dissection-transversus-abdominis-muscle-for-whole-mount-neuromuscular

Dissection of the <em>Transversus Abdominis</em> Muscle for Whole-mount Neuromuscular Junction Analysis

Analysis of neuromuscular junction morphology can give important insight into the physiological status of a given motor neuron. Analysis of thin flat ...

Ottawa Hospital Research Institute

Proximal spinal muscular atrophy (SMA) is a common autosomal recessive childhood form of motor neuron disease. Previous studies have highlighted nerve- and muscle-specific events in SMA, including atrophy of muscle fibres and post-synaptic motor endplates, loss of lower motor neuron cell bodies and denervation of neuromuscular junctions caused by loss of pre-synaptic inputs. Here we have undertaken a detailed morphological investigation of neuromuscular synaptic pathology in the Smn-/-;SMN2 and Smn-/-;SMN2;Delta7 mouse models of SMA. We show that neuromuscular junctions in the transversus abdominis (TVA), levator auris longus (LAL) and lumbrical muscles were disrupted in both mouse models. Pre-synaptic inputs were lost and abnormal accumulations of neurofilament were present, even in early/mid-symptomatic animals in the most severely affected muscle groups. Neuromuscular pathology was more extensive in the postural TVA muscle compared with the fast-twitch LAL and lumbrical muscles. Pre-synaptic pathology in Smn-/-;SMN2;Delta7 mice was reduced compared with Smn-/-;SMN2 mice at late-symptomatic time-points, although post-synaptic pathology was equally severe. We demonstrate that shrinkage of motor endplates does not correlate with loss of motor nerve terminals, signifying that one can occur in the absence of the other. We also demonstrate selective vulnerability of a subpopulation of motor neurons in the caudal muscle band of the LAL. Paralysis with botulinum toxin resulted in less terminal sprouting and ectopic synapse formation in the caudal band compared with the rostral band, suggesting that motor units conforming to a Fast Synapsing (FaSyn) phenotype are likely to be more vulnerable than those with a Delayed Synapsing (DeSyn) phenotype.

Selective vulnerability of motor neurons and dissociation of pre- and post-synaptic pathology at the neuromuscular junction in mouse models of spinal muscular atrophy.

Wallerian degeneration and dying-back pathology are two well-known cellular pathways capable of regulating the breakdown and loss of axonal and synaptic compartments of neurons in vivo. However, the underlying mechanisms and molecular triggers of these pathways remain elusive. Here, we show that loss of translation elongation factor eEF1A2 expression in lower motor neurons and skeletal muscle fibres in homozygous Wasted mice triggered a dying-back neuropathy. Synaptic loss at the neuromuscular junction occurred in advance of axonal pathology and by a mechanism morphologically distinct from Wallerian degeneration. Dying-back pathology in Wasted mice was accompanied by reduced expression levels of the zinc finger protein ZPR1, as found in other dying-back neuropathies such as spinal muscular atrophy. Surprisingly, experimental nerve lesion revealed that Wallerian degeneration was significantly delayed in homozygous Wasted mice; morphological assessment revealed that approximately 80% of neuromuscular junctions in deep lumbrical muscles at 24 h and approximately 50% at 48 h had retained motor nerve terminals following tibial nerve lesion. This was in contrast to wild-type and heterozygous Wasted mice where < 5% of neuromuscular junctions had retained motor nerve terminals at 24 h post-lesion. These data show that eEF1A2 expression is required to prevent the initiation of dying-back pathology at the neuromuscular junction in vivo. In contrast, loss of eEF1A2 expression significantly inhibited the initiation and progression of Wallerian degeneration in vivo. We conclude that loss of eEF1A2 expression distinguishes mechanisms underlying dying-back pathology from those responsible for Wallerian degeneration in vivo and suggest that eEF1A2-dependent cascades may provide novel molecular targets to manipulate neurodegenerative pathways in lower motor neurons.

Loss of translation elongation factor (eEF1A2) expression in vivo differentiates between Wallerian degeneration and dying-back neuronal pathology.

"Two-cysteine" peroxiredoxins are antioxidant enzymes that exert a cytoprotective effect in many models of oxidative stress. However, under highly oxidizing conditions they can be inactivated through hyperoxidation of their peroxidatic active site cysteine residue. Sulfiredoxin can reverse this hyperoxidation, thus reactivating peroxiredoxins. Here we review recent investigations that have shed further light on sulfiredoxin's role and regulation. Studies have revealed sulfiredoxin to be a dynamically regulated gene whose transcription is induced by a variety of signals and stimuli. Sulfiredoxin expression is regulated by the transcription factor AP-1, which mediates its up-regulation by synaptic activity in neurons, resulting in protection against oxidative stress. Furthermore, sulfiredoxin has been identified as a new member of the family of genes regulated by nuclear factor erythroid 2-related factor (Nrf2) via a conserved Aáë-acting antioxidant response element (ARE). As such, sulfiredoxin is likely to contribute to the net antioxidative effect of small molecule activators of Nrf2. As discussed here, the proximal AP-1 site of the sulfiredoxin promoter is embedded within the ARE, as is common with Nrf2 target genes. Other recent studies have shown that sulfiredoxin induction via Nrf2 may form an important part of the protective response to oxidative stress in the lung, preventing peroxiredoxin hyperoxidation and, in certain cases, subsequent degradation. We illustrate here that sulfiredoxin can be rapidly induced in vivo by administration of CDDO-TFEA, a synthetic triterpenoid inducer of endogenous Nrf2, which may offer a way of reversing peroxiredoxin hyperoxidation in vivo following chronic or acute oxidative stress.

Transcriptional regulation of the AP-1 and Nrf2 target gene sulfiredoxin.

