Dysfunction in endoplasmic reticulum-mitochondria crosstalk underlies SIGMAR1 loss of function mediated motor neuron degeneration.

Mutations in Sigma 1 receptor (SIGMAR1) have been previously identified in patients with amyotrophic lateral sclerosis and disruption of Sigmar1 in mouse leads to locomotor deficits. However, cellular mechanisms underlying motor phenotypes in human and mouse with disturbed SIGMAR1 function have not been described so far. Here we used a combination of in vivo and in vitro approaches to investigate the role of SIGMAR1 in motor neuron biology. Characterization of Sigmar1(-/-) mice revealed that affected animals display locomotor deficits associated with muscle weakness, axonal degeneration and motor neuron loss. Using primary motor neuron cultures, we observed that pharmacological or genetic inactivation of SIGMAR1 led to motor neuron axonal degeneration followed by cell death. Disruption of SIGMAR1 function in motor neurons disturbed endoplasmic reticulum-mitochondria contacts, affected intracellular calcium signalling and was accompanied by activation of endoplasmic reticulum stress and defects in mitochondrial dynamics and transport. These defects were not observed in cultured sensory neurons, highlighting the exacerbated sensitivity of motor neurons to SIGMAR1 function. Interestingly, the inhibition of mitochondrial fission was sufficient to induce mitochondria axonal transport defects as well as axonal degeneration similar to the changes observed after SIGMAR1 inactivation or loss. Intracellular calcium scavenging and endoplasmic reticulum stress inhibition were able to restore mitochondrial function and consequently prevent motor neuron degeneration. These results uncover the cellular mechanisms underlying motor neuron degeneration mediated by loss of SIGMAR1 function and provide therapeutically relevant insight into motor neuronal diseases.

Genetic Engineering of Induced Pluripotent Stem Cells and Reprogramming to Motor Neurons to Elucidate Selective Motor Neuron Death in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease, fatal within 1 to 5 years after onset of symptoms. About 3 out of 100’000 persons are diagnosed with ALS and there is still no cure available [1, 2]. 95% of all cases occur sporadically and the aetiology remains largely unknown [XXXX]. However, up to now 16 genes were identified to play a role in the development of familial ALS. One of these genes is FUS that encodes for the protein fused in sarcoma/translocated in liposarcoma (FUS/TLS). Mutations in this gene are responsible for some cases of sporadic as well as of inherited ALS [3]. FUS belongs to the family of heterogeneous nuclear ribonucleoproteins and is predicted to be involved in several cellular functions like transcription regulation [4], RNA splicing [5, 6], mRNA transport in neurons [7] and microRNA processing [8]. Aberrant accumulation of mutated FUS has been found in the cytoplasm of motor neurons from ALS patients [9]. The mislocalization of FUS is based on a mutation in the nuclear localization signal of FUS [10]. However, it is still unclear if the cytoplasmic localization of FUS leads to a toxic gain of cytoplasmic function and/or a loss of nuclear function that might be crucial in the course of ALS. The goal of this project is to characterize the impact of ALS-associated FUS mutations on in vitro differentiated motor neurons. To this end, we edit the genome of induced pluripotent stem cells (iPSC) using transcription activator-like effector nucleases (TALENs) [11,12] to create three isogenic cell lines, each carrying an ALS-associated FUS mutation (G156E, R244C and P525L). These iPSC’s will then be differentiated to motor neurons according to a recently establishe protocol (Ref Wichterle) and serve to study alterations in the transcriptome, proteome and metabolome upon the expression of ALS-associated FUS. With this approach, we hope to unravel the molecular mechanism leading to FUS-associated ALS and to provide new insight into the emerging connection between misregulation of RNA metabolism and neurodegeneration, a connection that is currently implied in a variety of additional neurological diseases, including spinocerebellar ataxia 2 (SCA-2), spinal muscular atrophy (SMA), fragile X syndrome, and myotonic dystrophy.

