Axon guidance relies on precise translation of extracellular signal gradients into local changes in cytoskeletal dynamics, but the molecular mechanisms regulating dose-dependent responses of growth cones are still poorly understood. Here, we show that during embryonic development in growing axons, a low level of Semaphorin3A stimulation is buffered by the prolyl isomerase Pin1. We demonstrate that Pin1 stabilizes CDK5-phosphorylated CRMP2A, the major isoform of CRMP2 in distal axons. Consequently, Pin1 knockdown or knockout reduces CRMP2A levels specifically in distal axons and inhibits axon growth, which can be fully rescued by Pin1 or CRMP2A expression. Moreover, Pin1 knockdown or knockout increases sensitivity to Sema3A-induced growth cone collapse in vitro and in vivo, leading to developmental abnormalities in axon guidance. These results identify an important isoform-specific function and regulation of CRMP2A in controlling axon growth and uncover Pin1-catalyzed prolyl isomerization as a regulatory mechanism in axon guidance.

• MeSH
• Axons metabolism   MeSH
• Zebrafish MeSH
• Phosphorylation MeSH
• Immunohistochemistry MeSH
• Immunoprecipitation MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Peptidylprolyl Isomerase genetics   metabolism   MeSH
• Zebrafish Proteins genetics   metabolism   MeSH
• Nerve Tissue Proteins genetics   metabolism   MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH

Regulation of axon guidance and pruning of inappropriate synapses by class 3 semaphorins are key to the development of neural circuits. Collapsin response mediator protein 2 (CRMP2) has been shown to regulate axon guidance by mediating semaphorin 3A (Sema3A) signaling; however, nothing is known about its role in synapse pruning. Here, using newly generated crmp2-/- mice we demonstrate that CRMP2 has a moderate effect on Sema3A-dependent axon guidance in vivo, and its deficiency leads to a mild defect in axon guidance in peripheral nerves and the corpus callosum. Surprisingly, crmp2-/- mice display prominent defects in stereotyped axon pruning in hippocampus and visual cortex and altered dendritic spine remodeling, which is consistent with impaired Sema3F signaling and with models of autism spectrum disorder (ASD). We demonstrate that CRMP2 mediates Sema3F signaling in primary neurons and that crmp2-/- mice display ASD-related social behavior changes in the early postnatal period as well as in adults. Together, we demonstrate that CRMP2 mediates Sema3F-dependent synapse pruning and its dysfunction shares histological and behavioral features of ASD.

• MeSH
• Dendritic Spines MeSH
• Membrane Proteins physiology   MeSH
• Intercellular Signaling Peptides and Proteins genetics   MeSH
• Mice, Knockout MeSH
• Mice MeSH
• Neurons MeSH
• Neuronal Plasticity MeSH
• Autism Spectrum Disorder * MeSH
• Nerve Tissue Proteins genetics   physiology   MeSH
• Semaphorins * MeSH
• Signal Transduction MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

• MeSH
• Axons * physiology   MeSH
• Humans MeSH
• Axon Guidance * physiology   MeSH
• Neuronal Outgrowth * MeSH
• Nerve Tissue Proteins MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH

Ear development requires the transcription factors ATOH1 for hair cell differentiation and NEUROD1 for sensory neuron development. In addition, NEUROD1 negatively regulates Atoh1 gene expression. As we previously showed that deletion of the Neurod1 gene in the cochlea results in axon guidance defects and excessive peripheral innervation of the sensory epithelium, we hypothesized that some of the innervation defects may be a result of abnormalities in NEUROD1 and ATOH1 interactions. To characterize the interdependency of ATOH1 and NEUROD1 in inner ear development, we generated a new Atoh1/Neurod1 double null conditional deletion mutant. Through careful comparison of the effects of single Atoh1 or Neurod1 gene deletion with combined double Atoh1 and Neurod1 deletion, we demonstrate that NEUROD1-ATOH1 interactions are not important for the Neurod1 null innervation phenotype. We report that neurons lacking Neurod1 can innervate the flat epithelium without any sensory hair cells or supporting cells left after Atoh1 deletion, indicating that neurons with Neurod1 deletion do not require the presence of hair cells for axon growth. Moreover, transcriptome analysis identified genes encoding axon guidance and neurite growth molecules that are dysregulated in the Neurod1 deletion mutant. Taken together, we demonstrate that much of the projections of NEUROD1-deprived inner ear sensory neurons are regulated cell-autonomously.

