Differential gene expression following SCI in trkB.T1 null
ABSTRACT: We asked what genes are significantly differentially regulated in the spinal cord of SCI trkB.T1 WT and trkB.T1 KO mice. TrkB.T1 is upregulated shortly after SCI although the precise mechanisms underyling this upregulation are poorly understood. In the trkB.T1 null, we show less mechanical allodynia and better locomotor recovery following SCI. The microarray studies helped us to elucidate a signaling pathway that is differently regulated in the WT versus KO mice at 1 day after SCI. In this study, we did not examine gene changes within a genotype after SCI. Rather, we examined DGE by genotype at each time point. Spinal cord tissue from WT and KO mice in a sham condition (intact spinal cord) versus 1D, 3D and 7D following SCI was harvested for microarray analyses.
Project description:We have previously shown that Il1a-knockout (KO) mice exhibit rapid (at day 1) and persistent improvements in locomotion associated with reduced lesion volume compared with Il1b-KO mice and C57BL/6 controls after traumatic spinal cord injury (SCI). To investigate the mechanism by which Il1a mediates its detrimental effect, we analyzed the transcriptome of the injured spinal cord of Il1a-KO, Il1b-KO and C57BL/6 mice at 24 hours after SCI using GeneChip microarrays. Il1a-KO, Il1b-KO and C57BL/6 mice were subjected to a 50-kdyn SCI and a 6-mm spinal cord segment centered over the site of contusion extracted for RNA isolation and microarray analysis.
Project description:Spinal cord injury (SCI) represents a major debilitating health issue with a direct socioeconomic burden on the public and private sectors worldwide. Although several studies have been conducted to identify the molecular progression of injury sequel due from the lesion site, still the exact underlying mechanisms and pathways of injury development have not been fully elucidated. In this work, based on OMICs, 3D MALDI imaging, cytokines arrays, confocal imaging we established for the first time that molecular and cellular processes occurring after spinal cord injury (SCI) are altered between the lesion proximity, i.e., rostral and caudal segments nearby the lesion (R1-C1) whereas segments distant from R1-C1, i.e., R2-C2 and R3-C3 levels co-expressed factors implicated in neurogenesis. Delay in T regulators recruitment between R1 and C1 favor discrepancies between the two segments. This is also reinforced by presence of neurites outgrowth inhibitors in C1, absent in R1. Moreover, the presence of immunoglobulins (IgGs) in neurons at the lesion site at 3 days, validated by mass spectrometry, may present additional factor that contributes to limited regeneration. Treatment in vivo with anti-CD20 one hour after SCI did not improve locomotor function and IgG expression. These results open the door of a novel view of the SCI treatment by considering the C1 as the therapeutic target.
Project description:Purpose: Spinal cord injury (SCI) is a devastating neurological disease without effective treatment. To generate a comprehensive view of the mechanisms involved in SCI pathology, we applied RNA-sequencing (RNA-seq) technology to characterize the temporal changes in global gene expression after contusive SCI in mice. Method Part1: A total of 27 female C57BI/6J mice (10-16 weeks of age; 20-25g; The Jackson Laboratory, Bar Harbor, ME) were used with 9 mice in each of following groups: shame control, 2 and 7 days after SCI. The surgical procedure for SCI were described previously [PMID:23289019]. Briefly, after anesthetization with a mixed solution of ketamine (80 mg/kg, ip) and xylazine (10 mg/kg, ip), mice received a dorsal laminectomy at the 9th thoracic vertebral (T9) level to expose the spinal cord and then a moderate T9 contusive injury using an Infinite Horizons impactor (PrecisionSystems and Instrumentation) at 60 kdyn with the spinestabilized using steel stabilizers inserted under the transverse processes one vertebra above and below the injury [PMID:19196178] . The shame control mice received only a dorsal laminectomy without contusive injury. Afterwards, the wound was sutured in layers, bacitracin ointment(Qualitest Pharmaceuticals,Huntsville, AL) was applied tothe wound area, 0.1mL of a 20 mg/ml stock of gentamicin(ButlerSchein, Dublin, OH) was injected subcutaneously, and the animals recovered on a water-circulating heating pad. Then mice received analgesic agent, buprenorphin(0.05 mg/kg, SQ; Reckitt Benckise, Hull, England)twice a day for two days. Bladders were manually expressed until automatic voiding returned spontaneously, which generally was within 7 days. At 2 or 7 days after SCI, the