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N Baeza

Publications and source records attributed to N Baeza.

12 recordsLinked to original sources
PubMed2006

Identification of genes differentially expressed in glioblastoma versus pilocytic astrocytoma using Suppression Subtractive Hybridization.

Glioblastoma (GBM) is a highly malignant glioma, which has the propensity to infiltrate throughout the brain in contrast to pilocytic astrocytoma (PA) of the posterior fossa, which does not spread and can be cured by surgery. We have used Suppression Subtractive Hybridization to define markers that better delineate the molecular basis of brain invasion and distinguish these tumor groups. We have identified 106 genes expressed in PA versus GBM and 80 genes expressed in GBM versus PA. Subsequent analysis identified a subset of 20 transcripts showing a common differential expression pattern for the two groups. GBM differs from PA by the expression of five genes involved in invasion and angiogenesis: fibronectin, osteopontin, chitinase-3-like-1 (YKL-40), keratoepithelin and fibromodulin. PA differs from GBM by the expression of genes related to metabolism (apolipoprotein D), proteolysis (protease-serine-11), receptor and signal transduction (PLEKHB1 for Pleckstrin-Homology-domain-containing-protein-family-B-member-1), transcription/translation (eukaryotic-translation-elongation-factor-1-alpha1) processes and cell adhesion (SPOCK1 for SPARC/Osteonectin-CWCV-kazal-like-domains-proteoglycan). The expression of these genes was confirmed by real-time quantitative RT-PCR and immunohistochemistry. This study highlights the crucial role of brain invasion in GBM and identifies specific molecules involved in this process. In addition, it offers a restricted list of markers that accurately distinguish PA from GBM.

Aged↗
PubMed2006

In vitro identification and functional characterization of glial precursor cells in human gliomas.

Human gliomas including astrocytomas and oligodendrogliomas are defined as being composed of neoplastic astrocytes and oligodendrocytes respectively. Here, on the basis of in vitro functional assays, we show that gliomas contain a mixture of glial progenitor cells and their progeny. We have set up explant cultures from pilocytic astrocytomas, glioblastomas and oligodendrogliomas and studied antigens that characterize glial lineage, from the precursor cells (glial restricted precursors and oligodendrocyte-type2-astrocyte/oligodendrocyte precursor cells expressing the A2B5 ganglioside) to the differentiated cells (oligodendrocyte and type-1 and type-2 astrocytes). All tumoral explants contain A2B5+ cells and can generate migrating cells with distinctive functional properties according to glioma subtypes. In pilocytic astrocytomas, very few migrating cells are dividing and can differentiate in type-2 astrocytes or towards the oligodendrocyte lineage. In glioblastomas, most migrating cells are dividing, express A2B5 or glial fibrillary acid protein (GFAP) and can generate oligodendrocytes and type-1 and type-2 astrocytes in appropriate medium. Oligodendroglioma explants are made by actively dividing glial precursor cells expressing A2B5 or PSA-NCAM. Only few cells can migrate and differentiation towards oligodendrocyte lineage does not occur. Isolated A2B5+ cells from both glioblastomas and oligodendrogliomas showed similar genetic alterations as the whole tumour. Therefore, pilocytic astrocytomas contain slowly dividing oligodendrocyte-type2-astrocyte/oligodendrocyte precursor cells in keeping with their benign behaviour whereas both glioblastomas and oligodendrogliomas contain neoplastic glial restricted precursor cells. In oligodendrogliomas, these cells are trapped in undifferentiated and proliferating state. The precursor cells properties present in gliomas give new insight into their histogenesis and open up new avenues for research in the field of gliomagenesis.

Adult↗
PubMed2001

Pancreatitis-associated protein (HIP/PAP) gene expression is upregulated in NOD mice pancreas and localized in exocrine tissue during diabetes.

