Project description:Protein hyperdeimination and deficiency of lyso-phospholipids (LPC 18:1) has been associated with the pathology of demyelinating disease in both humans and mice. We uncovered interesting biology of LPC 18:1, in which LPC 18:1 induced optic nerve function restoration through oligodendrocyte maturation and remyelination in mouse model systems. Our in vitro studies show LPC 18:1 protection against neuron-ectopic hyperdeimination and stimulation of oligodendrocyte maturation, while in vivo investigations recorded optic nerve function improvement following optic nerve injections of LPC 18:1, in contrast with LPC 18:0. Thus, just a change in a single bond renders a dramatic alternation in biological function. The incorporation of isobaric C13-histidine in newly synthesized myelin proteins and quantitative proteome shifts are consistent with remyelination underlying restoration in optic nerve function. These results suggest that exogenous LPC 18:1 may provide a therapeutic avenue for stemming vision loss in demyelinating diseases.
Project description:The optic nerve transfers visual information from the retina to the brain through the axons of retinal ganglion cells (RGCs). In adult mammals, optic nerve injuries and progressive degenerative diseases lead to the irreversible loss of RGCs, resulting in vision loss and blindness. Optogenetic models have proved useful in manipulating the growth of RGCs through expression and stimulation of channelrhodopsins (Chr2) in RGCs using the RGC-specific thy-1 promoter. Using transgenic Chr2 mouse (Thy1-ChR2-EYFP) as a model of regeneration, we profile the lipid changes which occur after traumatic optic nerve crush, light stimulation and forced RGC axonal growth. Thy1-ChR2-EYFP and control (C57BL/6) mice were divided in four groups each - 1) no crush and no stimulation, 2) no crush with stimulation, 3) crush and without stimulation, and 4) crush with stimulation. After euthanasia, the optic nerves were collected for lipidomic analysis. The Bligh and Dyer method was used for lipid extraction, followed by mass spectrometry lipid profiling with a Q-Exactive Orbitrap Liquid Chromatography-Mass Spectrometer (LC MS-MS). The raw scans were analysed with LipidSearch 4.1.3 and the statistical analysis was conducted through Metaboanalyst 4.0. This data is available at Metabolomics Workbench, study ID ST001381: [https://www.metabolomicsworkbench.org/data/DRCCMetadata.php?Mode=Study&StudyID=ST001381&StudyType=MS&ResultType=5].
Project description:We present lipid profiling data from mouse retina and optic nerve after optic nerve crush and during Wnt3a-induced axonal regeneration at 7 and 15 days post-crush. This data is available at the Metabolomics Workbench, http://www.metabolomicsworkbench.org (Project ID: PR000718).
Project description:In adult mammals, retinal ganglion cells (RGCs) fail to regenerate following damage. As a result, RGCs die after acute injury and in progressive degenerative diseases such as glaucoma; this can lead to permanent vision loss and, eventually, blindness. Lipids are crucial for the development and maintenance of cell membranes, myelin sheaths, and cellular signaling pathways, however, little is known about their role in axon injury and repair. Studies examining changes to the lipidome during optic nerve (ON) regeneration could greatly inform treatment strategies, yet these are largely lacking. Experimental animal models of ON regeneration have facilitated the exploration of the molecular determinants that affect RGC axon regeneration. Here, we analyzed lipid profiles of the ON and retina in an ON crush rat model using liquid chromatography-mass spectrometry. Furthermore, we investigated lipidome changes after ON crush followed by intravitreal treatment with Zymosan, a yeast cell wall derivative known to enhance RGC regeneration. This data is available at the NIH Common Fund's Metabolomics Data Repository and Coordinating Center (supported by NIH grant, U01-DK097430) website, the Metabolomics Workbench, http://www.metabolomicsworkbench.org, where it has been assigned Project ID: PR000661. The data can be accessed directly via it's Project DOI: doi: 10.21,228/M87D53.
