Enzyme lysosomal cathepsin D bảo vệ chống lại sự tích tụ và độc tính của alpha-synuclein

Molecular Brain - Tập 1 Số 1 - 2008
Li Qiao1, Shusei Hamamichi2, Kim A. Caldwell2, Talene A. Yacoubian3, Scott Wilson4, Zuolei Xie1, Lisa D Speake1, Rachael Parks1, Donna Crabtree1, Qiwei Liang1, Stephen Crimmins1, Lonnie Schneider1, Yasuo Uchiyama5, Takeshi Iwatsubo6, Yi Zhou4, Lisheng Peng7, Youming Lu7, David Standaert3, Ken C. Walls1, John J. Shacka8,9, Kevin A. Roth8, Jianhua Zhang8
1Department of Pathology, University of Alabama at Birmingham, Birmingham, USA </br>
2Department of Biological Sciences, The University of Alabama, Tuscaloosa, USA
3Department of Neurology, University of Alabama at Birmingham, Birmingham, USA
4Department of Neurobiology, University of Alabama at Birmingham, Birmingham, USA
5Department of Cell Biology and Neurosciences, Osaka University, Osaka, Japan
6Department of Neuropathology, Department of Neuropathology and Neuroscience, Graduate School of Medicine, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
7Biomolecular Science Center, Burnett College of Biomedical Sciences, Orlando, USA
8Department of Pathology, University of Alabama at Birmingham, Birmingham, USA
9Department of Veterans Affairs, Birmingham VA Medical Center, Birmingham, USA

Tóm tắt

Tóm tắtα-synuclein (α-syn) là thành phần chính của các thể Lewy (LB) mà xảy ra trong nhiều bệnh thoái hóa thần kinh, bao gồm bệnh Parkinson (PD), sa sút trí tuệ có thể Lewy (DLB) và suy giảm đa hệ thống. Các đột biến hoặc gia tăng α-syn chịu trách nhiệm cho một tập hợp các trường hợp PD gia đình chi phối tự động với tính ưu thế, và sự biểu hiện quá mức gây ra thoái hóa thần kinh và rối loạn vận động ở động vật. Để điều tra cơ chế tích tụ và độc tính của α-syn, chúng tôi đã nghiên cứu mô hình chuột có sự thiếu hụt enzyme lysosomal cathepsin D (CD), và phát hiện sự tích tụ rộng rãi của α-syn nội sinh trong các tế bào thần kinh mà không có sự gia tăng hàm lượng mRNA của α-syn. Ngoài việc suy giảm tự thực bào lớn, sự thiếu hụt CD đã làm giảm hoạt động của proteasome, cho thấy vai trò thiết yếu của chức năng CD lysosomal trong việc điều chỉnh nhiều con đường phân giải protein quan trọng cho sự trao đổi chất của α-syn. Ngược lại, sự biểu hiện quá mức của CD làm giảm sự tích tụ α-syn và bảo vệ thần kinh chống lại cái chết tế bào do sự biểu hiện quá mức α-syn gây ra trong ống nghiệm. Trong mô hình C. elegans, sự thiếu hụt CD làm trầm trọng thêm sự tích tụ α-syn trong khi sự biểu hiện quá mức của CD bảo vệ chống lại thoái hóa thần kinh dopaminergic do α-syn gây ra. CD đột biến với hoạt động enzyme giảm hoặc sự biểu hiện quá mức của các cathepsin B (CB) hoặc L (CL) không có tác dụng bảo vệ trong mô hình giun, cho thấy yêu cầu độc đáo cho CD hoạt động enzyme. Dữ liệu của chúng tôi xác định một chức năng CD bảo tồn trong sự phân hủy α-syn và xác định CD như một mục tiêu mới cho liệu pháp bệnh LB.

Từ khóa


Tài liệu tham khảo

Morris HR: Genetics of Parkinson's disease. Ann Med. 2005, 37: 86-96. 10.1080/07853890510007269.

Webb JL, Ravikumar B, Atkins J, Skepper JN, Rubinsztein DC: Alpha-Synuclein is degraded by both autophagy and the proteasome. J Biol Chem. 2003, 278: 25009-25013. 10.1074/jbc.M300227200.