The childhood motor neuron disease spinal muscular atrophy (SMA) results from reduced expression of the survival motor neuron (SMN) gene. Previous studies using in vitro model systems and lower organisms have suggested that low levels of Smn protein disrupt prenatal developmental processes in lower motor neurons, influencing neuronal outgrowth, axon branching and neuromuscular connectivity. The extent to which these developmental pathways contribute to selective vulnerability and pathology in the mammalian neuromuscular system in vivo remains unclear. Here, we have investigated the pre-symptomatic development of neuromuscular connectivity in differentially vulnerable motor neuron populations in Smn(-/-);SMN2 mice, a model of severe SMA. We show that reduced Smn levels have no detectable effect on morphological correlates of pre-symptomatic development in either vulnerable or stable motor units, indicating that abnormal pre-symptomatic developmental processes are unlikely to be a prerequisite for subsequent pathological changes to occur in vivo. Microarray analyses of spinal cord from two different severe SMA mouse models demonstrated that only minimal changes in gene expression were present in pre-symptomatic mice. In stark contrast, microarray analysis of late-symptomatic spinal cord revealed widespread changes in gene expression, implicating extracellular matrix integrity, growth factor signalling and myelination pathways in SMA pathogenesis. Taken together, these data suggest that reduced Smn levels induce SMA pathology by instigating rapidly progressive neurodegenerative pathways in lower motor neurons around the time of disease onset rather than by modulating pre-symptomatic neurodevelopmental pathways.

Pre-symptomatic development of lower motor neuron connectivity in a mouse model of severe spinal muscular atrophy.

Spinal muscular atrophy is a severe motor neuron disease caused by inactivating mutations in the SMN1 gene leading to reduced levels of full-length functional SMN protein. SMN is a critical mediator of spliceosomal protein assembly, and complete loss or drastic reduction in protein leads to loss of cell viability. However, the reason for selective motor neuron degeneration when SMN is reduced to levels which are tolerated by all other cell types is not currently understood. Widespread splicing abnormalities have recently been reported at end-stage in a mouse model of SMA, leading to the proposition that disruption of efficient splicing is the primary mechanism of motor neuron death. However, it remains unclear whether splicing abnormalities are present during early stages of the disease, which would be a requirement for a direct role in disease pathogenesis. We performed exon-array analysis of RNA from SMN deficient mouse spinal cord at 3 time points, pre-symptomatic (P1), early symptomatic (P7), and late-symptomatic (P13). Compared to littermate control mice, SMA mice showed a time-dependent increase in the number of exons showing differential expression, with minimal differences between genotypes at P1 and P7, but substantial variation in late-symptomatic (P13) mice. Gene ontology analysis revealed differences in pathways associated with neuronal development as well as cellular injury. Validation of selected targets by RT-PCR confirmed the array findings and was in keeping with a shift between physiologically occurring mRNA isoforms. We conclude that the majority of splicing changes occur late in SMA and may represent a secondary effect of cell injury, though we cannot rule out significant early changes in a small number of transcripts crucial to motor neuron survival.

Alternative splicing events are a late feature of pathology in a mouse model of spinal muscular atrophy.

Smoking cessation is essential after the diagnosis of cancer to improve clinical outcomes. The purpose of this chapter is to provide a systematic review of research on smoking cessation in the context of cancer care with an emphasis on nursing contributions to the field. Data sources included research reports of smoking cessation interventions conducted in people with cancer. Nineteen primary studies were reviewed. High intensity interventions, targeting multiple behaviors, and/or using a multicomponent intervention that included pharmacotherapy, behavioral counseling, and social support were characteristics of the most successful treatments for tobacco dependence. The majority of interventions were conducted in adults with smoking-related malignancies during acute phases of illness. The most striking finding was that more than one half of the studies tested the efficacy of nurse-delivered interventions. Conceptual and methodological issues that can be improved in future studies include: using theoretical frameworks to specify how the intervention will affect outcomes, ensuring adequate sample sizes, using biochemical verification to monitor smoking outcomes, and using standardized outcome measures of abstinence. Although effective interventions are available for healthy populations, further research is needed to determine if tailored cessation interventions are needed for patients with cancer. To provide optimal quality care it is imperative that delivery of evidence-based smoking cessation interventions be integrated into the cancer treatment trajectory. Multiple barriers, including patient and nurse attitudes toward smoking and lack of knowledge related to tobacco treatment, prevent translating evidence-based tobacco dependence treatment into clinical practice. Further nursing research is needed to address these barriers.

Smoking cessation interventions in cancer care: opportunities for oncology nurses and nurse scientists.

Reduced expression of the survival motor neuron (SMN) gene causes the childhood motor neuron disease spinal muscular atrophy (SMA). Low levels of ubiquitously expressed SMN protein result in the degeneration of lower motor neurons, but it remains unclear whether other regions of the nervous system are also affected. Here we show that reduced levels of SMN lead to impaired perinatal brain development in a mouse model of severe SMA. Regionally selective changes in brain morphology were apparent in areas normally associated with higher SMN levels in the healthy postnatal brain, including the hippocampus, and were associated with decreased cell density, reduced cell proliferation and impaired hippocampal neurogenesis. A comparative proteomics analysis of the hippocampus from SMA and wild-type littermate mice revealed widespread modifications in expression levels of proteins regulating cellular proliferation, migration and development when SMN levels were reduced. This study reveals novel roles for SMN protein in brain development and maintenance and provides the first insights into cellular and molecular pathways disrupted in the brain in a severe form of SMA.

SMN deficiency disrupts brain development in a mouse model of severe spinal muscular atrophy.