We have previously shown a specific significant overexpression in the exocrine pancreatic tissue of two members of the regenerating gene multifamily: reg I and reg II in the non-obese diabetic (NOD) mouse during active diabetogenesis. To strengthen the hypothesis that the overexpression of these genes may represent a defence of the acinar cell against pancreatic endocrine agression, we studied the pancreatic expression and the localization of another member of this family: the pancreatitis-associated protein (PAP) in NOD mice under the same conditions. We found that NOD mice present significantly higher PAP mRNA levels than control IOPS-OF1 mice. There is no difference between female NOD mice which progressively develop type I diabetes between 100 and 200 days and male NOD mice which are protected. The only difference observed was in function of the age of onset of diabetes. Before 180 days, the PAP mRNA levels were similar to those found in NOD males and nondiabetic females, but above 180 days the levels of PAP mRNA increased significantly. More importantly immunohistological studies demonstrate a striking difference in the protein localization between normal or nondiabetic NOD mice and diabetic NOD mice. If the protein is mainly detected in the islet cells in the absence of diabetes, a specific and intense expression of PAP was observed in the acinar cells of diabetic NOD mice. In conclusion, our data demonstrates that the acinar cells may react to a long-lasting pancreatic endocrine aggression by an induction of PAP and underlines the existence of a symbiotic relationship between endocrine and exocrine tissue.

Animals↗
PubMed2000

Attenuation of FGF signalling in mouse beta-cells leads to diabetes.

Fibroblast growth factor (FGF) signalling has been implicated in patterning, proliferation and cell differentiation in many organs, including the developing pancreas. Here we show that the FGF receptors (FGFRs) 1 and 2, together with the ligands FGF1, FGF2, FGF4, FGF5, FGF7 and FGF10, are expressed in adult mouse beta-cells, indicating that FGF signalling may have a role in differentiated beta-cells. When we perturbed signalling by expressing dominant-negative forms of the receptors, FGFR1c and FGFR2b, in the pancreas, we found that that mice with attenuated FGFR1c signalling, but not those with reduced FGFR2b signalling, develop diabetes with age and exhibit a decreased number of beta-cells, impaired expression of glucose transporter 2 and increased proinsulin content in beta-cells owing to impaired expression of prohormone convertases 1/3 and 2. These defects are all characteristic of patients with type-2 diabetes. Mutations in the homeobox gene Ipf1/Pdx1 are linked to diabetes in both mouse and human. We also show that Ipf1/Pdx1 is required for the expression of FGFR1 signalling components in beta-cells, indicating that Ipf1/Pdx1 acts upstream of FGFR1 signalling in beta-cells to maintain proper glucose sensing, insulin processing and glucose homeostasis.

Aging↗
PubMed2000

Sexual dimorphism of pancreatic gene expression in normal mice.

A differential pancreatic behavior observed between male and female mice in diabetes and pancreatitis led us to study the gene and protein expressions of endocrine and exocrine pancreatic proteins in normal mice. We compared the levels of expression of six pancreatic genes and of four of the corresponding proteins in male and female mice OF1. Amylase gene expression was found to be significantly higher in females than in males, whereas trypsinogen and lipase gene expression were significantly lower. For chymotrypsinogen, reg, and insulin the differences were not significant. This sexual dimorphism did not exist in rat pancreas, where no gender difference was observed. After characterization of mice enzymes by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and antibodies directed to the closely related human pancreatic enzymes, we have compared the levels of these proteins in mice pancreatic homogenates. No significant difference was observed between males and females at the level of protein expression. These data suggest a hormonal sexual difference in the regulation of pancreatic protein synthesis at the pre- and posttranscriptional levels in normal mice, which may play a role in the development of mice pancreatic diseases.

Amylases↗
PubMed2000

Overexpression of the reg gene in non-obese diabetic mouse pancreas during active diabetogenesis is restricted to exocrine tissue.

