Schizophrenia (SZ) is a complex disease characterized by impaired neuronal functioning. Although defective alternative splicing has been linked to SZ, the molecular mechanisms responsible are ...unknown. Additionally, there is limited understanding of the early transcriptomic responses to neuronal activation. Here, we profile these transcriptomic responses and show that long non-coding RNAs (lncRNAs) are dynamically regulated by neuronal activation, including acute downregulation of the lncRNA Gomafu, previously implicated in brain and retinal development. Moreover, we demonstrate that Gomafu binds directly to the splicing factors QKI and SRSF1 (serine/arginine-rich splicing factor 1) and dysregulation of Gomafu leads to alternative splicing patterns that resemble those observed in SZ for the archetypal SZ-associated genes DISC1 and ERBB4. Finally, we show that Gomafu is downregulated in post-mortem cortical gray matter from the superior temporal gyrus in SZ. These results functionally link activity-regulated lncRNAs and alternative splicing in neuronal function and suggest that their dysregulation may contribute to neurological disorders.
In this study in vitro and in vivo approaches were combined in order to investigate if the anti‐epileptic mechanism(s) of action of levetiracetam (LEV; Keppra®) may involve modulation of inhibitory ...neurotransmission.
GABA‐ and glycine‐gated currents were studied in vitro using whole‐cell patch‐clamp techniques applied on cultured cerebellar granule, hippocampal and spinal neurons. Protection against clonic convulsions was assessed in vivo in sound‐susceptible mice. The effect of LEV was compared with reference anti‐epileptic drugs (AEDs): carbamazepine, phenytoin, valproate, clonazepam, phenobarbital and ethosuximide.
LEV contrasted the reference AEDs by an absence of any direct effect on glycine‐gated currents. At high concentrations, beyond therapeutic relevance, it induced a small reduction in the peak amplitude and a prolongation of the decay phase of GABA‐gated currents. A similar action on GABA‐elicited currents was observed with the reference AEDs, except ethosuximide.
These minor direct effects contrasted with a potent ability of LEV (EC50=1 – 10 μM) to reverse the inhibitory effects of the negative allosteric modulators zinc and β‐carbolines on both GABAA and glycine receptor‐mediated responses.
Clonazepam, phenobarbital and valproate showed a similar ability to reverse the inhibition of β‐carbolines on GABA‐gated currents. Blockade of zinc inhibition of GABA responses was observed with clonazepam and ethosuximide. Phenytoin was the only AED together with LEV that inhibited the antagonism of zinc on glycine‐gated currents and only clonazepam and phenobarbital inhibited the action of DMCM.
LEV (17 mg kg−1) produced a potent suppression of sound‐induced clonic convulsions in mice. This protective effect was significantly abolished by co‐administration of the β‐carboline FG 7142, from a dose of 5 mg kg−1. In contrast, the benzodiazepine receptor antagonist flumazenil (up to 10 mg kg−1) was without any effect on the protection afforded by LEV.
The results of the present study suggest that a novel ability to oppose the action of negative modulators on the two main inhibitory ionotropic receptors may be of relevance for the anti‐epileptic mechanism(s) of action of LEV.
British Journal of Pharmacology (2002) 136, 659–672; doi:10.1038/sj.bjp.0704766
The International GNSS Service (IGS) Working Group on Ionosphere was created in 1998. Since then, the Scientific community behind IGS, in particular CODE, ESA, JPL and UPC, have been continuosly ...contributing to reliable IGS combined vertical total electron content (VTEC) maps in both rapid and final schedules. The details on how these products are being generated, performance numbers, proposed improvement as far as VTEC evolution trends during near one Solar Cycle, are summarized in this paper. The confirmation of (1) the good performance of the IGS combined VTEC maps, and (2) the characteristic VTEC variability periods, are two main results of this work.
