-
[show abstract]
[hide abstract]
ABSTRACT: Climbing fibers (CFs) originating in the inferior olive (IO) constitute one of the main inputs to the cerebellum. In the mammalian cerebellar cortex each of them climbs into the dendritic tree of up to 10 Purkinje cells (PCs) where they make hundreds of synaptic contacts and elicit the so-called all-or-none complex spikes controlling the output. While it has been proven that CFs contact molecular layer interneurons (MLIs) via spillover mechanisms, it remains to be elucidated to what extent CFs contact the main type of interneuron in the granular layer, i.e., the Golgi cells (GoCs). This issue is particularly relevant, because direct contacts would imply that CFs can also control computations at the input stage of the cerebellar cortical network. Here, we performed a systematic morphological investigation of labeled CFs and GoCs at the light microscopic level following their path and localization through the neuropil in both the granular and molecular layer. Whereas in the molecular layer the appositions of CFs to PCs and MLIs were prominent and numerous, those to cell-bodies and dendrites of GoCs in both the granular layer and molecular layer were virtually absent. Our results argue against the functional significance of direct synaptic contacts between CFs and interneurons at the input stage, but support those at the output stage.
Frontiers in Neural Circuits 01/2013; 7:59. · 5.10 Impact Factor
-
Boyan Todorov,
Lieke Kros,
Reinald Shyti,
Petra Plak, Elize D. Haasdijk,
Robert S. Raike,
Rune R. Frants,
Ellen J. Hess,
Freek E. Hoebeek,
Chris I. De Zeeuw,
Arn M. J. M. van den Maagdenberg
[show abstract]
[hide abstract]
ABSTRACT: The Cacna1a gene encodes the α1A subunit of voltage-gated CaV2.1 Ca2+ channels that are involved in neurotransmission at central synapses. CaV2.1-α1-knockout (α1KO) mice, which lack CaV2.1 channels in all neurons, have a very severe phenotype of cerebellar ataxia and dystonia, and usually die around postnatal
day20. This early lethality, combined with the wide expression of CaV2.1 channels throughout the cerebellar cortex and nuclei, prohibited determination of the contribution of particular cerebellar
cell types to the development of the severe neurobiological phenotype in Cacna1a mutant mice. Here, we crossed conditional Cacna1a mice with transgenic mice expressing Cre recombinase, driven by the Purkinje cell-specific Pcp2 promoter, to specifically ablate the CaV2.1-α1A subunit and thereby CaV2.1 channels in Purkinje cells. Purkinje cell CaV2.1-α1A-knockout (PCα1KO) mice aged without difficulties, rescuing the lethal phenotype seen in α1KO mice. PCα1KO mice exhibited
cerebellar ataxia starting around P12, much earlier than the first signs of progressive Purkinje cell loss, which appears
in these mice between P30 and P45. Secondary cell loss was observed in the granular and molecular layers of the cerebellum
and the volume of all individual cerebellar nuclei was reduced. In this mouse model with a cell type-specific ablation of
CaV2.1 channels, we show that ablation of CaV2.1 channels restricted to Purkinje cells is sufficient to cause cerebellar ataxia. We demonstrate that spatial ablation of
CaV2.1 channels may help in unraveling mechanisms of human disease.
