Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of zinc compounds on osteoclast-like cell formation in rat marrow culture in vitro was investigated. The bone marrow cells were cultured for 7 days in alpha-minimal essential medium containing a well-known bone resorbing hormone (1, 25-dihydroxyvitamin D3 and parathyroid hormone [1-34]). Osteoclast-like cell formation was estimated by staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of 1, 25-dihydroxyvitamin D3 (10(-8) M) or parathyroid hormone (PTH; 10(-8) M) induced a remarkable increase in osteoclast-like multinucleated cells (MNC). These increases were clearly inhibited by the presence of zinc sulfate or zinc-chelating dipeptide (beta-alanyl-L-histidinato zinc; AHZ) in the concentration range of 10(-7) to 10(-5) M. The inhibitory effect was seen at the earlier stage of osteoclast-like MNC formation. However, zinc compounds (10(-6) M) did not have an effect on PTH (10(-8) M)-induced osteoclast-like cell formation in the presence of EGTA (5 x 10(-4) M), dibucaine (10(-5) M) or staurosporine (10(-9) M). Moreover, when osteoclasts isolated from rat femoral-diaphyseal tissues were cultured for 24 h in the presence of zinc compounds (10(-7) to 10(-5) M), the compounds did not have an effect on cell numbers or lysosomal enzymes activity (acid phosphatase and beta-glucuronidase) in the cells. The present study clearly demonstrates that zinc compounds inhibit osteoclast-like cell formation at the earlier stage with differentiation of marrow cells.
Mol Cell Biochem 1996 May 24
PMID:Zinc compounds inhibit osteoclast-like cell formation at the earlier stage of rat marrow culture but not osteoclast function. 881 79

Site-directed mutagenesis was used to assess the role of transmembrane (TM)-charged amino acids in the expression and function of the G protein-coupled receptor for PTH and PTH-related protein (PTHrP). Charged residues that are conserved in the TM regions of most or all members of the PTH/secretin receptor subfamily were targeted. Four mutants (E296A, R337A, H414A, and E459K) displayed properties similar to the wild type PTH/PTHrP receptor with respect to agonist binding and stimulation of adenylyl cyclase when expressed in COS-7 cells. Several mutations, all in TM II, produced receptors that signaled extremely poorly. Mutation of three residues (227S, 230R, and 233S), predicted to be aligned on one helical face of TM II, displayed a similar phenotype: markedly blunted adenylyl cyclase activity in response to PTH (20-30% of the wild type response) and a lower binding affinity for agonist, with no reduction in cell surface receptor expression. These results suggest that TM II contains a polar face that is involved in TM signaling by the PTH/PTHrP receptor. Two of these mutations were made at the corresponding sites in the secretin receptor, and a similar reduction in secretin-stimulated adenylyl cyclase activity was observed. Thus this region of TM II may participate in a mechanism of TM signal transduction that is shared by the PTH/secretin sub-family of G protein-coupled receptors.
Mol Endocrinol 1996 Feb
PMID:Mutations of neighboring polar residues on the second transmembrane helix disrupt signaling by the parathyroid hormone receptor. 882 53

Analysis of the 5'-flanking region of the avian (chicken) PTH (cPTH) gene has revealed a DNA segment between -74 and -60 that is analogous to the consensus sequence for the vitamin D3 response element (VDRE). The DNA segment consists of two imperfect direct repeats, GGGTCA and GGGTGT, which are separated by a 3-bp spacer. The functionality of the putative VDRE was verified by transfection studies in opossum kidney cells using plasmid constructs that contained various regions of the cPTH gene 5'-flanking sequence and promoter fused to the gene for chloramphenicol acetyl transferase (CAT). Likewise, negative regulation of gene transcription by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] was detected when the cPTH VDRE was inserted immediately upstream from truncated forms of the cPTH or the SV40 early promoter. Using gel mobility shift assays, the cPTH VDRE was compared with the human osteocalcin (hOC) VDRE, which activates gene transcription in the presence of 1,25-(OH)2D3. With a partially purified nuclear extract from dog intestine, the two VDREs produced gel shift patterns that were remarkably similar, with the exception that the binding affinity for the hOC sequence was notably greater. Both VDREs produced two major bound complexes (B1 and B2), which could be completely abolished by the addition of an excess of unlabeled hOC VDRE or a monoclonal antibody specific for the VDR protein. Furthermore, similar protein:DNA complexes were observed when either the cPTH or hOC VDRE were incubated with a mixture of purified preparations of recombinant VDR and retinoid X receptor alpha proteins. Ethylation interference analysis showed that the base contacts made by complexes B1 and B2 with the cPTH VDRE were essentially the same and were restricted primarily to the two half-site sequences.
Mol Endocrinol 1996 Feb
PMID:Characterization of a response element in the 5'-flanking region of the avian (chicken) PTH gene that mediates negative regulation of gene transcription by 1,25-dihydroxyvitamin D3 and binds the vitamin D3 receptor. 882 60

