title: Identification of new hematopoietic cell subsets with a polyclonal antibody library specific for neglected proteins.
abstract: The identification of new markers, the expression of which defines new phenotipically and functionally distinct cell subsets, is a main objective in cell biology. We have addressed the issue of identifying new cell specific markers with a reverse proteomic approach whereby approximately 1700 human open reading frames encoding proteins predicted to be transmembrane or secreted have been selected in silico for being poorly known, cloned and expressed in bacteria. These proteins have been purified and used to immunize mice with the aim of obtaining polyclonal antisera mostly specific for linear epitopes. Such a library, made of about 1600 different polyclonal antisera, has been obtained and screened by flow cytometry on cord blood derived CD34+CD45dim cells and on peripheral blood derived mature lymphocytes (PBLs). We identified three new proteins expressed by fractions of CD34+CD45dim cells and eight new proteins expressed by fractions of PBLs. Remarkably, we identified proteins the presence of which had not been demonstrated previously by transcriptomic analysis. From the functional point of view, looking at new proteins expressed on CD34+CD45dim cells, we identified one cell surface protein (MOSC-1) the expression of which on a minority of CD34+ progenitors marks those CD34+CD45dim cells that will go toward monocyte/granulocyte differentiation. In conclusion, we show a new way of looking at the membranome by assessing expression of generally neglected proteins with a library of polyclonal antisera, and in so doing we have identified new potential subsets of hematopoietic progenitors and of mature PBLs.
authors.affiliation: Fondazione Istituto Nazionale di Genetica Molecolare, INGM, Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Moro
authors.forename: Mariacristina
authors.initials: M
authors.lastname: Crosti
authors.forename: Pasquale
authors.initials: P
authors.lastname: Creo
authors.forename: Pierangela
authors.initials: P
authors.lastname: Gallina
authors.forename: Serena
authors.initials: S
authors.lastname: Curti
authors.forename: Elisa
authors.initials: E
authors.lastname: Sugliano
authors.forename: Rossana
authors.initials: R
authors.lastname: Scavelli
authors.forename: Davide
authors.initials: D
authors.lastname: Cattaneo
authors.forename: Elena
authors.initials: E
authors.lastname: Canidio
authors.forename: Maurizio
authors.initials: M
authors.lastname: Marconi
authors.forename: Paolo
authors.initials: P
authors.lastname: Rebulla
authors.forename: Paolo
authors.initials: P
authors.lastname: Sarmientos
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Viale
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Pagani
authors.forename: Sergio
authors.initials: S
authors.lastname: Abrignani
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D018952:Antigens, CD34 / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis*; D002454:Cell Differentiation; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005434:Flow Cytometry; D015723:Gene Library; D006367:HeLa Cells; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D040081:Protein Array Analysis; D040901:Proteomics; D011994:Recombinant Proteins / Q000276:immunology*
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; D007074:Immunoglobulin G; D008565:Membrane Proteins; D011994:Recombinant Proteins