• MeSH
• Apoptosis genetics   MeSH
• Axons metabolism   MeSH
• Models, Biological MeSH
• Cell Differentiation genetics   MeSH
• Organ of Corti pathology   MeSH
• Gene Deletion MeSH
• Epithelium metabolism   MeSH
• Spiral Ganglion metabolism   MeSH
• Mutation genetics   MeSH
• Mice, Knockout MeSH
• Nerve Fibers metabolism   MeSH
• Nerve Tissue Proteins genetics   metabolism   MeSH
• Gene Expression Regulation MeSH
• Gene Expression Profiling MeSH
• Basic Helix-Loop-Helix Transcription Factors genetics   metabolism   MeSH
• SOXB1 Transcription Factors metabolism   MeSH
• Hair Cells, Auditory metabolism   pathology   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

Directing the organization of cells into a tissue with defined architectures is one use of biomaterials for regenerative medicine. To this end, hydrogels are widely investigated as they have mechanical properties similar to native soft tissues and can be formed in situ to conform to a defect. Herein, we describe the development of porous hydrogel tubes fabricated through a two-step polymerization process with an intermediate microsphere phase that provides macroscale porosity (66.5%) for cell infiltration. These tubes were investigated in a spinal cord injury model, with the tubes assembled to conform to the injury and to provide an orientation that guides axons through the injury. Implanted tubes had good apposition and were integrated with the host tissue due to cell infiltration, with a transient increase in immune cell infiltration at 1 week that resolved by 2 weeks post injury compared to a gelfoam control. The glial scar was significantly reduced relative to control, which enabled robust axon growth along the inner and outer surface of the tubes. Axon density within the hydrogel tubes (1744 axons/mm2) was significantly increased more than 3-fold compared to the control (456 axons/mm2), with approximately 30% of axons within the tube myelinated. Furthermore, implantation of hydrogel tubes enhanced functional recovery relative to control. This modular assembly of porous tubes to fill a defect and directionally orient tissue growth could be extended beyond spinal cord injury to other tissues, such as vascular or musculoskeletal tissue. STATEMENT OF SIGNIFICANCE: Tissue engineering approaches that mimic the native architecture of healthy tissue are needed following injury. Traditionally, pre-molded scaffolds have been implemented but require a priori knowledge of wound geometries. Conversely, hydrogels can conform to any injury, but do not guide bi-directional regeneration. In this work, we investigate the feasibility of a system of modular hydrogel tubes to promote bi-directional regeneration after spinal cord injury. This system allows for tubes to be cut to size during surgery and implanted one-by-one to fill any injury, while providing bi-directional guidance. Moreover, this system of tubes can be broadly applied to tissue engineering approaches that require a modular guidance system, such as repair to vascular or musculoskeletal tissues.

• MeSH
• Axons drug effects   pathology   MeSH
• Hydrogels pharmacology   MeSH
• Cicatrix pathology   MeSH
• Locomotion drug effects   MeSH
• Maleimides chemistry   MeSH
• Microspheres MeSH
• Myelin Sheath drug effects   metabolism   MeSH
• Mice, Inbred C57BL MeSH
• Neuroglia pathology   MeSH
• Polyethylene Glycols chemistry   MeSH
• Polymerization MeSH
• Spinal Cord Injuries pathology   physiopathology   MeSH
• Porosity MeSH
• Cross-Linking Reagents chemistry   MeSH
• Nerve Regeneration drug effects   MeSH
• Tissue Scaffolds chemistry   MeSH
• Hindlimb drug effects   physiology   MeSH
• Animals MeSH
• Check Tag
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, N.I.H., Extramural MeSH

