101
|
Gamma-secretase inhibition reduces spine density in vivo via an amyloid precursor protein-dependent pathway. J Neurosci 2009; 29:10405-9. [PMID: 19692615 DOI: 10.1523/jneurosci.2288-09.2009] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease (AD) represents the most common age-related neurodegenerative disorder. It is characterized by the invariant accumulation of the beta-amyloid peptide (Abeta), which mediates synapse loss and cognitive impairment in AD. Current therapeutic approaches concentrate on reducing Abeta levels and amyloid plaque load via modifying or inhibiting the generation of Abeta. Based on in vivo two-photon imaging, we present evidence that side effects on the level of dendritic spines may counteract the beneficial potential of these approaches. Two potent gamma-secretase inhibitors (GSIs), DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester) and LY450139 (hydroxylvaleryl monobenzocaprolactam), were found to reduce the density of dendritic spines in wild-type mice. In mice deficient for the amyloid precursor protein (APP), both GSIs had no effect on dendritic spine density, demonstrating that gamma-secretase inhibition decreases dendritic spine density via APP. Independent of the effects of gamma-secretase inhibition, we observed a twofold higher density of dendritic spines in the cerebral cortex of adult APP-deficient mice. This observation further supports the notion that APP is involved in the modulation of dendritic spine density--shown here for the first time in vivo.
Collapse
|
102
|
Holtmaat A, Bonhoeffer T, Chow DK, Chuckowree J, De Paola V, Hofer SB, Hübener M, Keck T, Knott G, Lee WCA, Mostany R, Mrsic-Flogel TD, Nedivi E, Portera-Cailliau C, Svoboda K, Trachtenberg JT, Wilbrecht L. Long-term, high-resolution imaging in the mouse neocortex through a chronic cranial window. Nat Protoc 2009; 4:1128-44. [PMID: 19617885 DOI: 10.1038/nprot.2009.89] [Citation(s) in RCA: 701] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To understand the cellular and circuit mechanisms of experience-dependent plasticity, neurons and their synapses need to be studied in the intact brain over extended periods of time. Two-photon excitation laser scanning microscopy (2PLSM), together with expression of fluorescent proteins, enables high-resolution imaging of neuronal structure in vivo. In this protocol we describe a chronic cranial window to obtain optical access to the mouse cerebral cortex for long-term imaging. A small bone flap is replaced with a coverglass, which is permanently sealed in place with dental acrylic, providing a clear imaging window with a large field of view (approximately 0.8-12 mm(2)). The surgical procedure can be completed within approximately 1 h. The preparation allows imaging over time periods of months with arbitrary imaging intervals. The large size of the imaging window facilitates imaging of ongoing structural plasticity of small neuronal structures in mice, with low densities of labeled neurons. The entire dendritic and axonal arbor of individual neurons can be reconstructed.
Collapse
Affiliation(s)
- Anthony Holtmaat
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, NY, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
103
|
Gray BC, Siskova Z, Perry VH, O'Connor V. Selective presynaptic degeneration in the synaptopathy associated with ME7-induced hippocampal pathology. Neurobiol Dis 2009; 35:63-74. [DOI: 10.1016/j.nbd.2009.04.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 03/24/2009] [Accepted: 04/03/2009] [Indexed: 10/20/2022] Open
|
104
|
Prion disease development in slow Wallerian degeneration (Wld(S)) mice. Neurosci Lett 2009; 456:93-8. [PMID: 19429141 DOI: 10.1016/j.neulet.2009.03.089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 03/26/2009] [Accepted: 03/27/2009] [Indexed: 11/22/2022]
Abstract
Axon destruction represents one aspect of prion disease-associated neurodegeneration. We characterized here the scrapie infection of Wld(S)-mice in comparison to wild-type C57Bl/6 controls to determine whether mechanisms involved in Wallerian degeneration contribute to disease development in this murine model system. The Wld(S) mutation had neither an effect on survival times, nor on typical hallmarks of a prion infection like deposition of misfolded PrP(Sc) and glia activation. At the ultrastructural level, axonal damage like loss of axoplasms and disintegration of myelin sheaths was evident. Moreover, lysosomes accumulated in neuronal cell bodies. These alterations occured however similarly in Wld(S)- and wild-type mice. In conclusion, it appears unlikely that axonal damage of the kind, which is slowed down in Wld(S)-mice, contributes significantly to disease progression. These findings distinguish the neurodegeneration occuring in this prion model from chronic neurodegenerative diseases, in which the Wld(S)-mutation provides axon protection and greatly improves the clinical outcome.
Collapse
|
105
|
In vivo voltage-sensitive dye imaging in adult mice reveals that somatosensory maps lost to stroke are replaced over weeks by new structural and functional circuits with prolonged modes of activation within both the peri-infarct zone and distant sites. J Neurosci 2009; 29:1719-34. [PMID: 19211879 DOI: 10.1523/jneurosci.4249-08.2009] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
After brain damage such as stroke, topographically organized sensory and motor cortical representations remap onto adjacent surviving tissues. It is conceivable that cortical remapping is accomplished by changes in the temporal precision of sensory processing and regional connectivity in the cortex. To understand how the adult cortex remaps and processes sensory signals during stroke recovery, we performed in vivo imaging of sensory-evoked changes in membrane potential, as well as multiphoton imaging of dendrite structure and tract tracing. In control mice, forelimb stimulation evoked a brief depolarization in forelimb cortex that quickly propagated to, and dissipated within, adjacent motor/hindlimb areas (<100 ms). One week after forelimb cortex stroke, the cortex was virtually unresponsive to tactile forelimb stimulation. After 8 weeks recovery, forelimb-evoked depolarizations reemerged with a characteristic pattern in which responses began within surviving portions of forelimb cortex (<20 ms after stimulation) and then spread horizontally into neighboring peri-infarct motor/hindlimb areas in which depolarization persisted 300-400% longer than controls. These uncharacteristically prolonged responses were not limited to the remapped peri-infarct zone and included distant posteromedial retrosplenial cortex, millimeters from the stroke. Structurally, the remapped peri-infarct area selectively exhibited high levels of dendritic spine turnover, shared more connections with retrosplenial cortex and striatum, and lost inputs from lateral somatosensory cortical regions. Our findings demonstrate that sensory remapping during stroke recovery is accompanied by the development of prolonged sensory responses and new structural circuits in both the peri-infarct zone as well as more distant sites.
