphosphoinositide breakdown.
- Application of inositol trisphosphate (InsP3) to permeabilized hepatocytes.
- Assessment of calcium release from intracellular stores.
Main Results:
- Hormone stimulation rapidly broke down phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) to form inositol trisphosphate (InsP3).
- InsP3 application to permeabilized hepatocytes induced calcium release from non-mitochondrial, ATP-dependent pools.
Conclusions:
- Inositol trisphosphate (InsP3) is likely the messenger linking hormone receptor activation to intracellular calcium release in liver cells.
- These findings support the role of InsP3 as a critical second messenger in hepatic calcium signaling.