Guanosine 5′-[γ-thio]triphosphate-Mediated Activation of Cytosol Phospholipase C Caused Lysosomal Destabilization

Guanosine 5′-[γ-thio]triphosphate-Mediated Activation of Cytosol Phospholipase C Caused... Lysosomal disintegration is critical for the organelle functions and cellular viability. In this study, we established that guanosine 5′-[γ-thio]triphosphate (GTP-γ-S)-activated cytosol of rat hepatocytes could increase lysosomal permeability to both potassium ions and protons and osmotically destabilize the lysosomes via K+/H+ exchange. These results were obtained through measurements of lysosomal β-hexosaminidase-free activity, membrane potential and intralysosomal pH. Assays of phospholipase C (PLC) activity show that cytosolic PLC was activated upon addition of GTP-γ-S to the cytosol. The effects of cytosol on the lysosomes could be abolished by D609, an inhibitor of PLC, but not by the inhibitors of phospholipase A2. The cytosol-treated lysosomes disintegrated markedly in hypotonic sucrose medium, reflecting that the lysosomal osmotic sensitivity increased. Microscopic observations showed that the lysosomes became more swollen in hypotonic sucrose medium. This indicates that the cytosol treatment induced osmotic shock to the lysosomes and an influx of water into the organelle. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Guanosine 5′-[γ-thio]triphosphate-Mediated Activation of Cytosol Phospholipase C Caused Lysosomal Destabilization

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Publisher
Springer-Verlag
Copyright
Copyright © 2006 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-006-0019-0
Publisher site
See Article on Publisher Site

Abstract

Lysosomal disintegration is critical for the organelle functions and cellular viability. In this study, we established that guanosine 5′-[γ-thio]triphosphate (GTP-γ-S)-activated cytosol of rat hepatocytes could increase lysosomal permeability to both potassium ions and protons and osmotically destabilize the lysosomes via K+/H+ exchange. These results were obtained through measurements of lysosomal β-hexosaminidase-free activity, membrane potential and intralysosomal pH. Assays of phospholipase C (PLC) activity show that cytosolic PLC was activated upon addition of GTP-γ-S to the cytosol. The effects of cytosol on the lysosomes could be abolished by D609, an inhibitor of PLC, but not by the inhibitors of phospholipase A2. The cytosol-treated lysosomes disintegrated markedly in hypotonic sucrose medium, reflecting that the lysosomal osmotic sensitivity increased. Microscopic observations showed that the lysosomes became more swollen in hypotonic sucrose medium. This indicates that the cytosol treatment induced osmotic shock to the lysosomes and an influx of water into the organelle.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Sep 18, 2006

References

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