An important physiological control of PTH gene expression is its transcriptional repression by 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)]. The mechanism of this 1,25-(OH)(2)D(3)-mediated transcriptional repression is poorly understood. Previous investigations have identified a DNA sequence in the 5'-regulatory region of the human PTH (hPTH) gene that binds the vitamin D receptor (VDR) and mediates transcription repression in response to 1,25(OH)(2)D(3) in GH4CI cells. The hPTH gene sequence does not mediate transcriptional repression in ROS 17/2.8 cells, even though up-regulatory vitamin D response elements (VDREs) are active in these cells. The hPTH DNA sequence differs from the upregulatory VDREs in that it contains a single copy of a hexameric motif (AGGUC) homologous to those repeated in the up-regulatory VDREs. The protein-DNA interactions of this sequence were examined using nuclear extracts from bovine parathyroid, GH4CI, and ROS 17/2.8 cells. In bovine parathyroid nuclear extracts, the VDR binds the down-regulatory hPTH DNA sequence independently of the retinoid X receptor (RXR). In GH4C1 nuclear extracts, two VDR-containing complexes are observed: one lacking RXR and one containing RXR. In ROS 17/2.8 nuclear extracts, a single VDRdependent complex containing RXR is observed. When the up-regulatory rat osteocalcin VDRE is used as a probe, only VDR-RXR-containing complexes are generated using nuclear extracts from all three cell types. These results demonstrate that the sequence that mediates transcriptional repression in response to 1 ,25-(OH)(2)D(3) differs from the up-regulatory response elements both in sequence composition and in its ability to bind VDR independently of RXR.
Mol Endocrinol 1996 Mar
PMID:Vitamin D receptor binding to the negative human parathyroid hormone vitamin D response element does not require the retinoid x receptor. 883 58

Using a PCR-based strategy, two variants of the PTH/PTH-related peptide (PTH-rp) receptor mRNA were identified in human kidney, SaOS-2 human osteoblast cells, and rat bone that are produced by alternative splicing of exons coding for the N-terminal portion of the receptor. In the S-N3-E2 isoform, the exon coding the signal peptide (S) is spliced to an alternative 3'-acceptor site, producing a product respecting the reading frame, but in which the E1 exon is replaced by 12 amino acids derived from the N3 intron. In the S-E2 isoform, in which the E1 exon is deleted by cassette exclusion, the reading frame is changed, but a truncated receptor may be produced by reinitiation of translation at an overlapping stop/start codon. After transfection of COS and Chinese hamster ovary cells with the originally described S-E1-E2 isoform and the two splice variants, active transcription of PTH/PTH-rp receptor mRNA was detected by RT-PCR in all cases. Cell lines transfected with the S-E1-E2 and S-N3-E2 isoforms displayed a 15- to 25-fold and 2- to 3-fold increase, respectively, in cAMP content after stimulation with 2.4 x 10(-7) M human PTH(1-34), whereas cells transfected with the S-E2 isoform did not respond. PTH elicited an increase in intracellular calcium only in cells transfected with the S-E1-E2 isoform. Studies evaluating the surface expression of receptors using anti-human PTH/PTH-rp receptor antibodies and the ability of transfected cells to bind [125I]PTH-rp indicated that the low or absent responses to PTH stimulation resulted, at least in part, from low surface expression of the S-N3-E2 and S-E2 isoforms. These studies support the conclusion that exon E1 is extremely important in promoting surface expression of the PTH/PTH-rp receptor but indicate that isoforms lacking this exon can retain the ability to recognize PTH. The possible intracellular expression of these splice variants, which account for 15-20% of total PTH/PTH-rp receptor mRNA, needs to be evaluated.
Mol Endocrinol 1996 Sep
PMID:Expression of alternatively spliced isoforms of the parathyroid hormone (PTH)/PTH-related peptide receptor messenger RNA in human kidney and bone cells. 888 41