The corpus callosum is the brain's largest commissural fiber tract and is crucial for interhemispheric integration of neural information. Despite the high relevance of the corpus callosum for several cognitive systems, the molecular determinants of callosal microstructure are largely unknown. Recently, it was shown that genetic variations in the myelin-related proteolipid 1 gene PLP1 and the axon guidance related contactin 1 gene CNTN1 were associated with differences in interhemispheric integration at the behavioral level. Here, we used an innovative new diffusion neuroimaging technique called neurite orientation dispersion and density imaging (NODDI) to quantify axonal morphology in subsections of the corpus callosum and link them to genetic variation in PLP1 and CNTN1. In a cohort of 263 healthy human adults, we found that polymorphisms in both PLP1 and CNTN1 were significantly associated with callosal microstructure. Importantly, we found a double dissociation between gene function and neuroimaging variables. Our results suggest that genetic variation in the myelin-related gene PLP1 impacts white matter microstructure in the corpus callosum, possibly by affecting myelin structure. In contrast, genetic variation in the axon guidance related gene CNTN1 impacts axon density in the corpus callosum. These findings suggest that PLP1 and CNTN1 gene variations modulate specific aspects of callosal microstructure that are in line with their gene function.

• MeSH
• White Matter anatomy & histology   MeSH
• Corpus Callosum anatomy & histology   MeSH
• Diffusion Magnetic Resonance Imaging methods   MeSH
• Adult MeSH
• Genotype MeSH
• Polymorphism, Single Nucleotide MeSH
• Contactin 1 genetics   physiology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Myelin Sheath genetics   MeSH
• Myelin Proteolipid Protein genetics   physiology   MeSH
• Neurites * MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

Poruchy autistického spektra (PAS) jsou heterogenní skupinou neurovývojových poruch charakterizovanou narušením sociálních interakcí, komunikace a stereotypními, opakujícími se vzorci chování, zájmů a aktivit. Příčiny vzniku a rizikové faktory PAS nejsou dosud plně objasněny, etiologie je komplexní se zastoupením jak genetických faktorů, tak faktorů vnějšího prostředí. V posledních dvou dekádách je stále více zkoumán vliv imunitního systému na vyvíjející se nervovou soustavu během prenatálního období. Dysregulace maternálního imunitního systému během gestace může vést k neurovývojovým změnám a vzniku neurovývojového onemocnění jako je PAS. Jedním z potenciálních etiologických imunologických faktorů ve vztahu k PAS jsou maternální autoprotilátky reaktivní vůči proteinům fetálního mozku. Pro takto podmíněný typ PAS používají výzkumné studie pojem MAR autism (maternal autoantibody related autism, autismus související s maternálními autoprotilátkami). Spojení bylo prokázáno jak klinickými studiemi, tak zvířecími modely. Je známo několik proteinů, proti kterým jsou namířeny maternální autoprotilátky ve vztahu k PAS. V článku se zaměříme na collapsin response mediator protein 2 (CRMP2), který hraje důležitou roli v regulaci růstu a navádění axonů v průběhu vývoje mozku, a roli autoprotilátek proti CRMP2 při vzniku PAS. Závěrem ještě krátce zmíníme hypotetickou možnost léčby PAS spojených s maternálními autoprotilátkami.

Autism spectrum disorders (ASD) are heterogeneous group of neurodevelopmental disorders characterized by impairments in social interaction, communication and stereotyped, repetitive patterns of behavior, interests and activities. The causes and risk factors of ASD are largely unknown with a complex etiology combining genetic as well as environmental factors. In the last two decades it has been well established that an important role in the prenatal brain development is played by the immune system. Deregulation of the immune system during embryonic development may lead to neurodevelopmental changes resulting in ASD and one of the potential etiologic factors in the development of ASD has been identified as presence of maternal autoantibodies targeting the fetal brain proteins. The type of ASD associated with the presence of maternal autoantibodies has been referred to as MAR autism (maternal antibodies related autism). The link between the maternal autoantibodies and ASD has been demonstrated in both clinical studies and animal models. Several protein targets of ASD-related maternal autoantibodies have been identified. In this article we focus on Collapsin response mediator protein 2 (CRMP2), which has been previously shown to play an important role in regulation of axon growth and guidance during brain development. In addition, we discuss the potential effect of CRMP2 targeting by maternal antibodies in ASD pathogenesis and future possibilities of MAR ASD treatment.