KeywordsP/Q-type Ca2+ channels–Conditional–Cell-specific knockout–
Cacna1a
–Ataxia
The Cerebellum 04/2012; 11(1):246-258. · 3.21 Impact Factor
-
Dick Jaarsma,
Ingrid van der Pluijm,
Monique C de Waard, Elize D Haasdijk,
Renata Brandt,
Marcel Vermeij,
Yvonne Rijksen,
Alex Maas,
Harry van Steeg,
Jan H J Hoeijmakers,
Gijsbertus T J van der Horst
[show abstract]
[hide abstract]
ABSTRACT: Neuronal degeneration is a hallmark of many DNA repair syndromes. Yet, how DNA damage causes neuronal degeneration and whether defects in different repair systems affect the brain differently is largely unknown. Here, we performed a systematic detailed analysis of neurodegenerative changes in mouse models deficient in nucleotide excision repair (NER) and transcription-coupled repair (TCR), two partially overlapping DNA repair systems that remove helix-distorting and transcription-blocking lesions, respectively, and that are associated with the UV-sensitive syndromes xeroderma pigmentosum (XP) and Cockayne syndrome (CS). TCR-deficient Csa(-/-) and Csb(-/-) CS mice showed activated microglia cells surrounding oligodendrocytes in regions with myelinated axons throughout the nervous system. This white matter microglia activation was not observed in NER-deficient Xpa(-/-) and Xpc(-/-) XP mice, but also occurred in Xpd(XPCS) mice carrying a point mutation (G602D) in the Xpd gene that is associated with a combined XPCS disorder and causes a partial NER and TCR defect. The white matter abnormalities in TCR-deficient mice are compatible with focal dysmyelination in CS patients. Both TCR-deficient and NER-deficient mice showed no evidence for neuronal degeneration apart from p53 activation in sporadic (Csa(-/-), Csb(-/-)) or highly sporadic (Xpa(-/-), Xpc(-/-)) neurons and astrocytes. To examine to what extent overlap occurs between both repair systems, we generated TCR-deficient mice with selective inactivation of NER in postnatal neurons. These mice develop dramatic age-related cumulative neuronal loss indicating DNA damage substrate overlap and synergism between TCR and NER pathways in neurons, and they uncover the occurrence of spontaneous DNA injury that may trigger neuronal degeneration. We propose that, while Csa(-/-) and Csb(-/-) TCR-deficient mice represent powerful animal models to study the mechanisms underlying myelin abnormalities in CS, neuron-specific inactivation of NER in TCR-deficient mice represents a valuable model for the role of NER in neuronal maintenance and survival.
PLoS Genetics 12/2011; 7(12):e1002405. · 8.69 Impact Factor
-
Boyan Todorov,
Lieke Kros,
Reinald Shyti,
Petra Plak, Elize D Haasdijk,
Robert S Raike,
Rune R Frants,
Ellen J Hess,
Freek E Hoebeek,
Chris I De Zeeuw,
Arn M J M van den Maagdenberg
[show abstract]
[hide abstract]
ABSTRACT: The Cacna1a gene encodes the α(1A) subunit of voltage-gated Ca(V)2.1 Ca(2+) channels that are involved in neurotransmission at central synapses. Ca(V)2.1-α(1)-knockout (α1KO) mice, which lack Ca(V)2.1 channels in all neurons, have a very severe phenotype of cerebellar ataxia and dystonia, and usually die around postnatal day 20. This early lethality, combined with the wide expression of Ca(V)2.1 channels throughout the cerebellar cortex and nuclei, prohibited determination of the contribution of particular cerebellar cell types to the development of the severe neurobiological phenotype in Cacna1a mutant mice. Here, we crossed conditional Cacna1a mice with transgenic mice expressing Cre recombinase, driven by the Purkinje cell-specific Pcp2 promoter, to specifically ablate the Ca(V)2.1-α(1A) subunit and thereby Ca(V)2.1 channels in Purkinje cells. Purkinje cell Ca(V)2.1-α(1A)-knockout (PCα1KO) mice aged without difficulties, rescuing the lethal phenotype seen in α1KO mice. PCα1KO mice exhibited cerebellar ataxia starting around P12, much earlier than the first signs of progressive Purkinje cell loss, which appears in these mice between P30 and P45. Secondary cell loss was observed in the granular and molecular layers of the cerebellum and the volume of all individual cerebellar nuclei was reduced. In this mouse model with a cell type-specific ablation of Ca(V)2.1 channels, we show that ablation of Ca(V)2.1 channels restricted to Purkinje cells is sufficient to cause cerebellar ataxia. We demonstrate that spatial ablation of Ca(V)2.1 channels may help in unraveling mechanisms of human disease.