Arachin subunit (mol. wt. 29,100) from peanut of variety G-201 was separated and isolated, its purity and homogeneity were ascertained. The subunit was cleaved with trypsin, chymotrypsin and Staphylococcus aureus V8 protease. The fragments obtained were separated and isolated by PAGE, gel filtration & ion exchange chromatography, these were subjected to amino acid analysis, and Edman degradation. The PTH amino acids obtained were identified by spectroscopy and TLC. The complete amino acid sequence of the subunit (226 residues) was established, and the structural class of arachin was predicted from the amino acid composition.
Biochem Mol Biol Int 1996 Feb
PMID:The amino acid sequence and structural class of the arachin subunit of molecular weight 29, 100A. 893 22

Two different activating PTH/PTH-related peptide (PTHrP) receptor mutations, H223R and T410P, were recently identified as the most likely cause of Jansen's metaphyseal chondrodysplasia. To assess the functional importance of either amino acid position in the human PTH/PTHrP receptor, H223 and T410 were individually replaced by all other amino acids. At position 223, only arginine and lysine led to agonist-independent cAMP accumulation; all other amino acid substitutions resulted in receptor mutants that lacked constitutive activity or were uninformative due to poor cell surface expression. In contrast, most amino acid substitutions at position 410 conferred constitutive cAMP accumulation and affected PTH/PTHrP receptor expression not at all or only mildly. Mutations corresponding to the H223R or T410P exchange in the human PTH/PTHrP receptor also led to constitutive activity when introduced into the opossum receptor homolog, but showed little or no change in basal cAMP accumulation when introduced into the rat PTH/PTHrP receptor. The PTH/PTHrP receptor residues mutated in Jansen's disease are conserved in all mammalian members of this family of G protein-coupled receptors. However, when the equivalent of either the H223R or the T410P mutation was introduced into several other related receptors, including the PTH2 receptor and the receptors for calcitonin, secretin, GH-releasing hormone, glucagon-like peptide I, and CRH, the resulting mutants failed to induce constitutive activity. These studies suggest that two residues in the human PTH/PTHrP receptor, 223 and 410, have critical roles in signal transduction, but with different sequence constrains.
Mol Endocrinol 1997 Jun
PMID:Constitutive activation of the cyclic adenosine 3',5'-monophosphate signaling pathway by parathyroid hormone (PTH)/PTH-related peptide receptors mutated at the two loci for Jansen's metaphyseal chondrodysplasia. 917 45

Differentiation of P19 embryonal carcinoma (EC) and embryonal stem (ES)-5 cells with retinoic acid (RA) induces expression of PTH-related peptide (PTHrP) mRNA. In this study we have characterized a region between nucleotide (nt) -88 and -58 relative to the transcription start site in the murine PTHrP gene that was involved in this expression. Sequence analysis identified two partially overlapping binding sites for the Ets family of transcription factors and an inverted Sp1-binding site. Two major specific bands were detected in a bandshift assay using an oligonucleotide spanning nt -88 and -58 as a probe and nuclear extracts from both undifferentiated and RA-differentiated P19 EC cells. The lower complex consisted of Ets-binding proteins as demonstrated by competition with consensus Ets-binding sites, while the upper complex contained Sp1-binding activity as demonstrated by competition with consensus Sp1-binding sites. The observed bandshift patterns using nuclear extracts of undifferentiated or RA-differentiated P19 cells were indistinguishable, suggesting that the differentiation-mediated expression was not caused by the induction of expression of new transcription factors. Mutations in either of the Ets-binding sites or the Sp1-binding site completely abolished RA-induced expression of PTHrP promoter reporter constructs, indicating that the RA effect was dependent on the simultaneous action of both Ets- and Sp1-like activities. Furthermore, these mutations also abolished promoter activity in cells that constitutively expressed PTHrP mRNA, suggesting a central role for the Ets and Sp1 families of transcription factors in the expression regulation of the mouse PTHrP gene.
Mol Endocrinol 1997 Sep
PMID:Expression of the parathyroid hormone-related peptide gene in retinoic acid-induced differentiation: involvement of ETS and Sp1. 928 59

