This Article Full Text Full Text (PDF) All Versions of this Article: 48/2/294    most recent 01.HYP.0000229825.98545.5ev1 Alert me when this article is cited 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 Tanigawa, H. Articles by Saku, K. Search for Related Content PubMed PubMed Citation Articles by Tanigawa, H. Articles by Saku, K. Related Collections Structure Cell signalling/signal transduction

(Hypertension. 2006;48:294.)
© 2006 American Heart Association, Inc.

Original Articles

Dominant-Negative Lox-1 Blocks Homodimerization of Wild-Type Lox-1–Induced Cell Proliferation Through Extracellular Signal Regulated Kinase 1/2 Activation

Hiroyuki Tanigawa; Shin-ichiro Miura; Yoshino Matsuo; Masahiro Fujino; Tatsuya Sawamura; Keijiro Saku

From the Department of Cardiology (H.T., S.M., Y.M., M.F., K.S.), Fukuoka University Hospital, Fukuoka, Japan, and Department of Bioscience (T.S.), National Cardiovascular Center Research Institute, Osaka, Japan.

Correspondence to Shin-ichiro Miura, Department of Cardiology, Fukuoka University School of Medicine, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan. E-mail miuras{at}cis.fukuoka-u.ac.jp

C-type lectin-like oxidized low-density lipoprotein (Ox-LDL) receptor-1 (Lox-1) belongs to the same family as natural killer cell receptors Ly49A and CD94 and functionally undergoes dimerization. Although Lys²⁶² and Lys²⁶³ in the C terminus of bovine (b)Lox-1 play an important role in the uptake of Ox-LDL, mutation of these residues has not been suggested to be a potential source of the dominant-negative property. We hypothesize that dominant-negative human (h)Lox-1 forms a heterodimer with Lox-1–wild-type (WT) and blocks Lox-1–WT–induced cell signaling. Based on the use of molecular imaging techniques with laser scanning confocal microscopy and immunoprecipitation in an hLox-1–expressing Chinese hamster ovary cell system, homodimerization of hLox-1–WT was localized in the cell membrane, and Ox-LDL activated extracellular signal regulated kinase (ERK)1/2 without the translocation of hLox-1-WT. Lys²⁶⁶ and Lys²⁶⁷ of hLox-1, corresponding with Lys²⁶² and Lys²⁶³ of bLox-1, were mutated (hLox1-K266A/K267A), and the mutant receptor inhibited hLox-1–WT–induced thymidine incorporation and ERK1/2 activation. Although Ox-LDL binds to the dominant-negative mutant receptor and is taken up by cytoplasm, ERK1/2 activation was blocked by heterodimerization with the mutant receptor and hLox-1–WT in the cell membrane. In addition, in human coronary artery smooth muscle cells, which express hLox-1–WT, we confirmed that the activation of ERK1/2 and [³H]-thymidine incorporation was caused by the addition of Ox-LDL, and these actions were blocked by hLox1-K266A/K267A. In conclusion, the present findings constitute the first evidence that strategies aimed at blocking cell-proliferative pathways at the receptor level could be useful for impairing Lox-1–induced cell proliferation.

Key Words: molecular biology • vascular resistance • atherosclerosis

This article has been cited by other articles:

				D. Namgaladze, A. Kollas, and B. Brune Oxidized LDL attenuates apoptosis in monocytic cells by activating ERK signaling J. Lipid Res., January 1, 2008; 49(1): 58 - 65. [Abstract] [Full Text] [PDF]

				H. Morawietz LOX-1 and Atherosclerosis: Proof of Concept in LOX-1-Knockout Mice Circ. Res., June 8, 2007; 100(11): 1534 - 1536. [Full Text] [PDF]