Cuervo AM, Stefanis L, Fredenburg R, Lansbury PT, Sulzer D: Impaired degradation of mutant alpha-synuclein by chaperone-mediated autophagy. Science. 2004, 305: 1292-1295. 10.1126/science.1101738.

Martinez-Vicente M, Talloczy Z, Kaushik S, Massey AC, Mazzulli J, Mosharov EV, Hodara R, Fredenburg R, Wu DC, Follenzi A, et al: Dopamine-modified alpha-synuclein blocks chaperone-mediated autophagy. J Clin Invest. 2008

Cuervo AM, Dice JF: When lysosomes get old. Exp Gerontol. 2000, 35: 119-131. 10.1016/S0531-5565(00)00075-9.

Marino G, Lopez-Otin C: Autophagy: molecular mechanisms, physiological functions and relevance in human pathology. Cell Mol Life Sci. 2004, 61: 1439-1454. 10.1007/s00018-004-4012-4.

Yamamoto A, Cremona ML, Rothman JE: Autophagy-mediated clearance of huntingtin aggregates triggered by the insulin-signaling pathway. J Cell Biol. 2006, 172: 719-731. 10.1083/jcb.200510065.

Berger Z, Ravikumar B, Menzies FM, Oroz LG, Underwood BR, Pangalos MN, Schmitt I, Wullner U, Evert BO, O'Kane CJ, et al: Rapamycin alleviates toxicity of different aggregate-prone proteins. Hum Mol Genet. 2006, 15: 433-442. 10.1093/hmg/ddi458.

Dean RT: Lysosomes and protein degradation. Ciba Found Symp. 1979, 139-149.

Jones EW, Zubenko GS, Parker RR: PEP4 gene function is required for expression of several vacuolar hydrolases in Saccharomyces cerevisiae. Genetics. 1982, 102: 665-677.

Hossain S, Alim A, Takeda K, Kaji H, Shinoda T, Ueda K: Limited proteolysis of NACP/alpha-synuclein. J Alzheimers Dis. 2001, 3: 577-584.

Whitaker JN, Terry LC, Whetsell WO: Immunocytochemical localization of cathepsin D in rat neural tissue. Brain Res. 1981, 216: 109-124. 10.1016/0006-8993(81)91281-6.

Erickson AH, Blobel G: Carboxyl-terminal proteolytic processing during biosynthesis of the lysosomal enzymes beta-glucuronidase and cathepsin D. Biochemistry. 1983, 22: 5201-5205. 10.1021/bi00291a021.

Cataldo AM, Barnett JL, Pieroni C, Nixon RA: Increased neuronal endocytosis and protease delivery to early endosomes in sporadic Alzheimer's disease: neuropathologic evidence for a mechanism of increased beta-amyloidogenesis. J Neurosci. 1997, 17: 6142-6151.

Siintola E, Partanen S, Stromme P, Haapanen A, Haltia M, Maehlen J, Lehesjoki AE, Tyynela J: Cathepsin D deficiency underlies congenital human neuronal ceroid-lipofuscinosis. Brain. 2006, 129: 1438-1445. 10.1093/brain/awl107.

Steinfeld R, Reinhardt K, Schreiber K, Hillebrand M, Kraetzner R, Bruck W, Saftig P, Gartner J: Cathepsin D deficiency is associated with a human neurodegenerative disorder. Am J Hum Genet. 2006, 78: 988-998. 10.1086/504159.

Lavrov AY, Ilyna ES, Zakharova EY, Boukina AM, Tishkanina SV: The first three Russian cases of classical, late-infantile, neuronal ceroid lipofuscinosis. Eur J Paediatr Neurol. 2002, 6: 161-164. 10.1053/ejpn.2002.0584.

Nijssen PC, Brusse E, Leyten AC, Martin JJ, Teepen JL, Roos RA: Autosomal dominant adult neuronal ceroid lipofuscinosis: parkinsonism due to both striatal and nigral dysfunction. Mov Disord. 2002, 17: 482-487. 10.1002/mds.10104.

Zimran A, Neudorfer O, Elstein D: The glucocerebrosidase gene and Parkinson's disease in Ashkenazi Jews. N Engl J Med. 2005, 352: 728-731. 10.1056/NEJM200502173520719.

