title: Involvement of cyclin-dependent kinases in axotomy-induced retinal ganglion cell death.
abstract: We have tested the role of cyclin-dependent kinases (CDKs) in the type 3B death of axotomized retinal ganglion cells, by injecting intraocularly olomoucine, roscovitine, or butyrolactone I. Each of these inhibits CDK1, CDK2, and CDK5; CDK1 and CDK2 are involved in cell proliferation, whereas CDK5 is involved in neuronal differentiation. The inhibitors partially protected ganglion cells against the effects of axotomy. These agents may affect the ganglion cells directly, because CDK1, its regulatory subunit cyclin B1, and CDK5 were identified immunohistochemically in the perikarya of ganglion cells, and this was confirmed for CDK1 and CDK5 in Western blots of the ganglion cell layer. These blots showed an axotomy-induced phosphorylation of CDK5 occurring remarkably quickly (within 6 hours of axotomy) but little if any change in the phosphorylation state of CDK1. In addition, we studied the expression of proliferation markers, including proliferating cell nuclear antigen (PCNA) and the synthesis of DNA, by immunohistochemical and autoradiographic methods. Normal or axotomized ganglion cells did not express PCNA and did not synthesize DNA. Although we cannot exclude the possibility that axotomized ganglion cells may leave their quiescent state, our data show that they did not progress beyond the G1 phase of the cell cycle. Finally, in contrast to inhibitors of CDKs, cell cycle blockers with different targets than CDKs did not protect ganglion cells. Globally, our results suggest that axotomy-induced death of ganglion cells involves the activation of CDK1, CDK2, or CDK5 (most probably CDK5) but not the full cell cycle machinery.
authors.affiliation: Institut de Biologie Cellulaire et de Morphologie, Université de Lausanne, 1005 Lausanne, Switzerland.
authors.forename: Karine
authors.initials: K
authors.lastname: Lefèvre
authors.forename: Peter G H
authors.initials: PG
authors.lastname: Clarke
authors.forename: Eve E
authors.initials: EE
authors.lastname: Danthe
authors.forename: Vincent
authors.initials: V
authors.lastname: Castagné
mesh_terms: D000818:Animals; D019771:Axotomy; D015415:Biomarkers / Q000032:analysis; D001973:Bromodeoxyuridine; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002642:Chick Embryo; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D051360:Cyclin-Dependent Kinase 5; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009410:Nerve Degeneration / Q000201:enzymology* / Q000503:physiopathology; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D013936:Thymidine
chemical_list: D015415:Biomarkers; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D004791:Enzyme Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D051360:Cyclin-Dependent Kinase 5; D016203:CDC2 Protein Kinase; D018844:Cyclin-Dependent Kinases; D001973:Bromodeoxyuridine; D013936:Thymidine