Biomedical subjects

Ariane Berdal

Publications and source records attributed to Ariane Berdal.

12 recordsLinked to original sources

PubMed2006

Insulin-like growth factor binding protein (IGFBP-1) involvement in intrauterine growth retardation: study on IGFBP-1 overexpressing transgenic mice.

In humans, intrauterine growth retardation is correlated to high levels of serum IGF binding protein-1 (IGFBP-1). This present study analyzes in vivo the impact of circulating IGFBP-1 on body growth associated to bone mineralization and carbohydrate resources. Transgenic mice used in this work overexpressed human IGFBP-1 in liver from embryonic day (E)14.5, concomitantly to the appearance of ossification centers, through to adulthood. Growth retardation was observed as early as E17.5 in homozygous (HM) mice being 20% smaller at birth (postnatal d 1). Anatomical analysis of the skeletons by alizarin red and alcian blue staining showed that the mice exhibited pleiotropic defects of several skeletal units. Some bones were small and dysmorphic. Our results showed reduced mineralization in the posterior area of the skull (delayed suture closure), as well as in the appendicular and axial skeleton. Heterozygous crossings showed a loss of HM animals. Moreover, IGFBP-1 overexpression contributed to decreased fetal hepatic glycogen and neonate blood glucose levels which constitute the main reservoir of carbohydrate resources for neonates. Thus, this reduced carbohydrate pool contributed to perinatal mortality. Maternal IGFBP-1 expression was also clearly associated with neonate growth retardation (newborn weights from HM mothers were 20% smaller than newborns from NT mothers) and reduced fetal carbohydrate resources. In conclusion, antenatal growth retardation and delayed mineralization in transgenic mice are related to overexpressed fetal and maternal circulating human IGFBP-1. Similar perturbations could be observed in human intrauterine growth retardation suggesting the IGF/IGFBP system is involved in fetal growth, biomineralization, and energetic status in humans.

Animals↗

PubMed2006

Vitamin D and tissue non-specific alkaline phosphatase in dental cells.

Dental epithelium comprises different cell populations, including ameloblasts and stratum intermedium cells. Ameloblasts are vitamin D targets, and at least five proteins undergo specific modulation of their expression following the addition of 1alpha,25(OH)2 vitamin D3[1alpha,25(OH)2D3]. Stratum intermedium cells have not been studied in any great detail regarding vitamin D impact. Interestingly, in these cells, the tissue non-specific alkaline phosphatase (TNAP) is overexpressed. On the other hand, TNAP is a reliable bone marker of vitamin D action, similar to calbindins in kidney and intestine, previously used for studies of vitamin D activity in ameloblasts. Here, TNAP expression and activity were investigated in vivo in the microdissected epithelium and mesenchyme of mandible incisors. Physiological doses of 1alpha,25(OH)2D3 injected in control rats failed to modify TNAP activity in both dental epithelium and mesenchyme. No significant differences were observed in the steady-state levels of TNAP mRNAs of dental tissues from wild-type and vitamin D nuclear receptor (VDRnuc)-deficient mice of the same litters. These data suggest that, in contrast to ameloblasts, stratum intermedium cells are not sensitive to 1alpha,25(OH)2D3. An explanation for such a responsiveness of stratum intermedium cells to 1alpha,25(OH)2D3 is proposed based on the respective expressions of both vitamin D receptors (VDRnuc and 1,25D3-[MARRS]) and the Dlx2 homeobox gene.

Alkaline Phosphatase↗

PubMed2005

Natural antisense transcripts: sound or silence?

Antisense RNA was a rather uncommon term in a physiology environment until short interfering RNAs emerged as the tool of choice to knock down the expression of specific genes. As a consequence, the concept of RNA having regulatory potential became widely accepted. Yet, there is more to come. Computational studies suggest that between 15 and 25% of mammalian genes overlap, giving rise to pairs of sense and antisense RNAs. The resulting transcripts potentially interfere with each other's processing, thus representing examples of RNA-mediated gene regulation by endogenous, naturally occurring antisense transcripts. Concerns that the large-scale antisense transcription may represent transcriptional noise rather than a gene regulatory mechanism are strongly opposed by recent reports. A relatively small, well-defined group of antisense or noncoding transcripts is linked to monoallelic gene expression as observed in genomic imprinting, X chromosome inactivation, and clonal expression of B and T leukocytes. For the remaining, much larger group of bidirectionally transcribed genes, however, the physiological consequences of antisense transcription as well as the cellular mechanism(s) involved remain largely speculative.

Alleles↗

PubMed2005

Expression pattern of Dlx3 during cell differentiation in mineralized tissues.

