This Article Full Text Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Garver, W. S. Articles by Oram, J. F. Search for Related Content PubMed PubMed Citation Articles by Garver, W. S. Articles by Oram, J. F.

(Arteriosclerosis, Thrombosis, and Vascular Biology. 1997;17:2698-2706.)
© 1997 American Heart Association, Inc.

Articles

Phosphoproteins Regulated by the Interaction of High-Density Lipoprotein With Human Skin Fibroblasts

William S. Garver; Mark A. Deeg; Rosario F. Bowen; Maria M. Culala; Edwin L. Bierman; ; John F. Oram

From the Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle.

Correspondence to John F. Oram, Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Box 356426, Seattle, WA 98195-6426. E-mail joram{at}u.washington.edu

Abstract Interaction of HDL with cells activates protein kinase C (PKC), a process that may be important in stimulating efflux of excess cellular cholesterol. Here we report that HDL treatment of cholesterol-loaded fibroblasts increases ³²P labeling of three acidic phosphoproteins. These phosphoproteins, called pp80, pp27, and pp18 based on apparent M_r in kD, were also phosphorylated by acute treatment of cells with phorbol myristate acetate, suggesting that they are regulated in response to PKC activation. The HDL-stimulated phosphorylation of pp80 and pp18 was significant after only 30 seconds and was sustained for at least 30 and 120 minutes, respectively, while increased phosphorylation of pp27 was transient, reaching a maximum at 10 minutes. Both pp27 and pp18 were phosphorylated on serine/threonine residues, whereas pp80 was phosphorylated on serine/threonine and tyrosine residues. Immunoprecipitation studies suggested that pp80 is the myristoylated alanine-rich C kinase substrate protein, but the identities of pp27 and pp18 are unknown. HDL and trypsin-digested HDL stimulated phosphorylation of pp80 and pp27, while purified apoA-I, apoA-II, or apoE had no stimulatory effects, indicating that the active component in HDL was trypsin resistant and unlikely to be an apolipoprotein. Conversely, HDL, apoA-I, apoA-II, and apoE all stimulated pp18 phosphorylation, while trypsin-digested HDL had less effect, consistent with pp18's being responsive to HDL apolipoproteins. Treatment of cholesterol-depleted cells with apoA-I also stimulated phosphorylation of pp18, but only transiently. These results suggest that HDL interaction with cells activates diverse PKC-mediated pathways that target different phosphoproteins. Of these three phosphoproteins, only pp18 has a phosphorylation response consistent with its being involved in apolipoprotein-mediated lipid transport.

Key Words: HDL • apolipoproteins • protein phosphorylation • protein kinases • cholesterol transport

This article has been cited by other articles:

				Y. Feng, M. van Eck, E. Van Craeyveld, F. Jacobs, V. Carlier, S. Van Linthout, M. Erdel, M. Tjwa, and B. De Geest Critical role of scavenger receptor-BI-expressing bone marrow-derived endothelial progenitor cells in the attenuation of allograft vasculopathy after human apo A-I transfer Blood, January 15, 2009; 113(3): 755 - 764. [Abstract] [Full Text] [PDF]

				Y. Wang and J. F. Oram Unsaturated Fatty Acids Phosphorylate and Destabilize ABCA1 through a Phospholipase D2 Pathway J. Biol. Chem., October 28, 2005; 280(43): 35896 - 35903. [Abstract] [Full Text] [PDF]

				R. S. Kiss, J. Maric, and Y. L. Marcel Lipid efflux in human and mouse macrophagic cells: evidence for differential regulation of phospholipid and cholesterol efflux J. Lipid Res., September 1, 2005; 46(9): 1877 - 1887. [Abstract] [Full Text] [PDF]

				C. Tang, A. M. Vaughan, and J. F. Oram Janus Kinase 2 Modulates the Apolipoprotein Interactions with ABCA1 Required for Removing Cellular Cholesterol J. Biol. Chem., February 27, 2004; 279(9): 7622 - 7628. [Abstract] [Full Text] [PDF]

				J.-R. Nofer, R. Feuerborn, B. Levkau, A. Sokoll, U. Seedorf, and G. Assmann Involvement of Cdc42 Signaling in ApoA-I-induced Cholesterol Efflux J. Biol. Chem., December 26, 2003; 278(52): 53055 - 53062. [Abstract] [Full Text] [PDF]

				T. Grewal, I. de Diego, M. F. Kirchhoff, F. Tebar, J. Heeren, F. Rinninger, and C. Enrich High Density Lipoprotein-induced Signaling of the MAPK Pathway Involves Scavenger Receptor Type BI-mediated Activation of Ras J. Biol. Chem., May 2, 2003; 278(19): 16478 - 16481. [Abstract] [Full Text] [PDF]

				D. Sviridov, L. E. Pyle, M. Jauhiainen, C. Ehnholm, and N. H. Fidge Deletion of the propeptide of apolipoprotein A-I reduces protein expression but stimulates effective conversion of pre{beta}-high density lipoprotein to {alpha}-high density lipoprotein J. Lipid Res., November 1, 2000; 41(11): 1872 - 1882. [Abstract] [Full Text]

				J. F. Oram, A. J. Mendez, J. Lymp, T. J. Kavanagh, and C. L. Halbert Reduction in apolipoprotein-mediated removal of cellular lipids by immortalization of human fibroblasts and its reversion by cAMP: lack of effect with Tangier disease cells J. Lipid Res., October 1, 1999; 40(10): 1769 - 1781. [Abstract] [Full Text]

				N. H. Fidge High density lipoprotein receptors, binding proteins, and ligands J. Lipid Res., February 1, 1999; 40(2): 187 - 201. [Abstract] [Full Text]

				D. Sviridov, A. Hoang, W. H. Sawyer, and N. H. Fidge Identification of a Sequence of Apolipoprotein A-I Associated with the Activation of Lecithin:Cholesterol Acyltransferase J. Biol. Chem., June 23, 2000; 275(26): 19707 - 19712. [Abstract] [Full Text] [PDF]