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: Boglarka Laczy, Susan A Marsh, Charlye A Brocks, Istvan Wittmann, John C Chatham
• Journal: American journal of physiology. Heart and circulatory physiology (Am J Physiol Heart Circ Physiol) Vol. 299 Issue 5 Pg. H1715-27 (Nov 2010) ISSN: 1522-1539 [Electronic] United States
• PMID: 20833964 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Desmin
• Enzyme Inhibitors
• Thiazoles
• hexosaminidase C
• beta-N-Acetylhexosaminidases
• N-acetylglucosamine thiazoline
• Acetylglucosamine

Topics

• Acetylglucosamine (analogs & derivatives, metabolism, pharmacology, therapeutic use)
• Animals
• Desmin (metabolism)
• Enzyme Inhibitors (pharmacology, therapeutic use)
• Male
• Models, Animal
• Myocardial Reperfusion Injury (metabolism, prevention & control)
• Myocardium (metabolism)
• Rats
• Rats, Sprague-Dawley
• Thiazoles (pharmacology, therapeutic use)
• beta-N-Acetylhexosaminidases (antagonists & inhibitors, metabolism)