The Cerebellum 08/2011; 11(1):246-58. · 3.21 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Motor neuron degeneration and skeletal muscle denervation are hallmarks of amyotrophic lateral sclerosis (ALS), but other neuron populations and glial cells are also involved in ALS pathogenesis. We examined changes in inhibitory interneurons in spinal cords of the ALS model low-copy Gurney G93A-SOD1 (G1del) mice and found reduced expression of markers of glycinergic and GABAergic neurons, that is, glycine transporter 2 (GlyT2) and glutamic acid decarboxylase (GAD65/67), specifically in the ventral horns of clinically affected mice. There was also loss of GlyT2 and GAD67 messenger RNA-labeled neurons in the intermediate zone. Ubiquitinated inclusions appeared in interneurons before 20 weeks of age, that is, after their development in motor neurons but before the onset of clinical signs and major motor neuron degeneration, which starts from 25 weeks of age. Because mutant superoxide dismutase 1 (SOD1) in glia might contribute to the pathogenesis, we also examined neuron-specific G93A-SOD1 mice; they also had loss of inhibitory interneuron markers in ventral horns and ubiquitinated interneuron inclusions. These data suggest that, in mutant SOD1-associated ALS, pathological changes may spread from motor neurons to interneuronsin a relatively early phase of the disease, independent of the presence of mutant SOD1 in glia. The degeneration of spinal inhibitory interneurons may in turn facilitate degeneration of motor neurons and contribute to disease progression.
Journal of Neuropathology and Experimental Neurology 08/2011; 70(8):662-77. · 4.26 Impact Factor
-
Monique C de Waard,
Ingrid van der Pluijm,
Nils Zuiderveen Borgesius,
Laura H Comley, Elize D Haasdijk,
Yvonne Rijksen,
Yanto Ridwan,
Gerben Zondag,
Jan H J Hoeijmakers,
Ype Elgersma,
Thomas H Gillingwater,
Dick Jaarsma
[show abstract]
[hide abstract]
ABSTRACT: Degeneration of motor neurons contributes to senescence-associated loss of muscle function and underlies human neurodegenerative conditions such as amyotrophic lateral sclerosis and spinal muscular atrophy. The identification of genetic factors contributing to motor neuron vulnerability and degenerative phenotypes in vivo are therefore important for our understanding of the neuromuscular system in health and disease. Here, we analyzed neurodegenerative abnormalities in the spinal cord of progeroid Ercc1(Delta/-) mice that are impaired in several DNA repair systems, i.e. nucleotide excision repair, interstrand crosslink repair, and double strand break repair. Ercc1(Delta/-) mice develop age-dependent motor abnormalities, and have a shortened life span of 6-7 months. Pathologically, Ercc1(Delta/-) mice develop widespread astrocytosis and microgliosis, and motor neuron loss and denervation of skeletal muscle fibers. Degenerating motor neurons in many occasions expressed genotoxic-responsive transcription factors p53 or ATF3, and in addition, displayed a range of Golgi apparatus abnormalities. Furthermore, Ercc1(Delta/-) motor neurons developed perikaryal and axonal intermediate filament abnormalities reminiscent of cytoskeletal pathology observed in aging spinal cord. Our findings support the notion that accumulation of DNA damage and genotoxic stress may contribute to neuronal aging and motor neuron vulnerability in human neuromuscular disorders.
