title: In vivo neuronal function of the fragile X mental retardation protein is regulated by phosphorylation.
abstract: Fragile X syndrome (FXS), caused by loss of the Fragile X Mental Retardation 1 (FMR1) gene product (FMRP), is the most common heritable cause of intellectual disability and autism spectrum disorders. It has been long hypothesized that the phosphorylation of serine 500 (S500) in human FMRP controls its function as an RNA-binding translational repressor. To test this hypothesis in vivo, we employed neuronally targeted expression of three human FMR1 transgenes, including wild-type (hFMR1), dephosphomimetic (S500A-hFMR1) and phosphomimetic (S500D-hFMR1), in the Drosophila FXS disease model to investigate phosphorylation requirements. At the molecular level, dfmr1 null mutants exhibit elevated brain protein levels due to loss of translational repressor activity. This defect is rescued for an individual target protein and across the population of brain proteins by the phosphomimetic, whereas the dephosphomimetic phenocopies the null condition. At the cellular level, dfmr1 null synapse architecture exhibits increased area, branching and bouton number. The phosphomimetic fully rescues these synaptogenesis defects, whereas the dephosphomimetic provides no rescue. The presence of Futsch-positive (microtubule-associated protein 1B) supernumerary microtubule loops is elevated in dfmr1 null synapses. The human phosphomimetic restores normal Futsch loops, whereas the dephosphomimetic provides no activity. At the behavioral level, dfmr1 null mutants exhibit strongly impaired olfactory associative learning. The human phosphomimetic targeted only to the brain-learning center restores normal learning ability, whereas the dephosphomimetic provides absolutely no rescue. We conclude that human FMRP S500 phosphorylation is necessary for its in vivo function as a neuronal translational repressor and regulator of synaptic architecture, and for the manifestation of FMRP-dependent learning behavior.
authors.affiliation: Department of Biological Sciences, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: R Lane
authors.initials: RL
authors.lastname: Coffee
authors.forename: Ashley J
authors.initials: AJ
authors.lastname: Williamson
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Adkins
authors.forename: Marisa C
authors.initials: MC
authors.lastname: Gray
authors.forename: Terry L
authors.initials: TL
authors.lastname: Page
authors.forename: Kendal
authors.initials: K
authors.lastname: Broadie
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D003599:Cytoskeleton / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000378:metabolism*; D005600:Fragile X Syndrome / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007858:Learning / Q000502:physiology; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009154:Mutation; D009469:Neuromuscular Junction / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D014176:Protein Biosynthesis; D012694:Serine / Q000235:genetics / Q000378:metabolism; D019076:Transgenes
chemical_list: D029721:Drosophila Proteins; D051860:Fragile X Messenger Ribonucleoprotein 1; D008869:Microtubule-Associated Proteins; D010768:Phosphoserine; D012694:Serine; C497683:FMR1 protein, human; C409635:futsch protein, Drosophila; C085284:microtubule-associated protein 1B
references.citation: Cereb Cortex. 2000 Oct;10(10):1045-52
references.pmid: 11007555
references.citation: Hum Mol Genet. 2003 Dec 15;12(24):3295-305
references.pmid: 14570712
references.citation: Development. 2008 Apr;135(8):1547-57
references.pmid: 18321984
references.citation: Curr Biol. 2008 Jan 22;18(2):R84-93
references.pmid: 18211849
