Endocytic pathways mediating oligomeric Aβ42 neurotoxicity
- 7.2k Downloads
One pathological hallmark of Alzheimer's disease (AD) is amyloid plaques, composed primarily of amyloid-β peptide (Aβ). Over-production or diminished clearance of the 42 amino acid form of Aβ (Aβ42) in the brain leads to accumulation of soluble Aβ and plaque formation. Soluble oligomeric Aβ (oAβ) has recently emerged to be as a likely proximal cause of AD.
Here we demonstrate that endocytosis is critical in mediating oAβ42-induced neurotoxicity and intraneuronal accumulation of Aβ. Inhibition of clathrin function either with a pharmacological inhibitor, knock-down of clathrin heavy chain expression, or expression of the dominant-negative mutant of clathrin-assembly protein AP180 did not block oAβ42-induced neurotoxicity or intraneuronal accumulation of Aβ. However, inhibition of dynamin and RhoA by expression of dominant negative mutants reduced neurotoxicity and intraneuronal Aβ accumulation. Pharmacologic inhibition of the dynamin-mediated endocytic pathway by genistein also reduced neurotoxicity.
These data suggest that dynamin-mediated and RhoA-regulated endocytosis are integral steps for oligomeric Aβ42-induced neurotoxicity and intraneuronal Aβ accumulation.
KeywordsEndocytic Pathway Clathrin Heavy Chain Mutant T19N Intraneuronal Accumulation Specific Endocytic Pathway
Amyloid-β peptide (Aβ) is believed to be a causative agent underlying the pathological mechanism for Alzheimer's disease, the major form of dementia in the elderly . The levels of soluble Aβ species appear to correlate with disease progression [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. Evidence points to soluble oligomeric Aβ (oAβ) as the assembly form of the peptide that is likely the proximal cause in AD [13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24], leading to synaptic dysfunction and eventual neuron loss in the vulnerable regions of AD brains (for recent review ). Extracellular oAβ has been proposed to bind the cell surface, leading to functional disruption of NMDAR [26, 27] and AMPAR [28, 29], and activation of caspases .
In addition to extracellular Aβ, Aβ accumulates inside neurons. Intraneuronal Aβ accumulation has been identified in Down syndrome and AD patients, amyloid precursor protein (APP) and PS1 Presenilin 1 transgenic mice, and cultured cells [31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48]. In AD patients, intraneuronal Aβ42 accumulation appears in vulnerable brain regions prior to extracellular amyloid formation and accumulates with aging [31, 32, 33, 34, 35, 36, 37, 39, 44, 45, 49, 50, 51, 52]. In addition, synaptic dysfunction occurs prior to, or in the absence of, amyloid plaques in both AD and APP transgenic mouse brains [9, 53, 54, 55, 56]. Studies using triple transgenic mice demonstrated that intraneuronal Aβ causes the onset of early AD-related cognitive deficits [43, 57, 58]. Intriguingly, clearance of intraneuronal Aβ by immunotherapy rescued early cognitive deficits, prior to changes in plaque density. Intraneuronal Aβ and cognitive deficits re-emerged with the subsequent withdrawal of immunotherapy [58, 59]. These observations support the hypothesis that intraneuronal Aβ accumulation may be one of the initial steps in a cascade of events leading to AD [60, 61]. Neurons internalize and accumulate exogenous Aβ [62, 63, 64, 65]. Intraneuronal Aβ could be viewed as compromised clearance of extracellular soluble Aβ by neurons, and excessive accumulation of intraneuronal Aβ could lead to cellular organelle dysfunction and eventual neuron death. For example, intraneuronal Aβ was reported to activate caspase 6 leading to neuronal apoptosis . We recently demonstrated that intracellular oAβ42 can activate casein kinase-2, causing inhibition of fast axonal transport .
Neurons, like many other cell types, have several major endocytic pathways, including clathrin-dependent, caveolae-dependent, and clathrin- and caveolar-independent pathways. However, the specific endocytic pathways involved in oAβ-uptake and neurotoxicity remain unclear. Using complementary approaches of pharmacological inhibition, genetic manipulation by over-expressing dominant-negative mutants and gene knock-down, we provide data that show that the endocytosis of oAβ42 is linked to neurotoxicity via a dynamin-dependent and RhoA-mediated endocytic pathway in vitro.