Wong K, Sidransky E, Verma A, Mixon T, Sandberg GD, Wakefield LK, Morrison A, Lwin A, Colegial C, Allman JM, et al: Neuropathology provides clues to the pathophysiology of Gaucher disease. Mol Genet Metab. 2004, 82: 192-207. 10.1016/j.ymgme.2004.04.011.

Saito Y, Suzuki K, Hulette CM, Murayama S: Aberrant phosphorylation of alpha-synuclein in human Niemann-Pick type C1 disease. J Neuropathol Exp Neurol. 2004, 63: 323-328.

Suzuki K, Iseki E, Togo T, Yamaguchi A, Katsuse O, Katsuyama K, Kanzaki S, Shiozaki K, Kawanishi C, Yamashita S, et al: Neuronal and glial accumulation of alpha- and beta-synucleins in human lipidoses. Acta Neuropathol (Berl). 2007, 114: 481-489. 10.1007/s00401-007-0264-z.

Hara T, Nakamura K, Matsui M, Yamamoto A, Nakahara Y, Suzuki-Migishima R, Yokoyama M, Mishima K, Saito I, Okano H, et al: Suppression of basal autophagy in neural cells causes neurodegenerative disease in mice. Nature. 2006, 441: 885-889. 10.1038/nature04724.

Komatsu M, Waguri S, Chiba T, Murata S, Iwata JI, Tanida I, Ueno T, Koike M, Uchiyama Y, Kominami E, et al: Loss of autophagy in the central nervous system causes neurodegeneration in mice. Nature. 2006, 441: 880-884. 10.1038/nature04723.

Eskelinen EL, Illert AL, Tanaka Y, Schwarzmann G, Blanz J, von FK, Saftig P: Role of LAMP-2 in lysosome biogenesis and autophagy. Mol Biol Cell. 2002, 13: 3355-3368. 10.1091/mbc.E02-02-0114.

Bove J, Zhou C, Jackson-Lewis V, Taylor J, Chu Y, Rideout HJ, Wu DC, Kordower JH, Petrucelli L, Przedborski S: Proteasome inhibition and Parkinson's disease modeling. Ann Neurol. 2006, 60: 260-264. 10.1002/ana.20937.

Saftig P, Hetman M, Schmahl W, Weber K, Heine L, Mossmann H, Koster A, Hess B, Evers M, von FK, et al: Mice deficient for the lysosomal proteinase cathepsin D exhibit progressive atrophy of the intestinal mucosa and profound destruction of lymphoid cells. EMBO J. 1995, 14: 3599-3608.

Koike M, Nakanishi H, Saftig P, Ezaki J, Isahara K, Ohsawa Y, Schulz-Schaeffer W, Watanabe T, Waguri S, Kametaka S, et al: Cathepsin D deficiency induces lysosomal storage with ceroid lipofuscin in mouse CNS neurons. J Neurosci. 2000, 20: 6898-6906.

Koike M, Shibata M, Ohsawa Y, Nakanishi H, Koga T, Kametaka S, Waguri S, Momoi T, Kominami E, Peters C, et al: Involvement of two different cell death pathways in retinal atrophy of cathepsin D-deficient mice. Mol Cell Neurosci. 2003, 22: 146-161. 10.1016/S1044-7431(03)00035-6.

Koike M, Shibata M, Waguri S, Yoshimura K, Tanida I, Kominami E, Gotow T, Peters C, von FK, Mizushima N, et al: Participation of autophagy in storage of lysosomes in neurons from mouse models of neuronal ceroid-lipofuscinoses (Batten disease). Am J Pathol. 2005, 167: 1713-1728.

Shacka JJ, Klocke BJ, Young C, Shibata M, Olney JW, Uchiyama Y, Saftig P, Roth KA: Cathepsin D deficiency induces persistent neurodegeneration in the absence of Bax-dependent apoptosis. J Neurosci. 2007, 27: 2081-2090. 10.1523/JNEUROSCI.5577-06.2007.

Suzuki K, Ohsumi Y: Molecular machinery of autophagosome formation in yeast, Saccharomyces cerevisiae. FEBS Lett. 2007, 581: 2156-2161. 10.1016/j.febslet.2007.01.096.

Hasegawa M, Fujiwara H, Nonaka T, Wakabayashi K, Takahashi H, Lee VM, Trojanowski JQ, Mann D, Iwatsubo T: Phosphorylated alpha-synuclein is ubiquitinated in alpha-synucleinopathy lesions. J Biol Chem. 2002, 277: 49071-49076. 10.1074/jbc.M208046200.

