Papers by Constantino Sotelo
Development, 1998
The semaphorins are the largest family of repulsive axon guidance molecules. Secreted semaphorins... more The semaphorins are the largest family of repulsive axon guidance molecules. Secreted semaphorins bind neuropilin receptors and repel sensory, sympathetic and motor axons. Here we show that CA1, CA3 and dentate gyrus axons from E15-E17 mouse embryo explants are selectively repelled by entorhinal cortex and neocortex. The secreted semaphorins Sema III and Sema IV and their receptors Neuropilin-1 and -2 are expressed in the hippocampal formation during appropriate stages. Sema III and Sema IV strongly repel CA1, CA3 and dentate gyrus axons; entorhinal axons are only repelled by Sema III. An antibody against Neuropilin-1 blocks the repulsive action of Sema III and the entorhinal cortex, but has no effect on Sema IV-induced repulsion. Thus, chemorepulsion plays a role in axon guidance in the hippocampus, secreted semaphorins are likely to be responsible for this action, and the same axons can be repelled by two distinct semaphorins via two different receptors.
Journal of comparative neurology, Dec 18, 2000
It has been reported that the arrival of primary olfactory axons is required to induce the develo... more It has been reported that the arrival of primary olfactory axons is required to induce the development of the olfactory bulb (OB). On the other hand, the Sey Neu /Sey Neu mutant mouse (Small eye) has been previously described as a model for the absence of olfactory bulbs, owing to the lack of olfactory epithelium (OE). In the present report, we take advantage of this mutant and study a neural structure in the rostral pole of the telencephalon that phenotypically resembles the prospective OB. We named this formation olfactory bulb-like structure (OBLS). We also report the occurrence, in the mutants, of small epithelial vesicles in the malformed craneofacial pits, resembling an atrophic OE, although a mature olfactory nerve was not identified. Axonal tracing, birthdating, immunohistochemistry, and in situ hybridization using antibodies and probes expressed in the olfactory system, indicated that two distinct structures observed in the OBLS correspond to the main and accessory olfactory bulbs of the control mouse. We propose that the OBLS has developed independently of the external influences exerted by the olfactory nerve. The presence of a prospective OB in the mutants, without intervening olfactory fibers, suggests that intrinsic factors could define brain territories even in absence of the proper afferent innervation. The intrinsic mechanisms and environmental cues in the telencephalon could be sufficient to promote axonogenesis in the projection neurons of the OB and guide their axons in a lateral prospective tract, in the absence of olfactory axons.
Fate of presynaptic afferents to Purkinje cells in the adult nervous mutant mouse: A model to study presynaptic stabilization
Brain Research, Oct 1, 1979
The hemispheric cerebellar cortex from 174- to 420-day-old nervous mice has been studied with Gol... more The hemispheric cerebellar cortex from 174- to 420-day-old nervous mice has been studied with Golgi, Cajal-reduced silver and electron microscopic techniques. In all mice, the existence of a continuous process of Purkinje cell death, indicated by the presence of few of these neurons in early stages of degeneration, has been established. The morphology of such degenerating cells, as well as the removal of the necrotic debris and the consecutive isolation of presynaptic fibers by glia are described. In the molecular layer, and in spite of the important Purkinje cell loss, numerous varicosities belonging to parallel fibers persist. They can be either synapsing on interneurons or concentrated in small clusters of 2-10 boutons covered by astrocytic processes. The synaptic investment of stellate and basket cells, as well as the length and the branching pattern of their dendritic fields are not significantly changed, besides the increase in afferent terminals deprived of their postsynaptic targets. Basket formations, as numerous as in control cerebellum, are forming a discontinuous row at the superficial third of the granular layer. Over 90% of these baskets are devoid of Purkinje cells, however, their ultrastructural features mimic those of the same terminals in control mice, with the exception that few of them can either establish heterologous synapses with granule cell dendrites, or develop gap junctions between them. The significance of the persistence of normal looking presynaptic elements long time after deprivation of their postsynaptic targets is discussed in relation to the role that function can play in the stabilization of synaptic contacts.
