Migraine-attributed burden, impact and disability, and migraine-impacted quality of life: Expert consensus on definitions from a Delphi process.

BACKGROUND: Migraine-attributed burden, impact, disability and migraine-impacted quality of life are important concepts in clinical management, clinical and epidemiological research, and health policy, requiring clear and agreed definitions. We aimed to formulate concise and precise definitions of these concepts by expert consensus. METHODS: We searched the terms migraine-attributed burden, impact, disability and migraine-impacted quality of life in Embase and Medline from 1974 and 1946 respectively. We followed a Delphi process to reach consensus on definitions. RESULTS: We found widespread conflation of concepts and inconsistent terminology within publications. Following three Delphi rounds, we defined migraine-attributed burden as "the summation of all negative consequences of the disease or its diagnosis"; migraine-attributed impact as "the effect of the disease, or its diagnosis, on a specified aspect of life, health or wellbeing"; migraine-attributed disability as "physical, cognitive and mental incapacities imposed by the disease"; and migraine-impacted quality of life as "the subjective assessment by a person with the disease of their general wellbeing, position and prospects in life". We complemented each definition with a detailed description. CONCLUSION: These definitions and descriptions should foster consistency and encourage more appropriate use of currently available quantifying instruments and aid the future development of others.

Rod Photoreceptor Neuroprotection in Dark-Reared Pde6brd10 Mice.

Purpose: The purpose of this study was to test the hypothesis that anti-oxidant and / or anti-inflammation drugs that suppress rod death in cyclic light-reared Pde6brd10 mice are also effective in dark-reared Pde6brd10 mice. Methods: In untreated dark-reared Pde6brd10 mice at post-natal (P) days 23 to 24, we measured the outer nuclear layer (ONL) thickness (histology) and dark-light thickness difference in external limiting membrane-retinal pigment epithelium (ELM-RPE) (optical coherence tomography [OCT]), retina layer oxidative stress (QUEnch-assiSTed [QUEST] magnetic resonance imaging [MRI]); and microglia/macrophage-driven inflammation (immunohistology). In dark-reared P50 Pde6brd10 mice, ONL thickness was measured (OCT) in groups given normal chow or chow admixed with methylene blue (MB) + Norgestrel (anti-oxidant, anti-inflammatory), or MB or Norgestrel separately. Results: P24 Pde6brd10 mice showed no significant dark-light ELM-RPE response in superior and inferior retina consistent with high cGMP levels. Norgestrel did not significantly suppress the oxidative stress of Pde6brd10 mice that is only found in superior central outer retina of males at P23. Overt rod degeneration with microglia/macrophage activation was observed but only in the far peripheral superior retina in male and female P23 Pde6brd10 mice. Significant rod protection was measured in female P50 Pde6brd10 mice given 5 mg/kg/day MB + Norgestrel diet; no significant benefit was seen with MB chow or Norgestrel chow alone, nor in similarly treated male mice. Conclusions: In early rod degeneration in dark-reared Pde6brd10 mice, little evidence is found in central retina for spatial associations among biomarkers of the PDE6B mutation, oxidative stress, and rod death; neuroprotection at P50 was limited to a combination of anti-oxidant/anti-inflammation treatment in a sex-specific manner.

Selective Histone Deacetylase 6 Inhibitors Restore Cone Photoreceptor Vision or Outer Segment Morphology in Zebrafish and Mouse Models of Retinal Blindness.

