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M Thomasset

Publications and source records attributed to M Thomasset.

At least 73 records · Page 4Linked to original sources
PubMed1988

Human colon cell line HT-29: characterisation of 1,25-dihydroxyvitamin D3 receptor and induction of differentiation by the hormone.

The human colon carcinoma cell line HT-29 differentiates into functional enterocytes upon replacement of glucose by galactose in the culture medium. Since the differentiation of other types of cells is associated with the modulation of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) receptor concentrations and since enterocytes are classical target cells for 1,25(OH)2D3 we have examined the HT-29 cells to determine whether the differentiated and undifferentiated stages could be directly linked to the presence of 1,25(OH)2D3 receptors. HT-29 cells were grown in Dulbecco's modified medium containing 10% fetal calf serum (FCS) and glucose or galactose. Cell differentiation was assessed by measuring the brush border hydrolase, maltase. 1,25(OH)2D3 receptors were studied in the cells after 48 h without FCS. Nuclear uptake was measured in intact dispersed cells and the receptor protein was further characterized by vitamin D metabolite binding specificity, sucrose density gradient analysis and binding to DNA-cellulose. Maltase activity was 5-fold greater in differentiated HT-29 cells than in undifferentiated cells. Scatchard analysis showed a highly specific saturable (9500 sites per cell) high affinity (2 x 10(-10) M), binding of 1,25(OH)2D3 in undifferentiated cells. This receptor-like protein sedimented at 3.3S, bound to and eluted from DNA-cellulose and had all the characteristics of a 1,25(OH)2D3 receptor. No specific binding was detected in differentiated HT-29 cells. The presence of 1,25(OH)2D3 receptors in undifferentiated HT-29 cells implies that these cells are targets for vitamin D. The maltase activity increased significantly when undifferentiated cells were exposed to 1,25(OH)2D3 for 5-6 days, indicating that the hormone can promote differentiation of HT-29 cells. These results demonstrate that HT-29 cells can provide a new model for studying steroid receptor regulation and cell differentiation.

Calcitriol↗
PubMed1988

Calbindin (CaBP 28 kDa) localization in the peripheral vestibular system of various vertebrates.

Previous reports on calbindin, a 28 kDa vitamin D-induced calcium-binding protein, located in the mammalian peripheral vestibular system indicated that it is specifically distributed and postulated that it could play a role in the electrophysiological functioning of the sensory cells. This immunocytochemical investigation of the distribution of calbindin in the vestibular system of various vertebrates: fishes (goldfish and sea-perch), amphibia (frog), birds (chicken) and mammals (mouse, cat and baboon), was performed to verify these observations. In the vestibular ganglion, only a few neurons were faintly immunoreactive in the fishes and the frog, while the staining was more intense but still not present in all neurons of the chicken, the mouse and the cat. All the neurons were immunoreactive in the baboon. No immunoreactivity was observed in the sensory epithelia of the fishes. All hair cells were strongly immunoreactive in the frog. In the other species, most of the hair cells in the cristae were immunostained except those situated in the peripheral areas. In the maculae, the hair cells of the striola were either the only ones stained or were more intensely stained or were more intensely stained than the others. The localization of calbindin in specific cellular types and its increasing abundance from the fishes to the mammals suggest that calbindin is associated with the capacity of sensory and nerve cells to analyze precise mechanical or biochemical stimulations.

Animals↗
PubMed1988

1,25(OH)2D3 and Ca-binding protein in fetal rats: relationship to the maternal vitamin D status.