It is well established that developmental maturity is a key factor regulating the response of lower motor neurons to injury. The influence of age on the survival of motor neuron cell somata following axotomy is well documented, but it remains unclear whether maturity also influences the degeneration of axonal and synaptic compartments at the neuromuscular junction. Such information is important for our interpretation of data suggesting that neonatal neuromuscular junctions are particularly vulnerable in neurodegenerative conditions that affect the developing postnatal nervous system, such as spinal muscular atrophy. Here, we have examined the role of development in regulating the vulnerability of mouse neuromuscular junctions to two mechanistically distinct degenerative insults: hypoxia and peripheral nerve injury. We report that neuromuscular junctions in neonatal mice are significantly more resistant to both hypoxia and nerve injury than those in adult mice, with a transition from the neonatal to adult phenotype occurring at 2-3 wk of age. We also demonstrate that the reduced vulnerability of neuromuscular junctions observed in neonatal mice is not determined by the maturity of the synapse per se, suggesting that properties associated with the neonatal environment and/or age of the neuron are responsible for modulating vulnerability. Our results are in stark contrast to previous studies showing that motor neuron cell somata are markedly more vulnerable to axotomy in neonatal mice. We conclude that neonatal neuromuscular junctions are resistant to a range of neurodegenerative insults in vivo and that this resistance is developmentally regulated.

The response of neuromuscular junctions to injury is developmentally regulated.

Mice expressing fluorescent proteins in neurons are one of the most powerful tools in modern neuroscience research and are increasingly being used for in vivo studies of neurodegeneration. However, these mice are often used under the assumption that the fluorescent proteins present are biologically inert.

Induction of cell stress in neurons from transgenic mice expressing yellow fluorescent protein: implications for neurodegeneration research.

Low levels of full-length survival motor neuron (SMN) protein cause the motor neuron disease, spinal muscular atrophy (SMA). Although motor neurons undoubtedly contribute directly to SMA pathogenesis, the role of muscle is less clear. We demonstrate significant disruption to the molecular composition of skeletal muscle in pre-symptomatic severe SMA mice, in the absence of any detectable degenerative changes in lower motor neurons and with a molecular profile distinct from that of denervated muscle. Functional cluster analysis of proteomic data and phospho-histone H2AX labelling of DNA damage revealed increased activity of cell death pathways in SMA muscle. Robust upregulation of voltage-dependent anion-selective channel protein 2 (Vdac2) and downregulation of parvalbumin in severe SMA mice was confirmed in a milder SMA mouse model and in human patient muscle biopsies. Molecular pathology of skeletal muscle was ameliorated in mice treated with the FDA-approved histone deacetylase inhibitor, suberoylanilide hydroxamic acid. We conclude that intrinsic pathology of skeletal muscle is an important and reversible event in SMA and also suggest that muscle proteins have the potential to act as novel biomarkers in SMA.

Reversible molecular pathology of skeletal muscle in spinal muscular atrophy.

&#x810A;&#x9AD3;&#x6027;&#x808C;&#x840E;&#x7F29;&#x75C7; (SMA) &#x7279;&#x70B9;&#x662F;&#x8F83;&#x4F4E;&#x7684;&#x8FD0;&#x52A8;&#x795E;&#x7ECF;&#x5143;&#x548C;&#x9AA8;&#x9ABC;&#x808C;&#x840E;&#x7F29;&#x7684;&#x635F;&#x5931;&#x548C;&#x9020;&#x6210;&#x7684;&#x5185; SMN1 &#x57FA;&#x56E0;&#x7A81;&#x53D8;/&#x5220;&#x9664;&#x64CD;&#x4F5C;&#x3002;SMA &#x662F;&#x4E34;&#x5E8A;&#x4E0A;&#x5F02;&#x7C7B;&#xFF0C;&#x4ECE;&#x4E25;&#x91CD;&#x5230;&#x6E29;&#x548C;&#x7684;&#x75BE;&#x75C5;&#x3002;&#x5728;&#x8FD9;&#x91CC;&#xFF0C;&#x6211;&#x4EEC;&#x627E;&#x51FA; Smn&#xFF0C;&#x7528;&#x4E8E;&#x6307;&#x793A;&#x4E2D;&#x95F4; Smn(2B/)(-) &#x5C0F;&#x9F20;&#x6A21;&#x578B;&#x7684; SMA &#x7206;&#x53D1;&#x4E34;&#x754C;&#x9608;&#x503C;&#x3002;&#x7EA6;&#x6709; 15%&#x6B63;&#x5E38;&#x6C34;&#x5E73;&#x7684;&#x5C0F;&#x9F20;&#x663E;&#x793A;&#x7684; Smn(2B/)(-) Smn &#x86CB;&#x767D;&#x51CF;&#x5C11;&#x8EAB;&#x4F53;&#x91CD;&#x91CF;&#x3001; &#x8FD0;&#x52A8;&#x795E;&#x7ECF;&#x5143;&#x4E22;&#x5931;&#x548C;&#x7535;&#x673A;&#x7684;&#x7F3A;&#x9677;&#x3002;&#x91CD;&#x8981;&#x7684;&#x662F;&#xFF0C;&#x8FD9;&#x4E9B;&#x5C0F;&#x9F20;&#x5747;&#x65E0;&#x8868;&#x578B;&#x7684;&#x76F4;&#x5230; P10 28days &#x4E2D;&#x4F4D;&#x6570;&#x4EBA;&#x7684;&#x9884;&#x671F;&#x5BFF;&#x547D;&#x3002;&#x4ED6;&#x4EEC;&#x663E;&#x793A;&#x795E;&#x7ECF;&#x808C;&#x8089;&#x63A5;&#x5934; &#xFF08;NMJ&#xFF09; &#x75C5;&#x7406;&#x5B66;&#x4E0E; inter-muscular &#x7684;&#x6613;&#x635F;&#x6027;&#x548C;&#x524D;&#x548C;&#x7A81;&#x89E6;&#x7F3A;&#x9677;&#x4E4B;&#x95F4;&#x7684;&#x5173;&#x8054;&#x3002;&#x6211;&#x4EEC;&#x7684;&#x5DE5;&#x4F5C;&#x8868;&#x660E;&#x53EA;&#x6709;&#x5FAE;&#x589E;&#x52A0; Smn &#x86CB;&#x767D;&#x6C34;&#x5E73;&#x53EF;&#x80FD;&#x662F;&#x91CD;&#x5927;&#x5229;&#x76CA;&#x56E0;&#x4E3A; Smn(2B/2B) &#x5C0F;&#x9F20;&#x662F;&#x6B63;&#x5E38;&#x7684;&#x8868;&#x3002;&#x8FDB;&#x4E00;&#x6B65;&#xFF0C;&#x8FD9;&#x4E00;&#x53D1;&#x73B0;&#x800C; NMJ &#x75C5;&#x7406;&#x5F02;&#x4E25;&#x91CD;&#x548C;&#x4E2D;&#x95F4; SMA &#x5C0F;&#x9F20;&#x6A21;&#x578B;&#xFF0C;&#x8868;&#x660E;&#x672A;&#x6765;&#x7597;&#x6CD5;&#x80FD;&#x9002;&#x5E94; SMA &#x7684;&#x4E25;&#x91CD;&#x6027;&#x3002;