We demonstrated pancreatic reg gene overexpression in non-obese diabetic (NOD) mice during active diabetogenesis. The aim of this study was to determine in which part of the pancreas (endocrine and/or exocrine) the gene(s) and the protein(s) were expressed and if their localization changed with progression of the disease. In situ hybridization analysis and immunocytochemical studies were carried out on pancreas of female and male NOD mice. Both develop insulitis but diabetes develops only in females and in males only when treated by cyclophosphamide. Our results show that whatever the age, sex, and presence of insulitis and/or diabetes, the expression of reg mRNAs and of the corresponding protein(s) was restricted to exocrine tissue. Moreover, reg remains localized in acinar cells in the two opposite situations of (a) cyclophosphamide-treated males in a prediabetic stage presenting a high level of both insulin and reg mRNAs, and (b) the overtly diabetic females with no insulin but a high level of reg mRNA. These findings suggest that overexpression of the reg gene(s) might represent a defense of the acinar cell against pancreatic aggression.

Animals↗
PubMed1999

Serum reg protein level is not related to the beta cell destruction/regeneration process during early phases of diabetogenesis in type I diabetes.

OBJECTIVE: In type I diabetes mellitus, early markers of beta cell damage are needed in order to detect the infraclinical development of the disease. The reg protein may be a good candidate, as the reg gene has been proposed to play a role in the pancreatic beta cell destruction/regeneration process during diabetogenesis in animal models of autoimmune diabetes. The aim of this study was to test the hypothesis whether serum reg protein level could be representative of either the destructive or regenerative process at the beta cell level during the early phases of type I diabetes in humans. DESIGN AND METHODS: We used a highly specific immunoassay to measure serum reg protein level in controls and in three groups of either diabetes prone or diabetic subjects: recently diagnosed diabetic patients, long-standing diabetic patients and islet cell antibody-positive non-diabetic subjects. RESULTS: We found no significant difference between the values observed in these three groups in comparison with control group (90.7+/-18.1ng/ml, 83.1+/-5.6ng/ml, 98.7+/-24.5ng/ml vs 85.5+/- 5.6ng/ml respectively). Moreover, when the insulin reserve was evaluated at 6 months in the recently diagnosed group, serum reg protein levels were not different between patients with or without residual insulin secretion (at onset: 103+/-42 vs 70.3+/-8. 5ng/ml respectively; at 6 months: 79.7+/-25.8ng/ml vs 81.6+/-15ng/ml respectively). In contrast, trypsin levels were significantly lower in every group of diabetic patients. Results were expressed as means +/- S.E.M. and groups compared by Student's t-test (P<0.05). CONCLUSIONS: We conclude that serum reg protein level cannot be used as a marker for the progression of the diabetogenic process in type I diabetes.

Adult↗
PubMed1998

Expression of peptide-23/pancreatitis-associated protein and Reg genes in human pituitary and adenomas: comparison with other fetal and adult human tissues.

Peptide 23, the rat homolog of the human pancreatitis-associated protein (PAP)/hepatocarcinoma-intestine-pancreas (HIP) protein, has been identified in primary culture of rat pituitary cells. Its secretion was shown to be stimulated by GH-releasing factor and inhibited by somatostatin in a similar fashion to GH. This observation led the researchers to speculate that peptide 23 does have a physiological hormonal role. We tested this hypothesis by screening by RT-PCR reactions the expression of the PAP/HIP gene in several human pituitary adenomas, especially GH-producing adenomas. Our results show a weak expression of the PAP/HIP gene in the pituitary gland and in most of the tumors, but independent of their origin. The significant homology of the PAP/HIP gene to the Reg gene family prompted us to study in the same pituitary adenomas the presence of the related Reg genes. Reg expression was never observed in the adenomas tested or in the pituitary gland. In contrast, the RegL transcript was observed in pituitary gland and in some subtypes of adenomas. We then extended our work to normal adults and developing human tissues to compare the expression patterns of the PAP/Reg gene family. We observed the presence of the PAP/HIP transcript in each tissue tested. In contrast, the Reg gene was expressed only in fetal pancreas and in some adult tissues, whereas the RegL gene was expressed not only in fetal pancreas but also in fetal colon and brain as well as some adult tissues. In conclusion, our results show that all of the human fetal and adult tissues examined express at least one of the different transcripts of the PAP/Reg family, suggesting that the regulation of these homologous genes is coordinately controlled.