We previously established a homogenous preparation of oAβ42  that causes neurotoxicity in co-cultures of primary neurons and glia, as well as Neuro-2A cells (N2A) [18, 68, 69]. This oAβ42 preparation also inhibits LTP , causes cognitive deficits , disrupts fast axonal transport , and induces neuroinflammation . Here we focus mainly on endocytic pathways in relation to oAβ42 toxicity in N2A cells.
Clathrin-dependent endocytic pathway is not involved in oAβ42 mediated toxicity
Dynamin mediates oAβ42 neurotoxicity and intracellular accumulation
RhoA regulates oAβ42 neurotoxicity and intracellular accumulation
In recent years, it has become increasingly clear that soluble oAβ plays an essential role in the neuronal loss characteristic of AD pathology. Soluble oAβ could mediate neuronal dysfunction extracellularly by binding to cell surface receptors and disturbing downstream signaling pathways, leading to disruption of LTP and LTD, and eventual neuronal death. Alternatively, soluble oAβ toxicity could arise from intraneuronal accumulation as a result of impaired exocytosis or failed clearance following endocytosis. The importance of endocytosis in AD is underscored by a recent report identifying genetic variances in phosphatidylinositol-binding clathrin assembly protein (PICALM) associated with late onset AD . PICALM facilitates endocytosis in hippocampal neurons and thus could play a role in Aβ clearance in the brain . However, the mechanisms underlying binding and subsequent signalling pathways or endocytosis leading to Aβ intracellular accumulation remain poorly understood.
Although a major endocytic pathway in neurons is clathrin-dependent , we show by three complementary approaches that inhibition of this pathway did not inhibit oAβ42 neurotoxicity (Figure 1). A reduced level of AP180 has been reported in AD patient brains . Our data that AP180 did not mediate Aβ toxicity suggests that AP180 could potentially regulate trafficking of proteins/enzymes involved in Aβ production .
There is increasing evidence of clathrin- and caveolin-independent pathways mediating ligand-induced endocytosis [76, 86]. The large GTPase dynamin is involved in both clathrin-dependent and -independent pathways . Our results suggest an important role for dynamin in oAβ42-induced neurotoxicity and intraneuronal Aβ accumulation. Interestingly, clathrin-independent but dynamin-dependent endocytosis was required for Aβ internalization in sympathetic neurons in vitro . The small monomeric GTPase RhoA regulates other clathrin-independent pathways, such as IL2-receptor endocytosis, . Our data show RhoA regulates oAβ42 endocytosis and neurotoxicity. The role of RhoA in oAβ42-induced neurotoxicity is further supported by recent reports of potential roles for this GTPase in AD. For example, RhoA had an altered subcellular localization in both AD and APP transgenic Tg2576 mouse brains . Further, RhoA levels increased specifically around amyloid plaques in these models .
As neurons do not express caveolin-1, the principal structural protein in caveolae, and do not have caveolae structure , we did not pursue this pathway. Another possible route for Aβ uptake is pinocytosis. Aβ40 directly conjugated with fluorescein was taken up by neurons via diffusion in a non-saturable, energy-independent process . In our experiments, ATP levels were used as a measurement of neurotoxicity, precluding results based on energy independence. More importantly, while we have been able to consistently label oligomers with Alexa-488 after formation and maintain conformational stability, we are unable to prepare consistent oligomeric conformations using pre-labeled fluorescein-Aβ42 . In addition, comparison between Aβ40 and 42 is problematic.
Our data (summarized in the schematic shown in Figure 4) show RhoA and dynamin-dependent steps involved in oAβ42 neurotoxicity and intracellular Aβ accumulation.
Our experiments identify the initial steps of endocytosis required for oAβ42-induced neurotoxicity and intracellular Aβ accumulation. Specifically, Aβ-induced neurotoxicity is dynamin-dependent and RhoA-regulated, but clathrin-independent. Further studies will be needed to identify potential steps in the endocytic pathways as therapeutic targets in AD.
Recombinant Aβ42 was purchased from rPeptide (Bogart, GA). Hexafluoroisopropanol (HFIP) and anhydrous dimethyl sulfoxide (DMSO) were purchased from Sigma-Aldrich. Phenol-red free Ham's F12 media was obtained from Promocell (Heidelberg, Germany) and supplemented with L-glutamine (146 mg/L) prior to use. Genistein and chlorpromazine were purchased from Sigma. PP2 was purchased from EMD Biosciences.