&#x5728;&#x5C0F;&#x9F20;&#x53D1;&#x53F7;&#x65BD;&#x4EE4;&#x53D1;&#x75C5;&#x7684;&#x5173;&#x8054;&#x4E0D;&#x540C;&#x7684;&#x795E;&#x7ECF;&#x808C;&#x8089;&#x63A5;&#x5934;&#x75C5;&#x7406;&#x4E2D;&#x95F4;&#x810A;&#x9AD3;&#x6027;&#x808C;&#x840E;&#x7F29;&#x75C7;&#x8868;&#x578B;&#x4E34;&#x754C; Smn &#x9608;&#x503C;&#x3002;

Spinal muscular atrophy (SMA) is caused by mutations/deletions within the SMN1 gene and characterized by loss of lower motor neurons and skeletal muscle atrophy. SMA is clinically heterogeneous, with disease ranging from severe to mild. Here, we identify a critical threshold of Smn that dictates onset of SMA in the intermediate Smn(2B/)(-) mouse model. With about 15% normal level of Smn protein, Smn(2B/)(-) mice display reduced body weight, motor neuron loss and motor defects. Importantly, these mice are phenotype-free until P10 with a median life expectancy of 28days. They show neuromuscular junction (NMJ) pathology with an inter-muscular differential vulnerability and an association between pre- and post-synaptic defects. Our work suggests that increasing Smn protein levels only minimally could be of significant benefit since Smn(2B/2B) mice are phenotypically normal. Further, the finding that NMJ pathology varies between severe and intermediate SMA mouse models, suggests that future therapies be adapted to the severity of SMA.

A critical Smn threshold in mice dictates onset of an intermediate spinal muscular atrophy phenotype associated with a distinct neuromuscular junction pathology.

L&#x26;#39;amyotrophie spinale (SMA) est caus&#xE9;e par des mutations ou d&#xE9;l&#xE9;tions dans le g&#xE8;ne SMN1 et caract&#xE9;ris&#xE9; par la perte de neurones moteurs inf&#xE9;rieurs et une atrophie du muscle squelettique. SMA est cliniquement h&#xE9;t&#xE9;rog&#xE8;ne, de la maladie allant de s&#xE9;v&#xE8;re &#xE0; l&#xE9;g&#xE8;re. Ici, nous identifions un seuil critique de Smn qui dicte le d&#xE9;but de la SMA dans le Smn interm&#xE9;diaire (2B /) (-) mod&#xE8;le de souris. Avec environ 15% un niveau normal de la prot&#xE9;ine SMN, Smn (2B /) (-) souris pr&#xE9;sentent r&#xE9;duction du poids corporel, la perte de neurones moteurs et des troubles moteurs. Surtout, ces souris sont ph&#xE9;notype-libre jusqu&#x26;#39;&#xE0; P10 avec une esp&#xE9;rance de vie m&#xE9;diane de 28 jours. Ils montrent jonction neuromusculaire (JNM) pathologie avec une vuln&#xE9;rabilit&#xE9; diff&#xE9;rentiel inter-musculaire et une association entre les d&#xE9;fauts pr&#xE9;-et post-synaptique. Notre travail sugg&#xE8;re que l&#x26;#39;augmentation des niveaux prot&#xE9;ine SMN que tr&#xE8;s peu pourrait &#xEA;tre un avantage important depuis SMN (2B/2B) souris sont ph&#xE9;notypiquement normale. En outre, la constatation que NMJ pathologie varie entre graves et interm&#xE9;diaires des mod&#xE8;les de souris SMA, sugg&#xE8;re que les th&#xE9;rapies futures &#xEA;tre adapt&#xE9;e &#xE0; la gravit&#xE9; de la SMA.

Un seuil critique chez la souris Smn Dicte apparition d&#x26;#39;un ph&#xE9;notype interm&#xE9;diaire amyotrophie spinale associ&#xE9;e &#xE0; une pathologie distincte jonction neuromusculaire

Spinale Muskelatrophie (SMA) ist verursacht durch Mutationen/Streichungen innerhalb des Gens SMN1 und gekennzeichnet durch Verlust des unteren Motoneuronen und Skelettmuskulatur Atrophie. SMA ist klinisch heterogen, mit Krankheit, die von schweren bis hin zu mild. Hier erkennen wir einen kritischen Grenzwert des Smn, der Beginn der SMA im mittleren Smn(2B/)(-) Mausmodell diktiert. Mit etwa 15 % normal Smn-Protein, Smn(2B/)(-) anzeigen von M&auml;usen verringert K&ouml;rper Gewicht, Motoneuron-Verlust und motor M&auml;ngel. Wichtig ist, sind solche M&auml;use Ph&auml;notyp-frei bis P10 mit einer durchschnittlichen Lebenserwartung von 28days. Sie zeigen neuromuskul&auml;re Synapse (NMJ) Pathologie mit einer inter-muscular differenzielle Anf&auml;lligkeit und einer Assoziation zwischen Pre- und post-synaptic M&auml;ngel. Unsere Arbeit legt nahe, dass zunehmende Smn-Protein-Ebene nur minimal von erheblichem Nutzen sein k&ouml;nnte, da Smn(2B/2B) M&auml;usen ph&auml;notypisch normal sind. Weitere, die Feststellung, die NMJ Pathologie variiert zwischen schweren und mittleren SMA Mausmodelle, zufolge zuk&uuml;nftige Therapien mit dem Schweregrad der SMA angepasst werden.

