Glucosamine inhibits angiotensin II-induced cytoplasmic Ca2+ elevation in neonatal cardiomyocytes via protein-associated O-linked N-acetylglucosamine.
We previously reported that glucosamine and hyperglycemia attenuate the response of cardiomyocytes to inositol 1,4,5-trisphosphate-generating agonists such as ANG II. This appears to be related to an increase in flux through the hexosamine biosynthesis pathway (HBP) and decreased Ca2+ entry into the cells; however, a direct link between HBP and intracellular Ca2+ homeostasis has not been established. Therefore, using neonatal rat ventricular myocytes, we investigated the relationship between glucosamine treatment; the concentration of UDP-N-acetylglucosamine (UDP-GlcNAc), an end product of the HBP; and the level of protein O-linked N-acetylglucosamine (O-GlcNAc) on ANG II-mediated changes in intracellular free Ca2+ concentration ([Ca2+]i). We found that glucosamine blocked ANG II-induced [Ca2+]i increase and that this phenomenon was associated with a significant increase in UDP-GlcNAc and O-GlcNAc levels. O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate, an inhibitor of O-GlcNAcase that increased O-GlcNAc levels without changing UDP-GlcNAc concentrations, mimicked the effect of glucosamine on the ANG II-induced increase in [Ca2+]i. An inhibitor of O-GlcNAc-transferase, alloxan, prevented the glucosamine-induced increase in O-GlcNAc but not the increase in UDP-GlcNAc; however, alloxan abrogated the inhibition of the ANG II-induced increase in [Ca2+]i. These data support the notion that changes in O-GlcNAc levels mediated via increased HBP flux may be involved in the regulation of [Ca2+]i homeostasis in the heart.
Nagy
Tamas
T
Dept. of Cell Biology, Univ. of Alabama at Birmingham, 1530 Third Ave. South, 684 MCLM Bldg., Birmingham, AL 35294-0005, USA.
Champattanachai
Voraratt
V
Marchase
Richard B
RB
Chatham
John C
JC
D000117:Acetylglucosamine / Q000378:metabolism*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005944:Glucosamine / Q000494:pharmacology*; D006595:Hexosamines / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019284:Thapsigargin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D006595:Hexosamines; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019284:Thapsigargin; D005944:Glucosamine; D002118:Calcium; D000117:Acetylglucosamine