Genetic Engineering of Induced Pluripotent Stem Cells and Reprogramming to Motor Neurons to Elucidate Selective Motor Neuron Death in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease, fatal within 1 to 5 years after onset of symptoms. About 3 out of 100’000 persons are diagnosed with ALS and there is still no cure available [1, 2]. 95% of all cases occur sporadically and the aetiology remains largely unknown [3]. However, up to now 16 genes were identified to play a role in the development of familial ALS. One of these genes is FUS that encodes for the protein fused in sarcoma (FUS). Mutations in this gene are responsible for some cases of sporadic as well as of inherited ALS [4]. FUS belongs to the family of heterogeneous nuclear ribonucleoproteins and is predicted to be involved in several cellular functions like transcription regulation, RNA splicing, mRNA transport in neurons and microRNA processing [5] Aberrant accumulation of mutated FUS has been found in the cytoplasm of motor neurons from ALS patients [6]. The mislocalization of FUS is based on a mutation in the nuclear localization signal of FUS [7]. However, it is still unclear if the cytoplasmic localization of FUS leads to a toxic gain of cytoplasmic function and/or a loss of nuclear function that might be crucial in the course of ALS. The goal of this project is to characterize the impact of ALS-associated FUS mutations on in vitro differentiated motor neurons. To this end, we edit the genome of induced pluripotent stem cells (iPSC) using transcription activator-like effector nucleases (TALENs) [8,9] to create three isogenic cell lines, each carrying an ALS-associated FUS mutation (G156E, R244C and P525L). These iPSC’s will then be differentiated to motor neurons according to a recently established protocol [10] and serve to study alterations in the transcriptome, proteome and metabolome upon the expression of ALS-associated FUS. With this approach, we hope to unravel the molecular mechanism leading to FUS-associated ALS and to provide new insight into the emerging connection between misregulation of RNA metabolism and neurodegeneration, a connection that is currently implied in a variety of additional neurological diseases, including spinocerebellar ataxia 2 (SCA-2), spinal muscular atrophy (SMA), fragile X syndrome, and myotonic dystrophy. [1] Cleveland, D.W. et al. (2001) Nat Rev Neurosci 2(11): 806-819 [2] Sathasivam, S. (2010) Singapore Med J 51(5): 367-372 [3] Schymick, J.C. et al. (2007) Hum Mol Genet Vol 16: 233-242 [4] Pratt, A.J. et al. (2012). Degener Neurol Neuromuscul Dis 2012(2): 1-14 [5] Lagier-Tourenne, C. Hum Mol Genet, 2010. 19(R1): p. R46-64 [6] Mochizuki, Y. et al. (2012) J Neurol Sci 323(1-2): 85-92 [7] Dormann, D. et al. (2010) EMBO J 29(16): 2841-2857 [8] Hockemeyer, D. et al. (2011) Nat Biotech 29(8): 731-734 [9] Joung, J.K. and J.D. Sander (2013) Nat Rev Mol Cell Biol 14(1): 49-55 [10]Amoroso, M.W. et al. (2013) J Neurosci 33(2): 574-586.

Marinesco-Sjögren syndrome protein SIL1 regulates motor neuron subtype-selective ER stress in ALS.

Mechanisms underlying motor neuron subtype-selective endoplasmic reticulum (ER) stress and associated axonal pathology in amyotrophic lateral sclerosis (ALS) remain unclear. Here we show that the molecular environment of the ER between motor neuron subtypes is distinct, with characteristic signatures. We identify cochaperone SIL1, mutated in Marinesco-Sjögren syndrome (MSS), as being robustly expressed in disease-resistant slow motor neurons but not in ER stress-prone fast-fatigable motor neurons. In a mouse model of MSS, we demonstrate impaired ER homeostasis in motor neurons in response to loss of SIL1 function. Loss of a single functional Sil1 allele in an ALS mouse model (SOD1-G93A) enhanced ER stress and exacerbated ALS pathology. In SOD1-G93A mice, SIL1 levels were progressively and selectively reduced in vulnerable fast-fatigable motor neurons. Mechanistically, reduction in SIL1 levels was associated with lowered excitability of fast-fatigable motor neurons, further influencing expression of specific ER chaperones. Adeno-associated virus-mediated delivery of SIL1 to familial ALS motor neurons restored ER homeostasis, delayed muscle denervation and prolonged survival.