Ein kritischer Grenzwert Smn bei M&auml;usen diktiert Beginn eine fortgeschrittene Spinale Muskelatrophie-Ph&auml;notyp unterschiedliche neuromuskul&auml;re Synapse Pathologie zugeordnet.

Atrofia muscolare spinale (SMA) &egrave; causata da mutazioni/delezioni del gene SMN1 e caratterizzata dalla perdita di neuroni motori inferiori e atrofia del muscolo scheletrico. SMA &egrave; clinicamente eterogenea, con malattie che vanno da gravi a lievi. Qui, noi identificare una soglia critica di Smn che determina l&#39;insorgenza di SMA nel modello del mouse Smn(2B/)(-) intermedio. Con circa 15% livello normale di proteina Smn, Smn(2B/)(-) topi display ridotto corpo peso, perdita di motoneuroni e difetti motori. Soprattutto, questi topi sono privo di fenotipo fino P10 con una speranza di vita mediana di 28days. Essi mostrano giunzione neuromuscolare patologia (NMJ) con una inter-muscular vulnerabilit&agrave; differenziale e un&#39;associazione tra pre e dei difetti. Il nostro lavoro suggerisce che aumentando i livelli di proteina Smn solo in minima parte potrebbe essere di beneficio significativo poich&eacute; Smn(2B/2B) topi sono fenotipicamente normali. Ulteriormente, la constatazione che patologia NMJ varia tra modelli gravi e intermedi del mouse SMA, suggerisce che le terapie future essere adattato alla gravit&agrave; della SMA.

Una soglia critica di Smn in topi determina la comparsa di un fenotipo intermedio atrofia muscolare spinale associato a una patologia della giunzione neuromuscolare distinti.

&#x810A;&#x9AC4;&#x6027;&#x7B4B;&#x840E;&#x7E2E;&#x75C7;&#xFF08;SMA&#xFF09;&#x306F;SMN1&#x907A;&#x4F1D;&#x5B50;&#x5185;&#x306E;&#x5909;&#x7570;/&#x6B20;&#x5931;&#x306B;&#x3088;&#x3063;&#x3066;&#x5F15;&#x304D;&#x8D77;&#x3053;&#x3055;&#x308C;&#x308B;&#x3068;&#x4E0B;&#x4F4D;&#x904B;&#x52D5;&#x30CB;&#x30E5;&#x30FC;&#x30ED;&#x30F3;&#x3068;&#x9AA8;&#x683C;&#x7B4B;&#x840E;&#x7E2E;&#x306E;&#x640D;&#x5931;&#x306B;&#x3088;&#x3063;&#x3066;&#x7279;&#x5FB4;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x308B;&#x3002; SMA&#x306F;&#x3001;&#x91CD;&#x5EA6;&#x304B;&#x3089;&#x8EFD;&#x5EA6;&#x306B;&#x81F3;&#x308B;&#x75BE;&#x60A3;&#x3067;&#x3001;&#x81E8;&#x5E8A;&#x7684;&#x306B;&#x4E0D;&#x5747;&#x8CEA;&#x3067;&#x3042;&#x308B;&#x3002; &#xFF08; - &#xFF09;&#x30DE;&#x30A6;&#x30B9;&#x30E2;&#x30C7;&#x30EB;&#x3053;&#x3053;&#x3067;&#x306F;&#x3001;&#x4E2D;&#x9593;&#x306E;SMN&#xFF08;2B /&#xFF09;&#x306B;SMA&#x306E;&#x767A;&#x75C7;&#x3092;&#x898F;&#x5B9A;&#x3059;&#x308B;SMN&#x306E;&#x30AF;&#x30EA;&#x30C6;&#x30A3;&#x30AB;&#x30EB;&#x306E;&#x3057;&#x304D;&#x3044;&#x5024;&#x3092;&#x8B58;&#x5225;&#x3057;&#x307E;&#x3059;&#x3002; SMN&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x306E;&#x7D04;15&#xFF05;&#x3001;&#x901A;&#x5E38;&#x306E;&#x30EC;&#x30D9;&#x30EB;&#x3067;&#x3001;SMN&#xFF08;2B /&#xFF09;&#xFF08; - &#xFF09;&#x30DE;&#x30A6;&#x30B9;&#x306F;&#x3001;&#x4F53;&#x91CD;&#x6E1B;&#x5C11;&#x3001;&#x904B;&#x52D5;&#x30CB;&#x30E5;&#x30FC;&#x30ED;&#x30F3;&#x306E;&#x640D;&#x5931;&#x3068;&#x30E2;&#x30FC;&#x30BF;&#x306E;&#x6B20;&#x9665;&#x304C;&#x8868;&#x793A;&#x3055;&#x308C;&#x307E;&#x3059;&#x3002;&#x91CD;&#x8981;&#x306A;&#x306E;&#x306F;&#x3001;&#x3053;&#x308C;&#x3089;&#x306E;&#x30DE;&#x30A6;&#x30B9;&#x306F;&#x3001;28days&#x306E;&#x4E2D;&#x592E;&#x5024;&#x306F;&#x5E73;&#x5747;&#x5BFF;&#x547D;&#x3067;P10&#x307E;&#x3067;&#x8868;&#x73FE;&#x578B;&#x30D5;&#x30EA;&#x30FC;&#x3067;&#x3059;&#x3002;&#x5F7C;&#x3089;&#x306F;&#x9593;&#x7B4B;&#x8089;&#x306E;&#x5DEE;&#x306E;&#x8106;&#x5F31;&#x6027;&#x3068;&#x30D7;&#x30EA;&#xB7;&#x30DD;&#x30B9;&#x30C8;&#x30B7;&#x30CA;&#x30D7;&#x30B9;&#x306E;&#x6B20;&#x9665;&#x3068;&#x306E;&#x9593;&#x306E;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x3068;&#x795E;&#x7D4C;&#x7B4B;&#x63A5;&#x5408;&#x90E8;&#xFF08;NMJ&#xFF09;&#x75C5;&#x7406;&#x3092;&#x793A;&#x3057;&#x3066;&#x3044;&#x307E;&#x3059;&#x3002;&#x79C1;&#x305F;&#x3061;&#x306E;&#x4ED5;&#x4E8B;&#x306F;&#x3001;SMN&#xFF08;2B/2B&#xFF09;&#x30DE;&#x30A6;&#x30B9;&#x8868;&#x73FE;&#x578B;&#x306F;&#x6B63;&#x5E38;&#x3067;&#x3042;&#x308B;&#x305F;&#x3081;&#x3001;&#x6700;&#x5C0F;&#x9650;&#x3057;&#x304B;SMN&#x30BF;&#x30F3;&#x30D1;&#x30AF;&#x8CEA;&#x30EC;&#x30D9;&#x30EB;&#x3092;&#x5897;&#x52A0;&#x3055;&#x305B;&#x308B;&#x91CD;&#x8981;&#x306A;&#x5229;&#x70B9;&#x3067;&#x3042;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x5506;&#x3057;&#x3066;&#x3044;&#x308B;&#x3002;&#x3055;&#x3089;&#x306B;&#x3001;NMJ&#x75C5;&#x7406;&#x304C;&#x6DF1;&#x523B;&#x306A;&#x4E2D;&#x9593;SMA&#x30DE;&#x30A6;&#x30B9;&#x30E2;&#x30C7;&#x30EB;&#x306E;&#x9593;&#x3067;&#x5909;&#x5316;&#x3059;&#x308B;&#x3068;&#x3044;&#x3046;&#x77E5;&#x898B;&#x306F;&#x3001;&#x5C06;&#x6765;&#x306E;&#x6CBB;&#x7642;&#x6CD5;&#x304C;SMA&#x306E;&#x91CD;&#x75C7;&#x5EA6;&#x306B;&#x9069;&#x5FDC;&#x3055;&#x305B;&#x308B;&#x3053;&#x3068;&#x3092;&#x793A;&#x5506;&#x3057;&#x3066;&#x3044;&#x308B;&#x3002;

