RAGE signaling mediates post-injury arterial neointima formation by suppression of liver kinase B1 and AMPK activity

Abstract

Objective Intima formation involves smooth muscle cell (SMC) proliferation and migration that ultimately drives arterial stenosis, thrombosis, and ischemia in atherosclerosis, hypertension, and arterial revascularization. Receptor for advanced glycation endproducts (RAGE) is a transmembrane signaling receptor implicated in diabetic renal and vascular complications, and post-injury intima formation, partly via Signal transducer and activator of transcription 3 (STAT3) activation. The metabolic super-regulator Adenosine monophosphate kinase (AMPK) inhibits SMC proliferation and intima formation. AMPK activation is promoted by liver kinase B1 (LKB1), and LKB1 inhibits STAT3 activation. Here, we tested the hypothesis that RAGE promotes arterial intima formation by modulating both LKB1 and AMPK. Methods and Results RAGE ligands (the calgranulin S100A11, and glycated albumin) suppressed AMPK activation in conjunction with increased proliferation and migration of cultured SMCs. These effects were inhibited both by RAGE deficiency and by prior AMPK activation. In SMCs, RAGE ligands decreased LKB1 activity. Moreover, knockdown of both LKB1 and AMPK were associated with increased STAT3 phosphorylation levels. In response to murine carotid artery ligation, expression of RAGE and S100A11 increased, whereas AMPK and LKB1 activity decreased in situ. Conversely, LKB1 and AMPK activity increased in situ, and neointima formation was attenuated in Rage−/− mice. Conclusion The linkage of decreased LKB1 and AMPK activity with increased STAT3 in SMCs mediates the capacity of RAGE ligand-induced signaling to promote neointima formation in response to arterial injury.

Metformin Inhibits Monocyte-to-Macrophage Differentiation via AMPK-Mediated Inhibition of STAT3 Activation: Potential Role in Atherosclerosis

“…The results also indicate that by negatively regulating STAT3 phosphorylation through increased activation of AMPK, metformin inhibits monocyte-to-macrophage differentiation. Activation of STAT3 signaling is essential for neointima formation in vivo in response to carotid artery angioplasty (15). Metformin-and AICAR-activated AMPK was shown to inhibit proinflammatory gene expression in human liver cells by repressing IL-6-stimulated STAT3 phosphorylation (24).…”

“…Activation of the AMPK signaling pathway suppresses proinflammatory responses and promotes macrophage polarization to an anti-inflammatory functional phenotype in macrophages (14). In addition, decreased AMPK activity with increased STAT3 in smooth muscle cells has been shown to promote receptor for advanced glycation end product signaling-induced neointima formation in response to arterial injury (15).…”

Glycated Serum Albumin and AGE Receptors

“…In vascular smooth muscle cells, RAGE activation by AGE enhanced proliferation and migration by suppressing AMP-kinase activation [281]. Lander et al showed that AGE treatment of rat pulmonary artery smooth muscle cells caused activation of p21(ras) and NF-κB in a RAGE-dependent manner [282].…”

Mono-allelic and bi-allelic ENPP1 deficiency promote post-injury neointimal hyperplasia associated with increased C/EBP homologous protein expression

“…Left carotid artery ligation was performed as described (16), in 7-8 weeks old mice. Carotid arteries in euthanized animals were fixed with 4% paraformaldehyde (PFA) in PBS for morphological analysis or frozen for protein extraction and analysis by tissue SDS-PAGE Western blot.…”

“…Moreover, ENPP1 deficiency is associated with decreased soluble RAGE production by VSMCs and increased expression of the RAGE ligand S100A11 in vitro , and RAGE knockout inhibits AMC in Enpp1 −/− mice (14). RAGE is an essential mediator of injury-induced neointimal hyperplasia (15,16). RAGE ligand-induced signaling stimulates dysregulated ER stress responses (17), one of multiple inflammatory mechanisms by which RAGE signaling can promote diabetic organ complications.…”