Journal of comparative neurology, Jan 10, 1984
The postnatal maturation of the GABAergic innervation of the rat inferior olive was studied with ... more The postnatal maturation of the GABAergic innervation of the rat inferior olive was studied with an antiserum to glutamic acid decarboxylase (GAD), the GABA-synthesizing enzyme. GAD-positive axons were present at a very low density in the periolivary and interlamellar regions of newborn rats, as well as in certain precise areas of the lamellae, at the mediodorsal limit. The immature distribution indicates that the GABAergic projections reach the inferior olive shortly before birth and that the greater part of synaptogenesis and the establishment of the adult organization occurs postnatally. Light and electron microscopic analyses disclosed that the maturation of this system of olivary afferents passes through three well-defined stages: (1) During the first, or immature stage (from PO to P5), GAD immunoreactivity is not confined to axon terminals, as in adult rats. The labeled fibers penetrate progressively into the periphery of the lamellae and reach their centers in a n irregular manner by the end of the immature stage. This staggered invasion of the lamellae accentuates intraregional olivary differences and begins to take the adult configuration. As fiber penetration advances, the density of labeled axons establishing synaptic contacts increases, while the number of completely immunostained fibers decreases. This distribution prevails until the end of the immature stage and suggests that the GABAergic afferent projections remain in a "waiting compartment" from their prenatal arrival until the moment they invade the olivary parenchyma. (2). The second stage is designated as a n intermediate stage of maturation and lasts from P7 to P10. During this period, GAD axoplasmic compartmentation occurs, and henceforth only axon terminals exhibit GAD immunoreactivity. Concomitantly, intraregional differences in the pattern of innervation become more marked, because of the continuing irregular distribution of the growing labeled axons. This intermediate maturational stage is also characterized by a rapid increase in labeled axon terminals bearing synaptic complexes and by the formation of complex synaptic arrangements, the protoglomeruli. From the beginning of protoglomeruli formation, GAD-positive axon terminals are one of their constituents, and they are systematically localized at the periphery of the incipient dendritic protrusions. (3) The final stage of maturation takes place from P10 to P15.
The Cerebellum, Oct 6, 2015
The development of the mammalian cerebellum is orchestrated by both cell-autonomous programs and ... more The development of the mammalian cerebellum is orchestrated by both cell-autonomous programs and inductive environmental influences. Here, we describe the main processes of cerebellar ontogenesis, highlighting the neurogenic strategies used by developing progenitors, the genetic programs involved in cell fate specification, the progressive
The Journal of Neuroscience, May 1, 2002
In organotypic cultures, mouse Purkinje cells regenerate their axons from embryonic day 18 (E18) ... more In organotypic cultures, mouse Purkinje cells regenerate their axons from embryonic day 18 (E18) to postnatal day 0 (P0), die of apoptosis between P1 and P7, and survive but do not regenerate at P10. This particular behavior of Purkinje cells did not allow us to find out when the developmental switch between regeneration and lack of regeneration occurs. This work was undertaken to suppress Purkinje cell apoptosis and to investigate whether the same molecules that prevent apoptosis could also influence axonal growth, regeneration, or both. We show that brain-derived neurotrophic factor, neurotrophin 3, and insulin-like growth factor I have marginal effects on P3 Purkinje cell death. The use of Gö 6976 [a protein kinase C (PKC) inhibitor] or a transgenic mouse line, in which a pseudosubstrate PKC inhibitor has been specifically targeted to Purkinje cells, prevents the massive Purkinje cell death in P3 organotypic cultures. In addition, Gö 6976 promotes axotomized Purkinje cell survival up to P7. Thus, the inhibition of PKC activity is able to prevent Purkinje cell apoptosis in organotypic cultures. Furthermore, Gö 6976 increases the outgrowth of dendrites and axon collateralization, as shown after gene gun enhanced green fluorescent protein transfection. In contrast, PKC inhibitors do not influence the axonal regenerative capability of Purkinje cell during development; the latter decreases between E18 and P7 after the same time course in control and Gö 6976-treated slices. Thus, because inhibition of PKC prevents Purkinje cell death but does not affect axonal regeneration, these two events (cell death and axonal regeneration) seem to be differentially regulated.
