title: The all-trans retinoic acid (atRA)-regulated gene Calmin (Clmn) regulates cell cycle exit and neurite outgrowth in murine neuroblastoma (Neuro2a) cells.
abstract: The vitamin A metabolite all-trans retinoic acid (atRA) functions in nervous system development and regulates cell proliferation and differentiation. Neuroblastoma cells (SH-SY5Y and Neuro2a or N2A) exposed to atRA undergo growth inhibition and neuronal differentiation, both of which are preceded by an increase in Clmn mRNA. Treatment of N2A cells with atRA produces a reduction in phosphohistone 3 immunostaining and BrdU incorporation, both indicators of a reduction in cell proliferation. These effects are nearly eliminated in atRA-treated shClmn knockdown cells. Loss of Clmn in the mouse N2A cell line also results in a significant reduction of atRA-mediated neurite outgrowth, a response that can be rescued by reintroduction of the Clmn sequence. In contrast, ectopic overexpression of Clmn produces an increase in the cyclin dependent kinase inhibitor, p21(Cip1), a decrease in cyclin D1 protein and an increase in hypophosphorylated Rb, showing that Clmn participates in G(1)/S arrest. Clmn overexpression alone is sufficient to inhibit N2A cell proliferation, whereas both Clmn and atRA must be present to induce neurite outgrowth. This study shows that the atRA-responsive gene Clmn promotes exit from the cell cycle, a requisite event for neuronal differentiation.
authors: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA.
authors: Mark A
authors: MA
authors: Marzinke
authors: Margaret
authors: M
authors: Clagett-Dame
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects* / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D055785:Gene Knockdown Techniques; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D016501:Neurites / Q000187:drug effects* / Q000473:pathology; D009447:Neuroblastoma / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D018797:Cell Cycle Proteins; C486659:Clmn protein, mouse; D008565:Membrane Proteins; D012333:RNA, Messenger; D014212:Tretinoin