Oligomer formation conditions
Oligomer preparations of Aβ42 were formed according to our previously established protocols [18, 19]. Briefly, following evaporation of HFIP in a fume hood overnight, the resulting Aβ42 peptide film was stored desiccated at -20°C. Immediately prior to use, the films were allowed to come to room temperature, solubilized to 5 mM in anhydrous DMSO, sonicated in a bath sonicator (Branson) for 10 minutes, diluted to 100 μM in phenol-red free Hams F12, and stored at 4°C for 24 hours. Oligomeric Aβ42 morphology was routinely confirmed by atomic force microscope .
Cell culture and cell viability assay
Mouse neuroblastoma, N2A cells (ATCC) were maintained in MEM (ATCC) supplemented with 10% FBS, 2 mM L-glutamine, 100 U/ml of penicillin, 100 ug/ml of streptomycin, as previously described [18, 69]. 5000 cells per well were plated on to 96-well plates 24 hours prior to treatment to allow attachment. Cells were then treated 10 mM oAβ42 in DMEM medium without phenol red and with 1% N2 supplement (Invitrogen). At the end of the experiment (24 hours post-treatment), cell viability was assessed by relative cellular ATP levels using CellTiter-Glo assay kit (Promega) according to the manufacture's instruction. Statistical significance was established at p < 0.01 by One-way ANOVA with Tukey test for comparison in different groups.
Pharmacological inhibition of endocytosis
N2A cells were treated with pharmacological inhibitors that block specific steps during endocytosis. Pilot experiments were performed to find inhibitor concentrations that did not significantly compromise cell viability as inhibitors for cellular endocytosis could adversely affect cell viability. For example, as has been reported, chlorpromazine at higher concentration (10-4-10-3 M) killed cells, while at lower concentration (10-6-10-5 M) inhibited Ca++-mediated toxicity in a neuroblastoma cell line . Genistein substantially inhibited the growth of N2A cells in a dose-dependent manner with an IC50 value of 18 mM, and PP2 at 3 mM was lethal to the N2A cells . Chlorpromazine (2 mM), genistein (10 mM), PP2 (1 mM) were added to cell cultures at indicated concentrations 1 hr before oAβ42 treatment in DMEM with 1% N2 supplement. The final concentration of vehicle (DMSO) was 0.05% in all cultures.
Genetic manipulation of selected endocytic pathway proteins
To block specific routes in the endocytic pathways, we blocked the function of key proteins in the endocytic pathway by either expressing dominant-negative proteins, or knock-down of endogenous proteins. N2A cells were transiently transfected with expression plasmids or siRNA using LipofeactAmine 2000 (Invitrogen). The following endocytic proteins were transfected for expression: Rat wild type (WT) Dynamin and the dominant-negative dynamin mutant K44A (myc-tag), the dominant-negative AP180 mutant AP180-CT (Flag-tag), and RhoA WT and dominant-negative mutant T19N (HA-tag). These plasmids were kindly provided by Dr. R. Minshall (UIC, dynamin) and Dr. L. Greene (NIH, AP180), or purchased from Missouri S&T (RhoA). To achieve highest possible transfection efficiency, we tested several transfection reagents (such as LipofectAmine and PLUS reagent, GenJet, and LipofectAmine 2000) and transfection conditions (cell density, pH of the medium and transfection incubation duration) with EGFP expression plasmid. We obtained the highest transfection efficiency with LipofectAmine 2000 at cell density of 90-100% confluence.
Small interfering RNA (siRNA) for the clathrin heavy chain (CLTC, SMARTpool L-004001-00-0005) and control Non-Targeting siRNA were purchased from Dharmacon. Cells were transfected at 20 pmol siRNA in 24-well culture plates using LipofectAmine 2000 according to vendor's recommended transfection protocol. A second transfection was done the next day. These transfected cells were then split and seeded on to 96-well plate in MEM with 10% FBS. 48 hours post-transfection, these cells were treated with oAβ42 for 24 hours.