The autonomy and functional role of fetal 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] were investigated in nondiabetic and diabetic BB rats fed diets containing 0.85% calcium-0.7% phosphorus or 0.2% calcium and phosphorus and in semistarved rats on the low calcium-phosphorus diet. The changes in maternal and fetal plasma 1,25(OH)2D3 were similar: the levels were increased by calcium-phosphorus restriction and decreased by diabetes and semistarvation. Maternal and fetal 1,25(OH)2D3 levels were correlated (r = 0.80; P less than 0.001). The vitamin D-dependent calcium-binding proteins (CaBP9K and CaBP28K) were measured in multiple maternal and fetal tissues and in the placenta of nondiabetic, diabetic, and calcium-phosphorus-restricted rats. The distributions of CaBP9K and CaBP28K in the pregnant rat were similar to that of the growing rat. The increased maternal plasma 1,25(OH)2D3 levels in calcium-phosphorus-restricted rats were associated with higher duodenal CaBP9K and renal CaBPs, but placental CaBP9K was not different. In diabetic pregnant rats, duodenal CaBP9K tended to be lower, while renal CaBPs were normal; placental CaBP9K was decreased. No significant changes in CaBP levels were observed in fetuses of low calcium-phosphorus diet rats or fetuses of diabetic rats. The results indicate that in the rat fetal 1,25(OH)2D3 depends on maternal 1,25(OH)2D3 or on factors regulating maternal 1,25(OH)2D3. The lack of changes in fetal CaBP in the presence of altered fetal plasma 1,25(OH)2D3 levels confirms earlier data showing that 1,25(OH)2D3 has a limited hormonal function during perinatal development in the rat.

Animals↗
PubMed1987

Transcriptional and post-transcriptional regulation of vitamin D-dependent calcium-binding protein gene expression in the rat duodenum by 1,25-dihydroxycholecalciferol.

Regulation of the expression of vitamin D-dependent calcium-binding protein (Mr 9000 CaBP) gene by 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was studied in the rat duodenum. In vivo stimulation of Mr 9000 CaBP synthesis was analyzed using a complementary DNA probe and by measuring the rate of Mr 9000 CaBP gene transcription in isolated nuclei (run-on assay). A single 1,25-(OH)2D3 injection (650 pmol/100 g of body weight) induced a 2-fold increase in Mr 9000 CaBP gene transcription within 15 min in the duodenum of vitamin D-deficient rats. RNA synthesis was maximal at 1 h, then decreased until 16 h of postinjection. There was an initial transient accumulation of Mr 9000 CaBP mRNA (from 7 to 15 min), which was followed by a second, significant increase, by 3 h which remained elevated until 16 h. The magnitude and time course of the Mr 9000 CaBP increase was similar to that of its mRNA as early as 1 h after 1,25-(OH)2D3 administration. Mr 9000 CaBP gene transcription was not significantly induced by 1,25-(OH)2D3 in vitamin D-replete rats and no transient accumulation of Mr 9000 CaBP mRNA was observed. Thus, 1,25-(OH)2D3 modulates Mr 9000 CaBP gene expression in at least two ways, a rapid transcriptional stimulation and a post-transcriptional effect preventing degradation of Mr 9000 CaBP transcripts and accounting for their accumulation several hours after the hormone treatment.

Animals↗
PubMed1987

Immuno-electronmicroscopic localization of 'vitamin D-dependent' calcium-binding protein (CaBP-28k) in the vestibular hair cells of the cat.

The PAP immunohistochemical method was used to carry out a light- and electronmicroscopic study of the distribution of the vitamin D-dependent calcium-binding protein (CaBP-28k, calbindin, cholecalcin) in the vestibule of the young cat. It was found that the two types of hair cells, types I and II, were stained differently. Type II cells were intensely immunoreactive and their staining did not vary with the location of the cells within the crista ampullaris. Type I cells at the top of the cristae were lightly stained, or unstained, while the type I cells laterally or basally were frequently intensely stained. The nerve fibers arriving at the top of the cristae are highly immunoreactive while the fibers of the base are not stained. Immunostaining for CaBP was correlated with differences in the innervation of hair cells at the top and base of the cristae. This differential CaBP-immunostaining may reflect differences in the physiological activity of the cells. The electronmicroscopic study showed that CaBP is present throughout the cytoplasm of the hair cells but that its concentration was particularly high in the cuticular plate and stereocilia. This specific intracellular distribution of CaBP is discussed with the possible role of Ca2+ in the physiology of the vestibular hair cells.

Animals↗
PubMed1987

The comparative immunocytochemical distribution of 28 kDa cholecalcin (CaBP) in the hippocampus of rat, guinea pig and hedgehog.

