title: Bradykinin-induced inhibition of proliferation rate during neurosphere differentiation: consequence or cause of neuronal enrichment?
abstract: Neural stem cells proliferate and differentiate into neurons and glial cells, being responsible for embryonic and postnatal development of the central nervous system (CNS) as well as for regeneration in the adult brain. These cells also play a key role in maintaining the physiological integrity of the CNS in face of injury or disease. The previous study has demonstrated that bradykinin (BK) treatment simultaneously induces neuronal enrichment (indicating that BK contributes to neurogenesis) and reduced proliferation rates during in vitro differentiation of rat embryonic telencephalon neural precursor cells (NPCs). Here, we provide a mechanism for the unresolved question whether (i) the low rate of proliferation is owed to enhanced neurogenesis or, conversely, (ii) the alteration of the population ratio could result from low proliferation of NPCs and glial cells. In agreement with the previous study, BK promoted neuron-specific β3-tubulin and MAP2 expression in differentiating embryonic mouse neurospheres, whereas glial protein expression and global proliferation rates decreased. Furthermore, BK augmented the global frequency of cells in G0 -phase of cell cycle after differentiation. Heterogeneous cell populations were observed at this stage, including neurons that always remaining a quiescent state (G0 -phase). It is noteworthy that BK did not interfere with proliferation of any particular cell type, evidenced by coimmunostaining for nestin, β3-tubulin, glial fibrillary acidic protein (GFAP), and 5-ethynyl-2'-deoxyuridine (EdU). Thus, we conclude that neuronal enrichment is owing only to the fostering of neurogenesis, and that the low proliferation rate on the seventh day of differentiation is a consequence and not the cause of BK-induced neuronal enrichment.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP05508-900, Brazil.
authors.forename: Micheli M
authors.initials: MM
authors.lastname: Pillat
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP05508-900, Brazil.
authors.forename: Arquimedes
authors.initials: A
authors.lastname: Cheffer
authors.affiliation: Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, 97105-900, Rio Grande do Sul, Brazil.
authors.forename: Cinthia M
authors.initials: CM
authors.lastname: de Andrade
authors.affiliation: Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, 97105-900, Rio Grande do Sul, Brazil.
authors.forename: Vera M
authors.initials: VM
authors.lastname: Morsch
authors.affiliation: Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, 97105-900, Rio Grande do Sul, Brazil.
authors.forename: Maria R C
authors.initials: MR
authors.lastname: Schetinger
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP05508-900, Brazil.
authors.forename: Henning
authors.initials: H
authors.lastname: Ulrich
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000008:administration & dosage*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects / Q000254:growth & development; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis; D058953:Neural Stem Cells / Q000166:cytology / Q000187:drug effects*; D055495:Neurogenesis / Q000235:genetics*; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects; D051381:Rats; D043782:Receptor, Bradykinin B2 / Q000378:metabolism; D014404:Tubulin / Q000096:biosynthesis
chemical_list: D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; D043782:Receptor, Bradykinin B2; D014404:Tubulin; C462941:beta3 tubulin, mouse; D001920:Bradykinin
keywords: bradykinin; cell cycle; neural progenitor cells; neurogenesis; proliferation