Blindness arising from retinal or macular degeneration results in significant social, health and economic burden. While approved treatments exist for neovascular ('wet') age-related macular degeneration, new therapeutic targets/interventions are needed for the more prevalent atrophic ('dry') form of age-related macular degeneration. Similarly, in inherited retinal diseases, most patients have no access to an effective treatment. Although macular and retinal degenerations are genetically and clinically distinct, common pathological hallmarks can include photoreceptor degeneration, retinal pigment epithelium atrophy, oxidative stress, hypoxia and defective autophagy. Here, we evaluated the potential of selective histone deacetylase 6 inhibitors to preserve retinal morphology or restore vision in zebrafish atp6v0e1 -/- and mouse rd10 models. Histone deacetylase 6 inhibitor, tubastatin A-treated atp6v0e1 -/- zebrafish show marked improvement in photoreceptor outer segment area (44.7%, p = 0.027) and significant improvement in vision (8-fold, p ≤ 0.0001). Tubastatin A-treated rd10/rd10 retinal explants show a significantly (p = 0.016) increased number of outer-segment labeled cone photoreceptors. In vitro, ATP6V0E1 regulated HIF-1α activity, but significant regulation of HIF-1α by histone deacetylase 6 inhibition in the retina was not detected. Proteomic profiling identified ubiquitin-proteasome, phototransduction, metabolism and phagosome as pathways, whose altered expression correlated with histone deacetylase 6 inhibitor mediated restoration of vision.

Norgestrel, a Progesterone Analogue, Promotes Significant Long-Term Neuroprotection of Cone Photoreceptors in a Mouse Model of Retinal Disease.

Purpose: Retinitis pigmentosa (RP) refers to a group of inherited blinding retinal diseases, whereby the death of mutated rod photoreceptors is followed closely by the death of cone photoreceptors. Cone cell death can be hugely debilitating as color/daytime vision becomes impaired. Thus, treatments that are effective against cone cell death are urgently needed. Our research has been working toward development of a neuroprotective treatment for RP. We have previously demonstrated significant neuroprotective properties of norgestrel, a progesterone analogue, in the mouse retina. The current study further investigates the potential of norgestrel as a treatment for RP, with a focus on long-term preservation of cone photoreceptors. Methods: Using the well-established rd10 mouse model of RP, we administered a norgestrel-supplemented diet at postnatal day (P)30, following widespread loss of rod photoreceptors and at the outset of cone degeneration. We subsequently assessed cone cell morphology and retinal function at P50, P60, and P80, using immunohistochemistry, electroretinograph recordings, and optomotor testing. Results: While cone cell degeneration was widespread in the untreated rd10 retina, we observed profound preservation of cone photoreceptor morphology in the norgestrel-treated mice for at least 50 days, out to P80. This was demonstrated by up to 28-fold more cone arrestin-positive photoreceptors. This protection transpired to functional preservation at all ages. Conclusions: This work presents norgestrel as an incredibly promising long-term neuroprotective compound for the treatment of RP. Crucially, norgestrel could be used in the mid-late stages of the disease to protect remaining cone cells and help preserve color/daytime vision.

Cell Death Analysis in Retinal Cultures.

Evaluating cell death is essential when investigating neurodegeneration and neuroprotection in the retina. Cell death assays provide us with a means to identify and quantify dying cells in a population. Terminal dUTP nick end-labeling (TUNEL) is one method used for the identification of dying cells. This technique is based upon the enzymatic incorporation of fluorescently tagged DNA base pairs to fragmented DNA. In this chapter, we describe two different techniques employing TUNEL. The first method uses TUNEL to analyze cell death in cultured retinal explants by fluorescence microscopy. The second technique describes a method for measuring cell death in a retinal cell line by flow cytometry.

Microglial-induced Müller cell gliosis is attenuated by progesterone in a mouse model of retinitis pigmentosa.