SDS-PAGE/Western blot characterization of targeted endocytic proteins
Transfected cells treated in parallel to those used for cell viability assays were lysed by 15-minute incubation in RIPA buffer (50 mM Tris-HCl, pH 8.0, with 150 mM sodium chloride, 1.0% Igepal CA-630 (NP-40), 0.5% sodium deoxycholate, and 0.1% SDS, Sigma-Aldrich) containing protease inhibitors (Protease Inhibitor Cocktail Set I, Calbiochem), followed by centrifugation. Equal amounts of total protein were analyzed for levels of indicated proteins by Western blot analysis following SDS-PAGE using 4-12% Bis-Tris 1.5 mm NuPAGE precast gels (Invitrogen). Supernatants were mixed with LDS sample buffer (Invitrogen) and electrophoresed at 90-100 V for 80-90 minutes. Proteins were transferred to 0.2 μm polyvinylidene difluoride membranes. Membranes were blocked for 1 hour in a solution of 5% nonfat dry milk in Tris-buffered saline containing 0.0625% Tween-20 prior to incubation with primary antibody solutions. Molecular mass was estimated using pre-stained molecular weight markers (Invitrogen). CLTC was detected using a mouse anti-CLTC monoclonal antibody (C1860, Sigma; 1:1,000), myc tagged dynamin with anti-myc antibody 9E10 (Sigma; 1:5000), Flag-tagged AP180-CT with Flag antibody M2 (Sigma, 1:5000), HA tagged RhoA with rat HA antibody 3F10 (Roche Applied Science; 1:2500), and appropriate horse radish peroxidase conjugated secondary antibody. Actin, as detected with rabbit anti-actin antibody (Sigma; 1:5000), was used as total lysate loading control. Proteins were visualized with enhanced chemiluminescence Western blotting substrate (Pierce) on the Kodak 4000R imaging system.
Cellular uptake of oligomeric Aβ42
Intracellular Aβ was detected by immunofluorescence analysis using a rabbit polyclonal anti-Aβ42 specific antibody (Invitrogen). N2A cells or transiently transfected N2A cells (24 hours post transfection) were seeded at 20,000 cells/well on poly-D-lysine glass coverslips in phenol-red free DMEM + 10% FBS overnight. Recombinant oAβ42 was added to cells in DMEM medium and incubated for 30 min at 37°C. At the end of the treatment, cells were washed with PBS. Cell surface bound oAβ was striped off in a solution of 0.2 M acetic acid and 0.5 M NaCl. Cells were fixed in 4% paraformaldehyde for 20 minutes at room temperature. Cells were permeablized with 0.3% Triton X-100 in 1×PBS for 5 minutes, and blocked for 15 minutes with 3% BSA, incubated overnight with rabbit anti-Aβ42 (1:100) at 4°C, followed by 1 hour incubation at room temperature with Alexa488-labeled donkey-anti-rabbit IgG (1:500, Invitrogen). Transfected cells were identified by co-staining with anti-Flag antibody (M2, 1:250, Sigma) for AP180, rat anti-HA (3F10, Roche) for RhoA, or mouse anti-myc antibody 9E10 (1:200, Abcam) for dynamin, and appropriate 2nd antibody conjugated with Alexa594 (all from Invitrogen). Coverslips were mounted with Prolong Gold antifade reagent with DAPI (Invitrogen) fluorescence mounting medium on glass slides. Confocal laser scanning microscopy images were acquired on a Zeiss LSM 510 META, Axiovert 200 M laser scanning confocal microscope using a Plan-Apochromate Zeiss 40×/1.3 oil immersion objective. Mean brightness of Aβ signals were quantified with NIH image software.