references.citation: Cell. 2011 Jul 22;146(2):247-61
references.pmid: 21784246
references.citation: Zoolog Sci. 2008 Jun;25(6):561-71
references.pmid: 18624566
references.citation: Neuron. 2005 Mar 3;45(5):753-64
references.pmid: 15748850
references.citation: Nat Neurosci. 2008 Oct;11(10):1143-5
references.pmid: 18776892
references.citation: Am J Hum Genet. 1994 Aug;55(2):225-37
references.pmid: 8037202
references.citation: Nature. 2004 Oct 14;431(7010):862-8
references.pmid: 15483615
references.citation: Genes Brain Behav. 2005 Mar;4(2):65-76
references.pmid: 15720403
references.citation: Mol Neurobiol. 2009 Apr;39(2):107-29
references.pmid: 19214804
references.citation: Mol Cell Biol. 2002 Dec;22(24):8438-47
references.pmid: 12446764
references.citation: Curr Opin Psychiatry. 2005 Sep;18(5):490-6
references.pmid: 16639106
references.citation: J Neurosci. 2008 Oct 8;28(41):10200-5
references.pmid: 18842880
references.citation: Curr Biol. 2006 Mar 21;16(6):591-8
references.pmid: 16546084
references.citation: Nature. 2004 Oct 14;431(7010):869-73
references.pmid: 15483616
references.citation: J Neurosci. 1999 Sep 15;19(18):7793-803
references.pmid: 10479682
references.citation: RNA. 2009 Mar;15(3):362-6
references.pmid: 19155329
references.citation: Nat Chem Biol. 2008 Apr;4(4):256-63
references.pmid: 18327252
references.citation: Proc Natl Acad Sci U S A. 1997 May 13;94(10):5401-4
references.pmid: 9144249
references.citation: Dis Model Mech. 2010 Nov-Dec;3(11-12):693-700
references.pmid: 20682752
references.citation: J Biol Chem. 2009 Sep 18;284(38):25479-87
references.pmid: 19640847
references.citation: J Neurol. 2012 Mar;259(3):401-13
references.pmid: 21748281
references.citation: Cell. 2001 Nov 16;107(4):489-99
references.pmid: 11719189
references.citation: Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13357-62
references.pmid: 15329415
references.citation: J Cell Biol. 1991 Oct;115(2):345-63
references.pmid: 1918145
references.citation: Brain Res Rev. 2007 Jan;53(1):27-38
references.pmid: 16844227
references.citation: PLoS Genet. 2009 Apr;5(4):e1000444
references.pmid: 19343200
references.citation: Curr Biol. 2005 Jun 21;15(12):1156-63
references.pmid: 15964283
references.citation: J Autism Dev Disord. 2005 Feb;35(1):103-16
references.pmid: 15796126
references.citation: Mol Cell Neurosci. 2008 Oct;39(2):170-9
references.pmid: 18655836
references.citation: Cell. 1994 Oct 7;79(1):35-47
references.pmid: 7923375
references.citation: Neuron. 2000 May;26(2):357-70
references.pmid: 10839355
references.citation: Trends Neurosci. 2005 Jan;28(1):12-9
references.pmid: 15626492
references.citation: Cell. 2001 Nov 30;107(5):591-603
references.pmid: 11733059
references.citation: Neuron. 2000 May;26(2):371-82
references.pmid: 10839356
references.citation: Development. 1999 Dec;126(24):5833-46
references.pmid: 10572057
references.citation: Cereb Cortex. 2000 Oct;10(10):1038-44
references.pmid: 11007554
references.citation: Cell. 1991 Aug 23;66(4):817-22
references.pmid: 1878973
references.citation: Proc Natl Acad Sci U S A. 2011 Feb 8;108(6):2587-92
references.pmid: 21262808
references.citation: Cell. 2003 Feb 7;112(3):317-27
references.pmid: 12581522
references.citation: J Neurosci. 2004 Nov 24;24(47):10579-83
references.pmid: 15564573
references.citation: Neuron. 2002 Jun 13;34(6):973-84
references.pmid: 12086644
references.citation: Proc Natl Acad Sci U S A. 2007 Sep 25;104(39):15537-42
references.pmid: 17881561
references.citation: Neuron. 2008 Oct 23;60(2):201-14
references.pmid: 18957214
references.citation: J Comp Physiol A. 1985 Sep;157(2):263-77
references.pmid: 3939242