Project description:Reactive gliosis is a complex process that involves profound changes in gene expression. We used microarray to indentify differentially expressed genes and to investigate the molecular mechanisms of reactive gliosis in optic nerve head in response to optic nerve crush injury. C57Bl/6 female mice were 6-8 weeks old at the time of optic nerve crush surgery. The optic nerve in the left eye was crush 1 mm behind the globe for 10 seconds and the right eye served as contralateral control. The animals were allowed to recover for 1 day, 3 day, 1 week, 3 weeks and 3 months before the optic nerve heads were collected. The naive control mice did not receive any surgery in either eye. Due to the small tissue size of the mouse optic nerve head, two optic nerve heads were pooled together for each microarray chip. The left eyes and the right eyes of two mice were combined respectively to form one pair of experiment and control samples. There were five biological replicates (10 mice) for each condition.
Project description:Neuron-glia interactions at paranodal junctions play important roles in action potential propagation. Among their many functions, they contribute to the passive electrical properties of myelinated nerve fibers and actively regulate the polarized distribution of ion channels along axons. Despite their importance, relatively little is known about the molecules responsible for paranode formation and function. Paranodal junction formation apparently depends on interactions among three cell adhesion molecules: caspr and contactin on the axon and neurofascin 155 (NF-155) on the glial membrane. Using Caspr-null paranodal mutant mice, we demonstrate that loss of paranodal junctions causes failure of NF-155 to partition into lipid rafts, indicating that proteins located at paranodal junctions have biochemical characteristics of lipid raft-associated proteins. Based on this property of paranodal junctions, mass spectrometry of lipid rafts isolated from a pure white matter tract (optic nerve) was used to search for new paranodal proteins. Because we used a relatively crude biochemical preparation, we identified several hundred different proteins. Among these, we found all previously described paranodal proteins. Further analysis based on antibody staining of central and peripheral nerves revealed beta-adducin, septin 2, and sh3p8 as putative paranodal proteins. We describe the localization of these proteins in relation to other markers of nodes, paranodes, and juxtaparanodes in adult and developing nerve fibers. Finally, we describe their distribution in dysmyelinating TremblerJ mice, a model for the peripheral neuropathy Charcot-Marie-Tooth disease.
Project description:Reactive remodeling of optic nerve head astrocytes is consistently observed in glaucoma and other optic nerve injuries. However, it is unknown whether this reactivity is beneficial or harmful for visual function. In this study, we used the Cre recombinase (Cre)-loxP system under regulation of the mouse glial fibrillary acidic protein promoter to knock out the transcription factor signal transducer and activator of transcription 3 (STAT3) from astrocytes and test the effect this has on reactive remodeling, ganglion cell survival, and visual function after experimental glaucoma and nerve crush. After injury, STAT3 knockout mice displayed attenuated astrocyte hypertrophy and reactive remodeling; astrocytes largely maintained their honeycomb organization and glial tubes. These changes were associated with increased loss of ganglion cells and visual function over a 30-day period. Thus, reactive astrocytes play a protective role, preserving visual function. STAT3 signaling is an important mediator of various aspects of the reactive phenotype within optic nerve astrocytes.
Project description:Astrocytes migrate from the optic nerve into the inner retina, forming a template upon which retinal vessels develop. In the Nuc1 rat, mutation in the gene encoding βA3/A1-crystallin disrupts both Notch signalling in astrocytes and formation of the astrocyte template. Here we show that loss of βA3/A1-crystallin in astrocytes does not impede Notch ligand binding or extracellular cleavages. However, it affects vacuolar-type proton ATPase (V-ATPase) activity, thereby compromising acidification of the endolysosomal compartments, leading to reduced γ-secretase-mediated processing and release of the Notch intracellular domain (NICD). Lysosomal-mediated degradation of Notch is also impaired. These defects decrease the level of NICD in the nucleus, inhibiting the expression of Notch target genes. Overexpression of βA3/A1-crystallin in those same astrocytes restored V-ATPase activity and normal endolysosomal acidification, thereby increasing the levels of γ-secretase to facilitate optimal Notch signalling. We postulate that βA3/A1-crystallin is essential for normal endolysosomal acidification, and thereby, normal activation of Notch signalling in astrocytes.