The distribution of 28 kDa cholecalcin (calcium-binding protein, CaBP) in the hippocampal formation of the rat, guinea pig and European hedgehog was examined by immunocytochemistry. The extension of the mossy fibers (the axons of the granule cells of the dentate gyrus) was also studied using the Timm's sulfide-silver method. Cholecalcin was present in all mossy fibers. In the rat, only those pyramidal cells not reached by the labeled mossy fibers displayed cholecalcin immunoreactivity. Immunocytochemical staining of the hedgehog hippocampus showed that contacts between cholecalcin-containing mossy fibers and cholecalcin-containing pyramidal cells are possible. Consequently, the protein is probably not involved in the control of mossy fiber extension. Strikingly, no guinea pig pyramidal cells showed cholecalcin immunoreactivity. The possible involvement of cholecalcin in the differential excitability of pyramidal cells in the CA3 and CA1 areas of the hippocampus could therefore be tested in a comparative study of rat, guinea pig and hedgehog.

Animals↗
PubMed1987

Analysis and in situ detection of cholecalcin messenger RNA (9000 Mr CaBP) in the uterus of the pregnant rat.

The molecular cloning of a cDNA fragment synthesised from rat duodenal mRNA coding for cholecalcin (calbindin), a 9000 Mr vitamin D-induced calcium-binding protein (CaBP), has been previously described. DNA/RNA hybridisation assays have been used to examine CaBP mRNA production in the uterine horns and duodena of pregnant (21 day) rats using the cloned CaBP cDNA. Northern hybridisation studies showed that the 32P cDNA sequence hybridised to a single 500-600 nucleotide species in both the uterus and the duodenum, thus demonstrating identical CaBP mRNA processing in both tissues. Dot blot hybridisation studies showed that the CaBP mRNA concentration was greatest in the duodenum while that of the uterine horns was about 10% of the duodenal level. The observed differences in CaBP mRNA levels correlate well with the in vivo CaBP concentrations. In situ hybridisation histochemistry using 3H cDNA revealed that CaBP mRNA visualised by silver grains was found in all the parts of the endometrium and the myometrium. However, CaBP mRNA was more concentrated in the outer and inner muscular fibres and in the luminal cells of the endometrium than in the stroma cells. These results demonstrate that the CaBP gene is expressed in specific cells of the rat uterus.

Animals↗
PubMed1987

Cholecalcin (28-kDa calcium-binding protein) in the rat hippocampus: development in normal animals and in altered thyroid states. An immunocytochemical study.

An immunocytochemical study of cholecalcin (28-kDa calcium-binding protein, CaBP, calbindin) was carried out during the development of the rat hippocampus. In normal animals, the protein appeared from Postnatal Day 3 in the granule cells of the dentate gyrus and from Day 5 in the CA1-CA2 pyramidal cells of Ammon's horn. The cells of both regions thus showed positive cholecalcin labeling about 1 week after their formation. The sequence of labeling of the granule cells was a reflection of the major sequences of neurogenesis. Cholecalcin could not be detected in hippocampal cells until dendritic arborization and axon growth had occurred. There was a good correlation between the appearance of cholecalcin and the onset of synaptogenesis. In animals with an experimentally altered thyroid state, in which hippocampal development is retarded or accelerated due to abnormal cell maturation, cholecalcin appearance was similarly retarded or accelerated. Cholecalcin seems to be synthesized at the same time as the hippocampal cells become functional.

Aging↗
PubMed1987

Cerebellar mutations affecting the postnatal survival of Purkinje cells in the mouse disclose a longitudinal pattern of differentially sensitive cells.

The pattern of surviving Purkinje cells (PCs) was investigated in three cerebellar mutant mice with severe postnatal PC death. Two of these mutations, nervous (nr) and Purkinje cell degeneration (pcd) mutations are already well characterized. The third mutation is a new one, which appeared spontaneously in DW/J-Pas mice and was called tambaleante (tbl). PCs were identified by immunocytochemistry using an antibody against vitamin D-dependent calcium-binding protein which labels all the PCs in adult control mice. In each of the three mutations, surviving PCs are arranged according to a different and reproducible pattern which is symmetric relative to the midline. In NR and young PCD mutants, PCs are closely packed in broad sagittal bands. In TBL, they are more loosely arranged in a rather patchy pattern. In PCD and in TBL mutants the death of resistant PCs is only shortly delayed but in NR there is little change in the number of surviving PCs after 3 months. The differential sensitivity of subsets of PCs to the effect of nr, pcd, and tbl mutations is topographically determined. These results provide a new evidence of the PC heterogeneity which has been previously demonstrated by histochemical and immunohistochemical techniques. Moreover, in the anterior vermis of control mice, three thin sagittal bands of PCs are labeled by the Q113 monoclonal antibody. Similarly, in the anterior lobe of the NR cerebellum, the thin longitudinal strips of missing PCs coincide with the absence of Q113 immunoreactivity: in this region the nr mutation affects specifically the survival of Q113 positive cells. However, other clusters of Q113 immunoreactive PCs do survive in NR mice suggesting that susceptibility to the nr mutation and Q113 positivity are two independent markers of the underlying PC compartmentalization.