Anderson JP, Walker DE, Goldstein JM, de LR, Banducci K, Caccavello RJ, Barbour R, Huang J, Kling K, Lee M, et al: Phosphorylation of Ser-129 is the dominant pathological modification of alpha-synuclein in familial and sporadic Lewy body disease. J Biol Chem. 2006, 281: 29739-29752. 10.1074/jbc.M600933200.

Sampathu DM, Giasson BI, Pawlyk AC, Trojanowski JQ, Lee VM: Ubiquitination of alpha-synuclein is not required for formation of pathological inclusions in alpha-synucleinopathies. Am J Pathol. 2003, 163: 91-100.

Fujiwara H, Hasegawa M, Dohmae N, Kawashima A, Masliah E, Goldberg MS, Shen J, Takio K, Iwatsubo T: alpha-Synuclein is phosphorylated in synucleinopathy lesions. Nat Cell Biol. 2002, 4: 160-164. 10.1038/ncb841.

Neumann M, Kahle PJ, Giasson BI, Ozmen L, Borroni E, Spooren W, Muller V, Odoy S, Fujiwara H, Hasegawa M, et al: Misfolded proteinase K-resistant hyperphosphorylated alpha-synuclein in aged transgenic mice with locomotor deterioration and in human alpha-synucleinopathies. J Clin Invest. 2002, 110: 1429-1439.

Hirai Y, Fujita SC, Iwatsubo T, Hasegawa M: Phosphorylated alpha-synuclein in normal mouse brain. FEBS Lett. 2004, 572: 227-232. 10.1016/j.febslet.2004.07.046.

Cantuti-Castelvetri I, Klucken J, Ingelsson M, Ramasamy K, McLean PJ, Frosch MP, Hyman BT, Standaert DG: Alpha-synuclein and chaperones in dementia with Lewy bodies. J Neuropathol Exp Neurol. 2005, 64: 1058-1066. 10.1097/01.jnen.0000190063.90440.69.

Nakanishi H, Zhang J, Koike M, Nishioku T, Okamoto Y, Kominami E, von FK, Peters C, Yamamoto K, Saftig P, et al: Involvement of nitric oxide released from microglia-macrophages in pathological changes of cathepsin D-deficient mice. J Neurosci. 2001, 21: 7526-7533.

McLean PJ, Kawamata H, Hyman BT: Alpha-synuclein-enhanced green fluorescent protein fusion proteins form proteasome sensitive inclusions in primary neurons. Neuroscience. 2001, 104: 901-912. 10.1016/S0306-4522(01)00113-0.

Masliah E, Rockenstein E, Veinbergs I, Mallory M, Hashimoto M, Takeda A, Sagara Y, Sisk A, Mucke L: Dopaminergic loss and inclusion body formation in alpha-synuclein mice: implications for neurodegenerative disorders. Science. 2000, 287: 1265-1269. 10.1126/science.287.5456.1265.

Giasson BI, Duda JE, Quinn SM, Zhang B, Trojanowski JQ, Lee VM: Neuronal alpha-synucleinopathy with severe movement disorder in mice expressing A53T human alpha-synuclein. Neuron. 2002, 34: 521-533. 10.1016/S0896-6273(02)00682-7.

Cooper AA, Gitler AD, Cashikar A, Haynes CM, Hill KJ, Bhullar B, Liu K, Xu K, Strathearn KE, Liu F, et al: Alpha-synuclein blocks ER-Golgi traffic and Rab1 rescues neuron loss in Parkinson's models. Science. 2006, 313: 324-328. 10.1126/science.1129462.

St Martin JL, Klucken J, Outeiro TF, Nguyen P, Keller-McGandy C, Cantuti-Castelvetri I, Grammatopoulos TN, Standaert DG, Hyman BT, McLean PJ: Dopaminergic neuron loss and up-regulation of chaperone protein mRNA induced by targeted over-expression of alpha-synuclein in mouse substantia nigra. J Neurochem. 2007, 100: 1449-1457.

McLean PJ, Kawamata H, Shariff S, Hewett J, Sharma N, Ueda K, Breakefield XO, Hyman BT: TorsinA and heat shock proteins act as molecular chaperones: suppression of alpha-synuclein aggregation. J Neurochem. 2002, 83: 846-854. 10.1046/j.1471-4159.2002.01190.x.

