Unique expression pattern of human nicotinamide mononucleotide adenylyltransferase isozymes in red blood cells

• Published in: Blood cells, molecules, & diseases Vol. 45; no. 1; pp. 33 - 39
• Main Authors: Di Stefano, M., Galassi, L., Magni, G.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.2010
• Subjects: Blotting, Western; Discrimination assay; Erythrocytes - enzymology; Erythrocytes - metabolism; Erythrocytes maturation; Gene Expression Regulation, Enzymologic; Humans; Isoenzymes - genetics; Isoenzymes - metabolism; NAD; Nicotinamide-Nucleotide Adenylyltransferase - genetics; Nicotinamide-Nucleotide Adenylyltransferase - metabolism; NMNAT isozymes; Red blood cells; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; NAD; NMNAT isozymes; Red blood cells; Discrimination assay; Erythrocytes maturation
• ISSN: 1079-9796; 1096-0961
• DOI: 10.1016/j.bcmd.2010.04.003

Nicotinamide mononucleotide adenylyltransferase (NMNAT) catalyzes the formation of nicotinamide adenine dinucleotide (NAD). In humans, three isozymes have been identified: NMNAT1, which is widely expressed in all tissues, NMNAT2 and NMNAT3, which show a tissue-specific expression and whose mRNA levels are generally lower compared to NMNAT1. In the present study we determined the individual NMNAT isozymes activity in human red blood cells (RBCs) by using a biochemical discrimination assay based on the distinctive catalytic properties of the three proteins. We found that isozyme 3 predominates over isozyme 1, whereas isozyme 2 is absent. This high prevalence of NMNAT3 is cell-aging independent and was also confirmed by analyzing the mRNA and protein levels. RBC represent the first human cell type with a remarkable predominance of NMNAT3, and this unique expression pattern is discussed in light of the catalytic properties of the isozymes and in consideration of the biochemical microenvironment of RBC.