We thank Lisa Jungbauer, Katie Younmans, and Jennifer Graham for technique assistance and manuscript preparation. This work was supported by grants from the Alzheimer's Association NIRG-06-26957 (CY); and ZEN-08-899000 and NIH/NIA PO1AG021184 (MJL). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
- 3.McLean CA, Cherny RA, Fraser FW, Fuller SJ, Smith MJ, Beyreuther K, Bush AI, Masters CL: Soluble pool of Abeta amyloid as a determinant of severity of neurodegeneration in Alzheimer's disease. Ann Neurol. 1999, 46 (6): 860-866. 10.1002/1531-8249(199912)46:6<860::AID-ANA8>3.0.CO;2-M.PubMedCrossRefGoogle Scholar
- 4.Roher AE, Chaney MO, Kuo YM, Webster SD, Stine WB, Haverkamp LJ, Woods AS, Cotter RJ, Tuohy JM, Krafft GA, Bonnell BS, Emmerling MR: Morphology and toxicity of Abeta-(1-42) dimer derived from neuritic and vascular amyloid deposits of Alzheimer's disease. J Biol Chem. 1996, 271 (34): 20631-20635. 10.1074/jbc.271.34.20631.PubMedCrossRefGoogle Scholar
- 9.Mucke L, Masliah E, Yu GQ, Mallory M, Rockenstein EM, Tatsuno G, Hu K, Kholodenko D, Johnson-Wood K, McConlogue L: High-level neuronal expression of abeta 1-42 in wild-type human amyloid protein precursor transgenic mice: synaptotoxicity without plaque formation. J Neurosci. 2000, 20 (11): 4050-4058.PubMedGoogle Scholar
- 11.Spires TL, Meyer-Luehmann M, Stern EA, McLean PJ, Skoch J, Nguyen PT, Bacskai BJ, Hyman BT: Dendritic spine abnormalities in amyloid precursor protein transgenic mice demonstrated by gene transfer and intravital multiphoton microscopy. J Neurosci. 2005, 25 (31): 7278-7287. 10.1523/JNEUROSCI.1879-05.2005.PubMedPubMedCentralCrossRefGoogle Scholar
- 14.Podlisny MB, Walsh DM, Amarante P, Ostaszewski BL, Stimson ER, Maggio JE, Teplow DB, Selkoe DJ: Oligomerization of endogenous and synthetic amyloid beta-protein at nanomolar levels in cell culture and stabilization of monomer by Congo red. Biochemistry. 1998, 37 (11): 3602-3611. 10.1021/bi972029u.PubMedCrossRefGoogle Scholar
- 17.Lambert MP, Barlow AK, Chromy BA, Edwards C, Freed R, Liosatos M, Morgan TE, Rozovsky I, Trommer B, Viola KL, Wals P, Zhang C, Finch CE, Krafft GA, Klein WL: Diffusible, nonfibrillar ligands derived from Abeta1-42 are potent central nervous system neurotoxins. Proc Natl Acad Sci USA. 1998, 95 (11): 6448-6453. 10.1073/pnas.95.11.6448.PubMedPubMedCentralCrossRefGoogle Scholar
- 21.Kayed R, Head E, Sarsoza F, Saing T, Cotman CW, Necula M, Margol L, Wu J, Breydo L, Thompson JL, Rasool S, Gurlo T, Butler P, Glabe CG: Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers. Mol Neurodegener. 2007, 2: 18-10.1186/1750-1326-2-18.PubMedPubMedCentralCrossRefGoogle Scholar
- 23.Barghorn S, Nimmrich V, Striebinger A, Krantz C, Keller P, Janson B, Bahr M, Schmidt M, Bitner RS, Harlan J, Barlow E, Ebert U, Hillen H: Globular amyloid beta-peptide oligomer - a homogenous and stable neuropathological protein in Alzheimer's disease. Journal of neurochemistry. 2005, 95 (3): 834-847. 10.1111/j.1471-4159.2005.03407.x.PubMedCrossRefGoogle Scholar
- 28.Chang EH, Savage MJ, Flood DG, Thomas JM, Levy RB, Mahadomrongkul V, Shirao T, Aoki C, Huerta PT: AMPA receptor downscaling at the onset of Alzheimer's disease pathology in double knockin mice. Proceedings of the National Academy of Sciences of the United States of America. 2006, 103 (9): 3410-3415. 10.1073/pnas.0507313103.PubMedPubMedCentralCrossRefGoogle Scholar
- 30.Gamblin TC, Chen F, Zambrano A, Abraha A, Lagalwar S, Guilloz Lu M, Fu Y, Garcia-Sierra F, LaPointe N, Miller R, Berry RW, Binder LI, Cryns VL, et al: Caspase cleavage of tau: Linking amyloid and neurofibrillary tangles in Alzheimer's disease. Proc Natl Acad Sci USA. 2003Google Scholar