Acta Neuropathologica 10/2010; 120(4):461-75. · 9.32 Impact Factor
-
Daniël Splinter,
Marvin E Tanenbaum,
Arne Lindqvist,
Dick Jaarsma,
Annette Flotho,
Ka Lou Yu,
Ilya Grigoriev,
Dieuwke Engelsma, Elize D Haasdijk,
Nanda Keijzer,
Jeroen Demmers,
Maarten Fornerod,
Frauke Melchior,
Casper C Hoogenraad,
René H Medema,
Anna Akhmanova
[show abstract]
[hide abstract]
ABSTRACT: BICD2 is one of the two mammalian homologues of the Drosophila Bicaudal D, an evolutionarily conserved adaptor between microtubule motors and their cargo that was previously shown to link vesicles and mRNP complexes to the dynein motor. Here, we identified a G2-specific role for BICD2 in the relative positioning of the nucleus and centrosomes in dividing cells. By combining mass spectrometry, biochemical and cell biological approaches, we show that the nuclear pore complex (NPC) component RanBP2 directly binds to BICD2 and recruits it to NPCs specifically in G2 phase of the cell cycle. BICD2, in turn, recruits dynein-dynactin to NPCs and as such is needed to keep centrosomes closely tethered to the nucleus prior to mitotic entry. When dynein function is suppressed by RNA interference-mediated depletion or antibody microinjection, centrosomes and nuclei are actively pushed apart in late G2 and we show that this is due to the action of kinesin-1. Surprisingly, depletion of BICD2 inhibits both dynein and kinesin-1-dependent movements of the nucleus and cytoplasmic NPCs, demonstrating that BICD2 is needed not only for the dynein function at the nuclear pores but also for the antagonistic activity of kinesin-1. Our study demonstrates that the nucleus is subject to opposing activities of dynein and kinesin-1 motors and that BICD2 contributes to nuclear and centrosomal positioning prior to mitotic entry through regulation of both dynein and kinesin-1.
PLoS Biology 01/2010; 8(4):e1000350. · 11.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative condition characterized by progressive motor neuron degeneration and muscle paralysis. Genetic evidence from man and mouse has indicated that mutations in the dynein/dynactin motor complex are correlated with motor neuron degeneration. In this study, we have generated transgenic mice with neuron-specific expression of Bicaudal D2 N-terminus (BICD2-N) to chronically impair dynein/dynactin function. Motor neurons expressing BICD2-N showed accumulation of dynein and dynactin in the cell body, Golgi fragmentation and several signs of impaired retrograde trafficking: the appearance of giant neurofilament swellings in the proximal axon, reduced retrograde labelling by tracer injected in the muscle and delayed expression of the injury transcription factor ATF3 after axon transection. Despite these abnormalities, BICD2-N mice did not develop signs of motor neuron degeneration and motor abnormalities. Interestingly, the BICD2-N transgene increased lifespan in 'low copy' SOD1-G93A ALS transgenic mice. Our findings indicate that impaired dynein/dynactin function can explain several pathological features observed in ALS patients, but may be beneficial in some forms of ALS.
Human Molecular Genetics 07/2008; 17(18):2849-62. · 7.64 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Mutations in superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS), an adult-onset progressive paralytic disease characterized by loss of motor neurons, and cause an ALS-like disease when expressed in mice. Recent data have suggested that motor neuron degeneration results from toxic actions of mutant SOD1 operating in both motor neurons and their neighboring glia, raising the question whether mutant SOD1 expression selectively in neurons is sufficient to induce disease. Here we show that neuronal expression of mutant SOD1 is sufficient to cause motor neuron degeneration and paralysis in transgenic mice with cytosolic dendritic ubiquitinated SOD1 aggregates as the dominant pathological feature. In addition, we show that crossing our neuron-specific mutant SOD1 mice with ubiquitously wild-type SOD1-expressing mice leads to dramatic wild-type SOD1 aggregation in oligodendroglia after the onset of neuronal degeneration. Together, our findings support a pathogenic scenario in which mutant SOD1 in neurons triggers neuronal degeneration, which in turn may facilitate aggregate formation in surrounding glial cells.
