Urocortin 2 autocrine/paracrine and pharmacologic effects to activate AMP-activated protein kinase in the heart

J Li, D Qi, H Cheng, X Hu, EJ Miller… - Proceedings of the …, 2013 - National Acad Sciences
J Li, D Qi, H Cheng, X Hu, EJ Miller, X Wu, KS Russell, N Mikush, J Zhang, L Xiao…
Proceedings of the National Academy of Sciences, 2013National Acad Sciences
Urocortin 2 (Ucn2), a peptide of the corticotropin-releasing factor (CRF) family, binds with
high affinity to type 2 CRF receptors (CRFR2) on cardiomyocytes and confers protection
against ischemia/reperfusion. The mechanisms by which the Ucn2-CRFR2 axis mitigates
against ischemia/reperfusion injury remain incompletely delineated. Activation of AMP-
activated protein kinase (AMPK) also limits cardiac damage during ischemia/reperfusion.
AMPK is classically activated by alterations in cellular energetics; however, hormones …
Urocortin 2 (Ucn2), a peptide of the corticotropin-releasing factor (CRF) family, binds with high affinity to type 2 CRF receptors (CRFR2) on cardiomyocytes and confers protection against ischemia/reperfusion. The mechanisms by which the Ucn2-CRFR2 axis mitigates against ischemia/reperfusion injury remain incompletely delineated. Activation of AMP-activated protein kinase (AMPK) also limits cardiac damage during ischemia/reperfusion. AMPK is classically activated by alterations in cellular energetics; however, hormones, cytokines, and additional autocrine/paracrine factors also modulate its activity. We examined the effects of both the endogenous cardiac Ucn2 autocrine/paracrine pathway and Ucn2 treatment on AMPK regulation. Ucn2 treatment increased AMPK activation and downstream acetyl-CoA carboxylase phosphorylation and glucose uptake in isolated heart muscles. These actions were blocked by the CRFR2 antagonist anti–sauvagine-30 and by a PKCε translocation-inhibitor peptide (εV1-2). Hypoxia-induced AMPK activation was also blunted in heart muscles by preincubation with either anti–sauvagine-30, a neutralizing anti-Ucn2 antibody, or εV1-2. Treatment with Ucn2 in vivo augmented ischemic AMPK activation and reduced myocardial injury and cardiac contractile dysfunction after regional ischemia/reperfusion in mice. Ucn2 also directly activated AMPK in ex vivo-perfused mouse hearts and diminished injury and contractile dysfunction during ischemia/reperfusion. Thus, both Ucn2 treatment and the endogenous cardiac Ucn2 autocrine/paracrine pathway activate AMPK signaling pathway, via a PKCε-dependent mechanism, defining a Ucn2-CRFR2-PKCε-AMPK pathway that mitigates against ischemia/reperfusion injury.
National Acad Sciences