ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism
Oxysterol binding protein (OSBP) related proteins (ORPs) constitute a family that has at least 12 members in humans. In the present study we characterize one of the novel OSBP homologs, ORP2, which we show to be expressed ubiquitously in mammalian tissues. The ORP2 cDNA encodes a deduced 55 kDa prot...
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doaj-73e419799b1c45b2b6cb5f7f0c5d5c592021-04-27T04:38:19ZengElsevierJournal of Lipid Research0022-22752002-02-01432245255ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolismSaara Laitinen0Markku Lehto1Sanna Lehtonen2Kati Hyvärinen3Sanna Heino4Eero Lehtonen5Christian Ehnholm6Elina Ikonen7Vesa M. Olkkonen8Department of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandDepartment of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandDepartment of Pathology, Haartman-Institute, P.O. Box 21, FIN-00014, University of Helsinki, FinlandDepartment of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandDepartment of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandDepartment of Pathology, Haartman-Institute, P.O. Box 21, FIN-00014, University of Helsinki, FinlandDepartment of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandDepartment of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandTo whom correspondence should be addressed.; Department of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, FinlandOxysterol binding protein (OSBP) related proteins (ORPs) constitute a family that has at least 12 members in humans. In the present study we characterize one of the novel OSBP homologs, ORP2, which we show to be expressed ubiquitously in mammalian tissues. The ORP2 cDNA encodes a deduced 55 kDa protein that lacks a pleckstrin homology (PH) domain, a feature found in the other family members. Sucrose gradient centrifugation analysis of Chinese hamster ovary (CHO) cell post-nuclear supernatant demonstrated that ORP2 is distributed in soluble and membrane-bound fractions. Immunofluorescence microscopy of the endogenous and overexpressed ORP2 in CHO cells suggested that the membrane-bound fraction of the protein localizes to the Golgi apparatus. Stably transfected CHO cells that overexpress ORP2 showed an increase in [14C]cholesterol efflux to serum, apolipoprotein A-I (apoA-I), and phosphatidyl choline vesicles. The proportion of cellular [14C]cholesterol that is esterified and the ACAT activity measured as [14C]oleyl-CoA conversion into cholesteryl [14C]oleate by the cellular membranes, were markedly decreased in the ORP2 expressing cells. Transient high level overexpression of ORP2 interfered with the clearance of a secretory pathway protein marker from the Golgi complex. The results implicate ORP2 as a novel regulator of cellular sterol homeostasis and intracellular membrane trafficking.—Laitinen, S., M. Lehto, S. Lehtonen, K. Hyvärinen, S. Heino, E. Lehtonen, C. Ehnholm, E. Ikonen, and V. M. Olkkonen. ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism.http://www.sciencedirect.com/science/article/pii/S0022227520301668cholesterol effluxcholesterol esterificationGolgi apparatusmRNA expressionprotein expressionmembrane trafficking |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Saara Laitinen Markku Lehto Sanna Lehtonen Kati Hyvärinen Sanna Heino Eero Lehtonen Christian Ehnholm Elina Ikonen Vesa M. Olkkonen |
spellingShingle |
Saara Laitinen Markku Lehto Sanna Lehtonen Kati Hyvärinen Sanna Heino Eero Lehtonen Christian Ehnholm Elina Ikonen Vesa M. Olkkonen ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism Journal of Lipid Research cholesterol efflux cholesterol esterification Golgi apparatus mRNA expression protein expression membrane trafficking |
author_facet |
Saara Laitinen Markku Lehto Sanna Lehtonen Kati Hyvärinen Sanna Heino Eero Lehtonen Christian Ehnholm Elina Ikonen Vesa M. Olkkonen |
author_sort |
Saara Laitinen |
title |
ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
title_short |
ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
title_full |
ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
title_fullStr |
ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
title_full_unstemmed |
ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
title_sort |
orp2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism |
publisher |
Elsevier |
series |
Journal of Lipid Research |
issn |
0022-2275 |
publishDate |
2002-02-01 |
description |
Oxysterol binding protein (OSBP) related proteins (ORPs) constitute a family that has at least 12 members in humans. In the present study we characterize one of the novel OSBP homologs, ORP2, which we show to be expressed ubiquitously in mammalian tissues. The ORP2 cDNA encodes a deduced 55 kDa protein that lacks a pleckstrin homology (PH) domain, a feature found in the other family members. Sucrose gradient centrifugation analysis of Chinese hamster ovary (CHO) cell post-nuclear supernatant demonstrated that ORP2 is distributed in soluble and membrane-bound fractions. Immunofluorescence microscopy of the endogenous and overexpressed ORP2 in CHO cells suggested that the membrane-bound fraction of the protein localizes to the Golgi apparatus. Stably transfected CHO cells that overexpress ORP2 showed an increase in [14C]cholesterol efflux to serum, apolipoprotein A-I (apoA-I), and phosphatidyl choline vesicles. The proportion of cellular [14C]cholesterol that is esterified and the ACAT activity measured as [14C]oleyl-CoA conversion into cholesteryl [14C]oleate by the cellular membranes, were markedly decreased in the ORP2 expressing cells. Transient high level overexpression of ORP2 interfered with the clearance of a secretory pathway protein marker from the Golgi complex. The results implicate ORP2 as a novel regulator of cellular sterol homeostasis and intracellular membrane trafficking.—Laitinen, S., M. Lehto, S. Lehtonen, K. Hyvärinen, S. Heino, E. Lehtonen, C. Ehnholm, E. Ikonen, and V. M. Olkkonen. ORP2, a homolog of oxysterol binding protein, regulates cellular cholesterol metabolism. |
topic |
cholesterol efflux cholesterol esterification Golgi apparatus mRNA expression protein expression membrane trafficking |
url |
http://www.sciencedirect.com/science/article/pii/S0022227520301668 |
work_keys_str_mv |
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