title: Nop2 is expressed during proliferation of neural stem cells and in adult mouse and human brain.
abstract: The nucleolar protein 2 gene encodes a protein specific for the nucleolus. It is assumed that it plays a role in the synthesis of ribosomes and regulation of the cell cycle. Due to its link to cell proliferation, higher expression of Nop2 indicates a worse tumor prognosis. In this work we used Nop2(gt1gaj) gene trap mouse strain. While lethality of homozygous animals suggested a vital role of this gene, heterozygous animals allowed the detection of expression of Nop2 in various tissues, including mouse brain. Histochemistry, immunohistochemistry and immunoelectron microscopy techniques, applied to a mature mouse brain, human brain and on mouse neural stem cells revealed expression of Nop2 in differentiating cells, including astrocytes, as well as in mature neurons. Nop2 was detected in various regions of mouse and human brain, mostly in large pyramidal neurons. In the human, Nop2 was strongly expressed in supragranular and infragranular layers of the somatosensory cortex and in layer III of the cingulate cortex. Also, Nop2 was detected in CA1 and the subiculum of the hippocampus. Subcellular analyses revealed predominant location of Nop2 within the dense fibrillar component of the nucleolus. To test if Nop2 expression correlates to cell proliferation occurring during tissue regeneration, we induced strokes in mice by middle cerebral artery occlusion. Two weeks after stroke, the number of Nop2/nestin double positive cells in the region affected by ischemia and the periventricular zone substantially increased. Our findings suggest a newly discovered role of Nop2 in both mature neurons and in cells possibly involved in the regeneration of nervous tissue.
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: ninakosi@hiim.hr.
authors.forename: Nina
authors.initials: N
authors.lastname: Kosi
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia; Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: ialic@vef.hr.
authors.forename: Ivan
authors.initials: I
authors.lastname: Alić
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: matea00@gmail.com.
authors.forename: Matea
authors.initials: M
authors.lastname: Kolačević
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: nvrsaljko@yahoo.com.
authors.forename: Nina
authors.initials: N
authors.lastname: Vrsaljko
authors.affiliation: Laboratory for Immunohistochemistry, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: njovanov@hiim.hr.
authors.forename: Nataša
authors.initials: N
authors.lastname: Jovanov Milošević
authors.affiliation: Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czech Republic. Electronic address: Margarita.Sobol@img.cas.cz.
authors.forename: Margarita
authors.initials: M
authors.lastname: Sobol
authors.affiliation: Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czech Republic. Electronic address: Anatoly.Philimonenko@img.cas.cz.
authors.forename: Anatoly
authors.initials: A
authors.lastname: Philimonenko
authors.affiliation: Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czech Republic. Electronic address: Pavel.Hozak@img.cas.cz.
authors.forename: Pavel
authors.initials: P
authors.lastname: Hozák
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia; Laboratory for Neurogenetics and Genetics of Development, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: srecko.gajovic@cmj.hr.
authors.forename: Srećko
authors.initials: S
authors.lastname: Gajović
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia; Laboratory for Neurogenetics and Genetics of Development, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia; Laboratory of Histology, Neuroanatomy and Neuropathology, Université Libre de Bruxelles, 1070 Bruxelles, Belgium. Electronic address: rpochet@ulb.ac.be.
authors.forename: Roland
authors.initials: R
authors.lastname: Pochet
authors.affiliation: Laboratory for Stem Cells, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia; Laboratory for Neurogenetics and Genetics of Development, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, 10 000 Zagreb, Croatia. Electronic address: dinko.mitrecic@mef.hr.
authors.forename: Dinko
authors.initials: D
authors.lastname: Mitrečić
mesh_terms: D000328:Adult; D000818:Animals; D001253:Astrocytes / Q000502:physiology; D001921:Brain / Q000502:physiology* / Q000503:physiopathology; D049109:Cell Proliferation / Q000502:physiology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006801:Humans; D020244:Infarction, Middle Cerebral Artery; D008297:Male; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D064231:Nestin / Q000378:metabolism; D058953:Neural Stem Cells / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011496:Protein Methyltransferases; D020521:Stroke / Q000503:physiopathology; D012359:tRNA Methyltransferases / Q000378:metabolism*
chemical_list: C577485:Nes protein, mouse; D064231:Nestin; D009687:Nuclear Proteins; C065028:NOP2 protein, human; C512901:Nop2 protein, mouse; D011496:Protein Methyltransferases; D012359:tRNA Methyltransferases
keywords: Brain; Cell cycle; Nop2; Nucleolus; Stem cells; Stroke