&#x30DE;&#x30A6;&#x30B9;&#x306E;&#x30AF;&#x30EA;&#x30C6;&#x30A3;&#x30AB;&#x30EB;SMN&#x306E;&#x3057;&#x304D;&#x3044;&#x5024;&#x306F;&#x3001;&#x500B;&#x5225;&#x306E;&#x795E;&#x7D4C;&#x7B4B;&#x63A5;&#x5408;&#x90E8;&#x75C5;&#x7406;&#x5B66;&#x306B;&#x95A2;&#x9023;&#x4ED8;&#x3051;&#x3089;&#x308C;&#x305F;&#x4E2D;&#x9593;&#x810A;&#x9AC4;&#x6027;&#x7B4B;&#x840E;&#x7E2E;&#x75C7;&#x306E;&#x8868;&#x73FE;&#x578B;&#x306E;&#x767A;&#x75C7;&#x3092;&#x898F;&#x5B9A;&#x3059;&#x308B;

&#xADFC;&#xC721; &#xC9C8; &#xCC99;&#xC218; &#xC704;&#xCD95; &#xC99D; (SMA) SMN1 &#xC720;&#xC804;&#xC790; &#xB0B4;&#xC758; &#xB3CC;&#xC5F0;&#xBCC0;&#xC774;/&#xC0AD;&#xC81C;&#xC5D0; &#xC758;&#xD574; &#xBC1C;&#xC0DD; &#xD558; &#xACE0; &#xACE8;&#xACA9; &#xADFC;&#xC721; &#xC704;&#xCD95; &#xB0AE;&#xC740; &#xBAA8;&#xD130; &#xB274;&#xB7F0;&#xC758; &#xC190;&#xC2E4;&#xC5D0; &#xC758;&#xD574; &#xD2B9;&#xC9D5;&#xC785;&#xB2C8;&#xB2E4;. SMA&#xB294; &#xC2EC;&#xAC01;&#xD55C;&#xC5D0;&#xC11C; &#xAC00;&#xBCBC;&#xC6B4;&#xC5D0; &#xC18D;&#xD558;&#xB294; &#xC9C8;&#xD658;&#xC73C;&#xB85C; &#xC784;&#xC0C1;&#xC801;&#xC73C;&#xB85C; &#xB2E4;&#xB978; &#xC720;&#xD615;&#xC758;. &#xC5EC;&#xAE30;, &#xC6B0;&#xB9AC;&#xB294; Smn &#xC9C0;&#xC2DC; &#xC911;&#xAC04; Smn(2B/)(-) &#xB9C8;&#xC6B0;&#xC2A4; &#xBAA8;&#xB378;&#xC5D0;&#xC11C; SMA&#xC758; &#xBC1C;&#xBCD1;&#xC758; &#xC911;&#xC694; &#xD55C; &#xC784;&#xACC4;&#xAC12;&#xC744; &#xC2DD;&#xBCC4; &#xD569;&#xB2C8;&#xB2E4;. &#xC57D; 15 %smn &#xB2E8;&#xBC31;&#xC9C8;, &#xC950;&#xB97C; &#xD45C;&#xC2DC; &#xD558;&#xB294; smn(2b/)(-)&#xC758; &#xC815;&#xC0C1; &#xC218;&#xC900; &#xAC10;&#xC18C; &#xB41C; &#xBAB8; &#xBB34;&#xAC8C;, &#xBAA8;&#xD130; &#xC2E0;&#xACBD; &#xC190;&#xC2E4;&#xACFC; &#xBAA8;&#xD130; &#xACB0;&#xD568;. &#xC911;&#xC694; &#xD55C; &#xAC83;&#xC740;,&#xC774; &#xB9C8;&#xC6B0;&#xC2A4;&#xB294; phenotype &#xBB34;&#xB8CC; p10&#xAE4C;&#xC9C0; 28days&#xC758; &#xD3C9;&#xADE0; &#xC218;&#xBA85;. &#xADF8;&#xB4E4;&#xC740; inter-muscular &#xCC28;&#xB3D9; &#xCDE8;&#xC57D;&#xC810; &#xBC0F; &#xC0AC;&#xC804; &#xBC0F; post-synaptic &#xACB0;&#xD568; &#xAC04;&#xC758; &#xC5F0;&#xACB0; (NMJ) &#xBCD1;&#xB9AC;&#xD559;&#xC744; &#xC2E0;&#xACBD; &#xADFC;&#xC721; &#xD559; &#xAD50;&#xCC28;&#xB85C; &#xBCF4;&#xC5EC;&#xC90D;&#xB2C8;&#xB2E4;. &#xC6B0;&#xB9AC;&#xC758; &#xC791;&#xD488;&#xB9CC; &#xCD5C;&#xC18C;&#xD55C; Smn &#xB2E8;&#xBC31;&#xC9C8; &#xC218;&#xC900;&#xC744; &#xC99D;&#xAC00; &#xB420; &#xC218; &#xC788;&#xB2E4;&#xACE0; &#xC911;&#xC694; &#xD55C; &#xD61C;&#xD0DD;&#xC758; Smn(2B/2B) &#xB9C8;&#xC6B0;&#xC2A4;&#xB294; phenotypically &#xC815;&#xC0C1; &#xC774;&#xD6C4; &#xB098;&#xC654;&#xB2E4;. &#xB610;&#xD55C;, NMJ &#xBCD1; &#xB9AC; &#xC2EC;&#xAC01; &#xD558; &#xACE0; &#xC911;&#xAC04; SMA &#xB9C8;&#xC6B0;&#xC2A4; &#xBAA8;&#xB378; &#xC0AC;&#xC774; &#xCC28;&#xC774;&#xAC00; &#xCC3E;&#xB294; &#xBBF8;&#xB798;&#xC758; &#xCE58;&#xB8CC; SMA&#xC758; &#xC2EC;&#xAC01;&#xB3C4; &#xC801;&#xC6A9;&#xD560; &#xB098;&#xC654;&#xB2E4;.