Although vertical total electron content (VTEC) forecasting is still an open subject of research, the use of predictions of the ionospheric state at a scale of several days is an area of increased ...interest. A global VTEC forecast product for two days ahead, which is based exclusively on actual Global Positioning System (GPS) data, has been developed in the frame of the International Global Navigation Satellite Systems (GNSS) Service (IGS) Ionospheric Working Group (IGS Iono‐WG). The UPC ionospheric VTEC prediction model is based on the Discrete Cosine Transform (DCT), which is widely used in image compression (for instance, in JPEG format). Additionally, a linear regression module is used to forecast the time evolution of each of the DCT coefficients. The use of the DCT coefficients is justified because they represent global features of the whole two‐dimensional VTEC map/image. Also, one can therefore introduce prior information affecting the VTEC, for instance, smoothness or the distribution of relevant features in different directions. For this purpose, the use of a long time series of final/rapid UPC VTEC maps is required. Currently, the UPC Predicted product is being automatically generated in test mode and is made available through the main IGS server for public access. This product is also used to generate two days ahead preliminary combined IGS Predicted product. Finally, the results presented in this work suggest that the two days ahead UPC Predicted product could become an official IGS product in the near future.
Key Points
Two‐day ahead prediction model of global VTEC maps
Based on the Discrete Cosine Transform (DCT) and a linear regression module
Tests against Final UPC products and JASON VTEC measurements
Treatment of solid-organ transplant (SOT) patients with ganciclovir (GCV)-valganciclovir (VGCV) according to the manufacturer's recommendations may result in over- or underexposure. Bayesian ...prediction based on a population pharmacokinetics model may optimize GCV-VGCV dosing, achieving the area under the curve (AUC) therapeutic target. We conducted a two-arm, randomized, open-label, 40% superiority trial in adult SOT patients receiving GCV-VGCV as prophylaxis or treatment of cytomegalovirus infection. Group A was treated according to the manufacturer's recommendations. For group B, the dosing was adjusted based on target exposures using a Bayesian prediction model (NONMEM). Fifty-three patients were recruited (27 in group A and 26 in group B). About 88.6% of patients in group B and 22.2% in group A reached target AUC, achieving the 40% superiority margin (P< 0.001; 95% confidence interval CI difference, 47 to 86%). The time to reach target AUC was significantly longer in group A than in group B (55.9 ± 8.2 versus 15.8 ± 2.3 days,P< 0.001). A shorter time to viral clearance was observed in group B than in group A (12.5 versus 17.6 days;P= 0.125). The incidences of relapse (group A, 66.67%, and group B, 9.01%) and late-onset infection (group A, 36.7%, and group B, 7.7%) were higher in group A. Neutropenia and anemia were related to GCV overexposure. GCV-VCGV dose adjustment based on a population pharmacokinetics Bayesian prediction model optimizes GCV-VGCV exposure. (This study has been registered at ClinicalTrials.gov under registration no. NCT01446445.).
The development of the cerebral cortex requires coordinated regulation of proliferation, specification, migration and differentiation of cortical progenitors into functionally integrated neurons. The ...completion of the neurogenic program requires a dynamic interplay between cell intrinsic regulators and extrinsic cues, such as growth factor and neurotransmitters. We previously demonstrated a role for extrasynaptic glycine receptors (GlyRs) containing the α2 subunit in cerebral cortical neurogenesis, revealing that endogenous GlyR activation promotes interneuron migration in the developing cortical wall. The proliferative compartment of the cortex comprises apical progenitors that give birth to neurons directly or indirectly through the generation of basal progenitors, which serve as amplification step to generate the bulk of cortical neurons. The present work shows that genetic inactivation of Glra2, the gene coding the α2 subunit of GlyRs, disrupts dorsal cortical progenitor homeostasis with an impaired capability of apical progenitors to generate basal progenitors. This defect results in an overall reduction of projection neurons that settle in upper or deep layers of the cerebral cortex. Overall, the depletion of cortical neurons observed in Glra2-knockout embryos leads to moderate microcephaly in newborn Glra2-knockout mice. Taken together, our findings support a contribution of GlyR α2 to early processes in cerebral cortical neurogenesis that are required later for the proper development of cortical circuits.
