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C Mas

Publications and source records attributed to C Mas.

At least 19 recordsLinked to original sources
PubMed2005

Sequential activation of p75 and TrkB is involved in dendritic development of subventricular zone-derived neuronal progenitors in vitro.

Dendritic arbor development of subventricular zone-derived interneurons is a critical step in their integration into functional circuits of the postnatal olfactory bulb. However, the mechanism and molecular control of this process remain unknown. In this study, we have developed a culture model where dendritic development of purified subventricular zone cells proceeds under serum-free conditions in the absence of added growth factors and non-neural cells. We demonstrate that the large majority of these cells in culture express GABA and elaborate dendritic arbors with spine-like protrusions but they do not possess axons. These neurons expressed receptors for neurotrophins including p75, TrkB and TrkC but not TrkA. Application of exogenous neurotrophins, including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and nerve growth factor (NGF), to cultures stimulated dendritic growth and led to more complex dendritic arbors during the initial 3 days in culture. Our results suggest that these effects are independent of Trk receptors and mediated by the p75/ceramide signaling pathway. We also show that brain-derived neurotrophic factor is the only neurotrophin that is able to influence late-phase dendritic development via TrkB receptor activation. These results suggest that dendritic arbor development of subventricular zone-derived cells may be regulated by neurotrophins through the activation of p75 and the TrkB receptor signaling pathways in a sequentially defined temporal pattern.

Actins↗
PubMed2002

Activity-dependent regulation of genes implicated in X-linked non-specific mental retardation.

X-linked forms of non-specific mental retardation are complex disorders, for which mutations in several genes have recently been identified. These include OPHN1, GDI1, PAK3, IL1RAPL, TM4SF2, FMR2 and RSK2. To investigate the mechanisms through which alterations of these gene products could result in cognitive impairment, we analyzed their expression using quantitative PCR technique in two in vitro models of activity-dependent gene regulation: kainate-induced seizures and long-term synaptic potentiation (LTP). We found that the level of expression of four genes, PAK3, IL1RAPL, RSK2 and TM4SF2, was significantly up-regulated following kainate treatment. Furthermore we observed a significant increase in mRNA levels of PAK3 and IL1RAPL following LTP induction. These results suggest a possible role for these four genes in activity-dependent brain plasticity.

Action Potentials↗
PubMed2002

Beta-cell crosstalk: a further dimension in the stimulus-secretion coupling of glucose-induced insulin release.

Pancreatic beta-cells are connected by gap junction channels made of a connexin protein, referred to as Cx36. Through these channels, beta-cells are coupled to each other, i.e. exchange cytoplasmic ions and small metabolites. Previous experiments have indicated that these exchanges are important for coordinating the function of individual cells within pancreatic islets, particularly with regard to glucose-induced insulin secretion. Advances in molecular biology, genetics and mouse transgenic approaches allow now for a direct experimental testing of this mechanism in vitro as well as in vivo. Recent experiments in rodent and culture models suggest that connexin-dependent cell-to-cell crosstalk is a significant player in the multifactorial regulation of insulin secretion and, possibly, of other beta-cell functions, such as growth. Elucidating the still obscure mechanism whereby connexin signalling exerts this influence will provide insights on the contribution of direct cell-to-cell interactions in the physiological regulation of beta-cell life. The presence of Cx36 within human pancreatic islets, raises the further challenge to determine whether a dysfunction of connexin signaling may contribute to the pathophysiology of beta-cell dysfunctions in type I and/or type II diabetes. Efforts to understand the functions of beta-cell connexins are also a prerequisite for the engineering of surrogate cells and their proper tridimensional packaging, which are instrumental for the future implementation of a replacement cell therapy in diabetic patients.

Amino Acid Sequence↗
PubMed2001

Heart transplantation changes the expression of distinct gene families.

We took advantage of the combination of a rat heart transplantation model with a modified differential display RT-PCR method to identify transcriptome changes in the right atria from transplanted compared with native hearts. Based on sequence homology search, the 37 cDNAs differentially displayed both 2 and 7 days posttransplantation were categorized into 7 unknown transcripts, 16 expressed sequence tags (ESTs), and 14 partially or completely characterized genes. The last group cDNAs, validated by relative RT-PCR, belonged to diverse gene families involved in specific metabolisms, protein synthesis, cell signaling, and transcription. Furthermore, we identified differential transcripts corresponding to denervation and fetal gene reexpression. We found coordinate downregulation of genes involved in energy metabolism and protein synthesis regulation, similar to that reported for senescent skeletal muscle. From these transcriptome changes, we propose that heart transplants and senescent muscles share common molecular mechanisms.