Survival motor neuron protein modulates neuron-specific apoptosis

Spinal muscular atrophy (SMA) is attributed to mutations in the SMN1 gene, leading to loss of spinal cord motor neurons. The neurotropic Sindbis virus vector system was used to investigate a role for the survival motor neuron (SMN) protein in regulating neuronal apoptosis. Here we show that SMN protects primary neurons and differentiated neuron-like stem cells, but not cultured cell lines from virus-induced apoptotic death. SMN also protects neurons in vivo and increases survival of virus-infected mice. SMN mutants (SMNΔ7 and SMN-Y272C) found in patients with SMA not only lack antiapoptotic activity but also are potently proapoptotic, causing increased neuronal apoptosis and animal mortality. Full-length SMN is proteolytically processed in brains undergoing apoptosis or after ischemic injury. Mutation of an Asp-252 of SMN abolished cleavage of SMN and increased the antiapoptotic function of full-length SMN in neurons. Taken together, deletions or mutations of the C terminus of SMN that result from proteolysis, splicing (SMNΔ7), or germ-line mutations (e.g., Y272C), produce a proapoptotic form of SMN that may contribute to neuronal death in SMA and perhaps other neurodegenerative disorders.

TDP-43-Immunoreactive pathology in frontotemporal lobar degeneration with TDP proteinopathy (FTLD-TDP) with and without associated motor neuron disease

A proportion of patients with motor neuron disease (MND) exhibit frontotemporal dementia (FTD) and some patients with FTD develop the clinical features of MND. Frontotemporal lobar degeneration (FTLD) is the pathological substrate of FTD and some forms of this disease (referred to as FTLD-U) share with MND the common feature of ubiquitin-immunoreactive, tau-negative cellular inclusions in the cerebral cortex and hippocampus. Recently, the transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) has been found to be a major protein of the inclusions of FTLD-U with or without MND and these cases are referred to as FTLD with TDP-43 proteinopathy (FTLD-TDP). To clarify the relationship between MND and FTLD-TDP, TDP-43 pathology was studied in nine cases of FTLD-MND and compared with cases of familial and sporadic FTLD–TDP without associated MND. A principal components analysis (PCA) of the nine FTLD-MND cases suggested that variations in the density of surviving neurons in the frontal cortex and neuronal cytoplasmic inclusions (NCI) in the dentate gyrus (DG) were the major histological differences between cases. The density of surviving neurons in FTLD-MND was significantly less than in FTLD-TDP cases without MND, and there were greater densities of NCI but fewer neuronal intranuclear inclusions (NII) in some brain regions in FTLD-MND. A PCA of all FTLD-TDP cases, based on TDP-43 pathology alone, suggested that neuropathological heterogeneity was essentially continuously distributed. The FTLD-MND cases exhibited consistently high loadings on PC2 and overlapped with subtypes 2 and 3 of FTLD-TDP. The data suggest: (1) FTLD-MND cases have a consistent pathology, variations in the density of NCI in the DG being the major TDP-43-immunoreactive difference between cases, (2) there are considerable similarities in the neuropathology of FTLD-TDP with and without MND, but with greater neuronal loss in FTLD-MND, and (3) FTLD-MND cases are part of the FTLD-TDP ‘continuum’ overlapping with FTLD-TDP disease subtypes 2 and 3.

