Radial glia fibers translate Fgf8 morphogenetic signals to generate a thalamic nuclear complex protomap in the mantle layer

Thalamic neurons are distributed between different nuclear groups of the thalamic multinuclear complex; they develop topologically ordered specific projections that convey information on voluntary motor programs and sensory modalities to functional areas in the cerebral cortex. Since thalamic neurons present a homogeneous morphology, their functional specificity is derived from their afferent and efferent connectivity. Adequate development of thalamic afferent and efferent connections depends on guide signals that bind receptors in nuclear neuropils and axonal growth cones, respectively. These are finally regulated by regionalization processes in the thalamic neurons, codifying topological information. In this work, we studied the role of Fgf8 morphogenetic signaling in establishing the molecular thalamic protomap, which was revealed by Igsf21, Pde10a and Btbd3 gene expression in the thalamic mantle layer. Fgf8 signaling activity was evidenced by pERK expression in radial glia cells and fibers, which may represent a scaffold that translates neuroepithelial positional information to the mantle layer. In this work, we describe the fact that Fgf8-hypomorphic mice did not express pERK in radial glia cells and fibers and presented disorganized thalamic regionalization, increasing neuronal death in the ventro-lateral thalamus and strong disruption of thalamocortical projections. In conclusion, Fgf8 encodes the positional information required for thalamic nuclear regionalization and the development of thalamocortical projections.This work was supported by the Spanish Ministry of Science and Innovation grant:FEDER BFU2011-27326, SAF2014-59347-C2-1-R, and Severo Ochoa Excellence Project SEV-2013-0317; ISCIII: Red TERCEL RD12/0019/0024, and CIBERSAM; GVA: PROMETEO II/2014/014, and the WOP Association.Peer reviewe

Beta-Amyloid Impairs Reelin Signaling

Reelin is a signaling protein increasingly associated with the pathogenesis of Alzheimer's disease that relevantly modulates tau phosphorylation. We have previously demonstrated that β-amyloid peptide (Aβ) alters reelin expression. We have now attempted to determine whether abnormal reelin triggered by Aβ will result in signaling malfunction, contributing to the pathogenic process. Here, we show that reelin forms induced by β-amyloid are less capable of down-regulating tau phosphorylation via disabled-1 and GSK3β kinase. We also demonstrate that the scaffold protein 14-3-3 that increases tau phosphorylation by modulating GSK3β activity, is up-regulated during defective reelin signaling. Binding of reelin to its receptor, mainly ApoER2 in the brain, relays the signal into the cell. We associate the impaired reelin signaling with inefficiency of reelin in forming active homodimers and decreased ability to bind efficiently to its receptor, ApoER2. More remarkably, reelin from Alzheimer cortex shows a tendency to form large complexes instead of homodimers, the active form for signaling. Our results suggest that reelin expression is altered by Aβ leading to impaired reelin signaling. © 2013 Cuchillo-Ibáñez et al.Fondo de Investigaciones Sanitarias (PS09/00684; PI12/00593); Fundación Ramón Areces; CIBERNED; Instituto de Salud Carlos III; Fondo Social Europeo (FSE)Peer Reviewe

FoxP2 protein levels regulate cell morphology changes and migration patterns in the vertebrate developing telencephalon

In the mammalian telencephalon, part of the progenitor cells transition from multipolar to bipolar morphology as they invade the mantle zone. This associates with changing patterns of radial migration. However, the molecules implicated in these morphology transitions are not well known. In the present work, we analyzed the function of FoxP2 protein in this process during telencephalic development in vertebrates. We analyzed the expression of FoxP2 protein and its relation with cell morphology and migratory patterns in mouse and chicken developing striatum. We observed FoxP2 protein expressed in a gradient from the subventricular zone to the mantle layer in mice embryos. In the FoxP2 low domain cells showed multipolar migration. In the striatal mantle layer where FoxP2 protein expression is higher, cells showed locomoting migration and bipolar morphology. In contrast, FoxP2 showed a high and homogenous expression pattern in chicken striatum, thus bipolar morphology predominated. Elevation of FoxP2 in the striatal subventricular zone by in utero electroporation promoted bipolar morphology and impaired multipolar radial migration. In mouse cerebral cortex we obtained similar results. FoxP2 promotes transition from multipolar to bipolar morphology by means of gradiental expression in mouse striatum and cortex. Together these results indicate a role of FoxP2 differential expression in cell morphology control of the vertebrate telencephalon.This work was supported by Spanish Ministry of Science and Innovation Grant BFU-2011-27326, Institute of Health Carlos III, Spanish Cell Therapy Network and Research Center of Mental Health (RD06/0010/0023; RD12/0019/0024), General Council of Valencia (Prometeo 2009/028 and 11/2011/042). E.G.C. was supported by the Postdoctoral Program of the “Consejo Superior de Investigaciones Científicas-Junta de Ampliación de Estudios.”Peer reviewe