The present study was designed to compare the expression pattern of Dlx3 in four different mineralized tissues because of: 1-its role in skeleton patterning, 2-its expression in dental epithelium and mesenchyme during morphogenesis, 3-the membranous and endochondral bone and tooth phenotype of tricho-dento-osseous syndrome related to Dlx3 gene mutation and 4-recently emerging knowledge on Dlx family members in the bone field. Ameloblasts, odontoblasts, osteoblasts and chondrocytes were analyzed in vitro and in vivo. Dlx3 transcripts were detected by RT-PCR in established model systems (microdissected dental epithelium and mesenchyme; primary cultures of rat chondrocytes), as recently performed in osteoblasts in vitro. A human 414-bp Dlx3 probe was generated. A 4.5-kb human Dlx3 sense RNA was identified in maxillo-facial samples by Northern blotting. Immunolabeling and in situ hybridization were performed in mice from Theiler stage E 14.5 until birth. In teeth, although Dlx3 was still expressed in differentiated ameloblasts, it was down regulated during odontoblast polarization. During endochondral bone formation, Dlx3 protein was detected in chondrocytes and was most strongly expressed in the prehypertrophic cartilage zone and in differentiating and differentiated osteoblasts of metaphyseal periosteum. In vitro, real-time PCR studies supported this upregulation in prehypertrophic chondrocytes, closely correlated with Ihh variations. In membranous bone, Dlx3 was present in preosteoblasts, osteoblasts and osteoid-osteocytes. The present data on Dlx3 and recently published functional studies show that this transcription factor may be instrumental during growth in the control of matrix deposition and biomineralization in the entire skeleton.

Ameloblasts↗

PubMed2005

Expression and regulation of the Msx1 natural antisense transcript during development.

Bidirectional transcription, leading to the expression of an antisense (AS) RNA partially complementary to the protein coding sense (S) RNA, is an emerging subject in mammals and has been associated with various processes such as RNA interference, imprinting and transcription inhibition. Homeobox genes do not escape this bidirectional transcription, raising the possibility that such AS transcription occurs during embryonic development and may be involved in the complexity of regulation of homeobox gene expression. According to the importance of the Msx1 homeobox gene function in craniofacial development, especially in tooth development, the expression and regulation of its recently identified AS transcripts were investigated in vivo in mouse from E9.5 embryo to newborn, and compared with the S transcript and the encoded protein expression pattern and regulation. The spatial and temporal expression patterns of S, AS transcripts and protein are consistent with a role of AS RNA in the regulation of Msx1 expression in timely controlled developmental sites. Epithelial-mesenchymal interactions were shown to control the spatial organization of S and also AS RNA expression during early patterning of incisors and molars in the odontogenic mesenchyme. To conclude, this study clearly identifies the Msx1 AS RNA involvement during tooth development and evidences a new degree of complexity in craniofacial developmental biology: the implication of endogenous AS RNAs.

Animals↗

PubMed2005

Modulation of 1alpha,25-dihydroxyvitamin D3-membrane associated, rapid response steroid binding protein expression in mouse odontoblasts by 1alpha,25-(OH)2D3.

The rapid, nongenomic effects of 1alpha,25-dihydroxyvitamin D3 (1alpha,25-(OH)2D3 have been related to a 1,25D3-membrane associated, rapid response steroid binding protein or 1,25D3-[MARRS]bp, with a molecular weight of 65 kDa, in several tissues and species. Currently, no information is available concerning the nongenomic responses to 1alpha,25-(OH)2D3 in dental tissues. In order to investigate the expression of 1,25D3-[MARRS]bp in dental cells, in the presence or absence of 1alpha,25-(OH)2D3, we have used rabbit polyclonal antibodies directed against the N-terminus of the 1,25D3-[MARRS]bp (Ab099) that recognizes the 1alpha,25-(OH)2D3 binding protein in chick intestinal basolateral membranes and a mouse odontoblast-like cell line (MO6-G3). Western blotting and flow cytometric analyses with Ab099 specifically detected 1,25D3-[MARRS]bp in MO6-G3 cells. Moreover, 1,25D3-[MARRS]bp was up-regulated, in vivo, in differentiated dental cells. Electron microscopic analysis confirmed the plasma membrane localization of this binding protein and also showed its intracellular presence. Incubation of MO6-G3 cells with different doses of 1alpha,25-(OH)2D3 for 36 h resulted in an inhibition of 1,25D3-[MARRS]bp expression with a maximal effect at 50 nM steroid. In addition, the culture media of MO6-G3 cells contains immunoreactive 1,25D3-[MARRS]bp. Immunogold positive membrane vesicle-like structures are present in the extracellular matrix of MO6-G3 cells. Altogether, these results indicate that the 1,25D3-[MARRS]bp expression in MO6-G3 cells is modulated by 1alpha,25-(OH)2D3. In conclusion, this 1alpha,25-(OH)2D3 binding protein could play an important role in the rapid, nongenomic responses to 1alpha,25-(OH)2D3 in dental cells.