Journal of Neuroscience 03/2008; 28(9):2075-88. · 7.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Learning motor skills is critical for motor abilities such as driving a car or playing piano. The speed at which we learn those skills is subject to many factors. Yet, it is not known to what extent gonadal hormones can affect the achievement of accurate movements in time and space. Here we demonstrate via different lines of evidence that estradiol promotes plasticity in the cerebellar cortex underlying motor learning. First, we show that estradiol enhances induction of long-term potentiation at the parallel fiber to Purkinje cell synapse, whereas it does not affect long-term depression; second, we show that estradiol activation of estrogen receptor beta receptors in Purkinje cells significantly improves gain-decrease adaptation of the vestibulo-ocular reflex, whereas it does not affect general eye movement performance; and third, we show that estradiol increases the density of parallel fiber to Purkinje cell synapses, whereas it does not affect the density of climbing fiber synapses. We conclude that estradiol can improve motor skills by potentiating cerebellar plasticity and synapse formation. These processes may be advantageous during periods of high estradiol levels of the estrous cycle or pregnancy.
Journal of Neuroscience 11/2007; 27(40):10832-9. · 7.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The cerebellum has been shown to be vulnerable to global ischemic damage in tightly controlled zones of Purkinje cells (PCs) that lack aldolase C, an enzyme critical for glycolysis. Here, we investigated whether aldolase C-negative PCs were more likely to die after cerebral trauma in vivo, and whether this death was mediated by excitotoxic [alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-mediated] means in vitro. Mice were subjected to controlled cortical impact, or remained uninjured, and were killed at 6 h, 24 h or 7 days after injury. Cerebellar sections (both ipsilateral and contralateral to the site of cerebral injury) were stained against aldolase C and calbindin (a marker of PCs). The number of viable, calbindin-positive PCs decreased significantly at 24 h and 7 days after injury, and the percentage of surviving, aldolase C-positive PCs significantly increased at those time-points. In addition, we subjected murine cerebellar cultures to AMPA (30 microm, 20 min), which killed a significant number of PCs at 24 h post-treatment. A similar number of PCs was lost after transfection with aldolase C siRNA, and this effect was exacerbated in transfected cultures treated with AMPA. The results from the present study indicate that aldolase C provides marked neuroprotection to PCs after trauma and excitotoxicity.
European Journal of Neuroscience 09/2007; 26(3):649-56. · 3.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: RET (for "rearranged during transfection") is a transmembrane tyrosine kinase signaling receptor for members of the glial cell line-derived neurotrophic factor (GDNF) family of ligands. We used RET immunohistochemistry (IHC), double-labeling immunofluorescence (IF), and in situ hybridization (ISH) in adult naïve and nerve-injured rats to study the distribution of RET in the spinal cord. In the dorsal horn, strong RET-immunoreactive (-ir) fibers were abundant in lamina II-inner (II(i)), although this labeling was preferentially observed after an antigen-unmasking procedure. After dorsal rhizotomy, RET-ir fibers in lamina II(i) completely disappeared from the dorsal horn, indicating that they were all primary afferents. After peripheral axotomy, RET-ir in primary afferents decreased in lamina II(i) and appeared to increase slightly in laminae III and IV. RET-ir was also observed in neurons and dendrites throughout the dorsal horn. Some RET-ir neurons in lamina I had the morphological appearance of nociceptive projection neurons, which was confirmed by the finding that 53% of RET-ir neurons in lamina I colocalized with neurokinin-1. GDNF-ir terminals were in close proximity to RET-ir neurons in the superficial dorsal horn. In the ventral horn, RET-ir was strongly expressed by motoneurons, with the strongest staining in small, presumably gamma-motoneurons. Increased RET expression following peripheral axotomy was most pronounced in alpha-motoneurons. The expression and regulation pattern of RET in the spinal cord are in line with its involvement in regenerative processes following nerve injury. The presence of RET in dorsal horn neurons, including nociceptive projection neurons, suggests that RET also has a role in signal transduction at the spinal level. This role may include mediating the effects of GDNF released from nociceptive afferent fibers.
