Integrins are cell surface receptors that form the link between extracellular matrix molecules of the cell environment and internal cell signalling and the cytoskeleton. They are involved in several processes, e.g. adhesion and migration during development and repair. This review focuses on the role of integrins in axonal regeneration. Integrins participate in spontaneous axonal regeneration in the peripheral nervous system through binding to various ligands that either inhibit or enhance their activation and signalling. Integrin biology is more complex in the central nervous system. Integrins receptors are transported into growing axons during development, but selective polarised transport of integrins limits the regenerative response in adult neurons. Manipulation of integrins and related molecules to control their activation state and localisation within axons is a promising route towards stimulating effective regeneration in the central nervous system.

• Klíčová slova
• axon regeneration, integrin, kindlin, receptor activation state, selective polarised transport, traumatic injury of the nervous system,
• MeSH
• axony fyziologie   MeSH
• integriny genetika   metabolismus   MeSH
• rány a poranění * MeSH
• regenerace nervu fyziologie   MeSH
• regulace genové exprese fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• integriny MeSH

Regeneration capacity is reduced as CNS axons mature. Using laser-mediated axotomy, proteomics and puromycin-based tagging of newly-synthesized proteins in a human embryonic stem cell-derived neuron culture system that allows isolation of axons from cell bodies, we show here that efficient regeneration in younger axons (d45 in culture) is associated with local axonal protein synthesis (local translation). Enhanced regeneration, promoted by co-culture with human glial precursor cells, is associated with increased axonal synthesis of proteins, including those constituting the translation machinery itself. Reduced regeneration, as occurs with the maturation of these axons by d65 in culture, correlates with reduced levels of axonal proteins involved in translation and an inability to respond by increased translation of regeneration promoting axonal mRNAs released from stress granules. Together, our results provide evidence that, as in development and in the PNS, local translation contributes to CNS axon regeneration.

• Klíčová slova
• Axon regeneration, Axotomy, Human stem cells, In vitro live imaging, Local translation, Proteomics,
• MeSH
• axony fyziologie   MeSH
• embryonální kmenové buňky fyziologie   MeSH
• kokultivační techniky MeSH
• lidé MeSH
• proteosyntéza fyziologie   MeSH
• regenerace nervu fyziologie   MeSH
• stárnutí buněk fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Investigating the molecular mechanisms governing developmental axon growth has been a useful approach for identifying new strategies for boosting axon regeneration after injury, with the goal of treating debilitating conditions such as spinal cord injury and vision loss. The picture emerging is that various axonal organelles are important centers for organizing the molecular mechanisms and machinery required for growth cone development and axon extension, and these have recently been targeted to stimulate robust regeneration in the injured adult central nervous system (CNS). This review summarizes recent literature highlighting a central role for organelles such as recycling endosomes, the endoplasmic reticulum, mitochondria, lysosomes, autophagosomes and the proteasome in developmental axon growth, and describes how these organelles can be targeted to promote axon regeneration after injury to the adult CNS. This review also examines the connections between these organelles in developing and regenerating axons, and finally discusses the molecular mechanisms within the axon that are required for successful axon growth.

• Klíčová slova
• axon growth, axon regeneration, inter-organelle membrane contact sites, organelles,
• MeSH
• lidé MeSH
• organely metabolismus   patologie   MeSH
• poranění míchy * metabolismus   patologie   terapie   MeSH
• regenerace nervu * MeSH
• růstové kužele metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Peripheral nervous system (PNS) neurons support axon regeneration into adulthood, whereas central nervous system (CNS) neurons lose regenerative ability after development. To better understand this decline whilst aiming to improve regeneration, we focused on phosphoinositide 3-kinase (PI3K) and its product phosphatidylinositol (3,4,5)-trisphosphate (PIP3 ). We demonstrate that adult PNS neurons utilise two catalytic subunits of PI3K for axon regeneration: p110α and p110δ. However, in the CNS, axonal PIP3 decreases with development at the time when axon transport declines and regenerative competence is lost. Overexpressing p110α in CNS neurons had no effect; however, expression of p110δ restored axonal PIP3 and increased regenerative axon transport. p110δ expression enhanced CNS regeneration in both rat and human neurons and in transgenic mice, functioning in the same way as the hyperactivating H1047R mutation of p110α. Furthermore, viral delivery of p110δ promoted robust regeneration after optic nerve injury. These findings establish a deficit of axonal PIP3 as a key reason for intrinsic regeneration failure and demonstrate that native p110δ facilitates axon regeneration by functioning in a hyperactive fashion.