Animals↗

PubMed2004

The modulation of tissue-specific gene expression in rat nasal chondrocyte cultures by bioactive glasses.

Since bone repair may occur, following endochondral ossification, we have investigated the behaviour of chondrocytes isolated from nasal septum cartilage of foetal rats and cultured up to 21 days in the presence of a melt-derived bioactive glass (Bioglass 45S5) and a less reactive glass with 60 wt% silica content (60S). In both cultures, chondrocytes proliferate and form typical cartilaginous nodules on day 5 of cultures. However, on day 12, the nodules in contact with 45S5 granules became darker than in 60S cultures, corresponding to the emergence of matrix biomineralization. Transmission electron microscopy showed a collagen-rich matrix composed of densely packed fibres and mineralized foci formed of needle-shaped crystals in contact with an electron-dense layer located at the periphery of the material. The specific activity of alkaline phosphatase was significant higher in 45S5 cultures on day 15 than in 60S cultures. Real time RT-PCR was used to monitor gene expression levels of specific chondrogenic markers. The transcription factor Sox9 was expressed throughout the culture period, but with no significant differences between the two kinds of cultures. In contrast, Runx2 expression was higher in experiment cultures on day 12. Type II collagen mRNA and aggrecan, showed an almost similar expression pattern with a strong expression at the beginning of cultures but higher in experiment cultures. Indian hedgehog was strongly expressed between day 9 and 12 with a significant stimulation in 45S5 cultures. Similarly, type X collagen mRNA seemed to be up-regulated in 45S5 cultures on day 20. In conclusion, this study shows hat 45S5 Bioglass has the ability to support the growth of chondrocytes and to stimulate some chondrogenic molecular markers.

Aggrecans↗

PubMed2004

Altered plakoglobin expression at mRNA and protein levels correlates with clinical outcome in patients with oropharynx squamous carcinomas.

Previous studies have established that expression of plakoglobin is down-regulated during malignant transformation. The aim of this study was to evaluate for the first time the expression of plakoglobin at the mRNA and protein levels in primary oropharyngeal squamous cell carcinomas (SCCs) and determine the extent to which the patterns of expression correlated with clinical parameters. Plakoglobin expression was evaluated in 37 new tumor cases and normal oral epithelium using immunofluorescence, reverse transcriptase-polymerase chain reaction (RT-PCR), and Northern and Western blotting analysis. The results indicated that the steady-state levels of plakoglobin protein were down-regulated in all tumors compared with normal epithelium. Furthermore, in 87.1% of the tumors, plakoglobin immunoreactivity displayed an abnormal cytoplasmic localization that was inversely correlated with tumor size and directly correlated with a poor clinical outcome for the patient. Northern blotting analysis revealed that down-regulation of mRNA expression occurred in only 65.6% of the tumors, with plakoglobin mRNA levels similar to normal epithelium in the remaining cases. In the tumors expressing mRNA levels similar to those of normal tissue, a 3.7-kb transcript was detected in addition to the expected 3.4-kb transcript observed in normal epithelium. RT-PCR analysis of the 3' untranslated region of the 3.7-kb plakoglobin mRNA transcript identified a 297-base insertion from +2369 to +2666 that had been previously reported only in transformed cell lines (GenBank M23410). Interestingly, the prognosis was poor for patients with tumors expressing both RNA transcripts. These results are consistent with the concept that complex regulation of plakoglobin expression and intracellular routing may contribute to malignant transformation. The study also shows evidence that the level of expression and intracellular localization of plakoglobin may be useful in predicting the course of disease in patients with oropharyngeal SCC.

Adult↗

PubMed2003

Regulation by glucocorticoids of cell differentiation and insulin-like growth factor binding protein production in cultured fetal rat nasal chondrocytes.