&#xACE0;&#xC720; &#xC2E0;&#xACBD; &#xADFC;&#xC721; &#xD559; &#xAD50;&#xCC28;&#xB85C; &#xBCD1; &#xB9AC;&#xC640; &#xAD00;&#xB828; &#xB41C; &#xC911;&#xAC04; &#xCC99;&#xC218; &#xADFC;&#xC721; &#xC704;&#xCD95; &#xC99D; &#xD615;&#xC758; &#xB9C8;&#xC6B0;&#xC2A4; &#xC9C0;&#xC2DC; &#xBC1C;&#xBCD1;&#xC5D0; &#xC911;&#xC694; &#xD55C; Smn &#xC784;&#xACC4;&#xAC12;.

La atrofia muscular espinal (SMA) est&#xE1; causada por mutaciones y deleciones en el gen SMN1 y se caracteriza por la p&#xE9;rdida de las neuronas motoras inferiores y la atrofia del m&#xFA;sculo esquel&#xE9;tico. SMA es cl&#xED;nicamente heterog&#xE9;nea, con la enfermedad que van desde graves a leves. En este sentido, identificar a un umbral cr&#xED;tico de SMN que dicta inicio de la SMA en el smn intermedio (2B /) (-) modelo de rat&#xF3;n. Con aproximadamente un 15% el nivel normal de la prote&#xED;na SMN, SMN (2B /) (-) ratones muestran disminuci&#xF3;n del peso corporal, la p&#xE9;rdida de las neuronas motoras y los defectos de motor. Es importante destacar que estos ratones son fenotipo-libre hasta P10, con una esperanza de vida media de 28 d&#xED;as. Ellos muestran la uni&#xF3;n neuromuscular (UNM) patolog&#xED;a con una vulnerabilidad diferencial entre las muscular y una asociaci&#xF3;n entre los defectos de pre y post-sin&#xE1;pticas. Nuestro trabajo sugiere que el aumento de los niveles de prote&#xED;na SMN s&#xF3;lo en forma m&#xED;nima podr&#xED;a ser de gran beneficio desde el SMN (2B/2B) ratones son fenot&#xED;picamente normales. Adem&#xE1;s, el hallazgo de que NMJ patolog&#xED;a var&#xED;a entre modelos de rat&#xF3;n graves e intermedia SMA, sugiere que las terapias futuras adaptarse a la severidad de la SMA.

Un umbral cr&#xED;tico en ratones Smn dicta aparici&#xF3;n de un fenotipo intermedio Atrofia Muscular Espinal asociado con una clara Patolog&#xED;a Neuromuscular Junction

Spinal muscular atrophy (SMA) is the leading genetic cause of infant death. It is caused by mutations/deletions of the survival motor neuron 1 (SMN1) gene and is typified by the loss of spinal cord motor neurons, muscular atrophy, and in severe cases, death. The SMN protein is ubiquitously expressed and various cellular- and tissue-specific functions have been investigated to explain the specific motor neuron loss in SMA. We have previously shown that the RhoA/Rho kinase (ROCK) pathway is misregulated in cellular and animal SMA models, and that inhibition of ROCK with the chemical Y-27632 significantly increased the lifespan of a mouse model of SMA. In the present study, we evaluated the therapeutic potential of the clinically approved ROCK inhibitor fasudil.