Animals↗
PubMed2001

MASH-1/RET pathway involvement in development of brain stem control of respiratory frequency in newborn mice.

Respiratory abnormalities have been described in MASH-1 (mammalian achaete-scute homologous gene) and c-RET ("rearranged during transfection") mutant newborn mice. However, the neural mechanisms underlying these abnormalities have not been studied. We tested the hypothesis that the MASH-1 mutation may impair c-RET expression in brain stem neurons involved in the control of breathing. To do this, we analyzed brain stem c-RET expression and respiratory phenotype in MASH-1 +/+ wild-type, MASH-1 +/- heterozygous, and MASH-1 -/- knock-out newborn mice during the first 2 h of life. In MASH-1 -/- newborns, c-RET gene expression was absent in the noradrenergic nuclei (A2, A5, A6, A7) that contribute to modulate respiratory frequency and in scattered cells of the rostral ventrolateral medulla. The c-RET transcript levels measured by quantitative RT-PCR were lower in MASH-1 -/- and MASH-1 +/- than in MASH-1 +/+ brain stems (P = 0.001 and P = 0.003, respectively). Breath durations were shorter in MASH-1 -/- and MASH-1 +/- than in MASH-1 +/+ mice (P = 0.022) and were weakly correlated with c-RET transcript levels (P = 0.032). Taken together, these results provide evidence that MASH-1 is upstream of c-RET in noradrenergic brain stem neurons important for respiratory rhythm modulation.

Adaptation, Physiological↗
PubMed2001

The murine orthologue of the Golgi-localized TPTE protein provides clues to the evolutionary history of the human TPTE gene family.

The human TPTE gene encodes a testis-specific protein that contains four potential transmembrane domains and a protein tyrosine phosphatase motif, and shows homology to the tumor suppressor PTEN/MMAC1. Chromosomal mapping revealed multiple copies of the TPTE gene present on the acrocentric chromosomes 13, 15, 21 and 22, and the Y chromosome. Zooblot analysis suggests that mice may possess only one copy of TPTE. In the present study, we report the isolation and initial characterization of the full-length cDNA of the mouse homologue Tpte. At least three different mRNA transcripts ( Tpte.a, b, c) are produced via alternative splicing, encoding predicted proteins that would contain four potential transmembrane domains and a protein tyrosine phosphatase motif. Transfection of a 5'EGFP-TPTE fusion protein in Hela cells revealed an intracellular localization within the Golgi apparatus. Tpte was mapped by radiation hybrid to a region of mouse chromosome 8 that shows conserved synteny with human 13q14.2-q21 between NEK3 and SGT1. This region of the human genome was found to contain a partial, highly diverged copy of TPTE that is likely to represent the ancestral copy from which the other copies of TPTE arose through duplication events. The Y chromosome copy of TPTE is a pseudogene and is not therefore involved in the testis expression of this gene family.

Amino Acid Motifs↗
PubMed2001

Caffeine-induced telencephalic vesicle evagination in early post-implantation mouse embryos involves cAMP-dependent protein kinase (PKA) inhibition.

Other studies have shown that caffeine accelerates telencephalic vesicle evagination in early post-implantation mouse embryos. The present study examines the effect of caffeine on gene modulation in post-implantation mouse embryos. Using mRNA differential display, we observed that caffeine increased gene expression of the regulatory subunit (RI alpha) of cAMP-dependent protein kinase (PKA). RT--PCR analysis confirmed an increase in expression of this gene in caffeine-exposed embryos when compared with saline-treated controls. Using a fluorescent substrate of PKA, we found that PKA activity in the presence of cAMP was lower in caffeine-treated embryos than in controls. Treatment with H89 and PKI(12-24)amide, two inhibitors of PKA activity, mimicked the effects of caffeine on telencephalic vesicle formation. Together these data suggest that in early post-implantation mouse embryos caffeine modulates gene expression of the RI alpha subunit of PKA and that caffeine-induced inhibition of PKA activity plays a role in early telencephalic evagination.

Animals↗
PubMed2001

Identification and isolation of a full-length clone of mouse GMFB (Gmfb), a putative intracellular kinase regulator, differentially expressed in telencephalon.

