Immunohistochemical detection of 28KDa calbindin in human tissues.
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Estrogenic compounds may influence the growth, differentiation and function in many target tissues, especially in the female reproductive tract during pregnancy. The present study was designed to investigate whether CaBP-9k expression in the maternal tissues and fetal uterus is altered following maternal treatment with diethylstilbestrol (DES), 17beta-estradiol (E2), 4-tert-octylphenol (OP), nonylphenol (NP) and bisphenol A (BPA) during late pregnancy. The expression level of CaBP-9k mRNA in maternal uterus significantly increased when treated with a high dose (600 mg/kg BW per day) of OP and NP. Interestingly, the expression level of CaBP-9k mRNA in extra-embryonic membrane decreased in a dose-dependent manner, suggesting that the expression level of CaBP-9k mRNA in the fetal membrane may be differentially regulated when compared to the expression of CaBP-9k in maternal uterus. In parallel with CaBP-9k mRNA level, a high dose (600 mg/kg) of OP and BPA resulted in an increase of CaBP-9k protein in maternal uterus and low dose of OP and NP increased the expression level of CaBP-9k protein in the placenta. High doses of BPA (400 and 600 mg/kg) resulted in an increase of CaBP-9k protein in maternal uterus and placenta, indicating that these estrogenic compounds may affect both maternal uterus and placenta in the induction of CaBP-9k mRNA and/or protein. In parallel with the expression level of CaBP-9k, mRNA decreased in extra-embryonic membrane, treatment with OP (400 and 600 mg/kg) resulted in a significant decrease of CaBP-9k protein in this tissue, suggesting that both CaBP-9k mRNA and protein may be conversely regulated by OP in extra-embryonic membrane when compared to other tissues. Treatment with OP, NP, and BPA induced a significant increase of CaBP-9k mRNA in fetal uterus, indicating that maternally injected estrogenic compounds may transfer directly from placenta to fetus in the induction of fetal uterus CaBP-9k gene. Taken together, we demonstrated for the first time that maternally injected estrogenic compounds resulted in an increase of CaBP-9k mRNA and/or protein in the maternal tissues (uterus and placenta) and fetal uterus during late pregnancy, suggesting that placenta may not be a reliable barrier against these estrogenic compounds for fetal health.
The vitamin D-dependent intestinal calcium binding protein gene is predominantly expressed in the intestine. In this report we have examined the possibility that methylation of the gene might play a role in its tissue-specific expression employing genomic Southern analysis. None of the Hpa II and Hha I sites examined by the indicated probes in and around the gene were found to be methylated in the intestine, kidney and liver. No change in the methylation of these sites was detected in response to 1,25-dihydroxy-vitamin D3 administration to vitamin D-deficient rats under conditions which stimulate the expression of the gene. These results indicate that the rat intestinal calcium binding protein gene is not methylated in these tissues, at the indicated sites and, therefore, methylation seems not to be involved in the regulation of this gene's expression.
1. The authors studied the morphology of CalbindinD28K (CaBp) immunoreactive cells and processes in the hippocampal formation and the prefrontal cortex of schizophrenics using the immunohistochemical technique of avidin-biotin-complex method (ABC method), and the results were compared with those from normal human brains. 2. In the hippocampal formation area CA2 of schizophrenics, many CaBp-immunopositive cell bodies and fibers were disordered in their arrangement compared to normal control brains. 3. In the prefrontal cortex (Brodmann area 9) of schizophrenics, many immunopositive cell bodies were exhibited irregular axis arrangement and fiber disarray. 4. The altered distribution pattern of CaBp-immunopositive structures in the hippocampal formation and the prefrontal cortex might indicate the existence of GABA(gamma-aminobutyric acid)ergic dysfunction in the brain of schizophrenic patients.