Norgestrel, a progesterone analogue, has demonstrated neuroprotective effects in a mouse model of retinitis pigmentosa. Neuroprotection is achieved in part through Norgestrels anti-inflammatory properties, alleviating detrimental microglial activity. Gliosis is a feature of many neurodegenerative diseases of the retina, including retinitis pigmentosa. Müller glia, a type of macroglia found in the retina, are major contributors of gliosis, characterized by the upregulation of glial fibrillary acidic protein (GFAP). Microglia-Müller glia crosstalk has been implicated in the initiation of gliosis. In the rd10 retina, increased microglial activity and gliotic events are observed prior to the onset of photoreceptor loss. We hypothesized that Norgestrels dampening effects on harmful microglial activity would consequently impact on gliosis. In the current study, we explore the role of microglia-Müller glia crosstalk in degeneration and Norgestrel-mediated neuroprotection in the rd10 retina. Norgestrels neuroprotective effects in the rd10 retina coincide with significant decreases in both microglial activity and Müller cell gliosis. Using a Müller glial cell line, rMC-1, and isolated microglia, we show that rd10 microglia stimulate GFAP production in rMC-1 cells. Norgestrel attenuates gliosis through direct actions on both microglia and Müller glia. Norgestrel reduces the release of harmful stimuli from microglia, such as interferon-γ, which might otherwise signal to Müller glia and stimulate gliosis. We propose that Norgestrel also targets Müller cell gliosis directly, by limiting the availability of pSTAT3, a known transcription factor for GFAP. These findings highlight an important aspect to Norgestrels neuroprotective effects in the diseased retina, in combating Müller cell gliosis.

Nuclear membrane-localised NOX4D generates pro-survival ROS in FLT3-ITD-expressing AML.

Internal tandem duplication of the juxtamembrane domain of FMS-like tyrosine kinase 3 (FLT3-ITD) is the most prevalent genetic aberration present in 20-30% of acute myeloid leukaemia (AML) cases and is associated with a poor prognosis. FLT3-ITD expressing cells express elevated levels of NADPH oxidase 4 (NOX4)-generated pro-survival hydrogen peroxide (H2O2) contributing to increased levels of DNA oxidation and double strand breaks. NOX4 is constitutively active and has been found to have various isoforms expressed at multiple locations within a cell. The purpose of this study was to investigate the expression, localisation and regulation of NOX4 28 kDa splice variant, NOX4D. NOX4D has previously been shown to localise to the nucleus and nucleolus in various cell types and is implicated in the generation of reactive oxygen species (ROS) and DNA damage. Here, we demonstrate that FLT3-ITD expressing-AML patient samples as well as -cell lines express the NOX4D isoform resulting in elevated H2O2 levels compared to FLT3-WT expressing cells, as quantified by flow cytometry. Cell fractionation indicated that NOX4D is nuclear membrane-localised in FLT3-ITD expressing cells. Treatment of MV4-11 cells with receptor trafficking inhibitors, tunicamycin and brefeldin A, resulted in deglycosylation of NOX4 and NOX4D. Inhibition of the FLT3 receptor revealed that the FLT3-ITD oncogene is responsible for the production of NOX4D-generated H2O2 in AML. We found that inhibition of the PI3K/AKT and STAT5 pathways resulted in down-regulation of NOX4D-generated pro-survival ROS. Taken together these findings indicate that nuclear membrane-localised NOX4D-generated pro-survival H2O2 may be contributing to genetic instability in FLT3-ITD expressing AML.

Pro-survival redox signalling in progesterone-mediated retinal neuroprotection.

Retinitis pigmentosa (RP) is a group of hereditary retinal diseases, characterised by photoreceptor cell loss. Despite a substantial understanding of the mechanisms leading to cell death, an effective therapeutic strategy is sought. Our laboratory has previously demonstrated the neuroprotective properties of Norgestrel, a progesterone analogue, in the degenerating retina, mediated in part by the neurotrophic factor basic fibroblast growth factor (bFGF). In other retinal studies, we have also presented a pro-survival role for reactive oxygen species (ROS), downstream of bFGF. Thus, we hypothesized that Norgestrel utilises bFGF-driven ROS production to promote photoreceptor survival. Using the 661W photoreceptor-like cell line, we now show that Norgestrel, working through progesterone receptor membrane complex 1 (PGRMC1); generates an early burst of pro-survival bFGF-induced ROS. Using the rd10 mouse model of RP, we confirm that Norgestrel induces a similar early pro-survival increase in retinal ROS. Norgestrel-driven protection in the rd10 retina was attenuated in the presence of antioxidants. This study therefore presents an essential role for ROS signalling in Norgestrel-mediated neuroprotection in vitro and demonstrates that Norgestrel employs a similar pro-survival mechanism in the degenerating retina.