Animals↗
PubMed1987

Ontogenesis of 28 kDa vitamin D-induced calcium-binding protein in human kidney.

The kidney distribution of 28 kDa vitamin D-induced calcium binding protein (CaBP) was studied in 15 fetuses (11 to 33 weeks old), six children and adults (12 days to 32 years old) by immunocytochemistry using a specific antibody to rat renal 28 kDa CaBP. Similar results were obtained on frozen and fixed tissues. Kidneys from one adult and three fetuses were studied by immunoelectronmicroscopy for antigen localization at the subcellular level using the indirect immunoperoxidase technique. The 28 kDa CaBP was present in all kidneys from the eleventh week of gestation. At that stage, all deep parts of collecting ducts were homogeneously stained and a few distal tubules located in the deep cortex were intensely labeled. No labeling was observed in the early stage of nephron differentiation (S-body). 28 kDa CaBP distribution changed with kidney maturation. There was a progressive reduction of the deep part of collecting duct labeling and a concomitant increase in the number and intensity of stained distal tubular cells. At the ultrastructural level, 28 kDa CaBP was observed in the cytosol and the nuclear euchromatin. Our study demonstrates the early cellular synthesis of 28 kDa CaBP and its transient expression by deep collecting duct cells during early fetal life, at a time when only a few distal convoluted tubular cells synthetize it.

Adult↗
PubMed1987

Vitamin D-dependent calcium-binding proteins (CaBPs) in human fetuses: comparative distribution of 9K CaBP mRNA and 28K CaBP during development.

The vitamin D-dependent calcium-binding protein (CaBP) cholecalcin or calbindin, has been used as a molecular marker of 1,25-dihydroxyvitamin D3 action. Mammals possess two CaBPs: a 9,000 mol wt (9K CaBP) and a 28,000 mol wt (28K CaBP). The distinct localization of each protein in the rat has been previously described with the aid of specific radioimmunoassays developed for each CaBP. Antibodies raised against the rat 28K CaBP can be used to detect this protein in a number of mammalian species including humans. In contrast, antibodies against rat 9K CaBP do not cross react with human 9K CaBP, but human 9K CaBP mRNA can be analyzed using a cDNA probe for rat 9K CaBP mRNA. Such a cross-hybridization between the rat cDNA probe and human CaBP mRNA was demonstrated by Northern analysis. We have documented the distribution and evolution of 28K CaBP and 9K CaBP mRNA in human tissues during fetal development from 14 to 32 wk of gestation. 28K CaBP was only present in kidney and cerebellum, and not detectable in duodenum. There was a 2-fold increase of 28K CaBP in the cerebellum between 14 and 24 wk of gestation. The 9K CaBP mRNA was unevenly distributed in human fetal tissues. 9K CaBP mRNA was present in classical vitamin D target tissues such as duodenum and placenta; high levels of 9K CaBP mRNA also were found in thymus and lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Immunohistochemical identification of neuron-specific enolase and calbindin in the vestibular receptors of human fetuses.

Immunohistochemical techniques were used to identify neuron-specific enolase (NSE) and calbindin in the vestibular receptors and ganglia of human fetuses at 10 weeks of gestation. NSE was found in vestibular ganglion cells and in a few sensory cells. The pattern of immunoreactivity in the sensory epithelia was characteristic of the appearance of NSE in these structures. Calbindin was found in vestibular ganglion cells and sensory cells which displayed a strong immunoreactivity. These findings are discussed with regard to synaptogenesis and they indicate that the vestibular receptors show biochemical signs of maturation consistent with the possibility of synaptic activity.

