Amyotrophic lateral sclerosis (ALS; Lou Gehrig's disease) affects motor neurons (MNs) in the brain and spinal cord. Understanding the pathophysiology of this condition seems crucial for therapeutic design, yet few electrophysiological studies in actively degenerating animal models have been reported. Here, we report a novel preparation of acute slices from adult mouse spinal cord, allowing visualized whole cell patch-clamp recordings of fluorescent lumbar MN cell bodies from ChAT-eGFP or superoxide dismutase 1-yellow fluorescent protein (SOD1YFP) transgenic animals up to 6 mo of age. We examined 11 intrinsic electrophysiologic properties of adult ChAT-eGFP mouse MNs and classified them into four subtypes based on these parameters. The subtypes could be principally correlated with instantaneous (initial) and steady-state firing rates. We used retrograde tracing using fluorescent dye injected into fast or slow twitch lower extremity muscle with slice recordings from the fluorescent-labeled lumbar MN cell bodies to establish that fast and slow firing MNs are connected with fast and slow twitch muscle, respectively. In a G85R SOD1YFP transgenic mouse model of ALS, which becomes paralyzed by 5-6 mo, where MN cell bodies are fluorescent, enabling the same type of recording from spinal cord tissue slices, we observed that all four MN subtypes were present at 2 mo of age. At 4 mo, by which time substantial neuronal SOD1YFP aggregation and cell loss has occurred and symptoms have developed, one of the fast firing subtypes that innvervates fast twitch muscle was lost. These results begin to describe an order of the pathophysiologic events in ALS.neurodegeneration | motor neurons | amyotrophic lateral sclerosis | electrophysiology A myotrophic lateral sclerosis (ALS; Lou Gehrig's disease) is a progressive and usually lethal neurodegenerative condition prominently featuring loss of motor neurons (MNs) and muscle denervation (1-3). Inherited forms of ALS, accounting for ∼10% of cases, potentially inform about disease mechanisms, including: protein folding and quality control [e.g., mutant superoxide dismutase 1 (SOD1), ubiquilin2, and VCP]; RNA binding proteins (e.g., TDP43, FUS, and HNRNPA1); or a DNA expansion (C9ORF72 hexanucleotide expansion). The clinical courses of the various heritable forms and the 90% of cases that are considered sporadic are not distinct, however, reflecting a potentially shared progressive loss of MNs and motor circuit dysfunction (4).ALS has been modeled in mice that are transgenic for a variety of mutant forms of SOD1, allowing for the study of the trajectory of the condition at various time points (5, 6). Among the studies conducted to date are a number addressing electrophysiological changes. From these studies, however, there does not appear to be a clear consensus on the changes that occur in MNs before and during the development of symptoms (7). For example, whereas research on the neuromuscular junction has revealed preferential denervation of fast twitch (type IIb) muscle fibers (8-10), t...

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by a severe decline of memory performance. A widely studied AD mouse model is the APPswe/PSEN1ΔE9 (APP/PS1) strain, as mice exhibit amyloid plaques as well as impaired memory capacities. To test whether restoring synaptic plasticity and decreasing β-amyloid load by Parkin could represent a potential therapeutic target for AD, we crossed APP/PS1 transgenic mice with transgenic mice overexpressing the ubiquitin ligase Parkin and analyzed offspring properties. Overexpression of Parkin in APP/PS1 transgenic mice restored activity-dependent synaptic plasticity and rescued behavioral abnormalities. Moreover, overexpression of Parkin was associated with down-regulation of APP protein expression, decreased β-amyloid load and reduced inflammation. Our data suggest that Parkin could be a promising target for AD therapy.

Mutations in the parkin gene are currently thought to be the most common cause of recessive familial Parkinsonism. Parkin functions as an E3 ligase to regulate protein turnover, and its function in mitochondrial quality control has been reported recently. Overexpression of parkin has been found to prevent neuronal degeneration under various conditions both in vivo and in vitro. Here, we generated a transgenic mouse model in which expression of wild type parkin was driven by neuron-specific enolase (NSE) promoter. We reported that both young and old parkin transgenic mice exhibited less reduction of striatal TH protein and number of TH positive neurons in the substantia nigra induced by 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP), compared to wild type littermates. MPTP-induced mitochondrial impairment in the substantia nigra was improved in young parkin transgenic mice. Decreased striatal α-synuclein was demonstrated in old parkin transgenic mice. These results provide reliable evidence from the transgenic mouse model for parkin that overexpression of parkin may attenuate dopaminergic neurodegeneration induced by MPTP through protection of mitochondria and reduction of α-synuclein in the nigrostriatal pathway.