We identified new transcribed sequences, using a differential display paradigm to select genes expressed in proliferating neuroblasts from mouse telencephalon at 10 days of embryonic development. In this systematic search, we isolated a 361-bp partial 3' untranslated region (3' UTR) homologous to the 3' UTR of the human gene encoding a putative intracellular kinase regulator, glia maturation factor beta (GMFB). We cloned a full-length, 4,311-bp mouse cDNA containing a 270-bp 5' UTR, a 3,615-bp 3' UTR, and an open reading frame of 426 nucleotides encoding a putative 142 amino-acid protein, identical to human GMFB, with the exception of two amino acids. This 4.3-kb transcript is present in a variety of adult tissues and is developmentally regulated as shown by Northern blot analysis. Differential expression in telencephalon was demonstrated by quantification of radioactive relative RT-PCR and confirmed by in situ hybridization. The isolation of this full-length clone of mouse Gmfb should facilitate investigation of the intracellular mechanisms involved in the development of telencephalon.

3' Untranslated Regions↗
PubMed2001

General and conditional replacement of connexin43-coding DNA by a lacZ reporter gene for cell-autonomous analysis of expression.

Using the Cre/loxP system, we have circumvented early postnatal lethality and possible pleiotropic effects of general Cx43 gene deletion, in order to determine the expression and function of connexin43 (Cx43) in defined cell types. General or cell type-specific, Cre-mediated deletion of the floxed (i.e. flanked by loxP sites) Cx43-coding region led to activation of the inserted lacZ reporter gene in cells with transcriptional activity of the Cx43 gene. As deduced from lacZ expression in mice with general deletion, transcriptional activity of the Cx43 gene was not only found in a broad range of cell types known to a express Cx43, but also inpancreatic duct cells and vascular cells of the gut and skeletal muscle. Cre-mediated deletion restricted to defined cell types led to lacZ activation highlighting corresponding subsets of cells expressing Cx43, such as vascular endothelial cells, hepatic duct cells and putative neural crest cells, which were otherwise masked by strong Cx43 expression in neighbouring cells. In Cx43 expressing cell types, the floxed Cx43 allele was useful as a Cre-excision reporter for the characterization of Cre transgenes.

Animals↗
PubMed2001

Cx36 and the function of endocrine pancreas.

The secretory, duct, connective and vascular cells of pancreas are connected by gap junctions, made of different connexins. The insulin-producing beta-cells, which form the bulk of endocrine pancreatic islets, express predominantly Cx36. To assess the function of this connexin, we have first studied its expression in rats, during sequential changes of pancreatic function which were induced by the implantation of a secreting insulinoma. We observed that changes in beta-cell function were paralleled by changes in Cx36 expression. We have also begun to investigate mutant mice lacking Cx36. The absence of this protein did not affect the development and differentiation of beta-cells but appeared to alter their secretion. We have studied this effect in MIN6 cells which spontaneously express Cx36. After stable transfection of a construct that markedly reduced the expression of this connexin, we observed that MIN6 cells were no more able to secrete insulin, in contrast to wild type controls, and differentially displayed a series of still unknown genes. The data provide evidence that Cx36-dependent signaling contributes to regulate the function of native and tumoral insulin-producing cells.

Animals↗
PubMed2000

Cloning and expression analysis of a novel gene, RP42, mapping to an autism susceptibility locus on 6q16.

We isolated a novel mouse gene, RP42, in a systematic search for genes expressed in proliferating neuroblasts whose human orthologs map to susceptibility loci for autism. This gene is intronless and encodes a putative 259-amino-acid protein that exhibits 30-36% overall sequence identity to a fission yeast and a nematode protein (GenPept Accession Nos. CAA17006 and CAB54261). Nevertheless, no homology to any known gene was found. RP42 has developmentally regulated expression, particularly in proliferating neuroblasts from which neocortical neurons originate. Its human ortholog is located in a cluster of embryonic neuronally expressed genes on the 6q16 chromosome, making it a positional candidate susceptibility gene for autism.

Amino Acid Sequence↗
PubMed2000

New interventional therapeutic approach for dual drainage of the scimitar vein.

A patient with scimitar syndrome and dual drainage of a right-sided scimitar vein into the inferior vena cava and the left atrium underwent coil occlusion of the right aortopulmonary collateral artery and device occlusion of the lower scimitar vein drainage, leaving it flowing solely into the left atrium.

Child, Preschool↗
PubMed2000

Pre-excitation syndrome secondary to cardiac rhabdomyomas in tuberous sclerosis.

Rhabdomyomas are not uncommon in infants with tuberous sclerosis. We describe a neonate who presented with hydrops fetalis arising from a tachyarrhythmia during fetal life related to rhabdomyomas. After reversion of the arrhythmia, pre-excitation was noted on an interval electrocardiogram. Following regression of the tumours, the delta wave disappeared with no further arrhythmias noted.