Fractalkine-CX3CR1 signaling is critical for progesterone-mediated neuroprotection in the retina.

Retinitis pigmentosa (RP) encompasses a group of retinal diseases resulting in photoreceptor loss and blindness. We have previously shown in the rd10 mouse model of RP, that rd10 microglia drive degeneration of viable neurons. Norgestrel, a progesterone analogue, primes viable neurons against potential microglial damage. In the current study we wished to investigate this neuroprotective effect further. We were particularly interested in the role of fractalkine-CX3CR1 signaling, previously shown to mediate photoreceptor-microglia crosstalk and promote survival in the rd10 retina. Norgestrel upregulates fractalkine-CX3CR1 signaling in the rd10 retina, coinciding with photoreceptor survival. We show that Norgestrel-treated photoreceptor-like cells, 661Ws, and C57 explants modulate rd10 microglial activity in co-culture, resulting in increased photoreceptor survival. Assessment of Norgestrel's neuroprotective effects when fractalkine was knocked-down in 661 W cells and release of fractalkine was reduced in rd10 explants confirms a crucial role for fractalkine-CX3CR1 signaling in Norgestrel-mediated neuroprotection. To further understand the role of fractalkine in neuroprotection, we assessed the release of 40 cytokines in fractalkine-treated rd10 microglia and explants. In both cases, treatment with fractalkine reduced a variety of pro-inflammatory cytokines. These findings further our understanding of Norgestrel's neuroprotective properties, capable of modulating harmful microglial activity indirectly through photoreceptors, leading to increased neuroprotection.

Progesterone Attenuates Microglial-Driven Retinal Degeneration and Stimulates Protective Fractalkine-CX3CR1 Signaling.

Retinitis pigmentosa (RP) is a degenerative disease leading to photoreceptor cell loss. Mouse models of RP, such as the rd10 mouse (B6.CXBl-Pde6brd10/J), have enhanced our understanding of the disease, allowing for development of potential therapeutics. In 2011, our group first demonstrated that the synthetic progesterone analogue 'Norgestrel' is neuroprotective in two mouse models of retinal degeneration, including the rd10 mouse. We have since elucidated several mechanisms by which Norgestrel protects stressed photoreceptors, such as upregulating growth factors. This study consequently aimed to further characterize Norgestrel's neuroprotective effects. Specifically, we sought to investigate the role that microglia might play; for microglial-derived inflammation has been shown to potentiate neurodegeneration. Dams of post-natal day (P) 10 rd10 pups were given a Norgestrel-supplemented diet (80mg/kg). Upon weaning, pups remained on Norgestrel. Tissue was harvested from P15-P50 rd10 mice on control or Norgestrel-supplemented diet. Norgestrel-diet administration provided significant retinal protection out to P40 in rd10 mice. Alterations in microglial activity coincided with significant protection, implicating microglial changes in Norgestrel-induced neuroprotection. Utilizing primary cultures of retinal microglia and 661W photoreceptor-like cells, we show that rd10 microglia drive neuronal cell death. We reveal a novel role of Norgestrel, acting directly on microglia to reduce pro-inflammatory activation and prevent neuronal cell death. Norgestrel effectively suppresses cytokine, chemokine and danger-associated molecular pattern molecule (DAMP) expression in the rd10 retina. Remarkably, Norgestrel upregulates fractalkine-CX3CR1 signaling 1 000-fold at the RNA level, in the rd10 mouse. Fractalkine-CX3CR1 signaling has been shown to protect neurons by regulating retinal microglial activation and migration. Ultimately, these results present Norgestrel as a promising treatment for RP, with dual actions as a neuroprotective and anti-inflammatory agent in the retina.

Progesterone analogue protects stressed photoreceptors via bFGF-mediated calcium influx.