mice were anesthetized again with ketamine and xylazine and perfused briefly with normal physical saline. The injured spinal cords were then dissected and three 0.5 mm pieces of spinal cord were cut in the injured epicenter. All spinal cords were immediately frozen in liquid nitrogen and processed for RNA isolation. The spinal cords from three mice were combined into one biological replicate for RNA extraction. Three biological replicates were used. Method Part2: RNA-Seq was performed on the polyadenylated fraction of RNA isolated from tissue samples of acute (2D) and subacute phase (7D) and normal tissues (control, denoted as CTR hereafter). Three biological replicates were used for each phase.150-300 ng total RNAs were used for each sequencing library. RNA samples were polyA selected and paired-end sequencing libraries were constructed using TruSeq RNA Sample Prep Kit as described in the TruSeq RNA Sample Preparation V2 Guide (Illumina).The samples were then sequenced using the Illumina HiSeq sequencer. More than 30 million 100bp paired-end reads were generated from each biological replicate. Method Part3: Read mapping and Transcriptome construction were done by using optimized pipeline which integrate Tophat followed by Cufflinks. Result: We sequenced tissue samples from acute and subacute phases (2 days and 7 days after injury) and systematically characterized the transcriptomes with the goal of identifying pathways and genes critical in SCI pathology. The top enriched functional categories include ‘inflammation response’, ‘neurological disease’, ‘cell death and survival’ and ‘nervous system development’. The top enriched pathways include LXR/RXR Activation and Atherosclerosis Signaling etc. Furthermore, we developed a systems-based analysis framework in order to identify key determinants in the global gene networks of the acute and sub-acute phases. Some candidate genes that we identified have been shown to play important roles in SCI, which demonstrates the validity of our approach. There are also many genes whose functions in SCI have not been well studied and can be further investigated by future experiments. We have also incorporated pharmacogenomic information into our analyses. Among the genes identified, the ones with existing drug information can be readily tested in SCI animal models. Conclusion: in this study we have described an example of how global gene profiling can be translated to screening genes of interest and generating new hypotheses. Additionally, the RNA-seq enables splicing isoform identification and the estimation of expression levels, thus providing useful information for increasing the specificity of drug design and reducing potential side effect. In summary, these results provide a valuable reference data resource for a better understanding of the SCI process in the acute and sub-acute phases. mRNA profiles of Acute/subacute phase Spinal Cord Injury sample from mice were generated by RNA-sequencing using Illumina HiSeq.
Project description:Adult zebrafish have the ability to recover from spinal cord injury and exhibit re-growth of descending axons from the brainstem to the spinal cord. We performed gene expression analysis using microarray to find damage-induced genes after spinal cord injury, which shows that Sox11b mRNA is up-regulated at 11 days after injury. However, the functional relevance of Sox11b for regeneration is not known. Here, we report that the up-regulation of Sox11b mRNA after spinal cord injury is mainly localized in ependymal cells lining the central canal and in newly differentiating neuronal precursors or immature neurons. Using an in vivo morpholino-based gene knockout approach, we demonstrate that Sox11b is essential for locomotor recovery after spinal cord injury. In the injured spinal cord, expression of the neural stem cell associated gene, Nestin, and the proneural gene Ascl1a (Mash1a), which are involved in the self-renewal and cell fate specification of endogenous neural stem cells, respectively, is regulated by Sox11b. Our data indicate that Sox11b promotes neuronal determination of endogenous stem cells and regenerative neurogenesis after spinal cord injury in the adult zebrafish. Enhancing Sox11b expression to promote proliferation and neurogenic determination of endogenous neural stem cells after injury may be a promising strategy in restorative therapy after spinal cord injury in mammals. Spinal cord injury or control sham injury was performed on adult zebrafish. After 4, 12, or 264 hrs, a 5 mm segment of spinal cord was dissected and processed (as a pool from 5 animals) in three replicate groups for each time point and treatment.
