Overexpression of the Fibroblast Growth Factor Receptor 1 (FGFR1) in a Model of Spinal Cord Injury in Rats

Synaptotagmin 4 Supports Spontaneous Axon Sprouting after Spinal Cord Injury

Injuries to the central nervous system (CNS) can cause severe neurological deficits. Axonal regrowth is a fundamental process for the reconstruction of compensatory neuronal networks after injury; however, it is extremely limited in the adult mammalian CNS. In this study, we conducted a loss-of-function genetic screen in cortical neurons, combined with a Web resource-based phenotypic screen, and identified synaptotagmin 4 (Syt4) as a novel regulator of axon elongation. Silencing Syt4 in primary cultured cortical neurons inhibits neurite elongation, with changes in gene expression involved in signaling pathways related to neuronal development. In a spinal cord injury model, inhibition of Syt4 expression in cortical neurons prevented axonal sprouting of the corticospinal tract, as well as neurological recovery after injury. These results provide a novel therapeutic approach to CNS injury by modulating Syt4 function.

Electroacupuncture-Regulated miR-34a-3p/PDCD6 Axis Promotes Post-Spinal Cord Injury Recovery in Both In Vitro and In Vivo Settings

Electroacupuncture (EA) could enhance neuroregeneration and posttraumatic conditions; however, the underlying regulatory mechanisms remain ambiguous. PDCD6 (programmed cell death 6) is an established proapoptotic regulator which is responsible for motoneuronal death. However, its potential regulatory role in post-spinal cord injury (SCI) regeneration has remained largely unknown. Further investigations are warranted to clarify the involvement of PDCD6 post-SCI recovery and the underlying mechanisms. In our study, based on bioinformatics prediction, we found that miR-34a-3p might be an upstream regulator miRNA for PDCD6, which was subsequently validated through combined utilization of the qRT-PCR, western blot, and dual-luciferase reporter system. Our in vitro results showed that miR-34a-3p might promote the in vitro differentiation of neural stem cell (NSC) through suppressing PDCD6 and regulating other important neural markers such as fibroblast growth factor receptor 1 (FGFR1), MAP1/2 (MAP kinase kinases 1/2), myelin basic protein (MBP), βIII-tubulin Class III β-tubulin (βIII tubulin), and glial fibrillary acidic protein (GFAP). Notably, in the post-SCI rat model, exogenous miR-34a-3p agomir obviously inhibited the expression of PDCD6 at the protein level and promoted neuronal proliferation, motoneurons regeneration, and axonal myelination. The restorations at cellular level might contribute to the improved hindlimbs functions of post-SCI rats, which was manifested by the Basso-Beattie-Bresnahan (BBB) locomotor test. The impact of miR-34a-3p was further promoted by EA treatment in vivo. Conclusively, this paper argues that a miR-34a-3p/PDCD6 axis might be a candidate therapeutic target for treating SCI and that the therapeutic effect of EA is driven through this pathway.

New developments in the biology of fibroblast growth factors

The fibroblast growth factor (FGF) family is composed of 18 secreted signaling proteins consisting of canonical FGFs and endocrine FGFs that activate four receptor tyrosine kinases (FGFRs 1-4) and four intracellular proteins (intracellular FGFs or iFGFs) that primarily function to regulate the activity of voltage-gated sodium channels and other molecules. The canonical FGFs, endocrine FGFs, and iFGFs have been reviewed extensively by us and others. In this review, we briefly summarize past reviews and then focus on new developments in the FGF field since our last review in 2015. Some of the highlights in the past 6 years include the use of optogenetic tools, viral vectors, and inducible transgenes to experimentally modulate FGF signaling, the clinical use of small molecule FGFR inhibitors, an expanded understanding of endocrine FGF signaling, functions for FGF signaling in stem cell pluripotency and differentiation, roles for FGF signaling in tissue homeostasis and regeneration, a continuing elaboration of mechanisms of FGF signaling in development, and an expanding appreciation of roles for FGF signaling in neuropsychiatric diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Neurological Diseases > Molecular and Cellular Physiology Congenital Diseases > Stem Cells and Development Cancer > Stem Cells and Development.

