title: CD38 and CD157 ectoenzymes mark cell subsets in the human corneal limbus.
abstract: Nicotinamide adenine dinucleotide (NAD(+)), a precursor of molecules involved in cell regulatory processes, is released in extra-cellular compartments after stress or inflammation.This study investigates the expression in the human cornea of CD38 and CD157, two NAD(+)-consuming ectoenzymes and surface receptors. The analysis in corneal epithelial and stromal cells was performed by means of multiple approaches, which included immunofluorescence, reverse transcriptase polymerase chain reaction (RT-PCR), Western blot, and confocal microscopy. The presence of enzymatically active NAD(+)-consumers in intact corneal cells was analyzed by high performance liquid chromatography (HPLC)-based assays. The results obtained show that CD38 and CD157 are expressed constitutively by corneal cells: CD38 appears as a 45-kDa monomer, while CD157 is a 42- to 45-kDa doublet. The molecules are enzymatically active, with features reminiscent of those observed in human leukocytes. CD38 is expressed by cells of the suprabasal limbal epithelium, whereas it is not detectable in central corneal epithelium and stroma. CD157 is expressed by basal limbal clusters, a p63(+)/cytokeratin 19(+) cell subset reported to contain corneal stem cells, and by stromal cells. The results of the work indicates that the human cornea is equipped with molecular tools capable of consuming extracellular NAD(+), and that CD157 is a potential marker of corneal limbal cells in the stem cell niche. The presence and characteristics of these ectoenzymes may be exploited to design drugs for wound repair or for applications in tissue transplantation.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Torino Medical School, Torino, Italy. alberto.horenstein@unito.it
authors.forename: Alberto L
authors.initials: AL
authors.lastname: Horenstein
authors.forename: Federico
authors.initials: F
authors.lastname: Sizzano
authors.forename: Riccardo
authors.initials: R
authors.lastname: Lusso
authors.forename: Federico Genzano
authors.initials: FG
authors.lastname: Besso
authors.forename: Enza
authors.initials: E
authors.lastname: Ferrero
authors.forename: Silvia
authors.initials: S
authors.lastname: Deaglio
authors.forename: Franco
authors.initials: F
authors.lastname: Corno
authors.forename: Fabio
authors.initials: F
authors.lastname: Malavasi
mesh_terms: D036541:ADP-ribosyl Cyclase / Q000235:genetics / Q000378:metabolism*; D051997:ADP-ribosyl Cyclase 1 / Q000235:genetics / Q000378:metabolism*; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D003315:Cornea / Q000033:anatomy & histology / Q000378:metabolism; D058851:GPI-Linked Proteins; D006801:Humans; D016850:Limbus Corneae / Q000166:cytology / Q000201:enzymology; D009243:NAD / Q000378:metabolism; D055153:Stem Cell Niche
chemical_list: D015703:Antigens, CD; D015415:Biomarkers; D058851:GPI-Linked Proteins; D009243:NAD; D036541:ADP-ribosyl Cyclase; C087521:ADP-ribosyl cyclase 2; D051997:ADP-ribosyl Cyclase 1