Journal of Clinical Medicine, 2020
Background. Atrial fibrillation (AF) increases the risk for stroke but also for non-stroke major ... more Background. Atrial fibrillation (AF) increases the risk for stroke but also for non-stroke major adverse cardiovascular events (MACE). The 2MACE score was recently proposed to predict these events. Since the interest of microRNAs (miRNAs) in cardiovascular diseases is increasing, we aimed to investigate whether miRNA levels may improve the predictive performance of the 2MACE score. Methods. We included consecutive AF patients stable on vitamin K antagonist therapy. Blood samples were drawn at baseline and plasma expression of miRNAs was assessed. During a median of 7.6 (interquartile range (IQR) 5.4–8.0) years, the occurrence of any MACE (nonfatal myocardial infarction/cardiac revascularization and cardiovascular death) was recorded. Results. We conducted a miRNA expression analysis in plasma from 19 patients with and without cardiovascular events. The miRNAs selected (miR-22-3p, miR-107, and miR-146a-5p) were later measured in 166 patients (47% male, median age 77 (IQR 70–81) years...
Cordillera Oriental de Colombia. Expectativas para la Exploración Petrolera
7th Simposio Bolivariano - Exploracion Petrolera en las Cuencas Subandinas, 2000
Platelets, 2019
MicroRNAs (miRNAs) are small non-coding RNAs involved in the regulation of gene expression. Dysre... more MicroRNAs (miRNAs) are small non-coding RNAs involved in the regulation of gene expression. Dysregulated expression of several miRNAs has been found in primary immune thrombocytopenia (ITP) suggesting that miRNAs are likely involved in the pathogenesis of ITP. We aimed to explore the differential expression of miRNAs in patients with ITP before and after starting treatment with thrombopoietin-receptor agonists (TPO-RAs) to clarify their roles in the pathophysiology of ITP, and as potential diagnostic and prognostic markers of this disorder. We performed a profiling study where 179 miRNAs were analyzed in eight ITP patients before and during treatment with TPO-RAs and in eight controls using miRNA PCR panel; 81 miRNAs were differentially expressed in ITP patients compared to controls, and 14 miRNAs showed significant changes during TPO-RA-treatment. Ten miRNAs were selected for validation that was performed in 23 patients and 22 controls using droplet digital PCR. Three miRNAs were found to be differentially expressed in ITP patients before TPO-RA-treatment compared to controls: miR-199a-5p was down-regulated (p=0.0001), miR-33a-5p (p=0.0002) and miR-195-5p (p=0.035) were up-regulated. Treatment with TPO-RAs resulted in changes in six miRNAs including miR-199a-5p (p=0.001), miR-33a-5p (p=0.003), miR-382-5p (p=0.004), miR-92b-3p (p=0.005), miR-26a-5p (p=0.008) and miR-221-3p (p=0.023); while miR-195-5p remained unchanged and significantly higher than in controls, despite the increase in the platelet count, which may indicate its possible role in the pathophysiology of ITP. Regression analysis revealed that pre-treatment levels of miR-199a-5p and miR-221-3p could help to predict platelet response to TPO-RA-treatment. ROC curve analysis showed that the combination of miR-199a-5p and miR-33a-5p could distinguish patients with ITP from controls with AUC of 0.93. This study identifies a number of differentially expressed miRNAs in ITP patients before and after initiation of TPO-RAs with potential roles in the pathophysiology, as well as with a possible utility as diagnostic and prognostic biomarkers. These interesting findings deserve further exploration and validation in future studies.
PLOS ONE, 2016
MiRNAs have been reported as CIS-acting elements of several hemostatic factors, however, their me... more MiRNAs have been reported as CIS-acting elements of several hemostatic factors, however, their mechanism as TRANSacting elements mediated by a transcription factor is little known and could have important effects. HNF4α has a direct and important role in the regulation of multiple hepatic coagulation genes. Previous in vitro studies have demonstrated that miR-24-3p and miR-34a-5p regulate HNF4A expression. Here we aimed to investigate the molecular mechanisms of miR-24 and miR-34a on coagulation through HNF4A. Transfections with miR-24 and miR-34a in HepG2 cells decreased not only HNF4A but also F10, F12, SERPINC1, PROS1, PROC, and PROZ transcripts levels. Positive and significant correlations were observed between levels of HNF4A and several hemostatic factors (F5, F8, F9, F11, F12, SERPINC1, PROC, and PROS1) in human liver samples (N = 104). However, miR-24 and miR-34a levels of the low (10 th) and high (90 th) percentiles of those liver samples were inversely correlated with HNF4A and almost all hemostatic factors expression levels. These outcomes suggest that miR-24 and miR-34a might be two indirect elements of regulation of several hemostatic factors. Additionally, variations in miRNA expression profiles could justify, at least in part, changes in HNF4A expression levels and its downstream targets of coagulation.