Therapeutics effects of [Pyr1] apelin-13 on rat contusion model of spinal cord injury: An experimental study

Spinal cord injury (SCI) can cause various symptoms, including pain, complete or incomplete loss of autonomic, sensory, motor and functions inferior to the site of the damage. Despite wondrous advances in medicine, treating spinal cord injuries remains a thorny issue yet. Recently, the control of inflammatory processes after damage to the nervous system has been noticed as a promising therapeutic target. The goal of the present experiment was to identify the effects of apelin-13 on the histological outcome, inflammatory factors, and functional recovery in the animal contusion model of SCI were analyzed. 40 Female Wistar rats were randomly but equally assigned in laminectomy, contusion, PBS (1 mL PBS, i.p), control group which received apelin-13 (control + apelin, 100 μg/kg, i.p), and apelin-13 treatment groups. In the treatment group, apelin-13 (100 μg/kg) was injected intraperitoneally 30 min after injury. The weight-dropping contusion model was used for inducing SCI. The Basso, Beattie, and Bresnahan scale (BBB), narrow beam test (NBT), rotarod test, and the open-field test was applied to evaluate locomotor and behavioral activity. Real-time polymerase chain reaction (PCR) and ELISA technique was accomplished eight weeks after inducing SCI to measure the level of fibroblast growth factor FGF-1, FGFR1 and the inflammatory factors including interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, and IL-10. Furthermore, histological change was estimated by H&E staining. Our results showed that apelin-13 treatment after SCI led to a significant increase in functional recovery and behavioral tests. Stereological estimation illustrated that apelin-13 could reduce significantly central cavity volume and number of glial cells, and also increase significantly spinal cord volume and number of neural cells. PCR and ELISA evaluation shows a significant increase in IL-10 level and decrease in levels of FGF-1, FGF-R1, and pro-inflammatory cytokines (PIC). This study suggested that apelin-13 has neuroprotective effects by regulating the inflammatory process after SCI.

Optimization of adeno-associated viral vector-mediated transduction of the corticospinal tract: comparison of four promoters

Adeno-associated viral vectors are widely used as vehicles for gene transfer to the nervous system. The promoter and viral vector serotype are two key factors that determine the expression dynamics of the transgene. A previous comparative study has demonstrated that AAV1 displays efficient transduction of layer V corticospinal neurons, but the optimal promoter for transgene expression in corticospinal neurons has not been determined yet. In this paper, we report a side-by-side comparison between four commonly used promoters: the short CMV early enhancer/chicken β actin (sCAG), human cytomegalovirus (hCMV), mouse phosphoglycerate kinase (mPGK) and human synapsin (hSYN) promoter. Reporter constructs with each of these promoters were packaged in AAV1, and were injected in the sensorimotor cortex of rats and mice in order to transduce the corticospinal tract. Transgene expression levels and the cellular transduction profile were examined after 6 weeks. The AAV1 vectors harbouring the hCMV and sCAG promoters resulted in transgene expression in neurons, astrocytes and oligodendrocytes. The mPGK and hSYN promoters directed the strongest transgene expression. The mPGK promoter did drive expression in cortical neurons and oligodendrocytes, while transduction with AAV harbouring the hSYN promoter resulted in neuron-specific expression, including perineuronal net expressing interneurons and layer V corticospinal neurons. This promoter comparison study contributes to improve transgene delivery into the brain and spinal cord. The optimized transduction of the corticospinal tract will be beneficial for spinal cord injury research.

Multifunctional biomimetic spinal cord: New approach to repair spinal cord injuries

The incidence of spinal cord injury (SCI) has been gradually increasing, and the treatment has troubled the medical field all the time. Primary and secondary injuries ultimately lead to nerve impulse conduction block. Microglia and astrocytes excessively accumulate and proliferate to form the glial scar. At present, to reduce the effect of glial scar on nerve regeneration is a hot spot in the research on the treatment of SCI. According to the preliminary experiments, we would like to provide a new bionic spinal cord to reduce the negative effect of glial scar on nerve regeneration. In this hypothesis we designed a new scaffold that combine the common advantage of acellular scaffold of spinal cord and thermosensitive gel, which could continue to release exogenous basic fibroblast growth factor (BFGF) in the spinal lesion area on the basis of BFGF modified thermosensitive gel. Meanwhile, the porosity, pore size and material of the gray matter and white matter regions were distinguished by an isolation layer, so as to induce the directed differentiation of cells into the defect site and promote regeneration of spinal cord tissue.

