PMID- 23741412 OWN - NLM STAT- MEDLINE DCOM- 20140110 LR - 20211021 IS - 1932-6203 (Electronic) IS - 1932-6203 (Linking) VI - 8 IP - 5 DP - 2013 TI - Brain-derived neurotrophic factor-dependent cdk1 inhibition prevents G2/M progression in differentiating tetraploid neurons. PG - e64890 LID - 10.1371/journal.pone.0064890 [doi] LID - e64890 AB - Neurodegeneration is often associated with DNA synthesis in neurons, the latter usually remaining for a long time as tetraploid cells before dying by apoptosis. The molecular mechanism preventing G2/M transition in these neurons remains unknown, but it may be reminiscent of the mechanism that maintains tetraploid retinal ganglion cells (RGCs) in a G2-like state during normal development, thus preventing their death. Here we show that this latter process, known to depend on brain-derived neurotrophic factor (BDNF), requires the inhibition of cdk1 by TrkB. We demonstrate that a subpopulation of chick RGCs previously shown to become tetraploid co-expresses TrkB and cdk1 in vivo. By using an in vitro system that recapitulates differentiation and cell cycle re-entry of chick retinal neurons we show that BDNF, employed at concentrations specific for the TrkB receptor, reduces the expression of cdk1 in TrkB-positive, differentiating neurons. In this system, BDNF also inhibits the activity of both endogenous cdk1 and exogenously-expressed cdk1/cyclin B1 complex. This inhibition correlates with the phosphorylation of cdk1 at Tyr15, an effect that can be prevented with K252a, a tyrosine kinase inhibitor commonly used to prevent the activity of neurotrophins through their Trk receptors. The effect of BDNF on cdk1 activity is Tyr15-specific since BDNF cannot prevent the activity of a constitutively active form of cdk1 (Tyr15Phe) when expressed in differentiating retinal neurons. We also show that BDNF-dependent phosphorylation of cdk1 at Tyr15 could not be blocked with MK-1775, a Wee1-selective inhibitor, indicating that Tyr15 phosphorylation in cdk1 does not seem to occur through the canonical mechanism observed in proliferating cells. We conclude that the inhibition of both expression and activity of cdk1 through a BDNF-dependent mechanism contributes to the maintenance of tetraploid RGCs in a G2-like state. FAU - Ovejero-Benito, Maria C AU - Ovejero-Benito MC AD - Department of Molecular, Cellular, and Developmental Neurobiology, Instituto Cajal, Consejo Superior de Investigaciones Cientificas, Madrid, Spain. FAU - Frade, Jose M AU - Frade JM LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20130531 PL - United States TA - PLoS One JT - PloS one JID - 101285081 RN - 0 (Brain-Derived Neurotrophic Factor) RN - EC 2.7.10.1 (Receptor, trkB) RN - EC 2.7.11.22 (CDC2 Protein Kinase) SB - IM MH - Animals MH - Apoptosis/drug effects/genetics MH - Brain-Derived Neurotrophic Factor/*metabolism/pharmacology MH - CDC2 Protein Kinase/*genetics/metabolism MH - Cell Division/drug effects/*genetics MH - Cell Line MH - Chick Embryo MH - Enzyme Activation/drug effects MH - G2 Phase/drug effects/*genetics MH - Gene Expression MH - Gene Expression Regulation/drug effects MH - Mitosis/genetics MH - Models, Biological MH - Neurons/*cytology/drug effects/*metabolism MH - Phosphorylation/drug effects MH - Protein Processing, Post-Translational/drug effects MH - Receptor, trkB/genetics/metabolism MH - Retinal Ganglion Cells/cytology/drug effects/metabolism MH - Tetraploidy PMC - PMC3669015 COIS- Competing Interests: The authors have declared that no competing interests exist. EDAT- 2013/06/07 06:00 MHDA- 2014/01/11 06:00 PMCR- 2013/05/31 CRDT- 2013/06/07 06:00 PHST- 2013/01/29 00:00 [received] PHST- 2013/04/19 00:00 [accepted] PHST- 2013/06/07 06:00 [entrez] PHST- 2013/06/07 06:00 [pubmed] PHST- 2014/01/11 06:00 [medline] PHST- 2013/05/31 00:00 [pmc-release] AID - PONE-D-13-04078 [pii] AID - 10.1371/journal.pone.0064890 [doi] PST - epublish SO - PLoS One. 2013 May 31;8(5):e64890. doi: 10.1371/journal.pone.0064890. Print 2013.