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Novel role of phospholipase C-delta1: regulation of liver mitochondrial Ca2+ uptake.
- Source :
-
American journal of physiology. Gastrointestinal and liver physiology [Am J Physiol Gastrointest Liver Physiol] 2004 Sep; Vol. 287 (3), pp. G533-40. Date of Electronic Publication: 2004 Apr 23. - Publication Year :
- 2004
-
Abstract
- Mitochondrial Ca2+ (mCa2+) handling is an important regulator of liver cell function that controls events ranging from cellular respiration and signal transduction to apoptosis. Cytosolic Ca2+ enters mitochondria through the ruthenium red-sensitive mCa2+ uniporter, but the mechanisms governing uniporter activity are unknown. Activation of many Ca2+ channels in the cell membrane requires PLC. This activation commonly occurs through phosphitidylinositol-4,5-biphosphate (PIP2) hydrolysis and the production of the second messengers inositol 1,4,5-trisphosphate [I(1,4,5)P3] and 1,2-diacylglycerol (DAG). PIP2 was recently identified in mitochondria. We hypothesized that PLC exists in liver mitochondria and regulates mCa2+ uptake through the uniporter. Western blot analysis with anti-PLC antibodies demonstrated the presence of PLC-delta1 in pure preparations of mitochondrial membranes isolated from rat liver. In addition, the selective PLC inhibitor U-73122 dose-dependently blocked mCa2+ uptake when whole mitochondria were incubated at 37 degrees C with 45Ca2+. Increasing extra mCa2+ concentration significantly stimulated mCa2+ uptake, and U-73122 inhibited this effect. Spermine, a uniporter agonist, significantly increased mCa2+ uptake, whereas U-73122 dose-dependently blocked this effect. The inactive analog of U-73122, U-73343, did not affect mCa2+ uptake in any experimental condition. Membrane-permeable I(1,4,5)P3 receptor antagonists 2-aminoethoxydiphenylborate and xestospongin C also inhibited mCa2+ uptake. Although extra mitochondrial I(1,4,5)P3 had no effect on mCa2+ uptake, membrane-permeable DAG analogs 1-oleoyl-2-acetyl-sn-glycerol and DAG-lactone, which inhibit PLC activity, dose-dependently inhibited mCa2+ uptake. These data indicate that PLC-delta1 exists in liver mitochondria and is involved in regulating mCa2+ uptake through the uniporter.
- Subjects :
- Adenosine pharmacology
Animals
Blotting, Western
Calcium Channel Agonists pharmacology
Calcium Channels
Calcium-Binding Proteins metabolism
Cell Membrane enzymology
Cell Membrane metabolism
Estrenes pharmacology
Fluorescent Dyes
In Vitro Techniques
Inositol 1,4,5-Trisphosphate pharmacology
Isoenzymes antagonists & inhibitors
Male
Microscopy, Fluorescence
Mitochondria, Liver metabolism
Phosphodiesterase Inhibitors pharmacology
Phospholipase C delta
Pyrrolidinones pharmacology
Rats
Rats, Sprague-Dawley
Spermine antagonists & inhibitors
Spermine pharmacology
Stimulation, Chemical
Type C Phospholipases antagonists & inhibitors
Adenosine analogs & derivatives
Calcium metabolism
Isoenzymes physiology
Mitochondria, Liver enzymology
Type C Phospholipases physiology
Subjects
Details
- Language :
- English
- ISSN :
- 0193-1857
- Volume :
- 287
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- American journal of physiology. Gastrointestinal and liver physiology
- Publication Type :
- Academic Journal
- Accession number :
- 15107298
- Full Text :
- https://doi.org/10.1152/ajpgi.00050.2004