• Klíčová slova
• CNS axon regeneration, axon transport, optic nerve, p110 delta, phosphoinositide 3-kinase,
• MeSH
• axony * MeSH
• centrální nervový systém MeSH
• dospělí MeSH
• fosfatidylinositol-3-kinasy * MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• myši MeSH
• neurony MeSH
• regenerace nervu MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Optineurin (OPTN) mutations are linked to amyotrophic lateral sclerosis (ALS) and normal tension glaucoma (NTG), but a relevant animal model is lacking, and the molecular mechanisms underlying neurodegeneration are unknown. We find that OPTN C-terminus truncation (OPTN∆C) causes late-onset neurodegeneration of retinal ganglion cells (RGCs), optic nerve (ON), and spinal cord motor neurons, preceded by a decrease of axonal mitochondria in mice. We discover that OPTN directly interacts with both microtubules and the mitochondrial transport complex TRAK1/KIF5B, stabilizing them for proper anterograde axonal mitochondrial transport, in a C-terminus dependent manner. Furthermore, overexpressing OPTN/TRAK1/KIF5B prevents not only OPTN truncation-induced, but also ocular hypertension-induced neurodegeneration, and promotes robust ON regeneration. Therefore, in addition to generating animal models for NTG and ALS, our results establish OPTN as a facilitator of the microtubule-dependent mitochondrial transport necessary for adequate axonal mitochondria delivery, and its loss as the likely molecular mechanism of neurodegeneration.

• MeSH
• amyotrofická laterální skleróza genetika   metabolismus   patologie   MeSH
• axonální transport MeSH
• axony * metabolismus   fyziologie   MeSH
• lidé MeSH
• membránové transportní proteiny metabolismus   MeSH
• mikrotubuly metabolismus   MeSH
• mitochondrie * metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• motorické neurony metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nervus opticus metabolismus   patologie   MeSH
• neuroprotekce * MeSH
• normotenzní glaukom genetika   metabolismus   patologie   MeSH
• proteiny buněčného cyklu MeSH
• regenerace nervu * fyziologie   MeSH
• retinální gangliové buňky metabolismus   patologie   MeSH
• transkripční faktor TFIIIA * metabolismus   genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• membránové transportní proteiny MeSH
• OPTN protein, human MeSH Prohlížeč
• Optn protein, mouse MeSH Prohlížeč
• proteiny buněčného cyklu MeSH
• transkripční faktor TFIIIA * MeSH

Wallerian degeneration is a cascade of stereotypical events in reaction to injury of nerve fibres. These events consist of cellular and molecular alterations, including macrophage invasion, activation of Schwann cells, as well as neurotrophin and cytokine upregulation. This review focuses on cellular and molecular changes distal to various types of peripheral nerve injury which simultaneously contribute to axonal regeneration and neuropathic pain induction. In addition to the stereotypical events of Wallerian degeneration, various types of nerve damage provide different conditions for both axonal regeneration and neuropathic pain induction. Wallerian degeneration of injured peripheral nerve is associated with an inflammatory response including rapid upregulation of the immune signal molecules like cytokines, chemokines and transcription factors with both beneficial and detrimental effects on nerve regeneration or neuropathic pain induction. A better understanding of the molecular interactions between the immune system and peripheral nerve injury would open the possibility for targeting these inflammatory mediators in therapeutic interventions. Understanding the pleiotropic effects of cytokines/chemokines, however, requires investigating their highly specific pathways and precise points of action.

• MeSH
• axony fyziologie   MeSH
• buněčná imunita imunologie   MeSH
• lidé MeSH
• modely neurologické MeSH
• modely u zvířat MeSH
• myši MeSH
• neuralgie patofyziologie   MeSH
• neurogenní zánět imunologie   metabolismus   patofyziologie   MeSH
• periferní nervy imunologie   patofyziologie   MeSH
• poranění periferního nervu MeSH
• regenerace nervu fyziologie   MeSH
• Wallerova degenerace imunologie   metabolismus   patofyziologie   MeSH
• zánět imunologie   metabolismus   patofyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The peripheral branch of sensory dorsal root ganglion (DRG) neurons regenerates readily after injury unlike their central branch in the spinal cord. However, extensive regeneration and reconnection of sensory axons in the spinal cord can be driven by the expression of α9 integrin and its activator kindlin-1 (α9k1), which enable axons to interact with tenascin-C. To elucidate the mechanisms and downstream pathways affected by activated integrin expression and central regeneration, we conducted transcriptomic analyses of adult male rat DRG sensory neurons transduced with α9k1, and controls, with and without axotomy of the central branch. Expression of α9k1 without the central axotomy led to upregulation of a known PNS regeneration program, including many genes associated with peripheral nerve regeneration. Coupling α9k1 treatment with dorsal root axotomy led to extensive central axonal regeneration. In addition to the program upregulated by α9k1 expression, regeneration in the spinal cord led to expression of a distinctive CNS regeneration program, including genes associated with ubiquitination, autophagy, endoplasmic reticulum (ER), trafficking, and signaling. Pharmacological inhibition of these processes blocked the regeneration of axons from DRGs and human iPSC-derived sensory neurons, validating their causal contributions to sensory regeneration. This CNS regeneration-associated program showed little correlation with either embryonic development or PNS regeneration programs. Potential transcriptional drivers of this CNS program coupled to regeneration include Mef2a, Runx3, E2f4, and Yy1. Signaling from integrins primes sensory neurons for regeneration, but their axon growth in the CNS is associated with an additional distinctive program that differs from that involved in PNS regeneration.SIGNIFICANCE STATEMENT Restoration of neurologic function after spinal cord injury has yet to be achieved in human patients. To accomplish this, severed nerve fibers must be made to regenerate. Reconstruction of nerve pathways has not been possible, but recently, a method for stimulating long-distance axon regeneration of sensory fibers in rodents has been developed. This research uses profiling of messenger RNAs in the regenerating sensory neurons to discover which mechanisms are activated. This study shows that the regenerating neurons initiate a novel CNS regeneration program which includes molecular transport, autophagy, ubiquitination, and modulation of the endoplasmic reticulum (ER). The study identifies mechanisms that neurons need to activate to regenerate their nerve fibers.