Retinitis pigmentosa (RP) is a degenerative retinal disease leading to photoreceptor cell loss. In 2011, our group identified the synthetic progesterone 'Norgestrel' as a potential treatment for RP. Subsequent research showed Norgestrel to work through progesterone receptor membrane component 1 (PGRMC1) activation and upregulation of neuroprotective basic fibroblast growth factor (bFGF). Using trophic factor deprivation of 661W photoreceptor-like cells, we aimed to further elucidate the mechanism leading to Norgestrel-induced neuroprotection. In the present manuscript, we show by flow cytometry and live-cell immunofluorescence that Norgestrel induces an increase in cytosolic calcium in both healthy and stressed 661Ws over 24 h. Specific PGRMC1 inhibition by AG205 (1 µm) showed this rise to be PGRMC1-dependent, primarily utilizing calcium from extracellular sources, for blockade of L-type calcium channels by verapamil (50 µm) prevented a Norgestrel-induced calcium influx in stressed cells. Calcium influx was also shown to be bFGF-dependent, for siRNA knock down of bFGF prevented Norgestrel-PGRMC1 induced changes in cytosolic calcium. Notably, we demonstrate PGRMC1-activation is necessary for Norgestrel-induced bFGF upregulation. We propose that Norgestrel protects through the following pathway: binding to and activating PGRMC1 expressed on the surface of photoreceptor cells, PGRMC1 activation drives bFGF upregulation and subsequent calcium influx. Importantly, raised intracellular calcium is critical to Norgestrel's protective efficacy, for extracellular calcium chelation by EGTA abrogates the protective effects of Norgestrel on stressed 661W cells in vitro.

The synthetic progestin norgestrel modulates Nrf2 signaling and acts as an antioxidant in a model of retinal degeneration.

Retinitis pigmentosa (RP) is one of the most common retinal degenerative conditions affecting people worldwide, and is currently incurable. It is characterized by the progressive loss of photoreceptors, in which the death of rod cells leads to the secondary death of cone cells; the cause of eventual blindness. As rod cells die, retinal-oxygen metabolism becomes perturbed, leading to increased levels of reactive oxygen species (ROS) and thus oxidative stress; a key factor in the secondary death of cones. In this study, norgestrel, an FDA-approved synthetic analog of progesterone, was found to be a powerful neuroprotective antioxidant, preventing light-induced ROS in photoreceptor cells, and subsequent cell death. Norgestrel also prevented light-induced photoreceptor morphological changes that were associated with ROS production, and that are characteristic of RP. Further investigation showed that norgestrel acts via post-translational modulation of the major antioxidant transcription factor Nrf2; bringing about its phosphorylation, subsequent nuclear translocation, and increased levels of its effector protein superoxide dismutase 2 (SOD2). In summary, these results demonstrate significant protection of photoreceptor cells from oxidative stress, and underscore the potential of norgestrel as a therapeutic option for RP.

Alterations to retinal architecture prior to photoreceptor loss in a mouse model of retinitis pigmentosa.

Mouse models of retinitis pigmentosa (RP) are essential tools in the pursuit to understand fully what cell types and processes underlie the degeneration observed in RP. Knowledge of these processes is required if we are to develop successful therapies to treat this currently incurable disease. We have used the rd10 mouse model of RP to study retinal morphology prior to photoreceptor loss, using immunohistochemistry and confocal microscopy on cryosections, since little is known about how the mutation affects the retina during this period. We report novel findings that the mutation in the rd10 mouse results in retinal abnormalities earlier than was previously thought. Defects in rod and cone outer segments, bipolar cells, amacrine cells and photoreceptor synapses were apparent in the retina during early stages of postnatal retinal development and prior to the loss of photoreceptors. Additionally, we observed a dramatic response of glial cells during this period. Microglia responded as early as postnatal day (P) 5; ?13 days before any photoreceptor loss is detected with Müller glia and astrocytes exhibiting changes from P10 and P15 respectively. Overall, these findings present pathological aspects to the postnatal development of the rd10 retina, contributing significantly to our understanding of disease onset and progression in the rd10 mouse and provide a valuable resource for the study of retinal dystrophies.