Regulation of cyclic AMP synthesis and degradation is modified in rat liver at late gestation
Biochemical Journal, 1992
Cyclic AMP (cAMP) is known to play a key role in regulating insulin action, and it is well docume... more Cyclic AMP (cAMP) is known to play a key role in regulating insulin action, and it is well documented that in several cases of physiological insulin resistance its concentration is increased. Since late pregnancy in the rat is associated with liver insulin resistance, we have studied possible alterations of some cellular mechanisms regulating the cAMP metabolism. (1) Liver cAMP concentration was shown to be increased by some 30% and 50% at 18 and 22 days of pregnancy respectively, compared with virgins. (2) Basal adenylate cyclase activity was higher only in the 18-days-pregnant rat, and the forskolin-stimulated maximal activity was similar in the three groups of animals. (3) alpha s protein is decreased in term-pregnant rats; however, coupling between Gs and adenylate cyclase is only impaired in the 18-days-pregnant animals, and stimulation by glucagon is impaired in both groups of pregnant animals. (4) Gi-2 protein was shown to be unable to elicit the tonic inhibition of adenylate...
General Medicine: Open Access, 2014
Molecular medicine (Cambridge, Mass.), Jan 18, 2012
Mutations affecting mobile domains of antithrombin induce conformational instability resulting in... more Mutations affecting mobile domains of antithrombin induce conformational instability resulting in protein polymerization that associates with a severe clinical phenotype, probably by an unknown gain of function. By homology with other conformational diseases, we speculated that these variants might infect wild-type (WT) monomers reducing the anticoagulant capacity. Infective polymerization of WT polymers and different P1 mutants (p.R425del, p.R425C and p.R425H) were evaluated by using native gels and radiolabeled WT monomers and functional assays. Human embryonic kidney cells expressing the Epstein-Barr nuclear antigen 1 (HEK-EBNA) cells expressing inducible (p.R425del) or two novel constitutive (p.F271S and p.M370T) conformational variants were used to evaluate intracellular and secreted antithrombin under mild stress (pH 6.5 and 39°C for 5 h). We demonstrated the conformational sensitivity of antithrombin London (p.R425del) to form polymers under mild heating. Under these conditio...
Potential Role of miRNAs in Developmental Haemostasis
PLoS ONE, 2011
Blood, 2004
Here we report the characterization of a mouse model of the Bernard-Soulier syndrome generated by... more Here we report the characterization of a mouse model of the Bernard-Soulier syndrome generated by a targeted disruption of the gene encoding the glycoprotein (GP) Ibβ subunit of the GP Ib-IX complex. Similar to a Bernard-Soulier model generated by disruption of the mouse GP Ibα subunit, GP IbβNull mice display macrothrombocytopenia and a severe bleeding phenotype. When examined by transmission electron microscopy, the large platelets produced by a GP IbβNull genotype revealed α-granules with increased size as compared with the α-granules from control mouse platelets. Data are presented linking the overexpression of a septin protein, SEPT5, to the presence of larger α-granules in the GP IbβNull platelet. The SEPT5 gene resides approximately 250 nucleotides 5′ to the GP Ibβ gene and has been associated with modulating exocytosis from neurons and platelets as part of a presynaptic protein complex. Fusion mRNA transcripts present in megakaryocytes can contain both the SEPT5 and GP Ibβ c...
Cerebellar oligodendroglial cells have a mesencephalic origin
Glia, Sep 7, 2011
While the origin of oligodendroglia in the prosencephalon and spinal cord has been extensively st... more While the origin of oligodendroglia in the prosencephalon and spinal cord has been extensively studied and accurately described, the origin of this cell type in the cerebellum is largely unknown. To investigate where cerebellar oligodendrocytes generate and which migratory pathways they follow to reach their final destination in the adult, in ovo transplants were performed using the quail/chick chimeric system. The chimeric embryos were developed up to HH43-49 (17-19 days of incubation) to map the location of donor cells and analyze their phenotype by immunohistochemistry. As a result, mesencephalic homotopic and homochronic transplants generated cellular migratory streams moving from the grafted epithelium into the host cerebellum, crossing the isthmus mainly through the velum medullare and invading the central white matter. From here, these mesencephalic cells invaded all the layers of the cerebellar cortex except the granular layer. The majority of the cells were detected in the central and folial white matter, as well as in superficial regions of the internal granular layer, surrounding the Purkinje cells. In the latter case, the donor cells presented a Bergmann glial morphology and were Vimentin positive, while in other areas they were PLP and Olig2-positive, indicating an oligodendroglial fate. The combinatory analysis of the different grafts allowed us to propose the fate map of chick cerebellar oligodendroglia at the neural tube stage. As a result, the majority of the cerebellar oligodendrocytes originate from the parabasal plate of the mesencephalon.