Beta-amyloid impairs reelin signaling.

Reelin is a signaling protein increasingly associated with the pathogenesis of Alzheimer's disease that relevantly modulates tau phosphorylation. We have previously demonstrated that β-amyloid peptide (Aβ) alters reelin expression. We have now attempted to determine whether abnormal reelin triggered by Aβ will result in signaling malfunction, contributing to the pathogenic process. Here, we show that reelin forms induced by β-amyloid are less capable of down-regulating tau phosphorylation via disabled-1 and GSK3β kinase. We also demonstrate that the scaffold protein 14-3-3 that increases tau phosphorylation by modulating GSK3β activity, is up-regulated during defective reelin signaling. Binding of reelin to its receptor, mainly ApoER2 in the brain, relays the signal into the cell. We associate the impaired reelin signaling with inefficiency of reelin in forming active homodimers and decreased ability to bind efficiently to its receptor, ApoER2. More remarkably, reelin from Alzheimer cortex shows a tendency to form large complexes instead of homodimers, the active form for signaling. Our results suggest that reelin expression is altered by Aβ leading to impaired reelin signaling

Bone marrow transplantation in hindlimb muscles of motoneuron degenerative mice reduces neuronal death and improves motor function

Bone marrow has proved to be an adequate source of stem cells for the treatment of numerous disorders, including neurodegenerative diseases. Bone marrow can be easily and relatively painlessly extracted from a patient or allogenic donor and then transplanted into the degenerative area. Here, the grafted cells will activate a number of mechanisms in order to protect, repair, and/or regenerate the damaged tissue. These properties make the bone marrow a feasible source for cell therapy. In this work, we transplanted bone marrow cells into a mouse model of motoneuron degeneration, with the particularity of placing the cells in the hindlimb muscles rather than in the spinal cord where neuronal degeneration occurs. To this end, we analyze the possibility for the transplanted cells to increase the survival rate of the spinal cord motoneurons by axonal-guided retrograde neurotrophism. As a result, the mice significantly improved their motor functions. This coincided with an increased number of motoneurons innervating the treated muscle compared with the neurons innervating the non-treated contralateral symmetric muscle. In addition, we detected an increase in glial-derived neurotrophic factor in the spinal cord, a neurotrophic factor known to be involved in the rescue of degenerating motoneurons, exerting a neuroprotective effect. Thus, we have proved that bone marrow injected into the muscles is capable of rescuing these motoneurons from death, which may be a possible therapeutic approach for spinal cord motoneuron degenerative diseases, such as amyotrophic lateral sclerosis.This work was supported by Ministerio Ciencia E Innovacion (MICINN BFU2010-27326), DIGESIC-MEC BFU2008-00588, Ingenio 2010 MEC-CONSOLIDER CSD2007-00023, from the GVA Prometeo grant 2009/028, and ISCIII Cibersam and Tercel (RD06/0010/0023), as well as ELA Foundation, Fundacion Diogenes-Elche City Government, Rotary Club Elche-Illice, and Fundacio Gent per Gent grant 24 NEURO.Peer reviewe

Bone Marrow Transplantation in Hindlimb Muscles of Motoneuron Degenerative Mice Reduces Neuronal Death and Improves Motor Function