The synthetic progestin norgestrel acts to increase LIF levels in the rd10 mouse model of retinitis pigmentosa.

PURPOSE: Retinal degenerative conditions affect thousands of people worldwide. Retinitis pigmentosa (RP) is among the most common, but it is currently incurable. It is characterized by the progressive death of photoreceptor cells, eventually leading to blindness. Neurotrophic factors play an important role in such retinopathies, and much research has been performed on their use as treatments. Our group previously demonstrated the ability of the synthetic progestin norgestrel to rescue photoreceptors from cell death, the mechanism of which is believed to include upregulation of the neurotrophic factor basic fibroblast growth factor (bFGF). The objective of the present study was to investigate whether the protection provided by norgestrel is likely to be mediated by other neurotrophins. METHODS: The 661W photoreceptor cells and retinal explants from P30 to P40 wild-type (wt) C57BL/6 mice were treated with norgestrel over time. Homozygous rd10/rd10 mice that mimic the human form of RP were fed either a control or a norgestrel-containing diet. Changes in neurotrophic factor expression in response to norgestrel were detected with real-time PCR, western blotting, or immunofluorescence staining. Using specific siRNA, leukemia inhibitory factor (Lif) expression was knocked down in 661W photoreceptor cells that were stressed by serum starvation. Cells were treated with norgestrel followed by measurement of cell viability with (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay. RESULTS: LIF, a potent neuroprotective cytokine, was found to be upregulated in response to norgestrel in vitro and in vivo. Upregulation of LIF in degenerating rd10 retinas coincided with preservation of the photoreceptor layer. We also found LIF was necessary for the norgestrel-mediated rescue of stressed photoreceptor cells from cell death in vitro. CONCLUSIONS: LIF was upregulated in response to norgestrel in all models studied and is necessary for the protective effects of norgestrel in vitro. The increase in LIF expression in rd10 mice undergoing retinal degeneration was concurrent with rescue of the photoreceptor cell layer. These results highlight the ability of norgestrel to induce prosurvival molecules in the compromised retina, underlining norgestrel's potential as a viable drug for treatment of RP.

Progesterone receptor signalling in retinal photoreceptor neuroprotection.

'Norgestrel', a synthetic form of the female hormone progesterone has been identified as potential drug candidate for the treatment of the degenerative eye disease retinitis pigmentosa. However, to date, no work has looked at the compound's specific cellular target. Therefore, this study aimed to identify the receptor target of Norgestrel and begin to examine its potential mechanism of action in the retina. In this work, we identify and characterize the expression of progesterone receptors present in the C57 wild type and rd10 mouse model of retinitis pigmentosa. Classical progesterone receptors A and B (PR A/B), progesterone receptor membrane components 1 and 2 (PGRMC1, PGRMC2) and membrane progesterone receptors α, ß and γ were found to be expressed. All receptors excluding PR A/B were also found in the 661W photoreceptor cell line. PGRMC1 is a key regulator of apoptosis and its expression is up-regulated in the degenerating rd10 mouse retina. Activated by Norgestrel through nuclear trafficking, siRNA knock down of PGRMC1 abrogated the protective properties of Norgestrel on damaged photoreceptors. Furthermore, specific inhibition of PGRMC1 by AG205 blocked Norgestrel-induced protection in stressed retinal explants. Therefore, we conclude that PGRMC1 is crucial to the neuroprotective effects of Norgestrel on stressed photoreceptors. The synthetic progestin 'Norgestrel' has been identified as a potential therapeutic for the treatment of Retinitis Pigmentosa, a degenerative eye disease. However, the mechanism behind this neuroprotection is currently unknown. In this work, we identify 'Progesterone Receptor Membrane Component 1' as the major progesterone receptor eliciting the protective effects of Norgestrel, both in vitro and ex vivo. This furthers our understanding of Norgestrel's molecular mechanism, which we hope will help bring Norgestrel one step closer to the clinic.