Haematologica, 2007
Background and Objectives Platelets play a fundamental role in hemostasis and alterations of thei... more Background and Objectives Platelets play a fundamental role in hemostasis and alterations of their function can be determinant in the onset of stroke. A polymorphism in β1-tubulin (TUBB1 Q43P), a protein specifically expressed in the megakaryocytic line, has been described as a protective factor in cardiovascular disease. The potential effect of this variant in the pathogenesis of hemorrhagic stroke has not yet been investigated. Design and Methods We evaluated the role of the TUBB1 Q43P polymorphism and its synergism with other polymorphisms in the risk of developing subarachnoid (SAH) and intracerebral hemorrhage (ICH). We performed the study in 109 patients with SAH, 259 patients with ICH, and 449 subjects from the general population from southern Spain. Results No relationship was found between the TUBB1 Q43P polymorphism and SAH. In contrast, this polymorphism significantly increased the risk of ICH in men (OR, 2.78; 95% CI, 1.16-6.63; p=0.021) and was associated with an earlier age of occurrence of an ICH event (p=0.011). Carriers of the TUBB1 Q43P polymorphism displayed lower platelet reactivity towards collagen. A potent synergistic effect was observed in ICH patients carrying the TUBB1 Q43P polymorphism combined with either FVII-323 Del/Ins of a decanucleotide (OR 20.76; 95% CI, 3.57-120.71; p<0.001) or FXIII V34L (OR 7.19; 95% CI, 1.99-25.95; p=0.003). Interpretation and Conclusions This is the first evidence linking the TUBB1 Q43P platelet polymorphism with hemorrhagic stroke in humans. The TUBB1 Q43P polymorphism, by causing a lower reactivity in platelets carrying the variant form of β1-tubulin, protects against thrombotic disorders but increases the risk of ICH in men.
The Journal of Neuroscience, 1999
This work was partially f unded by European Commission Grant ERBBI04-CT96-0774 and Association po... more This work was partially f unded by European Commission Grant ERBBI04-CT96-0774 and Association pour la Recherche contre le Cancer Grant 9954. We are gratef ul to Fre ´de ´ric Roger for technical assistance. We thank Drs. Patricia Gaspar, Pierre Angaut, and Nicole Dumesnil for critical reading of this manuscript, Charles Duyckaerts for assistance in cellular measurements, and Denis Le Cren for photographic work. We also thank Dr. D. S. Latchman for providing the Brn-3.b probe.
Journal of Neuroscience, 2008
Precerebellar neurons of the inferior olive (IO) and lateral reticular nucleus (LRN) migrate tang... more Precerebellar neurons of the inferior olive (IO) and lateral reticular nucleus (LRN) migrate tangentially from the rhombic lip toward the floor plate following parallel pathways. This process is thought to involve netrin-1 attraction. However, whereas the cell bodies of LRN neurons cross the midline, IO neurons are unable to do so. In many systems and species, axon guidance and cell migration at the midline are controlled by Slits and their receptor Robos. We showed previously that precerebellar axons and neurons do not cross the midline in the absence of the Robo3 receptor. To determine whether this signaling by Slits and the two other Robo receptors, Robo1 and Robo2, also regulates precerebellar neuron behavior at the floor plate, we studied the phenotype of Slit1/2 and Robo1/2/3 compound mutants. Our results showed that many IO neurons can cross the midline in absence of Slit1/2 or Robo1/2, supporting a role for midline repellents in guiding precerebellar neurons. We also show that these molecules control the development of the lamellation of the inferior olivary complex. Last, the analysis of Robo1/2/3 triple mutants suggests that Robo3 inhibits Robo1/2 repulsion in precrossing LRN axons but not in IO axons in which it has a dominant and distinct function.
Uploads
Papers by Constantino Sotelo