Fenofibrate activates AMPK and increases eNOS phosphorylation in HUVEC

https://doi.org/10.1016/j.bbrc.2006.01.052Get rights and content

Abstract

Fenofibrate improves endothelial function by lipid-lowering and anti-inflammatory effects. Additionally, fenofibrate has been demonstrated to upregulate endothelial nitric oxide synthase (eNOS). AMP-activated protein kinase (AMPK) has been reported to phosphorylate eNOS at Ser-1177 and stimulate vascular endothelium-derived nitric oxide (NO) production. We report here that fenofibrate activates AMPK and increases eNOS phosphorylation and NO production in human umbilical vein endothelial cells (HUVEC). Incubation of HUVEC with fenofibrate increased the phosphorylation of AMPK and acetyl-CoA carboxylase. Fenofibrate simultaneously increased eNOS phosphorylation and NO production. Inhibitors of protein kinase A and phosphatidylinositol 3-kinase failed to suppress the fenofibrate-induced eNOS phosphorylation. Neither bezafibrate nor WY-14643 activated AMPK in HUVEC. Furthermore, fenofibrate activated AMPK without requiring any transcriptional activities. These results indicate that fenofibrate stimulates eNOS phosphorylation and NO production through AMPK activation, which is suggested to be a novel characteristic of this agonist and unrelated to its effects on peroxisome proliferator-activated receptor α.

Section snippets

Materials and methods

Materials. Cell culture media and supplements were purchased from Kurabo Industries (Osaka, Japan). Fenofibrate was a kind gift from Kaken Pharmaceutical (Tokyo, Japan). Fetal bovine serum (FBS) was purchased from Gibco, Invitrogen (Carlsbad, CA). Wortmannin was purchased from EMD Biosciences (La Jolla, CA). Anti-phosphorylated AMPKα (Thr-172), AMPKα, phosphorylated acetyl-CoA carboxylase (ACC) (Ser-79), phosphorylated eNOS (Ser-1177), phosphorylated Akt (Thr-308), and Akt antibodies were from

Fenofibrate increased eNOS phosphorylation and NO production in HUVEC

First, we investigated the effects of fenofibrate on eNOS phosphorylation and expression in HUVEC. Fenofibrate treatment induced a rapid and significant increase in eNOS phosphorylation at Ser-1177. This increase was observed from 2.5 to 10 min after treatment (Figs. 1A and B). Although fenofibrate is known to increase eNOS expression, the total eNOS protein level was not altered over the 10 min.

We next examined the phosphorylation of AMPK and Akt, which are upstream kinases for eNOS [9]. In the

Discussion

In the present study, we demonstrated for the first time that fenofibrate can activate AMPK by increasing AMPK phosphorylation in HUVEC. Although we did not perform a strict kinase assay of AMPK, we are certain that fenofibrate indeed activates this kinase for following reasons. (1) The extent of AMPK phosphorylation at Thr-172 strongly reflects its activity [12]. (2) Fenofibrate indeed increased phosphorylation of its consensus substrate, ACC, at Ser-79. The ability of fenofibrate to activate

Acknowledgments

We thank Dr. Keiji Naruse (Department of Cardiovascular Physiology, Okayama University) and Mikie Takahashi (Department of Physiology II, Nagoya University) for their excellent technical assistance.

References (24)

  • J. Malik et al.

    Both fenofibrate and atorvastatin improve vascular reactivity in combined hyperlipidaemia (fenofibrate versus atorvastatin trial–FAT)

    Cardiovasc. Res.

    (2001)
  • N. Marx et al.

    PPARalpha activators inhibit cytokine-induced vascular cell adhesion molecule-1 expression in human endothelial cells

    Circulation

    (1999)
  • Cited by (76)

    • Role of PPARα in inflammatory response of C2C12 myotubes

      2024, Biochemical and Biophysical Research Communications
    • Exercise as medicine for COVID-19: On PPAR with emerging pharmacotherapy

      2020, Medical Hypotheses
      Citation Excerpt :

      Fibrates inhibit endothelin-1 production and increase nitric oxide production [16]. Specifically, fenofibrate has been shown to suppress microvascular inflammation and apoptosis through inhibition of nuclear factor-κB and activation of adenosine monophosphate (AMP)-activated protein kinase leading to endothelial nitric oxide synthase phosphorylation and NO production [17–21]. It is interesting to note that although AMPK is not a canonical NR co-regulator, it interacts with NRs and is highly involved in their regulation of energy metabolism.

    • Fenofibrate Inhibits Cytochrome P450 Epoxygenase 2C Activity to Suppress Pathological Ocular Angiogenesis

      2016, EBioMedicine
      Citation Excerpt :

      We also found that another PPARα antagonist GW6471 failed to alter the inhibitory effects of fenofibric acid on angiogenesis ex vivo and in vitro (Supplemental Fig. 1 & 2). In human umbilical vein endothelial cells, fenofibrate increases 5′ adenosine monophosphate-activated protein kinase phosphorylation, but neither PPARα activator bezafibrate nor WY-14,643 has the same effect (Murakami et al., 2006). Studies of PPARα-independent mechanisms of action of fenofibrate and identification of the master regulators of PPARα-independent effects are still limited.

    View all citing articles on Scopus

    Abbreviations: AMPK, 5′-AMP-activated protein kinase; eNOS, endothelial nitric oxide synthase; HUVEC, human umbilical vein endothelial cells.

    View full text