AP-1 (Fra-1/c-Jun)-mediated Induction of Expression of Matrix Metalloproteinase-2 Is Required for 15(S)-Hydroxyeicosatetraenoic Acid-induced Angiogenesis

Abstract

To understand the involvement of matrix metalloproteinases (MMPs) in 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE)-induced angiogenesis, we have studied the role of MMP-2. 15(S)-HETE induced MMP-2 expression and activity in a timedependent manner in human dermal microvascular endothelial cells (HDMVECs). Inhibition of MMP-2 activity or depletion of its levels attenuated 15(S)-Angiogenesis has been implicated in the pathogenesis of cancer, diabetic retinopathy, and atherosclerosis (1). On the other hand, a therapeutic role for angiogenesis in the treatment of coronary artery disease and wound healing has been identified (2). In the initiation of new capillaries, endothelial cells of existing blood vessels degrade the underlying basement membrane and invade into the stroma of the neighboring tissue (3, 4). The endothelial cell invasion and migration require the cooperative activity of the plasminogen activator system and the matrix metalloproteinases (MMPs) 2 (3). MMPs were initially discovered in 1962 as collagenolytic activity degrading extracellular matrix protein during tadpole tail resorption (5). Since then, more than 23 members of the MMP family of matrix-degrading enzymes have been identified, characterized, and sub-classified based on their ability to degrade a specific extracellular matrix protein (6). Besides their role in extracellular matrix protein degradation, MMPs have been reported to play a role in the activation of cell surface receptors (7). MMPs not only have been shown to play a role in a number of physiological processes such as embryogenesis (8) and angiogenesis (9, 10), but also have been reported to contribute to the pathogenesis of various diseases, including tumor metastasis (11) and inflammation (12). Among many MMPs, MMP-2 and -9 (also known as gelatinase A and gelatinase B, respectively) have been identified as important players in several cardiovascular diseases, including atherosclerosis, ischemic heart disease, heart failure, aneurysm, and stroke (13-17). MMP-2 is expressed ubiquitously in various cell types, including cardiomyocytes, endothelial cells, fibroblasts, and vascular smooth muscle cells, and plays a crucial role in the regulation of angiogenesis (18 -20). Despite the importance of MMPs in cardiovascular development and diseases (21-23), relatively very little is known in regard to the role of these enzymes in eicosanoid-mediated vascular wall remodeling. It is well established that lipoxygenases, particularly 12/15-lipoxygenase (12/15-Lox), play an important role in the pathogenesis of various vascular diseases and cancers (24 -28). One of the initial mechanisms by which 12/15-Lox is implicated in atherosclerosis is its capacity to oxidize low density lipoprotein particles (24). However, many studies also provided clues for additional mechanisms of 12/15-Lox involvement in the pathogenesis of atherosclerosis, restenosis, and cancer. Of these, its role in the regulation of cell growth, migration, and apoptosis have received much attention (29 -32). Besides, one of the...

12/15-Lipoxygenase gene knockout severely impairs ischemia-induced angiogenesis due to lack of Rac1 farnesylation

“…15(S)-HETE stimulated the tyrosine phosphorylation of ␣Pix in a timedependent manner ( Figure 4A). Because our previous studies showed that 15(S)-HETE stimulates Src, 24,25 we asked the question whether this non-receptor tyrosine kinase plays a role in 15(S)-HETE-induced ␣Pix phosphorylation. Adenovirus-mediated transduction of dominant negative Src completely blocked 15(S)-HETE-induced ␣Pix phosphorylation ( Figure 4B).…”

“…25 The treatment conditions were the same as those applied in migration assay. Vehicle or 15(S)-HETE, at the indicated concentrations, were added to the appropriate well and the cells were incubated at 37°C for 6 hours.…”

“…23,25 To understand the mechanisms by which 15(S)-HETE activates Rac1 in these cells, we have studied the role of HMG-CoA reductase and RhoGEFs as these molecules play an important role in RhoGTPase farnesylation and GDP/GTP exchange, respectively. [32][33][34][35] In agreement with our previous observations, 15(S)-HETE (0.1M) stimulated Rac1 in a time-dependent manner ( Figure 1A).…”

“…25 Vehicle or 15(S)-HETE were added to the lower chamber at the indicated concentrations. Both the upper and lower chambers contained medium 131.…”

“…25 Mice were anesthetized with intraperitoneal injection of ketamine (100 mg/kg) and xylazine (8 mg/kg). Aseptic surgery was performed to ligate the left common femoral artery as follows.…”