The effect of transforming growth factor beta1 (TGF-beta1) on the expression of mRNA for the parathyroid hormone receptor and binding of iodinated parathyroid hormone-related protein in ROS 17/2.8 osteosarcoma cells was evaluated. TGF-beta1 stimulated a 2-7-fold increase in steady state mRNA levels for the parathyroid hormone receptor at a maximal dose of 5 ng/ml, with increased levels of expression at 6 h of TGF-beta1-incubation, and peak levels at 8-24 h. Receptor binding studies revealed a significant increase in PTHrP-specific binding with TGF-beta1 doses as low as 0.5 ng/ml and a 55% increase in numbers of receptors with no alteration in binding affinity with 5.0 ng/ml TGF-beta1. Time course studies indicated that receptor binding was increased at 24 h with peak levels reached at 48 h of treatment. PTH-stimulated cAMP levels were significantly increased in ROS 17/2.8 cells treated with TGF-beta1 (0.5 ng/ml) for 48 h. These data indicate that TGF-beta1 upregulates steady-state mRNA, ligand binding and PTH/PTHrP receptor signaling in rat osteosarcoma cells. The effects of TGF-beta1 on bone may be attributed in part to regulation of the PTH/PTHrP receptor at the molecular level.
Mol Cell Endocrinol 1994 May
PMID:Transforming growth factor-beta1 regulates steady-state PTH/PTHrP receptor mRNA levels and PTHrP binding in ROS 17/2.8 osteosarcoma cells. 939 68

We investigated whether parathyroid hormone-related peptide (PTH-rP), recently found expressed in the heart, exerts growth and contractile effects on adult cardiomyocytes from rat hearts. Synthetic PTH-rP peptides were used covering either a protein kinase C (PKC)-activating domain [PTH-rP(107-111)], or an adenylate cyclase activating domain [PTH-rP(1-34) and PTH-rP(7-34)]. PTH-rP(107-111) (1 micro M) increased creatine kinase BB activity (CK-BB), a CK isoform re-expressed during cardiac hypertrophy, within 24 h by 62+/-12%. This induction was abolished in the presence of the mitogen-activated-protein (MAP)-kinase-kinase inhibitor PD 98059. PTH-rP(107-111) activated p42-MAP-kinase within 15 min, increased protein synthesis (19+/- 4%), total protein mass (19+/-5%), cell volume (45+/-7%), and cross-sectional area (38+/-9%) of cardiomyocytes. Activation of p42-MAP-kinase and increase in protein synthesis were abolished in presence of bisindolylmaleimide, a PKC inhibitor. PTH- rP(107-111) did not directly influence contractile activity but reduced the contractile response to isoprenaline. In contrast, PTH-rP(1-34) and PTH-rP(7-34) induced spontaneous contractile activity in 3-day-old cultures. This induction was abolished in presence of Rp-cAMPS, a protein kinase A inhibitor, indicating an involvement of cAMP in this response. PTH-rP(1-34) also increased the cellular accumulation of cAMP. It is concluded that PTH-rP exert direct effects on adult cardiomyocytes by activating either PKC via a functional domain covered by amino acids 107-111 or by activation of cAMP-dependent protein kinase via a functional domain covered by amino acids 7-34. Since these parts of PTH-rP have either no homology [PTH-rP(107-111)] or only a limited structural similarity [PTH-rP(7-34)] to parathyroid hormone, these activities of PTH-rP have to be clearly distinguished from those described for parathyroid hormone.
J Mol Cell Cardiol 1997 Nov
PMID:Effects of PTH-rP(107-111) and PTH-rP(7-34) on adult cardiomyocytes. 940 80


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