Lyso-phosphatidylcholine induces osteogenic gene expression and phenotype in vascular smooth muscle cells.
OBJECTIVE
Calcifying vascular cells in human atherosclerotic plaques actively contribute to ectopic vascular mineralization. Lyso-phosphatidylcholine (LPC), a product of oxidized phosphatidylcholine hydrolysis, is found at concentrations of 1-12 microg/g tissue throughout the atheroma. The objective of this study was to determine if LPC induces an osteogenic phenotype in vascular smooth muscle cells.


RESULTS
Proliferating human aortic smooth muscle cells were treated with a wide-range of LPC concentrations (0.1 nM to 100 microM) over 14 days. Von Kossa, Alizarin Red S, and alkaline phosphatase staining were used to identify mineralizations. RT-PCR, ELISA, alkaline phosphatase activity, and 45Ca incorporation assays were used to evaluate the osteo-inductive effect of LPC on smooth muscle phenotype. Histology and morphometry revealed that cells treated with as little as 10 nM LPC produced calcium phosphate deposits in culture. LPC-treated vascular smooth muscle cells showed a significant increase in 45Ca incorporation and alkaline phosphatase activity. Furthermore, LPC treatment induced a significant loss of Schnurri 3 protein, a key repressor of Runt-related transcription factor 2 stability. Genomic studies revealed that osteogenic gene expression was significantly up-regulated in LPC-treated cells, which is attributed to increased Runt-related transcription factor 2 expression and transcriptional activity.


CONCLUSIONS
LPC induces osteogenic morphology, physiology, gene expression, and phenotype in vascular smooth muscle cells. The present study suggests that localized concentrations of LPC in human atherosclerotic plaques may be a contributing factor to the generation of calcifying vascular cells.
Vickers
Kasey C
KC
Department of Medicine, Baylor College of Medicine, and Methodist Hospital, Houston, TX 77030, United States.
Castro-Chavez
Fernando
F
Morrisett
Joel D
JD
D000469:Alkaline Phosphatase / Q000096:biosynthesis; D001011:Aorta / Q000166:cytology; D050197:Atherosclerosis / Q000473:pathology; D002114:Calcinosis / Q000139:chemically induced*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008244:Lysophosphatidylcholines / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects*; D053495:Osteopontin / Q000096:biosynthesis; D010641:Phenotype
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D008244:Lysophosphatidylcholines; C493709:RUNX2 protein, human; D053495:Osteopontin; D000469:Alkaline Phosphatase
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