Loss of glial neurofascin155 delays developmental synapse elimination at the neuromuscular junction.

Postnatal synapse elimination plays a critical role in sculpting and refining neural connectivity throughout the central and peripheral nervous systems, including the removal of supernumerary axonal inputs from neuromuscular junctions (NMJs). Here, we reveal a novel and important role for myelinating glia in regulating synapse elimination at the mouse NMJ, where loss of a single glial cell protein, the glial isoform of neurofascin (Nfasc155), was sufficient to disrupt postnatal remodeling of synaptic circuitry. Neuromuscular synapses were formed normally in mice lacking Nfasc155, including the establishment of robust neuromuscular synaptic transmission. However, loss of Nfasc155 was sufficient to cause a robust delay in postnatal synapse elimination at the NMJ across all muscle groups examined. Nfasc155 regulated neuronal remodeling independently of its canonical role in forming paranodal axo-glial junctions, as synapse elimination occurred normally in mice lacking the axonal paranodal protein Caspr. Rather, high-resolution proteomic screens revealed that loss of Nfasc155 from glial cells was sufficient to disrupt neuronal cytoskeletal organization and trafficking pathways, resulting in reduced levels of neurofilament light (NF-L) protein in distal axons and motor nerve terminals. Mice lacking NF-L recapitulated the delayed synapse elimination phenotype observed in mice lacking Nfasc155, suggesting that glial cells regulate synapse elimination, at least in part, through modulation of the axonal cytoskeleton. Together, our study reveals a glial cell-dependent pathway regulating the sculpting of neuronal connectivity and synaptic circuitry in the peripheral nervous system.

The influence of storage parameters on measurement of survival motor neuron (SMN) protein levels: implications for pre-clinical studies and clinical trials for spinal muscular atrophy.

Spinal muscular atrophy (SMA) is caused by low levels of survival motor neuron (SMN) protein. A growing number of potential therapeutic strategies for SMA are entering pre-clinical and clinical testing, including gene therapy and antisense oligonucleotide-based approaches. For many such studies SMN protein levels are used as one major readout of treatment efficacy, often necessitating comparisons between samples obtained at different times and/or using different protocols. Whether differences in tissue sampling strategies or storage parameters have an influence on measurable SMN levels remains to be determined. We assessed murine SMN protein immunoreactivity over time and under differing tissue storage conditions. SMN protein levels, measured using sensitive quantitative fluorescent western blotting, declined rapidly over a period of several days following sample collection, especially when protein was extracted immediately and stored at -20°C. Storage of samples at lower temperatures (-80°C), and as intact tissue, led to significantly better preservation of SMN immunoreactivity. However, considerable deterioration in measurable SMN levels occurred, even under optimal storage conditions. These issues need to be taken into consideration when designing and interpreting pre-clinical and clinical SMA studies where SMN protein levels are being measured.

Canonical BMP-Smad signalling promotes neurite growth in rat midbrain dopaminergic neurons.

Ventral midbrain (VM) dopaminergic (DA) neurons project to the dorsal striatum via the nigrostriatal pathway to regulate voluntary movements, and their loss leads to the motor dysfunction seen in Parkinson's disease (PD). Despite recent progress in the understanding of VM DA neurogenesis, the factors regulating nigrostriatal pathway development remain largely unknown. The bone morphogenetic protein (BMP) family regulates neurite growth in the developing nervous system and may contribute to nigrostriatal pathway development. Two related members of this family, BMP2 and growth differentiation factor (GDF)5, have neurotrophic effects, including promotion of neurite growth, on cultured VM DA neurons. However, the molecular mechanisms regulating their effects on DA neurons are unknown. By characterising the temporal expression profiles of endogenous BMP receptors (BMPRs) in the developing and adult rat VM and striatum, this study identified BMP2 and GDF5 as potential regulators of nigrostriatal pathway development. Furthermore, through the use of noggin, dorsomorphin and BMPR/Smad plasmids, this study demonstrated that GDF5- and BMP2-induced neurite outgrowth from cultured VM DA neurons is dependent on BMP type I receptor activation of the Smad 1/5/8 signalling pathway.

A novel mouse model of Warburg Micro syndrome reveals roles for RAB18 in eye development and organisation of the neuronal cytoskeleton.

Mutations in RAB18 have been shown to cause the heterogeneous autosomal recessive disorder Warburg Micro syndrome (WARBM). Individuals with WARBM present with a range of clinical symptoms, including ocular and neurological abnormalities. However, the underlying cellular and molecular pathogenesis of the disorder remains unclear, largely owing to the lack of any robust animal models that phenocopy both the ocular and neurological features of the disease. We report here the generation and characterisation of a novel Rab18-mutant mouse model of WARBM. Rab18-mutant mice are viable and fertile. They present with congenital nuclear cataracts and atonic pupils, recapitulating the characteristic ocular features that are associated with WARBM. Additionally, Rab18-mutant cells exhibit an increase in lipid droplet size following treatment with oleic acid. Lipid droplet abnormalities are a characteristic feature of cells taken from WARBM individuals, as well as cells taken from individuals with other neurodegenerative conditions. Neurological dysfunction is also apparent in Rab18-mutant mice, including progressive weakness of the hind limbs. We show that the neurological defects are, most likely, not caused by gross perturbations in synaptic vesicle recycling in the central or peripheral nervous system. Rather, loss of Rab18 is associated with widespread disruption of the neuronal cytoskeleton, including abnormal accumulations of neurofilament and microtubule proteins in synaptic terminals, and gross disorganisation of the cytoskeleton in peripheral nerves. Global proteomic profiling of peripheral nerves in Rab18-mutant mice reveals significant alterations in several core molecular pathways that regulate cytoskeletal dynamics in neurons. The apparent similarities between the WARBM phenotype and the phenotype that we describe here indicate that the Rab18-mutant mouse provides an important platform for investigation of the disease pathogenesis and therapeutic interventions.

Dysregulation of ubiquitin homeostasis and ß-catenin signaling promote spinal muscular atrophy.

The autosomal recessive neurodegenerative disease spinal muscular atrophy (SMA) results from low levels of survival motor neuron (SMN) protein; however, it is unclear how reduced SMN promotes SMA development. Here, we determined that ubiquitin-dependent pathways regulate neuromuscular pathology in SMA. Using mouse models of SMA, we observed widespread perturbations in ubiquitin homeostasis, including reduced levels of ubiquitin-like modifier activating enzyme 1 (UBA1). SMN physically interacted with UBA1 in neurons, and disruption of Uba1 mRNA splicing was observed in the spinal cords of SMA mice exhibiting disease symptoms. Pharmacological or genetic suppression of UBA1 was sufficient to recapitulate an SMA-like neuromuscular pathology in zebrafish, suggesting that UBA1 directly contributes to disease pathogenesis. Dysregulation of UBA1 and subsequent ubiquitination pathways led to ß-catenin accumulation, and pharmacological inhibition of ß-catenin robustly ameliorated neuromuscular pathology in zebrafish, Drosophila, and mouse models of SMA. UBA1-associated disruption of ß-catenin was restricted to the neuromuscular system in SMA mice; therefore, pharmacological inhibition of ß-catenin in these animals failed to prevent systemic pathology in peripheral tissues and organs, indicating fundamental molecular differences between neuromuscular and systemic SMA pathology. Our data indicate that SMA-associated reduction of UBA1 contributes to neuromuscular pathogenesis through disruption of ubiquitin homeostasis and subsequent ß-catenin signaling, highlighting ubiquitin homeostasis and ß-catenin as potential therapeutic targets for SMA.