references.citation: Learn Mem. 2008 Dec 30;16(1):19-27
references.pmid: 19117913
references.citation: Genes Brain Behav. 2010 Feb;9(1):53-64
references.pmid: 19796132
references.citation: Proc Natl Acad Sci U S A. 2004 Oct 19;101(42):15201-6
references.pmid: 15475576
references.citation: Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):612-6
references.pmid: 7831339
references.citation: Development. 2008 Aug;135(15):2637-48
references.pmid: 18579676
references.citation: J Neurosci. 2004 Aug 18;24(33):7272-6
references.pmid: 15317853
references.citation: J Autism Dev Disord. 2007 Apr;37(4):738-47
references.pmid: 17031449
references.citation: J Neurosci. 2007 Dec 26;27(52):14349-57
references.pmid: 18160642
references.citation: Science. 1991 May 24;252(5009):1097-102
references.pmid: 2031184
references.citation: J Neurosci. 2005 Jun 22;25(25):5943-55
references.pmid: 15976083
references.citation: J Neurosci. 2007 Apr 11;27(15):4014-8
references.pmid: 17428978
references.citation: J Neurosci. 2007 Jan 31;27(5):1033-44
references.pmid: 17267557
references.citation: J Med Genet. 1992 Nov;29(11):794-801
references.pmid: 1453430
references.citation: Cell. 1999 Dec 23;99(7):791-802
references.pmid: 10619432
references.citation: Mol Cells. 2009 Dec 31;28(6):501-7
references.pmid: 20047076
references.citation: J Neurosci. 2004 Jun 23;24(25):5798-809
references.pmid: 15215302
references.citation: J Biol Chem. 2008 Jul 4;283(27):18478-82
references.pmid: 18474609
references.citation: Mol Cell. 2011 Jun 10;42(5):673-88
references.pmid: 21658607
references.citation: Curr Biol. 2004 Oct 26;14(20):1863-70
references.pmid: 15498496
references.citation: Dis Model Mech. 2010 Jul-Aug;3(7-8):471-85
references.pmid: 20442204
references.citation: J Neurosci. 2007 Mar 21;27(12):3120-30
references.pmid: 17376973
references.citation: J Neurosci. 2005 May 18;25(20):5087-95
references.pmid: 15901791
references.citation: J Neurosci. 2001 Dec 15;21(24):9757-69
references.pmid: 11739584
references.citation: Behav Processes. 2006 Feb 28;71(2-3):211-25
references.pmid: 16414209
references.citation: J Autism Dev Disord. 2002 Apr;32(2):107-14
references.pmid: 12058838
references.citation: Am J Med Genet. 2001 Jan 15;98(2):161-7
references.pmid: 11223852
references.citation: Cell. 2008 Sep 19;134(6):1042-54
references.pmid: 18805096
references.citation: J Neurosci. 2008 May 14;28(20):5178-88
references.pmid: 18480274
references.citation: Front Neural Circuits. 2009 Aug 20;3:8
references.pmid: 19738924
references.citation: Neurobiol Learn Mem. 2008 Jul;90(1):90-102
references.pmid: 18289890
references.citation: J Dev Behav Pediatr. 2001 Dec;22(6):409-17
references.pmid: 11773805
references.citation: Front Mol Neurosci. 2009 Jul 30;2:8
references.pmid: 19668708
references.citation: Neuron. 2002 Jun 13;34(6):961-72
references.pmid: 12086643
references.citation: Hum Mol Genet. 2001 Feb 15;10(4):329-38
references.pmid: 11157796
references.citation: Hum Mol Genet. 2002 Nov 15;11(24):3007-17
references.pmid: 12417522
references.citation: Dev Cell. 2008 Jun;14(6):926-39
references.pmid: 18539120
references.citation: Cell. 1993 Jul 30;74(2):291-8
references.pmid: 7688265
references.citation: Brain Res. 2006 Apr 21;1084(1):158-64
references.pmid: 16574084
references.citation: Neuron. 2006 Aug 17;51(4):441-54
references.pmid: 16908410
references.citation: Annu Rev Genomics Hum Genet. 2007;8:109-29
references.pmid: 17477822
references.citation: Dis Model Mech. 2011 Sep;4(5):673-85
references.pmid: 21669931
references.citation: Mol Cell Neurosci. 2008 Apr;37(4):747-60
references.pmid: 18280750
references.citation: Neuron. 2004 May 27;42(4):567-80
references.pmid: 15157419