Molecular characterization and expression analysis of olive flounder (Paralichthys olivaceus) phospholipase C gamma 1 and gamma 2

Phospholipase C gamma 1 and gamma 2 (PLCG1 and PLCG2) are influential in modulating Ca²⁺ and diacylglycerol, second messengers involved in tyrosine kinase-dependent signaling, including growth factor activation. Here, we used RACE (rapid amplification of cDNA ends) to clone cDNA encoding PLCG1 (PoPLCG1) and PLCG2 (PoPLCG2) in the olive flounder (Paralichthys olivaceus). The respective 1313 and 1249 amino acid sequences share high identity with human PLCG1 and PLCG2, and contain the following domains: pleckstrin homology (PH), EF-hand, catalytic X and Y, Src homology 2 (SH2), Src homology 3 (SH3), and C2. Phylogenic analysis and sequence comparison of PoPLCG1 and PoPLCG2 with other PLC isozymes showed a close relationship between the two PLCGs, supported by structural analysis. In addition, tissue expression analysis showed that PoPLCG1 was expressed predominantly in the brain, eye, and heart, whereas PoPLCG2 was expressed principally in gills, esophagus, spleen, and kidney. Following stimulation with LPS and Poly I:C, PoPLCG expression was compared with the expression of inflammatory cytokines IL-1β, IL-6, and TNF-α via reverse transcription-PCR and real-time quantitative PCR. Our results suggest that PoPLCG isozymes perform a critical immune function in olive flounder, being active in pathogen resistance and the inflammation process.

The Function of FGFR1 Signalling in the Spinal Cord: Therapeutic Approaches Using FGFR1 Ligands after Spinal Cord Injury

Extensive research is ongoing that concentrates on finding therapies to enhance CNS regeneration after spinal cord injury (SCI) and to cure paralysis. This review sheds light on the role of the FGFR pathway in the injured spinal cord and discusses various therapies that use FGFR activating ligands to promote regeneration after SCI. We discuss studies that use peripheral nerve grafts or Schwann cell grafts in combination with FGF1 or FGF2 supplementation. Most of these studies show evidence that these therapies successfully enhance axon regeneration into the graft. Further they provide evidence for partial recovery of sensory function shown by electrophysiology and motor activity evidenced by behavioural data. We also present one study that indicates that combination with additional, synergistic factors might further drive the system towards functional regeneration. In essence, this review summarises the potential of nerve and cell grafts combined with FGF1/2 supplementation to improve outcome even after severe spinal cord injury.

Thermo-sensitive hydrogels combined with decellularised matrix deliver bFGF for the functional recovery of rats after a spinal cord injury

Because of the short half-life, either systemic or local administration of bFGF shows significant drawbacks to spinal injury. In this study, an acellular spinal cord scaffold (ASC) was encapsulated in a thermo-sensitive hydrogel to overcome these limitations. The ASC was firstly prepared from the spinal cord of healthy rats and characterized by scanning electronic microscopy and immunohistochemical staining. bFGF could specifically complex with the ASC scaffold via electrostatic or receptor-mediated interactions. The bFGF-ASC complex was further encapsulated into a heparin modified poloxamer (HP) solution to prepare atemperature-sensitive hydrogel (bFGF-ASC-HP). bFGF release from the ASC-HP hydrogel was more slower than that from the bFGF-ASC complex alone. An in vitro cell survival study showed that the bFGF-ASC-HP hydrogel could more effectively promote the proliferation of PC12 cells than a bFGF solution, with an approximate 50% increase in the cell survival rate within 24 h (P < 0.05). Compared with the bFGF solution, bFGF-ASC-HP hydrogel displayed enhanced inhibition of glial scars and obviously improved the functional recovery of the SCI model rat through regeneration of nerve axons and the differentiation of the neural stem cells. In summary, an ASC-HP hydrogel might be a promising carrier to deliver bFGF to an injured spinal cord.