The Journal of Comparative Neurology 03/2007; 500(6):1136-53. · 3.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To obtain insight into the morphological and molecular correlates of motoneuron degeneration in amyotrophic lateral sclerosis (ALS) mice that express G93A mutant superoxide dismutase (SOD)1 (G93A mice), we have mapped and characterized 'sick' motoneurons labelled by the 'stress transcription factors' ATF3 and phospho-c-Jun. Immunocytochemistry and in situ hybridization showed that a subset of motoneurons express ATF3 from a relatively early phase of disease before the onset of active caspase 3 expression and motoneuron loss. The highest number of ATF3-expressing motoneurons occurred at symptom onset. The onset of ATF3 expression correlated with the appearance of ubiquitinated neurites. Confocal double-labelling immunofluorescence showed that all ATF3-positive motoneurons were immunoreactive for phosphorylated c-Jun. Furthermore, the majority of ATF3 and phospho-c-Jun-positive motoneurons were also immunoreactive for CHOP (GADD153) and showed Golgi fragmentation. A subset of ATF3 and phosphorylated c-Jun-immunoreactive motoneurons showed an abnormal appearance characterized by a number of distinctive features, including an eccentric flattened nucleus, perikaryal accumulation of ubiquitin immunoreactivity, juxta-nuclear accumulation of the Golgi apparatus and the endoplasmic reticulum, and intense Hsp70 immunoreactivity. These abnormal cells were not immunoreactive for active caspase 3. We conclude that motoneurons in ALS-SOD1 mice prior to their death and disappearance experience a prolonged sick phase, characterized by the gradual accumulation of ubiquitinated material first in the neurites and subsequently the cell body.
European Journal of Neuroscience 11/2005; 22(8):1881-94. · 3.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Apolipoprotein E (apoE) genotype is well known as a risk factor for Alzheimer's disease, but more recently also has been associated with the incidence or disease progression of other neurological diseases including amyotrophic lateral sclerosis (ALS). In the present study we have examined the distribution of apoE in the spinal cord of transgenic mice with a familial ALS-linked superoxide dismutase 1 (G93A-SOD1) mutation. Western immunoblotting and immunocytochemistry showed a strong increase in apoE expression in G93A-SOD1 mice coincident with the onset of paralysis (age > 24 weeks). Increased apoE expression occurred in astrocytes and throughout the neuropil. The increase in apoE expression closely correlated in time and spatial distribution with axonal and neuronal degeneration as determined with a silver staining procedure, consistent with a role as an 'injury-response' protein.
Neuroscience Letters 01/2003; 335(1):29-33. · 2.11 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Transgenic mice carrying amyotrophic lateral sclerosis (ALS)-linked superoxide dismutase 1 (SOD1) mutations develop a motoneuron disease resembling human ALS. c-Jun is a transcription factor frequently induced in injured neurons. In this study we have examined the distribution of c-Jun-immunoreactivity in the brainstem and spinal cord of transgenic SOD1 mice with a glycine 93 alanine (G93A) mutation. In non-transgenic littermates c-Jun immunostaining was predominantly situated in motoneurons. The number of c-Jun immunoreactive motoneuron was reduced in SOD1(G93A) mice due to pronounced loss of motoneurons. In SOD1(G93A) mice, however, c-Jun-immunoreactivity was strongly induced in neurons in the intermediate zone (Rexed's laminae V–VIII and X) of the spinal cord and throughout the brainstem reticular formation. These findings are of interest since increased levels of c-jun also have been found in the intermediate zone of the spinal cord of ALS patients. Thus c-Jun may be involved in the neurodegenerative processes both in ALS and in motoneuron disease in SOD1(G93A) mice.
Neuroscience Letters 12/1996; · 2.11 Impact Factor