TDP-43-immunoreactive pathology in frontotemporal lobar degeneration with TDP proteinopathy (FTLD-TDP) with and without associated motor neuron disease (MND)

A proportion of patients with motor neuron disease (MND) exhibit frontotemporal dementia (FTD) and some patients with FTD develop the clinical features of MND. Frontotemporal lobar degeneration (FTLD) is the pathological substrate of FTD and some forms of this disease (referred to as FTLD-U) share with MND the common feature of ubiquitin-immunoreactive, tau-negative cellular inclusions in the cerebral cortex and hippocampus. Recently, the transactive response (TAR) DNA-binding protein of 43 kDa (TDP-43) has been found to be a major protein of the inclusions of FTLD-U with or without MND and these cases are referred to as FTLD with TDP-43 proteinopathy (FTLD-TDP). To clarify the relationship between MND and FTLD-TDP, TDP-43 pathology was studied in nine cases of FTLD-MND and compared with cases of familial and sporadic FTLD-TDP without associated MND. A principal components analysis (PCA) of the nine FTLD-MND cases suggested that variations in the density of surviving neurons in the frontal cortex and neuronal cytoplasmic inclusions (NCI) in the dentate gyrus (DG) were the major histological differences between cases. The density of surviving neurons in FTLD-MND was significantly less than in FTLD-TDP cases without MND, and there were greater densities of NCI but fewer neuronal intranuclear inclusions (NII) in some brain regions in FTLD-MND. A PCA of all FTLD-TDP cases, based on TDP-43 pathology alone, suggested that neuropathological heterogeneity was essentially continuously distributed. The FTLD-MND cases exhibited consistently high loadings on PC2 and overlapped with subtypes 2 and 3 of FTLD-TDP. The data suggest: (1) FTLD-MND cases have a consistent pathology, variations in the density of NCI in the DG being the major TDP-43-immunoreactive difference between cases, (2) there are considerable similarities in the neuropathology of FTLD-TDP with and without MND, but with greater neuronal loss in FTLD-MND, and (3) FTLD-MND cases are part of the FTLD-TDP 'continuum' overlapping with FTLD-TDP disease subtypes 2 and 3. © 2012 Nova Science Publishers, Inc. All rights reserved.

A monster that lives in our lives - experiences of caregivers of people with motor neuron disease and identifying avenues for support.

Background A developing body of evidence has provided valuable insight into the experiences of caregivers of people with motor neuron disease; however, understandings of how best to support caregivers remain limited.

Aim This study sought to understand concepts related to the motor neuron disease caregiver experience which could inform the development of supportive interventions.

Design A qualitative thematic analysis of a one-off semistructured interview with caregivers was undertaken.

Setting/participants Caregivers of people with motor neuron disease were recruited from a progressive neurological diseases clinic in Melbourne, Australia.

Results 15 caregivers participated. Three key themes were identified: (1) The Thief: the experience of loss and grief across varied facets of life; (2) The Labyrinth: finding ways to address ever changing challenges as the disease progressed; (3) Defying fate: being resilient and hopeful as caregivers tried to make the most of the time remaining.

Conclusions Caregivers are in need of more guidance and support to cope with experiences of loss and to adapt to changeable care giving duties associated with disease progression. Therapeutic interventions which target these experiences of loss and change are worth investigation.

Could Cyclophosphamide exert a protective role avoiding esophagic neuron loss in Calomys callosus infected with Trypanosoma cruzi?

The protective role of Cyclophosphamide was studied in this work. Young male Calomys callosus were infected with Trypanosoma cruzi and allowed to age. Cyclophosphamide therapy was administered to animals during acute and late chronic phases of infection. Esophageal neurons were counted, displaying enhanced neuronal loss for the young and treated infected groups. For aged and cyclophosphamide treated animals, a protection was observed through a reduced loss of neurons as compared to the young and infected groups. Enhanced nitric oxide concentrations were observed for young animals as compared to aged counterparts. Splenocyte proliferation was reduced during the acute phase in comparison with those found in the chronic phase. Morphometry of neuronal body displayed a significant reduction concerning the area, perimeter, diameter and volume for aged animals as compared to young groups. These results indicate that the protective effects of cyclophosphamide together with process of neuroplasty of peripheral nervous system could lead to a protection against neuronal loss.

