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Axonal Regeneration: Underlying Molecular Mechanisms and Potential Therapeutic Targets. Biomedicines 2022; 10:biomedicines10123186. [PMID: 36551942 PMCID: PMC9775075 DOI: 10.3390/biomedicines10123186] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/21/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022] Open
Abstract
Axons in the peripheral nervous system have the ability to repair themselves after damage, whereas axons in the central nervous system are unable to do so. A common and important characteristic of damage to the spinal cord, brain, and peripheral nerves is the disruption of axonal regrowth. Interestingly, intrinsic growth factors play a significant role in the axonal regeneration of injured nerves. Various factors such as proteomic profile, microtubule stability, ribosomal location, and signalling pathways mark a line between the central and peripheral axons' capacity for self-renewal. Unfortunately, glial scar development, myelin-associated inhibitor molecules, lack of neurotrophic factors, and inflammatory reactions are among the factors that restrict axonal regeneration. Molecular pathways such as cAMP, MAPK, JAK/STAT, ATF3/CREB, BMP/SMAD, AKT/mTORC1/p70S6K, PI3K/AKT, GSK-3β/CLASP, BDNF/Trk, Ras/ERK, integrin/FAK, RhoA/ROCK/LIMK, and POSTN/integrin are activated after nerve injury and are considered significant players in axonal regeneration. In addition to the aforementioned pathways, growth factors, microRNAs, and astrocytes are also commendable participants in regeneration. In this review, we discuss the detailed mechanism of each pathway along with key players that can be potentially valuable targets to help achieve quick axonal healing. We also identify the prospective targets that could help close knowledge gaps in the molecular pathways underlying regeneration and shed light on the creation of more powerful strategies to encourage axonal regeneration after nervous system injury.
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Wei H, Wu X, You Y, Duran RCD, Zheng Y, Narayanan KL, Hai B, Li X, Tallapragada N, Prajapati TJ, Kim DH, Deneen B, Cao QL, Wu JQ. Systematic analysis of purified astrocytes after SCI unveils Zeb2os function during astrogliosis. Cell Rep 2021; 34:108721. [PMID: 33535036 PMCID: PMC7920574 DOI: 10.1016/j.celrep.2021.108721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/24/2020] [Accepted: 01/12/2021] [Indexed: 10/27/2022] Open
Abstract
Spinal cord injury (SCI) is one of the most devastating neural injuries without effective therapeutic solutions. Astrocytes are the predominant component of the scar. Understanding the complex contributions of reactive astrocytes to SCI pathophysiologies is fundamentally important for developing therapeutic strategies. We have studied the molecular changes in the injury environment and the astrocyte-specific responses by astrocyte purification from injured spinal cords from acute to chronic stages. In addition to protein-coding genes, we have systematically analyzed the expression profiles of long non-coding RNAs (lncRNAs) (>200 bp), which are regulatory RNAs that play important roles in the CNS. We have identified a highly conserved lncRNA, Zeb2os, and demonstrated using functional assays that it plays an important role in reactive astrogliosis through the Zeb2os/Zeb2/Stat3 axis. These studies provide valuable insights into the molecular basis of reactive astrogliosis and fill the knowledge gap regarding the function(s) of lncRNAs in astrogliosis and SCI.
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Affiliation(s)
- Haichao Wei
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Xizi Wu
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Yanan You
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Raquel Cuevas-Diaz Duran
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA; Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Monterrey, N.L. 64710, Mexico
| | - Yiyan Zheng
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - K Lakshmi Narayanan
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Bo Hai
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Xu Li
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | | | | | - Dong H Kim
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Benjamin Deneen
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA
| | - Qi-Lin Cao
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA
| | - Jia Qian Wu
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA; Center for Stem Cell and Regenerative Medicine, UT Brown Foundation Institute of Molecular Medicine, Houston, TX 77030, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA.
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UTX/KDM6A deletion promotes the recovery of spinal cord injury by epigenetically triggering intrinsic neural regeneration. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 20:337-349. [PMID: 33553483 PMCID: PMC7820127 DOI: 10.1016/j.omtm.2020.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 12/02/2020] [Indexed: 12/20/2022]
Abstract
Interrupted axons that fail to regenerate mainly cause poor recovery after spinal cord injury (SCI). How neurons epigenetically respond to injury determines the intrinsic growth ability of axons. However, the mechanism underlying epigenetic regulation of axonal regeneration post-SCI remains largely unknown. In this study, we elucidated the role of the epigenetic regulatory network involving ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX)/microRNA-24 (miR-24)/NeuroD1 in axonal regeneration and functional recovery in mice following SCI. Our results showed that UTX was significantly increased post-SCI and repressed axonal regeneration in vitro. However, downregulation of UTX remarkably promoted axonal regeneration. Furthermore, miR-24 was increased post-SCI and positively regulated by UTX. miR-24 also inhibited axonal regeneration. Chromatin immunoprecipitation (ChIP) indicated that UTX binds to the miR-24 promoter and regulates miR-24 expression. Genome sequencing and bioinformatics analysis suggested that NeuroD1 is a potential downstream target of UTX/miR-24. A dual-luciferase reporter assay indicated that miR-24 binds to NeuroD1; moreover, it represses axonal regeneration by negatively regulating the expression of NeuroD1 via modulation of microtubule stability. UTX deletion in vivo prominently promoted axonal regeneration and improved functional recovery post-SCI, and silencing NeuroD1 restored UTX function. Our findings indicate that UTX could be a potential target in SCI.