Tyynela J, Sohar I, Sleat DE, Gin RM, Donnelly RJ, Baumann M, Haltia M, Lobel P: A mutation in the ovine cathepsin D gene causes a congenital lysosomal storage disease with profound neurodegeneration. EMBO J. 2000, 19: 2786-2792. 10.1093/emboj/19.12.2786.

Rideout HJ, Lang-Rollin I, Stefanis L: Involvement of macroautophagy in the dissolution of neuronal inclusions. Int J Biochem Cell Biol. 2004, 36: 2551-2562. 10.1016/j.biocel.2004.05.008.

Pandey UB, Nie Z, Batlevi Y, McCray BA, Ritson GP, Nedelsky NB, Schwartz SL, DiProspero NA, Knight MA, Schuldiner O, et al: HDAC6 rescues neurodegeneration and provides an essential link between autophagy and the UPS. Nature. 2007, 447: 859-863. 10.1038/nature05853.

Stefanis L, Larsen KE, Rideout HJ, Sulzer D, Greene LA: Expression of A53T mutant but not wild-type alpha-synuclein in PC12 cells induces alterations of the ubiquitin-dependent degradation system, loss of dopamine release, autophagic cell death. J Neurosci. 2001, 21: 9549-9560.

Bifsha P, Landry K, Ashmarina L, Durand S, Seyrantepe V, Trudel S, Quiniou C, Chemtob S, Xu Y, Gravel RA, et al: Altered gene expression in cells from patients with lysosomal storage disorders suggests impairment of the ubiquitin pathway. Cell Death Differ. 2007, 14: 511-523. 10.1038/sj.cdd.4402013.

Colell A, Ricci JE, Tait S, Milasta S, Maurer U, Bouchier-Hayes L, Fitzgerald P, Guio-Carrion A, Waterhouse NJ, Li CW, et al: GAPDH and autophagy preserve survival after apoptotic cytochrome c release in the absence of caspase activation. Cell. 2007, 129: 983-997. 10.1016/j.cell.2007.03.045.

Tsuchiya K, Tajima H, Kuwae T, Takeshima T, Nakano T, Tanaka M, Sunaga K, Fukuhara Y, Nakashima K, Ohama E, et al: Pro-apoptotic protein glyceraldehyde-3-phosphate dehydrogenase promotes the formation of Lewy body-like inclusions. Eur J Neurosci. 2005, 21: 317-326. 10.1111/j.1460-9568.2005.03870.x.

Olah J, Tokesi N, Vincze O, Horvath I, Lehotzky A, Erdei A, Szajli E, Medzihradszky KF, Orosz F, Kovacs GG, et al: Interaction of TPPP/p25 protein with glyceraldehyde-3-phosphate dehydrogenase and their co-localization in Lewy bodies. FEBS Lett. 2006, 580: 5807-5814. 10.1016/j.febslet.2006.09.037.

Furukawa K, Matsuzaki-Kobayashi M, Hasegawa T, Kikuchi A, Sugeno N, Itoyama Y, Wang Y, Yao PJ, Bushlin I, Takeda A: Plasma membrane ion permeability induced by mutant alpha-synuclein contributes to the degeneration of neural cells. J Neurochem. 2006, 97: 1071-1077. 10.1111/j.1471-4159.2006.03803.x.

Smith WW, Jiang H, Pei Z, Tanaka Y, Morita H, Sawa A, Dawson VL, Dawson TM, Ross CA: Endoplasmic reticulum stress and mitochondrial cell death pathways mediate A53T mutant alpha-synuclein-induced toxicity. Hum Mol Genet. 2005, 14: 3801-3811. 10.1093/hmg/ddi396.

Gosavi N, Lee HJ, Lee JS, Patel S, Lee SJ: Golgi fragmentation occurs in the cells with prefibrillar alpha-synuclein aggregates and precedes the formation of fibrillar inclusion. J Biol Chem. 2002, 277: 48984-48992. 10.1074/jbc.M208194200.