Hearing impairment is the most common sensory disorder, with congenital hearing impairment present in approximately 1 in 1,000 newborns. Hereditary deafness is often mediated by the improper ...development or degeneration of cochlear hair cells. Until now, it was not known whether such congenital failures could be mitigated by therapeutic intervention. Here we show that hearing and vestibular function can be rescued in a mouse model of human hereditary deafness. An antisense oligonucleotide (ASO) was used to correct defective pre-mRNA splicing of transcripts from the USH1C gene with the c.216G>A mutation, which causes human Usher syndrome, the leading genetic cause of combined deafness and blindness. Treatment of neonatal mice with a single systemic dose of ASO partially corrects Ush1c c.216G>A splicing, increases protein expression, improves stereocilia organization in the cochlea, and rescues cochlear hair cells, vestibular function and low-frequency hearing in mice. These effects were sustained for several months, providing evidence that congenital deafness can be effectively overcome by treatment early in development to correct gene expression and demonstrating the therapeutic potential of ASOs in the treatment of deafness.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
During brain ontogenesis, the temporal and spatial generation of the different types of neuronal and glial cells from precursors occurs as a sequence of successive progenitor stages whose ...proliferation, survival and cell-fate choice are controlled by environmental and cellular regulatory molecules. Neurotransmitters belong to the chemical microenvironment of neural cells, even at the earliest stages of brain development. It is now established that specific neurotransmitter receptors are present on progenitor cells of the developing central nervous system and could play, during neural development, a role that has remained unsuspected until recently. The present review focuses on the occurrence of neurotransmitters and their corresponding ligand-gated ion channel receptors in immature cells, including neural stem cells of specific embryonic and neonatal brain regions. We summarize in vitro and in vivo data arguing that neurotransmitters could regulate morphogenetic events such as proliferation, growth, migration, differentiation and survival of neural precursor cells. The understanding of neurotransmitter function during early neural maturation could lead to the development of pharmacological tools aimed at improving adult brain repair strategies.
Bone marrow mesenchymal stem cells (MSCs) can differentiate into several types of mesenchymal cells, including osteocytes, chondrocytes, and adipocytes, but, under appropriate experimental ...conditions, can also differentiate into nonmesenchymal cells—for instance, neural cells. These observations have raised interest in the possible use of MSCs in cell therapy strategies for various neurological disorders. In the study reported here, we addressed the question of in vitro differentiation of MSCs into functional neurons. First, we demonstrate that when they are co‐cultured with cerebellar granule neurons, adult MSCs can express neuronal markers. Two factors are needed for the emergence of neuronal differentiation of the MSCs: the first one is nestin expression by MSCs (nestin is a marker for the responsive character of MSCs to extrinsic signals), and the second one is a direct cell–cell interaction between neural cells and MSCs that allows the integration of these extrinsic signals. Three different approaches suggest that neural phenotypes arise from MSCs by a differentiation rather than a cell fusion process, although this last phenomenon can also coexist. The expression of several genes—including sox, pax, notch, delta, frizzled, and erbB—was analyzed by quantitative reverse transcription polymerase chain reaction (RT‐PCR) in order to further characterize the nestin‐positive phenotype compared to the nestin‐negative one. An overexpression of sox2, sox10, pax6, fzd, erbB2, and erbB4 is found in nestin‐positive MSCs. Finally, electrophysiological analyses demonstrate that MSC‐derived neuron‐like cells can fire single‐action potentials and respond to several neurotransmitters such as GABA, glycine, and glutamate. We conclude that nestin‐positive MSCs can differentiate in vitro into excitable neuron‐like cells.
PDF