• Keywords
• CRMP2, maternální autoprotilátky,
• MeSH
• Autoantibodies * MeSH
• Phosphoproteins MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Brain growth & development   MeSH
• Autism Spectrum Disorder * genetics   MeSH
• Fetal Development MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH

Interaction with the world around us requires extracting meaningful signals to guide behavior. Each of the six mammalian senses (olfaction, vision, somatosensation, hearing, balance, and taste) has a unique primary map that extracts sense-specific information. Sensory systems in the periphery and their target neurons in the central nervous system develop independently and must develop specific connections for proper sensory processing. In addition, the regulation of sensory map formation is independent of and prior to central target neuronal development in several maps. This review provides an overview of the current level of understanding of primary map formation of the six mammalian senses. Cell cycle exit, combined with incompletely understood molecules and their regulation, provides chemoaffinity-mediated primary maps that are further refined by activity. The interplay between cell cycle exit, molecular guidance, and activity-mediated refinement is the basis of dominance stripes after redundant organ transplantations in the visual and balance system. A more advanced level of understanding of primary map formation could benefit ongoing restoration attempts of impaired senses by guiding proper functional connection formations of restored sensory organs with their central nervous system targets.

• MeSH
• Axons MeSH
• Smell * MeSH
• Mice MeSH
• Neurogenesis * MeSH
• Neurons MeSH
• Cues * MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Research Support, N.I.H., Extramural MeSH

Autism spectrum disorder (ASD) is a heterogeneous condition with multiple etiologies and risk factors - both genetic and environmental. Recent data demonstrate that the immune system plays an important role in prenatal brain development. Deregulation of the immune system during embryonic development can lead to neurodevelopmental changes resulting in ASD. One of the potential etiologic factors in the development of ASD has been identified as the presence of maternal autoantibodies targeting fetal brain proteins. The type of ASD associated with the presence of maternal autoantibodies has been referred to as maternal antibodies related to ASD (MAR ASD). The link between maternal autoantibodies and ASD has been demonstrated in both clinical studies and animal models, but the exact mechanism of their action in the pathogenesis of ASD has not been clarified yet. Several protein targets of ASD-related maternal autoantibodies have been identified. Here, we discuss the role of microtubule-associated proteins of the collapsin response mediator protein (CRMP) family in neurodevelopment and ASD. CRMPs have been shown to integrate multiple signaling cascades regulating neuron growth, guidance or migration. Their targeting by maternal autoantibodies could change CRMP levels or distribution in the developing nervous system, leading to defects in axon growth/guidance, cortical migration, or dendritic projection, which could play an etiological role in ASD development. In addition, we discuss the future possibilities of MAR ASD treatment.

• Publication type
• Journal Article MeSH
• Review MeSH

MICAL proteins play a crucial role in cellular dynamics by binding and disassembling actin filaments, impacting processes like axon guidance, cytokinesis, and cell morphology. Their cellular activity is tightly controlled, as dysregulation can lead to detrimental effects on cellular morphology. Although previous studies have suggested that MICALs are autoinhibited, and require Rab proteins to become active, the detailed molecular mechanisms remained unclear. Here, we report the cryo-EM structure of human MICAL1 at a nominal resolution of 3.1 Å. Structural analyses, alongside biochemical and functional studies, show that MICAL1 autoinhibition is mediated by an intramolecular interaction between its N-terminal catalytic and C-terminal coiled-coil domains, blocking F-actin interaction. Moreover, we demonstrate that allosteric changes in the coiled-coil domain and the binding of the tripartite assembly of CH-L2α1-LIM domains to the coiled-coil domain are crucial for MICAL activation and autoinhibition. These mechanisms appear to be evolutionarily conserved, suggesting a potential universality across the MICAL family.

• MeSH
• Actins metabolism   chemistry   MeSH
• Allosteric Regulation MeSH
• Calponins MeSH
• Cryoelectron Microscopy * MeSH
• Humans MeSH
• Actin Cytoskeleton metabolism   ultrastructure   MeSH
• Microfilament Proteins metabolism   chemistry   ultrastructure   MeSH
• Models, Molecular MeSH
• Mixed Function Oxygenases MeSH
• Protein Domains MeSH
• LIM Domain Proteins metabolism   chemistry   genetics   MeSH
• Protein Binding * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH