Glucose metabolism is required for oxidized LDL-induced macrophage survival: Role of PI3K and Bcl-2 family proteins

Abstract

OBJECTIVE-: Oxidized low-density lipoprotein (oxLDL) induces survival of colony stimulating factor-1 (CSF-1)-dependent macrophages in vitro. Because atherosclerotic lesion-associated macrophages take up large amounts of glucose, we investigated whether, and how, oxLDL promotes glucose uptake and how glucose metabolism regulates oxLDL-induced macrophage survival. METHODS AND RESULTS-: OxLDL-induced macrophage survival required glucose metabolism. OxLDL stimulated 2 phases of glucose uptake, namely acute and chronic, which required PI3K but not MEK1/2 activity. PI3K appeared to regulate glucose transport via glucose transporter affinity and/or mobilization. OxLDL also maintained levels of the prosurvival proteins, Bcl-2 and Bcl-xL, after CSF-1 had been removed through a combination of mechanisms including transcription, translation, and protein stabilization. Significantly, inhibition of glucose metabolism reduced Bcl-2 and Bcl-xL protein levels. MEK1/2 and PI3K activities were also required for oxLDL-induced Bcl-2 and Bcl-xL mRNA upregulation. CONCLUSIONS-: These results suggest that oxLDL enhances macrophage survival in the absence of CSF-1 by inducing PI3K-dependent glucose uptake, which is metabolized to maintain Bcl-2 and Bcl-xL protein levels. © 2009 American Heart Association, Inc.