title: Overexpression of OSBP-related protein 2 (ORP2) in CHO cells induces alterations of phospholipid species composition.
abstract: We have previously shown that overexpression of human OSBP-related protein 2 (ORP2) in Chinese hamster ovary (CHO) cells results in increased efflux and reduced esterification of cholesterol. The ORP2-expressing cells also have a reduced level of triacylglycerols. We investigated the effects of ORP2 expression on the phospholipid (PL) molecular species and the neutral lipid (NL) fatty acid composition of CHO cells cultured in the presence or absence of serum lipoproteins. In the presence of lipoproteins, ORP2/CHO cells display an increase in polyunsaturated PL species, and polyunsaturated fatty acids (PUFA) in the diminished NL pool are reduced. The increase of polyunsaturated PL may represent a compensatory response to alterations in cholesterol metabolism. Upon lipoprotein deprivation, the ORP2/CHO cells display a drop in polyunsaturated and an increase in mono and diunsaturated PL species. Our results suggest that this is due to defective recycling of PUFA from the diminished NL pool to PL. Furthermore, the PL PUFA, which are elevated in ORP2/CHO cells, are most likely subject to more rapid turnover than the NL-associated pool. The results provide evidence for a delicate integration of cholesterol, PL, and NL metabolism and a role of ORP2 as a regulator of the cellular lipidome.
authors.affiliation: Department of Biochemistry, Insitute of Biomedicine, P.O.Box 63, University of Helsinki, Finland.
authors.forename: Reijo
authors.initials: R
authors.lastname: Käkelä
authors.forename: Kimmo
authors.initials: K
authors.lastname: Tanhuanpää
authors.forename: Saara
authors.initials: S
authors.lastname: Laitinen
authors.forename: Pentti
authors.initials: P
authors.lastname: Somerharju
authors.forename: Vesa M
authors.initials: VM
authors.lastname: Olkkonen
mesh_terms: D000818:Animals; D016466:CHO Cells; D002853:Chromatography, Liquid; D006224:Cricetinae; D010743:Phospholipids / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D000098825:Oxysterol Binding Proteins
chemical_list: D010743:Phospholipids; D011987:Receptors, Steroid; D011994:Recombinant Proteins; C461064:OSBPL2 protein, human; D000098825:Oxysterol Binding Proteins