Hypertrophy and neuron loss: structural changes in sheep SCG induced by unilateral sympathectomy

Recently, superior cervical ganglionectomy has been performed to investigate a variety of scientific topics from regulation of intraocular pressure to suppression of lingual tumour growth. Despite these recent advances in our understanding of the functional mechanisms underlying superior cervical ganglion (SCG) growth and development after surgical ablation, there still exists a need for information concerning the quantitative nature of the relationships between the removed SCG and its remaining contralateral ganglion and between the remaining SCG and its modified innervation territory. To this end, using design-based stereological methods, we have investigated the structural changes induced by unilateral ganglionectomy in sheep at three distinct timepoints (2, 7 and 12 weeks) after surgery. The effects of time, and lateral (left-right) differences, were examined by two-way analyses of variance and paired t-tests. Following removal of the left SCG, the main findings were: (i) the remaining right SCG was bigger at shorter survival times, i.e. 74% at 2 weeks, 55% at 7 weeks and no increase by 12 weeks, (ii) by 7 weeks after surgery, the right SCG contained fewer neurons (no decrease at 2 weeks, 6% fewer by 7 weeks and 17% fewer by 12 weeks) and (iii) by 7 weeks, right SCG neurons were also larger and the magnitude of this increase grew substantially with time (no rise at 2 weeks, 77% by 7 weeks and 215% by 12 weeks). Interaction effects between time and ganglionectomy-induced changes were significant for SCG volume and mean perikaryal volume. These findings show that unilateral superior cervical ganglionectomy has profound effects on the contralateral ganglion. For future investigations, it would be interesting to examine the interaction between SCGs and their innervation targets after ganglionectomy. Is the ganglionectomy-induced imbalance between the sizes of innervation territories the milieu in which morphoquantitative changes, particularly changes in perikaryal volume and neuron number, occur? Mechanistically, how would those changes arise? Are there any grounds for believing in a ganglionectomy-triggered SCG cross-innervation and neuroplasticity? (C) 2011 ISDN. Published by Elsevier Ltd. All rights reserved.

Exploring motor neuron degeneration in ALS - prevention by glycoursodeoxycholic acid and signaling to microglia

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

Exploring deregulated signals involved in motor neuron-microglia cross-talk in ALS

Part of the results discussed in this thesis was presented in the following meetings: Cunha MI, Cunha C, Vaz AR, Brites D. Studying microglial-motoneuron cross-talk in ALS pathology. 6th iMed.UL Postgraduate Students Meeting, Lisbon, July 2, 2014. [Abstract and Poster] Vaz AR. Motoneuron degeneration and glial reactivity in ALS: insights from cellular to animal models. Neuroscience Seminars at IMM 2012, Instituto de Medicina Molecular, Universidade de Lisboa, Lisbon, Portugal, June 9, 2014. [Oral Communication (by invitation)]

Evaluation of motor neuron excitability by CMAP scanning with modulated current

It is important to have better evaluation and understanding of the motor neuron physiology, with the goal to early and objectively diagnose and treat patients with neurodegenerative pathologies. The Compound Muscle Action Potential (CMAP) scan is a non-invasive diagnosis technique for neurodegenerative pathologies, such as ALS, and enables a quick analysis of the muscle action potentials in response to motor nerve stimulation. This work aims to study the influence of different pulse modulated waveforms in peripheral nerve excitability by CMAP scan technique on healthy subjects. A total of 13 healthy subjects were submitted to the same test. The stimuli were applied in the medium nerve on the right wrist and electromyography signal collected on the Abductor Pollicis Brevis (APB) muscle surface on the right thumb. Stimulation was performed with an increasing intensities range from 4 to 30 mA, with varying steps, 3 stimuli per step. The procedure was repeated 4 times per subject, each repetition using a different single pulse stimulation waveform: monophasic square, monophasic triangular, monophasic quadratic and biphasic square. Results were retrieved from the averaging of the stimuli on each current intensity step. The square pulse needs less current intensity to generate the same response amplitude regarding the other waves and presents a more steep curve slope and this effect is gradually decreasing for the triangular and quadratic pulse,respectively, being the difference even more evident regarding the biphasic pulse. The control of the waveform stimulation pulse allows varying the stimulusresponse curve slope.