Collapse
|
106
|
Seki T, Shimahara T, Yamamoto K, Abe N, Amano T, Adachi N, Takahashi H, Kashiwagi K, Saito N, Sakai N. Mutant γPKC found in spinocerebellar ataxia type 14 induces aggregate-independent maldevelopment of dendrites in primary cultured Purkinje cells. Neurobiol Dis 2009; 33:260-73. [DOI: 10.1016/j.nbd.2008.10.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 10/18/2008] [Indexed: 12/23/2022] Open
|
107
|
Bakota L, Brandt R. Chapter 2 Live‐Cell Imaging in the Study of Neurodegeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 276:49-103. [DOI: 10.1016/s1937-6448(09)76002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
|
108
|
Asuni AA, Cunningham C, Vigneswaran P, Perry VH, O'Connor V. Unaltered SNARE complex formation in an in vivo model of prion disease. Brain Res 2008; 1233:1-7. [PMID: 18706894 DOI: 10.1016/j.brainres.2008.07.083] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 07/02/2008] [Accepted: 07/13/2008] [Indexed: 11/16/2022]
Abstract
The ME7 model of prion disease is a chronic slowly evolving model of neurodegeneration in which cell death is preceded by synaptic dysfunction. Previous studies in cell culture show that accumulation of misfolded prion inhibits the formation of the SNARE complexes involving synaptobrevin, syntaxin and SNAP-25 that play an essential role in neurotransmitter release. Such observations suggest that similar phenomenon may contribute to synaptic dysfunction observed in vivo. We have thus used detergent extraction of hippocampal tissue to investigate the status of SNARE complexes in the ME7 model. In the presence of increasing PrP(Sc) deposition we failed to see a change in the amount of SNARE complexes directly extracted into SDS and resolved by SDS-PAGE. Conversely pre-extraction in Triton X-100, a treatment that promotes SNARE complexes ex vivo, demonstrated a modest reduction in hippocampal SNARE complexes when homogenates were made from tissue at late stage disease. This suggests that accumulated PrP(Sc), or perhaps fibrillar complexes formed of prion only inhibit SNARE complexes that are formed ex vivo following biochemical extraction. Thus the accumulation of PrP(Sc) although deleterious to synaptic function in vivo, does not exert its synaptic effects by disrupting the formation of SNARE complexes that are core to transmitter release.
Collapse
Affiliation(s)
- Ayodeji A Asuni
- School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, SO16 7PX, UK
| | | | | | | | | |
Collapse
|
109
|
Julius C, Heikenwalder M, Schwarz P, Marcel A, Karin M, Prinz M, Pasparakis M, Aguzzi A. Prion propagation in mice lacking central nervous system NF-κB signalling. J Gen Virol 2008; 89:1545-1550. [DOI: 10.1099/vir.0.83622-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Prions induce highly typical histopathological changes including cell death, spongiosis and activation of glia, yet the molecular pathways leading to neurodegeneration remain elusive. Following prion infection, enhanced nuclear factor-κB (NF-κB) activity in the brain parallels the first pathological changes. The NF-κB pathway is essential for proliferation, regulation of apoptosis and immune responses involving induction of inflammation. The IκB kinase (IKK) signalosome is crucial for NF-κB signalling, consisting of the catalytic IKKα/IKKβ subunits and the regulatory IKKγ subunit. This study investigated the impact of NF-κB signalling on prion disease in mouse models with a central nervous system (CNS)-restricted elimination of IKKβ or IKKγ in nearly all neuroectodermal cells, including neurons, astrocytes and oligodendrocytes, and in mice containing a non-phosphorylatable IKKα subunit (IKKα
AA/AA). In contrast to previously published data, the observed results showed no evidence supporting the hypothesis that impaired NF-κB signalling in the CNS impacts on prion pathogenesis.
Collapse
Affiliation(s)
- C. Julius
- Institute of Neuropathology, University Hospital of Zürich, Zürich, Switzerland
| | - M. Heikenwalder
- Institute of Neuropathology, University Hospital of Zürich, Zürich, Switzerland
| | - P. Schwarz
- Institute of Neuropathology, University Hospital of Zürich, Zürich, Switzerland
| | - A. Marcel
- Institute of Neuropathology, University Hospital of Zürich, Zürich, Switzerland
| | - M. Karin
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California, San Diego, USA
| | - M. Prinz
- Department of Neuropathology, University of Freiburg, Freiburg, Germany
| | - M. Pasparakis
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - A. Aguzzi
- Institute of Neuropathology, University Hospital of Zürich, Zürich, Switzerland
| |
Collapse
|
110
|
Uppington KM, Brown DR. Resistance of cell lines to prion toxicity aided by phospho-ERK expression. J Neurochem 2008; 105:842-52. [DOI: 10.1111/j.1471-4159.2007.05192.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|