Calbindins↗
PubMed1986

Immunocytochemical detection of vitamin D-dependent calcium-binding protein (CaBP-28K) in vestibular sensory hair cells and vestibular ganglion neurones of the cat.

Vestibular sensory hair cells, afferent fibres and vestibular ganglion neurones of the cat are intensely labelled by a specific antibody to rat kidney vitamin D-dependent calcium-binding protein (CaBP-28K). Type I hair cells are more weakly CaBP immunoreactive than type II hair cells. Ganglion neurones also present a differential staining. The presence of calcium-binding protein in sensory hair cells could be of interest for the understanding of transductional mechanisms.

Animals↗
PubMed1986

Vitamin-D-dependent calcium-binding protein (CaBP-9K) in rat growth cartilage.

The presence of vitamin-D-dependent calcium-binding protein (CaBP-9K) in tibial growth-plate cartilage was immunohistochemically demonstrated using a specific antibody to rat duodenal CaBP-9K. The protein was found to be mainly localized in the cytoplasm of maturing chondrocytes. In hypertrophic chondrocytes, CaBP-9K concentrations decreased, and the protein was found in the cytoplasmic processes. No CaBP-specific immunoreactivity was seen in the hypertrophic chondrocytes of the lower calcified hypertrophic zone; in contrast, the protein was found in the extracellular lateral edges of longitudinal septa, i.e. where matrix vesicles are preferentially localized and where cartilage mineralization is initiated. These findings suggest that vitamin D has a direct function in this tissue. It also seems likely that CaBP-9K is an indicator of chondrocyte maturation, and that it is involved in the matrix vesicle-associated process of cartilage calcification.

Animals↗
PubMed1986

Effects of suppression and resumption of shell formation and parathyroid hormone on uterine calcium-binding protein, carbonic anhydrase activity, and intestinal calcium absorption in hens.

The calcium absorption and duodenal and uterine vitamin D-dependent calcium-binding protein (CaBP-28K) levels were decreased in hens when eggshell calcification was suppressed by premature expulsion of the egg. Nevertheless, these levels remained higher than those of immature pullets or pullets treated with estrogen. The resumption of shell formation by hens which had previously laid soft-shell eggs was associated during calcification of the first egg with increases in intestinal Ca absorption. CaBP concentration, and alkaline phosphatase activity. The increase in uterine CaBP concentration preceded the stage of rapid calcium deposition. Uterine carbonic anhydrase activity was increased by sexual maturity but not consistently by shell formation. Ablation of the parathyroids just before the resumption of shell formation suppressed the increases in duodenal calcium absorption and CaBP concentration elicited by egg calcification. In contrast, the increase in CaBP level was maintained in the uterus of parathyroidectomized hens, in spite of the decreased shell deposition. Previous studies indicated that increased uterine CaBP associated with eggshell calcification is not elicited by vitamin D. The present study confirms this observation and also shows that these changes are not elicited by either PTH or sex steroid hormones.

Animals↗
PubMed1986

Thyroid state and cholecalcin (calcium-binding protein) in cerebellum of the developing rat.

Cholecalcin (28,000 Da, vitamin D-dependent calcium-binding protein) is a marker of Purkinje cell development in the rat cerebellum from embryonic day 17 when these cells can first be distinguished. Specific antibodies raised against human cerebellar or rat renal cholecalcin were used in an immunocytochemical and quantitative study in altered thyroid states. The immunocytochemical staining was qualitatively similar in both normal and hypothyroid animals but clearly demonstrated the slowing of Purkinje cell development resulting from the lack of thyroxine. This effect was also reflected in quantitative studies which showed that the total cholecalcin per cerebellum was lower in thyroid-deficient rats. However, there was, in these animals, no specific reduction in cholecalcin level. Moreover, the response to thyroxine treatment indicated that the synthesis of cholecalcin occurred later and slower than that of the majority of cerebellar proteins and even after other more complex mechanisms of cerebellar cortex development (such as neurite outgrowth) have been induced. Thus, cholecalcin synthesis does not appear particularly sensitive to thyroid hormone level but might rather follow the increase in cell size induced by the hormone.

Animals↗