- 31.D'Andrea MR, Reiser PA, Polkovitch DA, Gumula NA, Branchide B, Hertzog BM, Schmidheiser D, Belkowski S, Gastard MC, Andrade-Gordon P: The use of formic acid to embellish amyloid plaque detection in Alzheimer's disease tissues misguides key observations. Neurosci Lett. 2003, 342 (1-2): 114-118. 10.1016/S0304-3940(03)00252-0.PubMedCrossRefGoogle Scholar
- 42.Wirths O, Multhaup G, Czech C, Blanchard V, Moussaoui S, Tremp G, Pradier L, Beyreuther K, Bayer TA: Intraneuronal Abeta accumulation precedes plaque formation in beta-amyloid precursor protein and presenilin-1 double-transgenic mice. Neurosci Lett. 2001, 306 (1-2): 116-120. 10.1016/S0304-3940(01)01876-6.PubMedCrossRefGoogle Scholar
- 43.Oddo S, Caccamo A, Shepherd JD, Murphy MP, Golde TE, Kayed R, Metherate R, Mattson MP, Akbari Y, LaFerla FM: Triple-transgenic model of Alzheimer's disease with plaques and tangles: intracellular Abeta and synaptic dysfunction. Neuron. 2003, 39 (3): 409-421. 10.1016/S0896-6273(03)00434-3.PubMedCrossRefGoogle Scholar
- 48.Casas C, Sergeant N, Itier JM, Blanchard V, Wirths O, Kolk van der N, Vingtdeux V, Steeg van de E, Ret G, Canton T, Drobecq H, Clark A, Bonici B, Delacourte A, Benavides J, Schmitz C, Tremp G, Bayer TA, Benoit P, Pradier L: Massive CA1/2 neuronal loss with intraneuronal and N-terminal truncated Abeta42 accumulation in a novel Alzheimer transgenic model. Am J Pathol. 2004, 165 (4): 1289-1300.PubMedPubMedCentralCrossRefGoogle Scholar
- 50.Oddo S, Caccamo A, Tran L, Lambert MP, Glabe CG, Klein WL, Laferla FM: Temporal profile of Abeta oligomerization in an in vivo model of Alzheimer's disease: A link between Abeta and tau pathology. J Biol Chem. 2005Google Scholar
- 51.Kawarabayashi T, Shoji M, Younkin LH, Wen-Lang L, Dickson DW, Murakami T, Matsubara E, Abe K, Ashe KH, Younkin SG: Dimeric amyloid beta protein rapidly accumulates in lipid rafts followed by apolipoprotein E and phosphorylated tau accumulation in the Tg2576 mouse model of Alzheimer's disease. J Neurosci. 2004, 24 (15): 3801-3809. 10.1523/JNEUROSCI.5543-03.2004.PubMedCrossRefGoogle Scholar
- 52.Oshima N, Morishima-Kawashima M, Yamaguchi H, Yoshimura M, Sugihara S, Khan K, Games D, Schenk D, Ihara Y: Accumulation of amyloid beta-protein in the low-density membrane domain accurately reflects the extent of beta-amyloid deposition in the brain. Am J Pathol. 2001, 158 (6): 2209-2218.PubMedPubMedCentralCrossRefGoogle Scholar
- 53.Moechars D, Dewachter I, Lorent K, Reverse D, Baekelandt V, Naidu A, Tesseur I, Spittaels K, Haute CV, Checler F, Godaux E, Cordell B, Van Leuven F: Early phenotypic changes in transgenic mice that overexpress different mutants of amyloid precursor protein in brain. J Biol Chem. 1999, 274 (10): 6483-6492. 10.1074/jbc.274.10.6483.PubMedCrossRefGoogle Scholar
- 54.Hsia AY, Masliah E, McConlogue L, Yu GQ, Tatsuno G, Hu K, Kholodenko D, Malenka RC, Nicoll RA, Mucke L: Plaque-independent disruption of neural circuits in Alzheimer's disease mouse models. Proc Natl Acad Sci USA. 1999, 96 (6): 3228-3233. 10.1073/pnas.96.6.3228.PubMedPubMedCentralCrossRefGoogle Scholar
- 55.Chapman PF, White GL, Jones MW, Cooper-Blacketer D, Marshall VJ, Irizarry M, Younkin L, Good MA, Bliss TVP, Hyman BT, Younkin SG, Hsiao KK: Impaired synpatic plasticity and learning in aged amyloid precursor protein transgenic mice. Nature Genet. 1999, 2: 271-276.Google Scholar