Recombinant human insulin-like growth factor I (rhIGF-I) for the treatment of amyotrophic lateral sclerosis/motor neuron disease.

BACKGROUND: Recombinant human insulin-like growth factor I (rhIGF-I) is a possible disease modifying therapy for amyotrophic lateral sclerosis (ALS, which is also known as motor neuron disease (MND)). OBJECTIVES: To examine the efficacy of rhIGF-I in affecting disease progression, impact on measures of functional health status, prolonging survival and delaying the use of surrogates (tracheostomy and mechanical ventilation) to sustain survival in ALS. Occurrence of adverse events was also reviewed. SEARCH METHODS: We searched the Cochrane Neuromuscular Disease Group Specialized Register (21 November 2011), CENTRAL (2011, Issue 4), MEDLINE (January 1966 to November 2011) and EMBASE (January 1980 to November 2011) and sought information from the authors of randomised clinical trials and manufacturers of rhIGF-I. SELECTION CRITERIA: We considered all randomised controlled clinical trials involving rhIGF-I treatment of adults with definite or probable ALS according to the El Escorial Criteria. The primary outcome measure was change in Appel Amyotrophic Lateral Sclerosis Rating Scale (AALSRS) total score after nine months of treatment and secondary outcome measures were change in AALSRS at 1, 2, 3, 4, 5, 6, 7, 8, 9 months, change in quality of life (Sickness Impact Profile scale), survival and adverse events. DATA COLLECTION AND ANALYSIS: Each author independently graded the risk of bias in the included studies. The lead author extracted data and the other authors checked them. We generated some missing data by making ruler measurements of data in published graphs. We collected data about adverse events from the included trials. MAIN RESULTS: We identified three randomised controlled trials (RCTs) of rhIGF-I, involving 779 participants, for inclusion in the analysis. In a European trial (183 participants) the mean difference (MD) in change in AALSRS total score after nine months was -3.30 (95% confidence interval (CI) -8.68 to 2.08). In a North American trial (266 participants), the MD after nine months was -6.00 (95% CI -10.99 to -1.01). The combined analysis from both RCTs showed a MD after nine months of -4.75 (95% CI -8.41 to -1.09), a significant difference in favour of the treated group. The secondary outcome measures showed non-significant trends favouring rhIGF-I. There was an increased risk of injection site reactions with rhIGF-I (risk ratio 1.26, 95% CI 1.04 to 1.54). . A second North American trial (330 participants) used a novel primary end point involving manual muscle strength testing. No differences were demonstrated between the treated and placebo groups in this study. All three trials were at high risk of bias. AUTHORS' CONCLUSIONS: Meta-analysis revealed a significant difference in favour of rhIGF-I treatment; however, the quality of the evidence from the two included trials was low. A third study showed no difference between treatment and placebo. There is no evidence for increase in survival with IGF1. All three included trials were at high risk of bias.

Familial frontotemporal dementia with ubiquitin inclusion bodies and without motor neuron disease.

Frontotemporal dementia (FTD) is the second most common degenerative dementia after Alzheimer's disease and its Lewy body variant. Clinical pathology can be subdivided in three main neuropathological subtypes: frontal lobe dementia, Pick's disease and FTD with motor neuron disease (MND), all characterised by distinct histological features. Until recently the presence of ubiquitin-positive intraneuronal inclusions in the dentate gyrus, and the temporal and frontal cortex was usually associated with the MND type. Such inclusions were also observed in a few sporadic cases of FTD without or with parkinsonism (FTDP) in the absence of MND. We present here clinical, neuropathological and immunohistochemical data about a Swiss FTD family with FTDP-like features but without MND. Spongiosis and mild gliosis were observed in the grey matter. No neurofibrillary tangles, Pick bodies, Lewy bodies, senile plaques or prion-positive signals were present. However, ubiquitin-positive intracytoplasmic inclusions were detected in various structures but predominantly in the dentate gyrus. These observations support the existence of a familial form of FTDP with ubiquitin-positive intracytoplasmic inclusions (Swiss FTDP family).