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Wang Q, Zhang H, Xu H, Zhao Y, Li Z, Li J, Wang H, Zhuge D, Guo X, Xu H, Jones S, Li X, Jia X, Xiao J. Novel multi-drug delivery hydrogel using scar-homing liposomes improves spinal cord injury repair. Am J Cancer Res 2018; 8:4429-4446. [PMID: 30214630 PMCID: PMC6134929 DOI: 10.7150/thno.26717] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/11/2018] [Indexed: 12/15/2022] Open
Abstract
Proper selection and effective delivery of combination drugs targeting multiple pathophysiological pathways key to spinal cord injury (SCI) hold promise to address the thus far scarce clinical therapeutics for improving recovery after SCI. In this study, we aim to develop a clinically feasible way for targeted delivery of multiple drugs with different physiochemical properties to the SCI site, detail the underlying mechanism of neural recovery, and detect any synergistic effect related to combination therapy. Methods: Liposomes (LIP) modified with a scar-targeted tetrapeptide (cysteine-alanine-glutamine-lysine, CAQK) were first constructed to simultaneously encapsulate docetaxel (DTX) and brain-derived neurotrophic factor (BDNF) and then were further added into a thermosensitive heparin-modified poloxamer hydrogel (HP) with affinity-bound acidic fibroblast growth factor (aFGF-HP) for local administration into the SCI site (CAQK-LIP-GFs/DTX@HP) in a rat model. In vivo fluorescence imaging was used to examine the specificity of CAQK-LIP-GFs/DTX binding to the injured site. Multiple comprehensive evaluations including biotin dextran amine anterograde tracing and magnetic resonance imaging were used to detect any synergistic effects and the underlying mechanisms of CAQK-LIP-GFs/DTX@HP both in vivo (rat SCI model) and in vitro (primary neuron). Results: The multiple drugs were effectively delivered to the injured site. The combined application of GFs and DTX supported neuro-regeneration by improving neuronal survival and plasticity, rendering a more permissive extracellular matrix environment with improved regeneration potential. In addition, our combination therapy promoted axonal regeneration via moderation of microtubule function and mitochondrial transport along the regenerating axon. Conclusion: This novel multifunctional therapeutic strategy with a scar-homing delivery system may offer promising translational prospects for the clinical treatment of SCI.
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Liu JM, Lan M, Zhou Y, Chen XY, Huang SH, Liu ZL. Serum Concentrations of Fibrinogen in Patients with Spinal Cord Injury and Its Relationship with Neurologic Function. World Neurosurg 2017; 106:219-223. [PMID: 28673884 DOI: 10.1016/j.wneu.2017.06.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/20/2017] [Accepted: 06/24/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND Many studies have focused on axon regeneration after spinal cord injury (SCI), and fibrinogen has been reported to be an inhibitory factor for axon regeneration. However, most of these studies were based on animal experiments and in vitro trials. Few studies reported serum concentrations of fibrinogen in patients with SCI. OBJECTIVE We sought to investigate the circulating serum concentrations of fibrinogen in patients with SCI and determine the relationship between fibrinogen concentrations and patients' neurologic function. METHODS A total of 306 patients who were diagnosed with acute SCI between January 2008 and March 2016 were included in this study. Patients with traumatic fractures of the extremities at the same period (220 of them with single fracture and 207 with multiple fractures) were enrolled as a control group. Additionally, 151 patients with no injury were involved as the normal group. The fibrinogen concentrations in each group were recorded and compared at different time points, and the correlation between fibrinogen serum concentrations and American Spinal Injury Association impairment scale in patients with SCI were analyzed. RESULTS The mean serum concentrations of fibrinogen within 2 days after injury were 2.63 ± 0.76 g/L in the SCI group, 3.03 ± 0.82 g/L in the single-fracture group, and 2.86 ± 0.91 g/L in the multiple-fractures group, respectively, which were significant higher than those in the normal group (2.33 ± 0.43 g/L). Additionally, the concentrations of fibrinogen in SCI group were significantly lower compared with those in single- and multiple-fractures groups (P < 0.001 and P = 0.001). The positive rate of fibrinogen concentrations was 12.42% in the SCI group, which was significantly lower than that of the single-fracture group (25.45%) and multiple-fractures group (25.13%) (P < 0.01). In patients with SCI, Spearman correlation analysis revealed that a significant correlation was found between fibrinogen serum concentrations and patients' American Spinal Injury Association impairment scales (r = 0.17, P < 0.001). CONCLUSIONS The serum concentrations of fibrinogen in patients with SCI were significantly increased after injury and were correlated with the severity of neurologic deficit in patients with SCI.
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Affiliation(s)
- Jia-Ming Liu
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China
| | - Min Lan
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China
| | - Yang Zhou
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China
| | - Xuan-Yin Chen
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China
| | - Shan-Hu Huang
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China.
| | - Zhi-Li Liu
- Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, PR China.
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