Glucocorticoids (GCs) modulate insulin-like growth factor action in cartilage through mechanisms that are complex and insufficiently defined, especially in the context of cranio-facial growth. Because the family of IGF-binding proteins (IGFBP-1 to -6) is important in the regulation of IGF availability and bioactivity, we examined the effect of GCs on chondrocyte differentiation in correlation with IGFBP production in cultured fetal rat chondrocytes isolated from nasal septum cartilage of fetal rat. Dexamethasone (DEX) effects were tested before and at the onset of extracellular matrix maturation. DEX induced a dose-dependent increase in the size of cartilage nodule formed, (45)Ca incorporation into extracellular matrix, alkaline phosphatase activity, and sulfatation of glycosaminoglycans, maximal effects being obtained with a 10-mM DEX concentration. The IGFBPs produced by cultured chondrocytes were characterized in culture medium which had been conditioned for 24 h under serum-free conditions by these cells. Western ligand blotting with a mixture of [(125)I]IGF-I and -II revealed bands of 20, 24, 29, a 31-32 kDa doublet and a 39-41 kDa triplet which were differently regulated by DEX. Immunoblotting showed that following DEX exposure, IGFBP-3 and -6 were up-regulated whereas IGFBP-2, -5, and the 24 kDa band were down-regulated. The effect of DEX on both differentiation and IGFBP production showed a same dependence, and developed when extracellular matrix maturation had been just induced. The results obtained in this chondrocyte culture system show that production of IGFBPs is modulated by DEX at physiological concentrations thus regulating IGF availability and action, a control which could promote the primordial role of the rat nasal septum in craniofacial growth.

Animals↗

PubMed2003

Osteoblast precursors at different anatomic sites.

Skeletal morphology depends on the local regulation of bone formation, both in a quantitative and qualitative sense. The formative cells, osteoblasts, adjust their synthetic activity in response to signals that influence cell differentiation and matrix production. Here, we review data concerning the morphological patterning during bone ontogenesis and its direct cause: osteoblasts at specific anatomic sites. An overview of the possible origins of osteogenic cells is presented, considering bone growth and homeostasis, and discussing the repair process. A testable model is proposed, in which functional differences between osteoblast populations are explained by homeobox-gene regulation. Newly developed markers for osteoblast recruitment and differentiation provide an experimental system to test the impact of homeobox-gene expression on osteoblast differentiation and bone matrix production.

Animals↗

PubMed2002

The biomimetics of bone: engineered glass-ceramics a paradigm for in vitro biomineralization studies.

In this study, we investigated the behavior of fetal rat osteoblasts cultured up to 23 days on a bioactive apatite-wollastonite glass-ceramic (AW) and on the same material on which a carbonated apatite layer was formed by a biomimetic process (AWa). The specific activity of alkaline phosphatase activity was about 30% increased on AWa compared to AW disks at the last day of culture. Scanning electron microscopic (SEM) observations of the material surfaces after scrapping off the cell layers revealed that mineralized bone nodules remained attached to both surfaces but in larger numbers on AWa. The AWa/bone interfaces were also analyzed after fracturing the disks and by transmission electron microscopy (TEM). All these results indicated the importance of the surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix. Furthermore, prefabrication of a biological apatite layer by a biomimetic method could improve our knowledge of biomineralization processes and could find application as bone-repairing material.

Alkaline Phosphatase↗

PubMed2002

Expression of a 1,25-dihydroxyvitamin D3 membrane-associated rapid-response steroid binding protein during human tooth and bone development and biomineralization.

The calciotropic hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] has been established to control skeletal tissue formation and biomineralization via the regulation of gene expression. This action involves the well-characterized nuclear 1,25(OH)2D3 receptor. However, it has been recognized that several cellular responses to 1,25(OH)2D3 may not to be related to the exclusive nuclear receptor. Indeed, this secosteroid is able to generate rapid responses that have been proposed to be mediated by interactions of the ligand, which is a putative cell membrane-associated rapid-response steroid (MARRS) binding protein for 1,25(OH)2D3 [1,25D3-MARRS]. The nongenomic pathway of 1,25(OH)2D3 was studied here in detail by immunolocalization of the 1,25D3-MARRS during the specific context of human prenatal development. Western blotting with proteins extracted from 4 week- to 27-week-old embryos was performed, evidencing a 65-kDa molecular species recognized by antibody Ab 099 generated against synthetic peptides corresponding to the N terminus of the 1,25D3-MARRS from chick intestinal basolateral membranes. Based on this biochemical conservation of protein in the human species, the temporospatial expression patterns were established in the craniofacial skeleton at the same ages. Comparative analysis was performed in teeth and bones from early morphogenesis to terminal cell differentiation and extracellular biomineralization. The data show the potential implication of 1,25D3-MARRS in the heterogeneous cell population including ameloblasts, odontoblasts, osteoblasts, and osteoclasts. The epithelial-mesenchymal cascade related to odontogenesis was coincident with a sequence of up- and down-regulation of immunoreactive 1,25D3-MARRS. Biomineralization was associated with a striking up-regulation in the adjoining secretory cells in all tissues. Finally, osteoclasts appeared also to express the 1,25D3-MARRS during these early phases of bone modeling. Previously obtained data of the nuclear vitamin D receptor (VDR) expression and this study on 1,25D3-MARRS suggest the existence of cross-talk between the genomic and nongenomic pathways during human development.

Ameloblasts↗