Project description:Mice lacking the developmental axon guidance molecule EphA4 have previously been shown to exhibit extensive axonal regeneration and functional recovery following spinal cord injury. To assess mechanisms by which EphA4 may modify the response to neural injury, a microarray was performed on spinal cord tissue from mice with spinal cord injury and sham injured controls. RNA was purified from spinal cords of adult EphA4 knockout and wild-type mice four days following lumbar spinal cord hemisection or laminectomy only and was hybridised to Affymetrix All-Exon Array 1.0 GeneChips. While subsequent analyses indicated that several pathways were altered in EphA4 knockout mice, of particular interest was the attenuated or otherwise altered expression of a number of inflammatory genes, including Arginase 1, expression of which was lower in injured EphA4 knockout compared to wild-type mice. Immunohistological analyses of different cellular components of the immune response were then performed in injured EphA4 knockout and wild-type spinal cords. While numbers of infiltrating CD3+ T cells were low in the hemisection model, a robust CD11b+ macrophage / microglial response was observed post-injury. There was no difference in the overall number or spread of macrophages / activated microglia in injured EphA4 knockout compared to wild-type spinal cords at two, four or fourteen days post-injury, however a lower proportion of Arginase-1 immunoreactive macrophages / activated microglia was observed in EphA4 knockout spinal cords at four days post-injury. Subtle alterations in the neuroinflammatory response in injured EphA4 knockout spinal cords may contribute to the regeneration and recovery observed in these mice following injury. Comparison was made between gene expression in wild-type and knockout samples both before and after injury. 3 replicates per group.
Project description:Spinal cord injury (SCI) causes severe bone loss and disrupts connections between higher centers in the central nervous system (CNS) and bone. Muscle contraction elicited by functional electrical stimulation (FES) partially protects against loss of bone but cellular and molecular events by which this occurs are unknown. Here, using a rat model, we characterized effects of 7 days of contraction-induced loading of tibia and fibula due to FES when begun 16 weeks after SCI. SCI reduced tibial and femoral BMD by 12-17% and promoted bone resorption, as indicated by increased serum CTX; SCI-related changes in CTX were reversed by FES. In cultures of bone marrow cell-derived cells, SCI increased the number of osteoclasts and mRNA levels of the several osteoclast differentiation markers; these changes were significantly reversed by FES. The number of osteoblasts was also reduced by SCI as was the ratio of OPG/RANKL mRNAs therein; the unfavorable change in OPG/RANKL ratio was partially reversed by FES. cDNA microarray analysis revealed that alterations in genes involved in signaling through Wnt, FSH/LH, PTH and calcineurin/NFAT pathways may be linked to the favorable action of FES on SCI-induced bone resorption. In particular, SCI increased levels of the Wnt inhibitors DKK1, sFRP2 and SOST in osteoblasts, These effects were completely or partially reversed by FES. Our results demonstrate an anti-bone resorptive activity of acute FES in bone loss after SCI and suggest potential underlying mechanisms, among them involving increased Wnt signaling to cause more favorable ratios of OPG and RANKL for the inhibition of osteoclastogenesis. The present study indicates that the effects of bone reloading on SCI- related bone remodeling occurred independently of the effects of higher CNS centers on bone. Implantation of the FES microstimulators was performed 14 weeks after SCI. The FES was begun during the 16th week following spinal cord transection. Stimulation was provided for 60 minutes on each training day and consisted of brief periods of contraction (2 seconds) at 40 Hz at 1.5 V with longer periods of rest (18 seconds). Animals received FES on 7 consecutive days; collection of blood and tissues occurred at day at after initiating FES, as described below. The SCI-Sham FES animals received the implant surgery and gastrocnemius ablation during the 14th week after the spinal cord transection, but did not have a stimulator unit inserted; samples were collected from these animals at week 17. To provide age-matched non-SCI controls, additional animals underwent a sham-SCI surgery identical to that for the SCI animals, except that the spinal cord was not transected. Tissues were collected from these animals at 12-14 weeks after surgery. Of note, at this age, animals were sexually mature and their growth minimal. To collect blood and tissues, animals were anesthetized by inhalation of isofluorane followed by removal of the soleus and plantaris muscles after careful dissection and collection of blood by ventricular puncture and aspiration. Animals were euthanized by aortic transaction and tibia and femur were removed as a single piece, leaving the knee joint intact, and placed in a-MEM for isolation of bone marrow cells. Muscles were weighed; weights are expressed after being normalized to body weight before SCI or sham-SCI surgeries to control for individual variations in size.
