title: Human CMP-N-acetylneuraminic acid hydroxylase is a novel stem cell marker linked to stem cell-specific mechanisms.
abstract: Human stem cells contain substantial amounts of the xenoantigen N-glycolylneuraminic acid (Neu5Gc), although the levels of Neu5Gc are low or undetectable in human body fluids and most other human tissues. The lack of Neu5Gc in human tissues has been previously explained by the loss of hydroxylase activity of the human CMP-N-acetylneuraminic acid hydroxylase (CMAH) protein caused by a genetic error in the human Cmah gene. We thus wanted to investigate whether the human redundant Cmah gene could still function in stem cell-specific processes. In this study, we show that CMAH gene expression is significantly upregulated in the adult stem cell populations studied, both of hematopoietic and mesenchymal origin, and identify CMAH as a novel stem cell marker. The CMAH content co-occurs with higher levels of Neu5Gc within stem cells as measured by mass spectrometric profiling. It seems that despite being enzymatically inactive, human CMAH may upregulate the Neu5Gc content of cells by enhancing Neu5Gc uptake from exogenous sources. Furthermore, exposure to exogenous Neu5Gc caused rapid phosphorylation of beta-catenin in both CMAH overexpressing cells and bone marrow-derived mesenchymal stem cells, thereby inactivating Wnt/beta-catenin signaling. The data demonstrate the first molecular evidence for xenoantigen Neu5Gc-induced alteration of crucial stem cell-specific signaling systems for the maintenance of self renewal. These results add further emphasis to the crucial need for completely xenofree culturing conditions for human stem cells.
authors.affiliation: Research and Development, Finnish Red Cross Blood Service, Helsinki, Finland. johanna.nystedt@bts.redcross.fi
authors.forename: Johanna
authors.initials: J
authors.lastname: Nystedt
authors.forename: Heidi
authors.initials: H
authors.lastname: Anderson
authors.forename: Tia
authors.initials: T
authors.lastname: Hirvonen
authors.forename: Ulla
authors.initials: U
authors.lastname: Impola
authors.forename: Taina
authors.initials: T
authors.lastname: Jaatinen
authors.forename: Annamari
authors.initials: A
authors.lastname: Heiskanen
authors.forename: Maria
authors.initials: M
authors.lastname: Blomqvist
authors.forename: Tero
authors.initials: T
authors.lastname: Satomaa
authors.forename: Jari
authors.initials: J
authors.lastname: Natunen
authors.forename: Juhani
authors.initials: J
authors.lastname: Saarinen
authors.forename: Petri
authors.initials: P
authors.lastname: Lehenkari
authors.forename: Leena
authors.initials: L
authors.lastname: Valmu
authors.forename: Jarmo
authors.initials: J
authors.lastname: Laine
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009438:Neuraminic Acids / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012794:Sialic Acids / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D009438:Neuraminic Acids; D012794:Sialic Acids; C032592:N-glycolylneuraminic acid; D006899:Mixed Function Oxygenases; C074383:CMPacetylneuraminate monooxygenase