title: Inhibition of O-GlcNAcase in perfused rat hearts by NAG-thiazolines at the time of reperfusion is cardioprotective in an O-GlcNAc-dependent manner.
abstract: Acute increases in O-linked β-N-acetylglucosamine (O-GlcNAc) levels of cardiac proteins exert protective effects against ischemia-reperfusion (I/R) injury. One strategy to rapidly increase cellular O-GlcNAc levels is inhibition of O-GlcNAcase (OGA), which catalyzes O-GlcNAc removal. Here we tested the cardioprotective efficacy of two novel and highly selective OGA inhibitors, the NAG-thiazoline derivatives NAG-Bt and NAG-Ae. Isolated perfused rat hearts were subjected to 20 min global ischemia followed by 60 min reperfusion. At the time of reperfusion, hearts were assigned to the following four groups: 1) untreated control; 2) 50 μM NAG-Bt; 3) 100 μM NAG-Bt; or 4) 50 μM NAG-Ae. All treatment groups significantly increased total O-GlcNAc levels (P < 0.05 vs. control), and this was significantly correlated with improved contractile function and reduced cardiac troponin I release (P < 0.05). Immunohistochemistry of normoxic hearts showed intense nuclear O-GlcNAc staining and higher intensity at Z-lines with colocalization of O-GlcNAc and the Z-line proteins desmin and vinculin. After I/R, there was a marked loss of both cytosolic and nuclear O-GlcNAcylation and disruption of normal striated Z-line structures. OGA inhibition largely preserved structural integrity and attenuated the loss of O-GlcNAcylation; however, nuclear O-GlcNAc levels remained low. Immunoblot analysis confirmed ∼50% loss in both nuclear and cytosolic O-GlcNAcylation following I/R, which was significantly attenuated by OGA inhibition (P < 0.05). These data provide further support for the notion that increasing cardiac O-GlcNAc levels by inhibiting OGA may be a clinically relevant approach for ischemic cardioprotection, in part, by preserving the integrity of O-GlcNAc-associated Z-line protein structures.
authors.affiliation: Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0007, USA.
authors.forename: Boglarka
authors.initials: B
authors.lastname: Laczy
authors.forename: Susan A
authors.initials: SA
authors.lastname: Marsh
authors.forename: Charlye A
authors.initials: CA
authors.lastname: Brocks
authors.forename: Istvan
authors.initials: I
authors.lastname: Wittmann
authors.forename: John C
authors.initials: JC
authors.lastname: Chatham
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D003893:Desmin / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D023421:Models, Animal; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013844:Thiazoles / Q000494:pharmacology / Q000627:therapeutic use*; D001619:beta-N-Acetylhexosaminidases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D003893:Desmin; D004791:Enzyme Inhibitors; D013844:Thiazoles; C110628:hexosaminidase C; D001619:beta-N-Acetylhexosaminidases; C487818:N-acetylglucosamine thiazoline; D000117:Acetylglucosamine