• Klíčová slova
• autophagy, axon regeneration, integrin, sensory, signaling, spinal cord,
• MeSH
• axony * fyziologie   MeSH
• integriny metabolismus   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• mícha metabolismus   MeSH
• nervové receptory fyziologie   MeSH
• poranění míchy * terapie   metabolismus   MeSH
• potkani Sprague-Dawley MeSH
• regenerace nervu fyziologie   MeSH
• spinální ganglia metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• integriny MeSH

This chapter provides a review of immune reactions involved in classic as well as alternative methods of peripheral nerve regeneration, and mainly with a view to understanding their beneficial effects. Axonal degeneration distal to nerve damage triggers a cascade of inflammatory events alongside injured nerve fibers known as Wallerian degeneration (WD). The early inflammatory reactions of WD comprise the complement system, arachidonic acid metabolites, and inflammatory mediators that are related to myelin fragmentation and activation of Schwann cells. Fine-tuned upregulation of the cytokine/chemokine network by Schwann cells activates resident and hematogenous macrophages to complete the clearance of axonal and myelin debris and stimulate regrowth of axonal sprouts. In addition to local effects, immune reactions of neuronal bodies and glial cells are also implicated in the survival and conditioning of neurons to regenerate severed nerves. Understanding of the cellular and molecular interactions between the immune system and peripheral nerve injury opens new possibilities for targeting inflammatory mediators to improve functional reinnervation.

• Klíčová slova
• Axonal regeneration, Cytokines, Immune cells, Inflammatory mediators, Neuroinflammation, Wallerian degeneration,
• MeSH
• cytokiny imunologie   metabolismus   MeSH
• lidé MeSH
• periferní nervy imunologie   metabolismus   MeSH
• poranění periferního nervu imunologie   metabolismus   MeSH
• regenerace nervu fyziologie   MeSH
• signální transdukce fyziologie   MeSH
• Wallerova degenerace imunologie   metabolismus   MeSH
• zánět imunologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• cytokiny MeSH

A soft agar culture system was used for the cultivation of spinal cord slices with the purpose of improving the evaluation of the dynamics of axonal outgrowth and development. Slices of the spinal cord of 15-day-old fetal Wistar rats were cultured in a 0.5% agar culture medium. The sprouting and outgrowth of axons from the slices was observed at 6-24-h intervals. The morphology and growth rates of axons could be easily investigated by light microscopy. Quantification of growth parameters of individual neurites is made easy because no cells migrate out of the slices, so that the outgrowth is not masked by migrating neurons, fibroblasts, glial cells etc. The axons had well-developed growth cones, comparable to those observed in liquid medium; the daily growth rate was on average 318 microns during the 6 days of observation, with a maximum of 1050 microns per day. Back-labelling with a fluorescent dye (DiI) indicated that the longest neurites originated from motoneurons. Our experiments show that axons can develop and grow in a soft agar medium without the need for adding any growth promoting factor or substrate molecule.

• MeSH
• agar MeSH
• axony fyziologie   MeSH
• časové faktory MeSH
• histologické techniky * MeSH
• inbrední kmeny potkanů MeSH
• krysa rodu Rattus MeSH
• kultivační média MeSH
• kultivační techniky MeSH
• mícha cytologie   embryologie   ultrastruktura   MeSH
• plod MeSH
• regenerace nervu fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• agar MeSH
• kultivační média MeSH

Optineurin (OPTN) mutations are linked to amyotrophic lateral sclerosis (ALS) and normal tension glaucoma (NTG), but a relevant animal model is lacking, and the molecular mechanisms underlying neurodegeneration are unknown. We found that OPTN C-terminus truncation (OPTN∆C) causes late-onset neurodegeneration of retinal ganglion cells (RGCs), optic nerve (ON), and spinal cord motor neurons, preceded by a striking decrease of axonal mitochondria. Surprisingly, we discover that OPTN directly interacts with both microtubules and the mitochondrial transport complex TRAK1/KIF5B, stabilizing them for proper anterograde axonal mitochondrial transport, in a C-terminus dependent manner. Encouragingly, overexpressing OPTN/TRAK1/KIF5B reverses not only OPTN truncation-induced, but also ocular hypertension-induced neurodegeneration, and promotes striking ON regeneration. Therefore, in addition to generating new animal models for NTG and ALS, our results establish OPTN as a novel facilitator of the microtubule-dependent mitochondrial transport necessary for adequate axonal mitochondria delivery, and its loss as the likely molecular mechanism of neurodegeneration.

• Publikační typ
• časopisecké články MeSH
• preprinty MeSH