- 56.Zerbinatti CV, Wahrle SE, Kim H, Cam JA, Bales K, Paul SM, Holtzman DM, Bu G: Apolipoprotein E and low density lipoprotein receptor-related protein facilitate intraneuronal Abeta42 accumulation in amyloid model mice. The Journal of biological chemistry. 2006, 281 (47): 36180-36186. 10.1074/jbc.M604436200.PubMedCrossRefGoogle Scholar
- 59.Gimenez-Llort L, Blazquez G, Canete T, Johansson B, Oddo S, Tobena A, Laferla FM, Fernandez-Teruel A: Modeling behavioral and neuronal symptoms of Alzheimer's disease in mice: A role for intraneuronal amyloid. Neurosci Biobehav Rev. 2006, 31 (1): 125-147. 10.1016/j.neubiorev.2006.07.007.PubMedCrossRefGoogle Scholar
- 60.Shie FS, LeBoeuf RC, Jin LW: Early intraneuronal Abeta deposition in the hippocampus of APP transgenic mice.[erratum appears in Neuroreport. 2004 Aug 26;15(12):1993 Note: LeBoeur, Renee C [corrected to LeBoeuf, Renee C]]. Neuroreport. 2003, 14 (1): 123-129. 10.1097/00001756-200301200-00023.PubMedCrossRefGoogle Scholar
- 63.Burdick D, Kosmoski J, Knauer MF, Glabe CG: Preferential adsorption, internalization and resistance to degradation of the major isoform of the Alzheimer's amyloid peptide, A beta 1-42, in differentiated PC12 cells. Brain Res. 1997, 746 (1-2): 275-284. 10.1016/S0006-8993(96)01262-0.PubMedCrossRefGoogle Scholar
- 64.Bahr BA, Hoffman KB, Yang AJ, Hess US, Glabe CG, Lynch G: Amyloid beta protein is internalized selectively by hippocampal field CA1 and causes neurons to accumulate amyloidogenic carboxyterminal fragments of the amyloid precursor protein. J Comp Neurol. 1998, 397 (1): 139-147. 10.1002/(SICI)1096-9861(19980720)397:1<139::AID-CNE10>3.0.CO;2-K.PubMedCrossRefGoogle Scholar
- 67.Pigino G, Morfini G, Atagi Y, Deshpande A, Yu C, Jungbauer L, LaDu M, Busciglio J, Brady S: Disruption of fast axonal transport is a pathogenic mechanism for intraneuronal amyloid beta. Proc Natl Acad Sci USA. 2009, 106 (14): 5907-5912. 10.1073/pnas.0901229106.PubMedPubMedCentralCrossRefGoogle Scholar
- 71.Reed MN, Hofmeister JJ, Jungbauer L, Welzel AT, Yu C, Sherman MA, Lesne S, Ladu MJ, Walsh DM, Ashe KH, Cleary JP: Cognitive effects of cell-derived and synthetically derived Abeta oligomers. Neurobiology of aging. 2009Google Scholar
- 80.Pan ZK, Ye RD, Christiansen SC, Jagels MA, Bokoch GM, Zuraw BL: Role of the Rho GTPase in bradykinin-stimulated nuclear factor-kappaB activation and IL-1beta gene expression in cultured human epithelial cells. Journal of immunology (Baltimore, Md). 1998, 160 (6): 3038-3045.Google Scholar
- 81.Harold D, Abraham R, Hollingworth P, Sims R, Gerrish A, Hamshere ML, Pahwa JS, Moskvina V, Dowzell K, Williams A, Jones N, Thomas C, Stretton A, Morgan AR, Lovestone S, Powell J, Proitsi P, Lupton MK, Brayne C, Rubinsztein DC, Gill M, Lawlor B, Lynch A, Morgan K, Brown KS, Passmore PA, Craig D, McGuinness B, Todd S, Holmes C, et al: Genome-wide association study identifies variants at CLU and PICALM associated with Alzheimer's disease. Nat Genet. 2009, 41 (10): 1088-1093. 10.1038/ng.440.PubMedPubMedCentralCrossRefGoogle Scholar
- 82.Bushlin I, Petralia RS, Wu F, Harel A, Mughal MR, Mattson MP, Yao PJ: Clathrin assembly protein AP180 and CALM differentially control axogenesis and dendrite outgrowth in embryonic hippocampal neurons. J Neurosci. 2008, 28 (41): 10257-10271. 10.1523/JNEUROSCI.2471-08.2008.PubMedPubMedCentralCrossRefGoogle Scholar
- 89.Huesa G, Baltrons MA, Gomez-Ramos P, Moran A, Garcia A, Hidalgo J, Frances S, Santpere G, Ferrer I, Galea E: Altered Distribution of RhoA in Alzheimer's Disease and AbetaPP Overexpressing Mice. J Alzheimers Dis. 2009, 19 (1): 37-56.Google Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.