Fasudil improves survival and promotes skeletal muscle development in a mouse model of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a devastating childhood motor neuron disease caused by mutations and deletions within the survival motor neuron 1 (SMN1) gene. Although other tissues may be involved, motor neurons remain primary pathological targets, with loss of neuromuscular junctions (NMJs) representing an early and significant event in pathogenesis. Although defects in axonal outgrowth and pathfinding have been observed in cell culture and in lower organisms upon Smn depletion, developmental defects in mouse models have been less obvious. Here, we have employed the Smn(2B/-) mouse model to investigate NMJ remodelling during SMA pathology, induced reinnervation, and paralysis. We show that whilst NMJs are capable of remodelling during pathogenesis, there is a marked reduction in paralysis-induced remodelling and in the nerve-directed re-organisation of acetylcholine receptors. This reduction in remodelling potential could not be attributed to a decreased rate of axonal growth. Finally, we have identified a loss of terminal Schwann cells which could contribute to the defects in remodelling/maintenance observed. Our work demonstrates that there are specific defects in NMJ remodelling in an intermediate SMA mouse model, which could contribute to or underlie pathogenesis in SMA. The development of strategies that can promote the remodelling potential of NMJs may therefore be of significant benefit to SMA patients.

Defects in neuromuscular junction remodelling in the Smn(2B/-) mouse model of spinal muscular atrophy.

SMN1, the causative gene for spinal muscular atrophy (SMA), plays a housekeeping role in the biogenesis of small nuclear RNA ribonucleoproteins. SMN is also present in granular foci along axonal projections of motoneurons, which are the predominant cell type affected in the pathology. These so-called RNA granules mediate the transport of specific mRNAs along neurites and regulate mRNA localization, stability, as well as local translation. Recent work has provided evidence suggesting that SMN may participate in the assembly of RNA granules, but beyond that, the precise nature of its role within these structures remains unclear. Here, we demonstrate that SMN associates with polyribosomes and can repress translation in an in vitro translation system. We further identify the arginine methyltransferase CARM1 as an mRNA that is regulated at the translational level by SMN and find that CARM1 is abnormally up-regulated in spinal cord tissue from SMA mice and in severe type I SMA patient cells. We have previously characterized a novel regulatory pathway in motoneurons involving the SMN-interacting RNA-binding protein HuD and CARM1. Thus, our results suggest the existence of a potential negative feedback loop in this pathway. Importantly, an SMA-causing mutation in the Tudor domain of SMN completely abolished translational repression, a strong indication for the functional significance of this novel SMN activity in the pathology.

A novel function for the survival motoneuron protein as a translational regulator.

The childhood neuromuscular disease spinal muscular atrophy (SMA) is caused by mutations or deletions of the survival motor neuron (SMN1) gene. Although SMA has traditionally been considered a motor neuron disease, the muscle-specific requirement for SMN has never been fully defined. Therefore, the purpose of this study was to investigate muscle defects in mouse models of SMA.

Article	Year
Selective vulnerability of motor neurons and dissociation of pre- and post-synaptic pathology at the neuromuscular junction in mouse models of spinal muscular atrophy. Human molecular genetics\| PubMed ID: 18065780	2008
Loss of translation elongation factor (eEF1A2) expression in vivo differentiates between Wallerian degeneration and dying-back neuronal pathology. Journal of anatomy\| PubMed ID: 19094180	2008
Transcriptional regulation of the AP-1 and Nrf2 target gene sulfiredoxin. Molecules and cells\| PubMed ID: 19326073	2009
Pre-symptomatic development of lower motor neuron connectivity in a mouse model of severe spinal muscular atrophy. Human molecular genetics\| PubMed ID: 19884170	2010
Alternative splicing events are a late feature of pathology in a mouse model of spinal muscular atrophy. PLoS genetics\| PubMed ID: 20019802	2009
Smoking cessation interventions in cancer care: opportunities for oncology nurses and nurse scientists. Annual review of nursing research\| PubMed ID: 20192107	2009
SMN deficiency disrupts brain development in a mouse model of severe spinal muscular atrophy. Human molecular genetics\| PubMed ID: 20705736	2010
The response of neuromuscular junctions to injury is developmentally regulated. FASEB journal : official publication of the Federation of American Societies for Experimental Biology\| PubMed ID: 21228222	2011
Induction of cell stress in neurons from transgenic mice expressing yellow fluorescent protein: implications for neurodegeneration research. PloS one\| PubMed ID: 21408118	2011
Reversible molecular pathology of skeletal muscle in spinal muscular atrophy. Human molecular genetics\| PubMed ID: 21840928	2011
A critical Smn threshold in mice dictates onset of an intermediate spinal muscular atrophy phenotype associated with a distinct neuromuscular junction pathology. Neuromuscular disorders : NMD\| PubMed ID: 22071333	2011
Fasudil improves survival and promotes skeletal muscle development in a mouse model of spinal muscular atrophy. BMC medicine\| PubMed ID: 22397316	2012
Defects in neuromuscular junction remodelling in the Smn(2B/-) mouse model of spinal muscular atrophy. Neurobiology of disease\| PubMed ID: 22960106	2012
A novel function for the survival motoneuron protein as a translational regulator. Human molecular genetics\| PubMed ID: 23136128	2013
Early onset muscle weakness and disruption of muscle proteins in mouse models of spinal muscular atrophy. Skeletal muscle\| PubMed ID: 24119341	2013

Lyndsay Murray

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