Effect of protein kinase C on endoplasmic reticulum cholesterol. |
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Authors: | Yvonne Lange Jin Ye Theodore L Steck |
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Institution: | Department of Pathology, Rush-Presbyterian-St. Luke's Medical Center, 1653 West Congress Parkway, Chicago, IL 60612, USA. ylange@rush.edu |
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Abstract: | Plasma membrane cholesterol both regulates and is regulated by effector proteins in the endoplasmic reticulum (ER) through a feedback system that is poorly understood. We now show that ER cholesterol varies over a fivefold range in response to experimental agents that act upon protein kinase C (PKC). Agents that activate Ca(2+)-dependent PKC phorbol-12-myristate-13-acetate (PMA) and bryostatin 1] increased the level of ER cholesterol; inhibitors such as staurosporine and calphostin C decreased it. Rottlerin, a selective inhibitor of the PKC-delta isoform, also increased ER cholesterol. The esterification of plasma membrane cholesterol was altered by protein kinase C-directed agents in a corresponding fashion. Furthermore, the regulatory effect of plasma membrane cholesterol on the esterification of ER cholesterol was blocked by PKC-directed agents. These findings suggest that multiple protein kinase C isoforms participate in the regulation of ER cholesterol and therefore in cholesterol homeostasis. |
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Keywords: | cholesterol homeostasis protein kinase C endoplasmic reticulum cholesterol |
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