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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., Highlights • Laser-mediated axotomy of hESC-derived neurons is used as a model for axonal regeneration and local protein translation. • Pull down of newly synthesized axonal proteins is used to identify local protein synthesis following axonal injury. • Reduced axonal regeneration is associated with reduced levels of local translation. • Enhancing regeneration by co-culturing with human glial precursor cells is associated with enhanced levels of translation. • Proteomics profiling of axonal proteins during aging reveals reduced protein translation machinery as axons age.

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.

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 (PIP 3). We demonstrate that adult PNS neurons utilise two catalytic subunits of PI3K for axon regeneration: p110α and p110δ. However, in the CNS, axonal PIP 3 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 PIP 3 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 PIP 3 as a key reason for intrinsic regeneration failure and demonstrate that native p110δ facilitates axon regeneration by functioning in a hyperactive fashion., CNS axons lose the ability to regenerate with maturity, whilst PNS axons do not. This study shows that PIP3 levels decline in CNS neurons at the time when regenerative ability is lost. CNS overexpression of one isoform of PI3K, p110δ, enhances axonal PIP3, axon transport, and regenerative ability.

Objective: To identify determinants of limitations in unpaid work (household work, shopping, caring for children and odd jobs around the house) in patients who had suffered major trauma (ISS >= 16) and who were in full-time employment (>= 80%) at the time of injury. Design: Prospective cohort study. Setting: University Medical Centre Utrecht, a level 1 trauma centre in the Netherlands. Method: All severely injured (ISS >= 16) adult (age >= 16) trauma survivors admitted from January 1999 to December 2000 who were full-time employed at time of the injury were invited for follow-up (n = 214). Outcome was assessed with the 'Health and Labour Questionnaire' (HLQ) at a mean of 15 months (SD = 1.5) after injury. The HLQ was completed by 211 patients. Results: Response rate was 93%. Logistic regression analyses identified the percentage of permanent impairment (% PI), level of participation (RtW), co-morbidity, lower extremity injury (LEI) and female gender as determinants of limitations in unpaid work. Patients with a post-injury status of part-time or no return to work experienced more limitations in unpaid work than those who returned to full-time employment. Conclusions: Resuming paid work after major trauma is not associated with reductions in unpaid activities. To assess the long-term outcome of rehabilitation programmes, we recommend a measure that combines patient's satisfaction in their post-injury jobs with a satisfactory level of activities in their private lives. (C) 2013 Elsevier Ltd. All rights reserved.

Mesial temporal lobe epilepsy (mTLE) is a chronic neurological disorder characterized by recurrent seizures. The pathogenic mechanisms underlying mTLE may involve defects in the post-transcriptional regulation of gene expression. MicroRNAs (miRNAs) are non-coding RNAs that control the expression of genes at the post-transcriptional level. Here, we performed a genome-wide miRNA profiling study to examine whether miRNA-mediated mechanisms are affected in human mTLE. miRNA profiles of the hippocampus of autopsy control patients and two mTLE patient groups were compared. This revealed segregated miRNA signatures for the three different patient groups and 165 miRNAs with up- or down-regulated expression in mTLE. miRNA in situ hybridization detected cell type-specific changes in miRNA expression and an abnormal nuclear localization of select miRNAs in neurons and glial cells of mTLE patients. Of several cellular processes implicated in mTLE, the immune response was most prominently targeted by deregulated miRNAs. Enhanced expression of inflammatory mediators was paralleled by a reduction in miRNAs that were found to target the 3′-untranslated regions of these genes in reporter assays. miR-221 and miR-222 were shown to regulate endogenous ICAM1 expression and were selectively co-expressed with ICAM1 in astrocytes in mTLE patients. Our findings suggest that miRNA changes in mTLE affect the expression of immunomodulatory proteins thereby further facilitating the immune response. This mechanism may have broad implications given the central role of astrocytes and the immune system in human neurological disease. Overall, this work extends the current concepts of human mTLE pathogenesis to the level of miRNA-mediated gene regulation. Electronic supplementary material The online version of this article (doi:10.1007/s00018-012-0992-7) contains supplementary material, which is available to authorized users.

Bicaudal-D (BICD) belongs to an evolutionary conserved family of dynein adaptor proteins. It was first described in Drosophila as an essential factor in fly oogenesis and embryogenesis. Missense mutations in a human BICD homologue, BICD2, have been linked to a dominant mild early onset form of spinal muscular atrophy. Here we further examine the in vivo function of BICD2 in Bicd2 knockout mice. BICD2-deficient mice develop disrupted laminar organization of cerebral cortex and the cerebellum, pointing to impaired radial neuronal migration. Using astrocyte and granule cell specific inactivation of BICD2, we show that the cerebellar migration defect is entirely dependent upon BICD2 expression in Bergmann glia cells. Proteomics analysis reveals that Bicd2 mutant mice have an altered composition of extracellular matrix proteins produced by glia cells. These findings demonstrate an essential non-cell-autonomous role of BICD2 in neuronal cell migration, which might be connected to cargo trafficking pathways in glia cells.

RGM Proteins Members of the repulsive guidance molecule (RGM) family of proteins can be secreted or reside on the surface of cells where they bind to the cell surface receptor, neogenin. The RGM proteins are named for their role in axon guidance for developing neurons, but their function is also linked to a range of human diseases, including inflammation, multiple sclerosis, and cancer. Bell et al. (p. 77 ) solved the crystal structures of the external portions of the RGMB protein with portions of neogenin. The structures revealed interactions of dimers of RGMB with neogenin in which ligand binding induced conformational changes that may initiate intracellular signaling from the receptor. RGM proteins contain a site of autocatalytic cleavage that affects secretion of the proteins, and some disease-associated mutations in RGM proteins were clustered at this site.