BackgroundPhotoreceptor death leads to vision impairment in several retinal degenerative disorders. Therapies protecting photoreceptor from degeneration remain to be developed. Anti-inflammation, anti-oxidative stress, and neuroprotective effects of celastrol have been demonstrated in a variety of disease models. The current study aimed to investigate the photoreceptor protective effect of celastrol.MethodsBright light-induced retinal degeneration in BALB/c mice was used, and morphological, functional, and molecular changes of retina were evaluated in the absence and presence of celastrol treatment.ResultsSignificant morphological and functional protection was observed as a result of celastrol treatment in bright light-exposed BALB/c mice. Celastrol treatment resulted in suppression of cell death in photoreceptor cells, alleviation of oxidative stress in the retinal pigment epithelium and photoreceptors, downregulation of retinal expression of proinflammatory genes, and suppression of microglia activation and gliosis in the retina. Additionally, leukostasis was found to be induced in the retinal vasculature in light-exposed BALB/c mice, which was significantly attenuated by celastrol treatment. In vitro, celastrol attenuated all-trans-retinal-induced oxidative stress in cultured APRE19 cells. Moreover, celastrol treatment significantly suppressed lipopolysaccharides-stimulated expression of proinflammatory genes in both APRE19 and RAW264.7 cells.ConclusionsThe results demonstrated for the first time that celastrol prevents against light-induced retinal degeneration through inhibition of retinal oxidative stress and inflammation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0516-8) contains supplementary material, which is available to authorized users.

No abstract

The failure of adult CNS neurons to survive and regenerate their axons after injury or in neurodegenerative disease remains a major target for basic and clinical neuroscience. Recent data demonstrated in the adult mouse that exogenous expression of Sry-related high-mobility-box 11 (Sox11) promotes optic nerve regeneration after optic nerve injury but exacerbates the death of a subset of retinal ganglion cells (RGCs), α-RGCs. During development, Sox11 is required for RGC differentiation from retinal progenitor cells (RPCs), and we found that mutation of a single residue to prevent SUMOylation at lysine 91 (K91) increased Sox11 nuclear localization and RGC differentiation in vitro . Here, we explored whether this Sox11 manipulation similarly has stronger effects on RGC survival and optic nerve regeneration. In vitro , we found that non-SUMOylatable Sox11 K91A leads to RGC death and suppresses axon outgrowth in primary neurons. We furthermore found that Sox11 K91A more strongly promotes axon regeneration but also increases RGC death after optic nerve injury in vivo in the adult mouse. RNA sequence (RNA-seq) data showed that Sox11 and Sox11 K91A increase the expression of key signaling pathway genes associated with axon growth and regeneration but downregulated Spp1 and Opn4 expression in RGC cultures, consistent with negatively regulating the survival of α-RGCs and ipRGCs. Thus, Sox11 and its SUMOylation site at K91 regulate gene expression, survival and axon growth in RGCs, and may be explored further as potential regenerative therapies for optic neuropathy.

No abstract

Photoreceptor degeneration is a central pathology of various retinal degenerative diseases which currently lack effective therapies. Antioxidant and anti-inflammatory activities are noted for Panax notoginsenoside saponins (PNS) and related saponin compound(s). However, the photoreceptor protective potentials of PNS or related saponin compound(s) remain unknown. The current study revealed that PNS protected against photoreceptor loss in bright light-exposed BALB/c mice. Combination of ginsenoside Rb1 and Rd, two major saponin compounds of PNS, recapitulated the retinal protection of PNS and attenuated retinal oxidative stress and inflammatory changes. Rb1 or Rd partially alleviated all-trans-Retinal-induced oxidative stress in ARPE19 cells. Rb1 or Rd suppressed lipopolysaccharides (LPS)-induced proinflammatory gene expression in ARPE19 and RAW264.7 cells. Rb1 or Rd also modulated the expression of proinflammatory microRNA, miR-155 and its direct target, anti-inflammatory SHIP1, in LPS-stimulated RAW264.7 cells. The retinal expression of miR-155 and SHIP1 was altered preceding extensive retinal damage, which was maintained at normal level by Rb1 and Rd combination. This work shows for the first time that altered expression of miR-155 and SHIP1 are involved in photoreceptor degeneration. Most importantly, novel retinal protective activities of combination of Rb1 and Rd justify further evaluation for the treatment of related retinal degenerative disorders.