Bone marrow has proved to be an adequate source of stem cells for the treatment of numerous disorders, including neurodegenerative diseases. Bone marrow can be easily and relatively painlessly extracted from a patient or allogenic donor and then transplanted into the degenerative area. Here, the grafted cells will activate a number of mechanisms in order to protect, repair, and/or regenerate the damaged tissue. These properties make the bone marrow a feasible source for cell therapy. In this work, we transplanted bone marrow cells into a mouse model of motoneuron degeneration, with the particularity of placing the cells in the hindlimb muscles rather than in the spinal cord where neuronal degeneration occurs. To this end, we analyze the possibility for the transplanted cells to increase the survival rate of the spinal cord motoneurons by axonal-guided retrograde neurotrophism. As a result, the mice significantly improved their motor functions. This coincided with an increased number of motoneurons innervating the treated muscle compared with the neurons innervating the non-treated contralateral symmetric muscle. In addition, we detected an increase in glial-derived neurotrophic factor in the spinal cord, a neurotrophic factor known to be involved in the rescue of degenerating motoneurons, exerting a neuroprotective effect. Thus, we have proved that bone marrow injected into the muscles is capable of rescuing these motoneurons from death, which may be a possible therapeutic approach for spinal cord motoneuron degenerative diseases, such as amyotrophic lateral sclerosis

HNK-1 carrier glycoproteins are decreased in the Alzheimer’s disease brain

The human natural killer-1 (HNK-1), 3-sulfonated glucuronic acid, is a glycoepitope marker of cell adhesion that participates in cell-cell and cell-extracellular matrix interactions and in neurite growth. Very little is known about the regulation of the HNK-1 glycan in neurodegenerative disease, particularly in Alzheimer’s disease (AD). In this study, we investigate changes in the levels of HNK-1 carrier glycoproteins in AD. We demonstrate an overall decrease in HNK-1 immunoreactivity in glycoproteins extracted from the frontal cortex of AD subjects, compared with levels from non-demented controls (NDC). Immunoblotting of ventricular post-mortem and lumbar ante-mortem cerebrospinal fluid with HNK-1 antibodies indicate similar levels of carrier glycoproteins in AD and NDC samples. Decrease in HNK-1 carrier glycoproteins were not paralleled by changes in messenger RNA (mRNA) levels of the enzymes involved in the synthesis of the glycoepitope, β-1,4-galactosyltransferase (β4GalT), glucuronyltransferases GlcAT-P and GlcAT-S, or sulfotransferase HNK-1ST. Over-expression of amyloid precursor protein in Tg2576 transgenic mice and in vitro treatment of SH-SY5Y neuroblastoma cells with the amyloidogenic Aβ42 peptide resulted in a decrease in HNK-1 immunoreactivity levels in brain and cellular extracts, whereas the levels of soluble HNK-1 glycoproteins detected in culture media were not affected by Aβ treatment. HNK-1 levels remain unaffected in the brain extracts of Tg-VLW mice, a model of mutant hyperphosphorylated tau, and in SH-SY5Y cells over-expressing hyperphosphorylated wild-type tau. These results provide evidence that cellular levels of HNK-1 carrier glycoforms are decreased in the brain of AD subjects, probably influenced by the β-amyloid protein.This study was funded in part by Consejeria de Sanidad, Generalitat Valenciana (AP-091/08) and the Instituto de Salud Carlos III (ISCIII), Fondo de Investigaciones Sanitaria (grants PS09/00684 and PI11/03026 for JSV and CP11/00067 and PI14/00566 to MSGA); cofinanced by Fondo Europeo de Desarrollo Regional), the Torsten Söderberg Foundation at the Royal Swedish Academy of Sciences, and under the aegis of the EU BIOMARKAPD-Joint Programming on Neurodegenerative Diseases (JPND) project; and through CIBERNED, ISCIII, Spain.Peer reviewe

Clinical Phenotypes Associated to Engrailed 2 Gene Alterations in a Series of Neuropediatric Patients