Project description:Analysis of the expression of genes in the spinal cord using the Affymetrix whole chicken genome chip, Genes expressed in the spinal cord were sorted according to identifiable protein domains using the Ensembl chicken genome assembly and cadherin domain containing genes were then knocked down by RNAi in the spinal cord to analyse their function in spinal cord development
Project description:Microarray analysis has been applied to the study of ALS in order to investigate gene expression in whole spinal cord homogenates of SOD1 G93A mice and human ALS cases, although the massive presence of glial cells and inflammatory factors has made it difficult to define which gene expression changes were motor neuron specific. Recently, laser capture microdissection (LCM), combined with microarray analysis, has allowed the identification of motor neuron specific changes in gene expression in human ALS cases. The aim of the present study is to combine LCM and microarray analysis to study how motor neurons in the spinal cord of transgenic SOD1 G93A mice and transgenic SOD1 WT respond to stimuli determined by the presence of the human mutant protein throughout the evolution of the stages in motor neuron injury Experiment Overall Design: Motor neurons have been isolated from the spinal cord of G93A mice and non transgenic littermates at different time points and the transcription expression profile of the isolated motor neurons has been analysed
Project description:We have investigated the process of disease-induced functional perturbation and the related transcriptional changes occurring in thoraco-lumbar spinal cord extracted from Sprague-Dawley rats heterozygous for the G93A SOD1 gene mutation (Emerging Model 2148 Het Male, Taconic USA; Wyeth and Amyotrophic Lateral Sclerosis Association 2002) using spinal cord from wild type females littermates as reference tissues. Rats were obtained from a breeding project at Taconic Breeding Services (USA). We have applied large-scale gene expression analysis to define the pattern or transcriptional changes occurring in spinal cord from the G93A SOD1 rat model from a pre-symptomatic stage, at disease onset and at end-stage disease, using Bead Array analysis (Illumina, San Diego, USA). We have pooled spinal cord from N:5 transgenic rats for each of the time points considered, using the same pools of spinal cord from sex and age-matched WT rats as reference. In this specific project, the aim was to obtain a gene ontology (GO) pathway analysis of the transcriptional changes induced by the G93A SOD1 mutation in rat spinal cord. Hence, we have opted for a sample pooling strategy, well aware that in so doing, we would not obtaineed information about individuals genes variation across the samples in study but an overall view of the activation of multi-genes molecular signals. Total RNA was isolated from the spinal cords of mutant (G93A SOD1 gene mutation) female rats sacrificed at a pre-symptomatic stage (10-week old), at disease onset and at end stage disease and from age and sex-matched wild type (WT) littermates. RNA samples obtained from spinal cord extracted from rats of the same genetic types and sacrificed at the same time points (e.g. 5 RNA samples from mutant spinal cord from end-stage rats; 5 RNA samples from mutant spinal cord from rats at disease onset; 5 RNA samples from mutant pre-symptomatic rats and 5 RNA samples from spinal cord obtained from age-matched WT rats sacrificed at each of the 3 time points) were pooled and used for gene expression analysis and Ontology analysis of the expression profiles.