Acute-Phase Proteins↗
PubMed1997

Pseudomonas aeruginosa lipopolysaccharide induces CF-like alteration of protein secretion by human tracheal gland cells.

Human tracheal gland (HTG) serous cells are now believed to play a major role in the physiopathology of cystic fibrosis. Because of the persistent inflammation and the specific infection by Pseudomonas aeruginosa in the lung, we looked for the action of the lipopolysaccharide (LPS) of this bacteria on human tracheal gland cells in culture by studying the secretion of the secretory leukocyte proteinase inhibitor (SLPI) which is a specific serous secretory marker of these cells. Treatment with Pseudomonas aeruginosa LPS resulted in a significant dose-dependent increase in the basal production of SLPI (+ 250 +/- 25%) whilst the SLPI transcript mRNA levels remained unchanged. This LPS-induced increase in secretion was inhibited by glucocorticoides. Furthermore, LPS treatment of HTG cells induces a loss of responsiveness to carbachol and isoproterenol but not to adenosine triphosphate. These findings indicate that HTG cells treated by Pseudomonas aeruginosa LPS have the same behavior as those previously observed with CF-HTG cells. Exploration by using reverse transcriptase polymerase chain reaction amplification showed that LPS downregulated cystic fibrosis transmembrane conductance regulator (CFTR) mRNA expression in HTG cells indicative of a link between CFTR function and consequent CF-like alteration in protein secretory process.

Adenosine Triphosphate↗
PubMed1997

Specific reg II gene overexpression in the non-obese diabetic mouse pancreas during active diabetogenesis.

The reg gene, previously described in islets of 90% pancreatectomized and nicotinamide-treated rats, has been shown to be expressed in many pharmacological or surgical animal models of beta cell regeneration. We have studied the non-obese diabetic (NOD) mouse, which represents a good model of spontaneous autoimmune diabetes in which regenerative processes have recently been demonstrated. Two reg genes have been described in the mouse genome, both recognized by the human reg cDNA. In a previous work, using the human probe, we have demonstrated a strong correlation between pancreatic reg gene expression and the likelihood of developing diabetes. In the present study, we have examined the respective levels of both mouse reg I and reg II mRNA in the NOD mouse pancreas using their specific cDNA probes. We found that reg II expression was specifically prevalent compared to reg I, irrespective of sex or state of the disease. Reg II mRNA was particularly increased in overtly diabetic female mice and in cyclophosphamide-treated male mice. These data underline the need to study separately the reg genes using specific probes and show that both reg genes are subjected to various regulations, strongly suggesting that their physiological functions may be different.

Animals↗
PubMed1996

Reg protein: a potential beta-cell-specific growth factor?

Beta-cell regeneration in adult pancreas is usually considered to be limited. However, various animal models suggest that this tissue is still capable of regeneration under certain conditions. Reg protein could be responsible for this replicative process. The reg gene codes for a 166 amino-acid protein usually synthesized and secreted by pancreatic acinar cells but expressed in islet beta cells during experimental regenerative processes in animals (90% pancreatectomy + nicotinamide, or insulinoma tumor removal in rats, or the "wrapping pancreas model" in the hamster). In addition, recombinant rat reg protein can stimulate beta-cell replication in vivo and in vitro. In animal models of Type 1 diabetes mellitus, reg gene overexpression occurs during active phases of diabetogenesis and could be a defence mechanism. During human pancreatic development, reg gene is expressed at an early stage but is not associated with the expression of other pancreatic genes. Conversely, gene expression for reg and insulin are correlated in adult pancreas. Accordingly, reg protein could be a beta-cell-specific growth factor implicated in the maintenance of beta-cell mass, especially in adult pancreas.

Animals↗