The engrailed homeobox protein (EN) plays an important role in the regionalization of the neural tube. EN distribution regulates the cerebellum and midbrain morphogenesis, as well as retinotectal synaptogenesis. In humans, the EN1 and EN2 genes code for the EN family of transcription factors. Genetic alterations in the expression of EN2 have been related to different neurologic conditions and more particularly to autism spectrum disorders (ASD). We aimed to study and compare the phenotypes of three series of patients: (1) patients with encephalic structural anomalies (ESA) and abnormalities in the genomic (DNA) and/or transcriptomic (RNAm) of EN2 (EN2-g), (2) ESA patients having other gene mutations (OG-g), and (3) ESA patients free of these mutations (NM-g).Subjects and Methods: We have performed a descriptive study on 109 patients who suffer from mental retardation (MR), cerebral palsy (CP), epilepsy (EP), and behavioral disorders (BD), showing also ESA in their encephalic MRI. We studied genomic DNA and transcriptional analysis (cDNA) on EN2 gene (EN2), and in other genes (OG): LIS1, PTAFR, PAFAH1B2, PAFAH1B3, FGF8, PAX2, D17S379, D17S1866, and SMG6 (D17S5), as a routine genetic diagnosis in ESA patients.Results: From 109 patients, fifteen meet the exclusion criteria. From the remaining 94 patients, 12 (12.8%) showed mutations in EN2 (EN2-g), 20 showed mutations in other studied genes (OG-g), and 62 did not showed any mutation (NM-g). All EN2-g patients, suffered from MR, nine EP, seven BD and four CP. The proportions of these phenotypes in EN2-g did not differ from those in the OG-g, but it was significantly higher when comparing EN2-g with NM-g (MR: p = 0.013; EP: p = 0.001; BD: p = 0.0001; CP: p = 0.07, ns). Groups EN2-g and OG-g showed a 100 and a 70% of comorbidity, respectively, being significantly (p = 0.04) greater than NM-group (62.9%).Conclusion: Our series reflects a significant effect of EN2 gene alterations in neurodevelopmental abnormalities associated to ESA. Conversely, although these EN2 related anomalies might represent a predisposition to develop brain diseases, our results did not support direct relationship between EN2 mutations and specific clinical phenotypes

Aβ-Reelin fails to induce phosphorylation of Dab1 and GSK3β.

<p>Total cell lysates from primary mouse cortical neuron cultures treated without Reelin (No Reel) or with similar amounts of Reelin obtained from SH-SY5Y cells treated with 0 (control, C-Reel) or 10 µM of Aβ42 (Aβ-Reel) were probed with antibodies specific for total Dab1 and anti-phosphotyrosine Dab1 (P-Dab1), and GSK3β phosphorylated at serine 9 and total GSK3β. Levels of phosphorylated Dab1, GSK3β and tau were normalized to total Dab1, and GSK3β levels and tau respectively (n= 5 independent experiments for Dab1, GSK3β; n= 3 independent experiments for CR50). Data (means ± SEM) were analyzed using ANOVA analysis of variance, followed by Tukey test to compare all groups. *Significantly different (<i>p</i> < 0.05) from C-Reel treated cells.</p

Aβ-Reelin fails to reduce tau phosphorylation.

<p>Levels of phospho-tau (P-tau; antibodies AT8 and PHF13) and total tau were calculated in primary mouse cortical neuron cultures treated with similar amounts of Reelin obtained from SH-SY5Y cells treated with 0 (control, C-Reel), 1 or 10 µM of Aβ42 (Aβ-Reel), or scrambled Aβ42 peptide (Aβsc-Reel; 10 µM) (at least n= 6, from 3 independent experiments). The comparison with non-treated cultures (No Reel) is also shown. In some experiments Cont-Reelin was pre-incubated with the antibody CR50 (15 µg/ml) for 1 h prior to treatment (n=3). Neuronal cultures were also incubated with Reelin glycoforms obtained from SH-SY5Y cells treated with 0 (control, C-Reel) or 100 µM of the mannosidase inhibitor DMJ (DMJ-Reel) (n= 6, from 2 independent experiments). The data represent the percentages of variation (means ± SEM) with respect to values determined for C-Reel treated cells. Data were analyzed using ANOVA analysis of variance, followed by Tukey test to compare all groups. *Significantly different (<i>p</i> < 0.05) from C-Reel treated cells.</p