STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC
STARD4, a member of the evolutionarily conserved START gene family, has been implicated in the nonvesicular intracellular transport of cholesterol. However, the direction of transport and the membranes with which this protein interacts are not clear. We present studies of STARD4 function using small...
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| Format: | Article |
| Language: | English |
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Elsevier
2012-12-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520418061 |
| _version_ | 1818735006690836480 |
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| author | Jeanne Garbarino Meihui Pan Harvey F. Chin Frederik W. Lund Frederick R. Maxfield Jan L. Breslow |
| author_facet | Jeanne Garbarino Meihui Pan Harvey F. Chin Frederik W. Lund Frederick R. Maxfield Jan L. Breslow |
| author_sort | Jeanne Garbarino |
| collection | DOAJ |
| description | STARD4, a member of the evolutionarily conserved START gene family, has been implicated in the nonvesicular intracellular transport of cholesterol. However, the direction of transport and the membranes with which this protein interacts are not clear. We present studies of STARD4 function using small hairpin RNA knockdown technology to reduce STARD4 expression in HepG2 cells. In a cholesterol-poor environment, we found that a reduction in STARD4 expression leads to retention of cholesterol at the plasma membrane, reduction of endoplasmic reticulum-associated cholesterol, and decreased ACAT synthesized cholesteryl esters. Furthermore, D4 KD cells exhibited a reduced rate of sterol transport to the endocytic recycling compartment after cholesterol repletion. Although these cells displayed normal endocytic trafficking in cholesterol-poor and replete conditions, cell surface low density lipoprotein receptor (LDLR) levels were increased and decreased, respectively. We also observed a decrease in NPC1 protein expression, suggesting the induction of compensatory pathways to maintain cholesterol balance. These data indicate a role for STARD4 in nonvesicular transport of cholesterol from the plasma membrane and the endocytic recycling compartment to the endoplasmic reticulum and perhaps other intracellular compartments as well. |
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| format | Article |
| id | doaj.art-c731a71c1fdc40c0aded5bcc11b35939 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-18T00:14:24Z |
| publishDate | 2012-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-c731a71c1fdc40c0aded5bcc11b359392022-12-21T21:27:33ZengElsevierJournal of Lipid Research0022-22752012-12-01531227162725STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERCJeanne Garbarino0Meihui Pan1Harvey F. Chin2Frederik W. Lund3Frederick R. Maxfield4Jan L. Breslow5The Laboratory of Biochemical Genetics and Metabolism, The Rockefeller University, New York, NY 10065; andThe Laboratory of Biochemical Genetics and Metabolism, The Rockefeller University, New York, NY 10065; andDepartment of Biochemistry, Weill Medical College of Cornell University, New York, NY 10065; andDepartment of Biochemistry, Weill Medical College of Cornell University, New York, NY 10065; and; Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, DenmarkDepartment of Biochemistry, Weill Medical College of Cornell University, New York, NY 10065; andTo whom correspondence should be addressed. e-mail: breslow@rockefeller.edu.; The Laboratory of Biochemical Genetics and Metabolism, The Rockefeller University, New York, NY 10065; and; To whom correspondence should be addressed. e-mail: breslow@rockefeller.edu.STARD4, a member of the evolutionarily conserved START gene family, has been implicated in the nonvesicular intracellular transport of cholesterol. However, the direction of transport and the membranes with which this protein interacts are not clear. We present studies of STARD4 function using small hairpin RNA knockdown technology to reduce STARD4 expression in HepG2 cells. In a cholesterol-poor environment, we found that a reduction in STARD4 expression leads to retention of cholesterol at the plasma membrane, reduction of endoplasmic reticulum-associated cholesterol, and decreased ACAT synthesized cholesteryl esters. Furthermore, D4 KD cells exhibited a reduced rate of sterol transport to the endocytic recycling compartment after cholesterol repletion. Although these cells displayed normal endocytic trafficking in cholesterol-poor and replete conditions, cell surface low density lipoprotein receptor (LDLR) levels were increased and decreased, respectively. We also observed a decrease in NPC1 protein expression, suggesting the induction of compensatory pathways to maintain cholesterol balance. These data indicate a role for STARD4 in nonvesicular transport of cholesterol from the plasma membrane and the endocytic recycling compartment to the endoplasmic reticulum and perhaps other intracellular compartments as well.http://www.sciencedirect.com/science/article/pii/S0022227520418061cholesterolStAR-related lipid transfer domain proteinhepatocellular carcinomaintracellular cholesterol transportendoplasmic reticulumendocytic recycling compartment |
| spellingShingle | Jeanne Garbarino Meihui Pan Harvey F. Chin Frederik W. Lund Frederick R. Maxfield Jan L. Breslow STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC Journal of Lipid Research cholesterol StAR-related lipid transfer domain protein hepatocellular carcinoma intracellular cholesterol transport endoplasmic reticulum endocytic recycling compartment |
| title | STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC |
| title_full | STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC |
| title_fullStr | STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC |
| title_full_unstemmed | STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC |
| title_short | STARD4 knockdown in HepG2 cells disrupts cholesterol trafficking associated with the plasma membrane, ER, and ERC |
| title_sort | stard4 knockdown in hepg2 cells disrupts cholesterol trafficking associated with the plasma membrane er and erc |
| topic | cholesterol StAR-related lipid transfer domain protein hepatocellular carcinoma intracellular cholesterol transport endoplasmic reticulum endocytic recycling compartment |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520418061 |
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