The compounds that bind the estrogen receptors (ER) and induce or modulate an ER-mediated response can be defined as estrogenic endocrine disruptors (EDs). We demonstrated that environmental estrogens induced the uterine CaBP-9k mRNA in rats using Northern blot assay suggesting that CaBP-9k gene could be a biomarker for the estrogenicity of chemicals in the previous studies. In the present studies, we further collaborated this idea by investigating the regulation and localization of CaBP-9k protein in response to estrogenic compounds. Immature rats were injected with estrogenic chemicals, 4-tert-octylphenol (OP), nonylphenol (NP) and bisphenol A (BPA) or 17beta-estradiol (E2). After treatment with these estrogenic compounds, the effects on the accumulation of CaBP-9k protein and uterine localization were examined by Western blot analysis and immunohistochemical staining (IHC), respectively. A dose- and time-dependent increase in CaBP-9k protein was observed in the uterus of immature rats when treated with OP and NP. In addition, treatment with BPA resulted in a significant increase in CaBP-9k protein at dose of 500mg/kg BW/day. Taken together, CaBP-9k protein is strongly up-regulated by estrogenic compounds (OP, NP and BPA) and E2 itself in the uterus of immature rats. These results indicate that CaBP-9k protein can be a useful biomarker for detection of the estrogenicity of putative estrogenic compounds. Thus, regarding to risk assessment, we propose that CaBP-9k protein assay in the immature rat uterus can be a very sensitive and powerful tool to identify compounds with estrogenic activity when used in combination with classical assays.
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Using a simple model of linear response of polarizable centers to an electric field, function delta is defined to characterize structural organization of protein polar groups. The function makes it possible to detect specific structures of nonuniformly distributed and mutually coupled groups that can transmit local structural and charge density perturbations, induced by an ion over long distances to functionally active sites of a protein molecule. In 9 kd calbinding (a small protein from the troponin C superfamily) two structural chains have been demonstrated that link together both Ca2+ ions coordinated by the protein. The chains form a rigid structure stabilized by coordination of one of the ions, so that binding of the other is promoted. Such a structure is probably common to all members of the superfamily and plays an important role in the mechanism of calcium binding by these proteins.
The 9-kilodalton vitamin D-dependent calcium-binding protein (CaBP9K) is expressed in the intestine and uterus of mammals. In this study, we demonstrated the intracellular location of CaBP9K and quantified its expression in human myometrial tissues from nonpregnant and pregnant women (before and after the onset of labor). By Western blot analysis, we found that antiserum raised against bovine intestinal CaBP9K was specific for CaBP9K in human myometrium. By Northern blot analysis, with an oligodeoxynucleotide probe specific for human CaBP9K, we identified a single 0.7-kilobase messenger ribonucleic acid (mRNA) species in myometrial tissues from pregnant women before and after the onset of labor. CaBP9K mRNA and immunoreactive protein were localized within myometrial smooth muscle cells by in situ hybridization and immunohistochemistry. The highest levels of CaBP9K mRNA and immunoreactive protein were found in myometrial tissues obtained from pregnant women at term before the onset of labor. CaBP9K mRNA and immunoreactive levels of CaBP9K were decreased significantly in myometrial tissues obtained after the onset of labor (2- and 8-fold, respectively). These findings demonstrated for the first time that CaBP9K was present in human myometrium and suggested that it may play a role in regulating uterine smooth muscle function during pregnancy.
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The effects of vitamin D deficiency on the ontogeny of calcium-binding proteins (CaBPs) and the vitamin D receptor (VDR) in the placenta and yolk sac of the mouse were examined. Maternal vitamin D status did not affect the time of appearance of CaBP-D9k (9 kDa) in the yolk sac endoderm or trophoblastic giant cells (TGCs) of the placenta. VDRs were undetectable in TGCs and yolk sac endoderm, but were present in the intraplacental yolk sac. Since yolk sac endoderm and TGCs contain CaBP but not VDR, it is unlikely that CaBP synthesis and/or activity in these cells is controlled by vitamin D. The TGCs, therefore, may be involved in vitamin D-independent transplacental transfer of calcium.
It is well known that light resets the circadian clock only at specific times of day. The mechanisms mediating such gating of environmental input to the CNS are not well understood. We show that calbindinD28K (CalB)-containing cells of the suprachiasmatic nucleus (SCN), which are directly retinorecipient, gate photic entrainment of cellular circadian oscillators and thereby determine the timing of locomotor rhythmicity. Specifically, we demonstrate a circadian rhythm of subcellular localization of CalB: whereas the protein is detected at all times in the cytoplasm, it is low or absent in the nucleus during the night. Under normal circumstances, light-induced behavioral phase shifts and Period (Per) gene expression in the SCN occur only during the subjective night. Surprisingly, both behavioral phase shifts and light-induced Per are blocked during the subjective night and enhanced during the subjective day after administration of CalB antisense oligodeoxynucleotides. These results suggest a cellular basis for temporal gating of photic input to the circadian clock.
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