Larsen KE, Schmitz Y, Troyer MD, Mosharov E, Dietrich P, Quazi AZ, Savalle M, Nemani V, Chaudhry FA, Edwards RH, et al: Alpha-synuclein overexpression in PC12 and chromaffin cells impairs catecholamine release by interfering with a late step in exocytosis. J Neurosci. 2006, 26: 11915-11922. 10.1523/JNEUROSCI.3821-06.2006.

Volles MJ, Lansbury PT: Relationships between the sequence of alpha-synuclein and its membrane affinity, fibrillization propensity, yeast toxicity. J Mol Biol. 2007, 366: 1510-1522. 10.1016/j.jmb.2006.12.044.

Zhou Y, Gu G, Goodlett DR, Zhang T, Pan C, Montine TJ, Montine KS, Aebersold RH, Zhang J: Analysis of alpha-synuclein-associated proteins by quantitative proteomics. J Biol Chem. 2004, 279: 39155-39164. 10.1074/jbc.M405456200.

Tanaka M, Kim YM, Lee G, Junn E, Iwatsubo T, Mouradian MM: Aggresomes formed by alpha-synuclein and synphilin-1 are cytoprotective. J Biol Chem. 2004, 279: 4625-4631. 10.1074/jbc.M310994200.

Hashimoto M, Hsu LJ, Rockenstein E, Takenouchi T, Mallory M, Masliah E: alpha-Synuclein protects against oxidative stress via inactivation of the c-Jun N-terminal kinase stress-signaling pathway in neuronal cells. J Biol Chem. 2002, 277: 11465-11472. 10.1074/jbc.M111428200.

Manning-Bog AB, McCormack AL, Purisai MG, Bolin LM, Di Monte DA: Alpha-synuclein overexpression protects against paraquat-induced neurodegeneration. J Neurosci. 2003, 23: 3095-3099.

Drolet RE, Behrouz B, Lookingland KJ, Goudreau JL: Mice lacking alpha-synuclein have an attenuated loss of striatal dopamine following prolonged chronic MPTP administration. Neurotoxicology. 2004, 25: 761-769. 10.1016/j.neuro.2004.05.002.

Robertson DC, Schmidt O, Ninkina N, Jones PA, Sharkey J, Buchman VL: Developmental loss and resistance to MPTP toxicity of dopaminergic neurones in substantia nigra pars compacta of gamma-synuclein, alpha-synuclein and double alpha/gamma-synuclein null mutant mice. J Neurochem. 2004, 89: 1126-1136. 10.1111/j.1471-4159.2004.02378.x.

Dauer W, Kholodilov N, Vila M, Trillat AC, Goodchild R, Larsen KE, Staal R, Tieu K, Schmitz Y, Yuan CA, et al: Resistance of alpha -synuclein null mice to the parkinsonian neurotoxin MPTP. Proc Natl Acad Sci USA. 2002, 99: 14524-14529. 10.1073/pnas.172514599.

Fountaine TM, Wade-Martins R: RNA interference-mediated knockdown of alpha-synuclein protects human dopaminergic neuroblastoma cells from MPP(+) toxicity and reduces dopamine transport. J Neurosci Res. 2007, 85: 351-363. 10.1002/jnr.21125.

Hayashita-Kinoh H, Yamada M, Yokota T, Mizuno Y, Mochizuki H: Down-regulation of alpha-synuclein expression can rescue dopaminergic cells from cell death in the substantia nigra of Parkinson's disease rat model. Biochem Biophys Res Commun. 2006, 341: 1088-1095. 10.1016/j.bbrc.2006.01.057.

Brenner S: The genetics of Caenorhabditis elegans. Genetics. 1974, 77: 71-94.

Kamath RS, Ahringer J: Genome-wide RNAi screening in Caenorhabditis elegans. Methods. 2003, 30: 313-321. 10.1016/S1046-2023(03)00050-1.

Hamamichi S, Rivas RN, Knight AL, Cao S, Caldwell KA, Caldwell GA: Hypothesis-based RNAi screening identifies neuroprotective genes in a Parkinson's disease model. Proc Natl Acad Sci USA. 2008, 105: 728-733. 10.1073/pnas.0711018105.

Cao S, Gelwix CC, Caldwell KA, Caldwell GA: Torsin-mediated protection from cellular stress in the dopaminergic neurons of Caenorhabditis elegans. J Neurosci. 2005, 25: 3801-3812. 10.1523/JNEUROSCI.5157-04.2005.