Cesarean Section↗
PubMed1999

Persistent truncus arteriosus in monozygotic twins: case report and literature review.

We report on a pair of monozygotic twins with persistent truncus arteriosus. They had no evident clinical signs of DiGeorge syndrome. Pathologic examination of the placenta and DNA analysis in chromosomes 7, 8, and 15 was consistent with monozygosity. Fluorescence in situ hybridization test was negative for chromosome 22q11 microdeletion. Family history revealed a female cousin with tetralogy of Fallot. The isolated presence of this conotruncal abnormality in monozygotic twins is extremely rare. The genetic considerations are discussed.

Diseases in Twins↗
PubMed1999

Does left ventricular outflow tract obstruction influence outcome of interrupted aortic arch repair?

BACKGROUND: In previous studies left ventricular outflow tract obstruction (LVOTO) has been recognized as an important factor affecting survival and reoperation probability in patients having repair of an interrupted aortic arch (IAA). METHODS: All 72 patients who underwent operation for IAA from January 1, 1985 to June 30, 1997 were reviewed. The presence or absence of LVOTO was noted and the immediate and long-term results were analyzed. RESULTS: Type A IAA was found in 23 patients and type B IAA in 49 patients. Anomalous right subclavian artery was noted in 15 patients, all of whom had type B IAA. LVOTO was identified in 36 patients before arch repair and was associated with the presence of type B IAA and anomalous right subclavian artery (p = 0.02 and 0.007, respectively). There were 2 hospital deaths (within 30 days) for a mortality of 2.8% (confidence limit [CL] = 0% to 6.6%). There were 7 late deaths over 3,737 patient-months of follow-up (9.7%, CL = 2.9% to 16.6%). Actuarial survival for the whole cohort was 84.8% (CL = 73.2% to 94.4%) at 12 years. There was 87% 10-year survival (CL = 60% to 93%) for patients with LVOTO at presentation compared with 83% (CL = 62% to 92%) for patients without LVOTO (p = 0.85, hazard function 0.87). Twenty-eight patients have required at least one reoperation. The use of conduits to restore right ventricular to pulmonary artery continuity predicted the need for reoperation (p = 0.0001). Patients with presence of a nonseptatable heart were also more likely to need reoperation (p = 0.027) when compared to the rest of the cohort. Freedom from reoperation was 47.3% (CL = 30% to 62%) at 12 years. In patients with LVOTO, freedom from reoperation (55% at 10 years, CL = 33% to 72%) was not significantly different from those patients without LVOTO at presentation (29% at 10 years, CL = 7% to 56%; p = 0.97, hazard function 0.7). Actuarial freedom from recurrent arch obstruction requiring reintervention was 82.7% (CL = 66.7% to 98.7%) at 12 years. CONCLUSIONS: Neonatal complete repair of patients with IAA is possible with low mortality. LVOTO was not a significant risk factor for hospital or late death in patients having complete repair of IAA during this period. The use of conduits for right ventricular to pulmonary artery continuity and the presence of a nonseptatable heart are important risk factors for further operation and will continue to provide added morbidity to these patients.

Aorta, Thoracic↗
PubMed1999

Ventilatory responses to hypercapnia and hypoxia in Mash-1 heterozygous newborn and adult mice.

Normal control of breathing is characterized by maintenance of CO2 and O2 arterial pressures at constant levels by appropriate ventilatory responses to changes in CO2 production and O2 consumption. Abnormal development of this regulatory system during embryogenesis may produce early impairments in chemosensitivity, as in congenital central hypoventilation syndrome. The present study addresses the role of the mammalian achaetescute homologous gene (Mash-1) in the development of respiratory control. We analyzed ventilatory responses to hypercapnia (8% CO2, 21% O2, 71% N2) and hypoxia (10% O2, 3% CO2, 87% N2) in newborn and adult Mash-1 heterozygous mice (Mash-1+/-) and their wild-type littermates (Mash-1+/+). Ventilation, breath duration, and tidal volume were measured using whole-body plethysmography. Ventilatory responses to hypercapnia were significantly weaker in newborn male Mash-1+/- compared with Mash-1+/+ mice as a result of a weaker breath-duration response. No differences were observed between adult Mash-1+/- and Mash-1+/+ mice. Our data suggest that Mash-1 may be involved in respiratory control development via mechanisms linked to the X chromosome.

Animals↗