Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined the effects of C-type natriuretic peptide (CNP) and B-type natriuretic peptide receptor (NPR-B) system, which stimulates the intracellular production of cGMP, on osteoblastic differentiation using clonal murine calvarial MC3T3-E1 cells. CNP-like immunoreactivity was detected in the conditioned medium and in lysates of MC3T3-E1 cells. Exposure of cells to CNP caused an increase in the intracellular production of cGMP and the increase was dose-dependent, while ANP had no effect. These results imply that CNP regulates osteoblastic metabolism via NPR-B in an autocrine manner. Northern blot analysis revealed that treatment of MC3T3-E1 cells with CNP increased the steady-state levels of mRNAs for type-I collagen, cellular alkaline phosphatase (ALPase), and osteocalcin, which are well known as markers of osteoblastic differentiation. Our observations suggest the possibility that CNP functions as a local regulator of osteoblastic differentiation, acting via a cGMP-mediated pathway.
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PMID:Stimulation by C-type natriuretic peptide of the differentiation of clonal osteoblastic MC3T3-E1 cells. 863 25

C-type natriuretic peptide (CNP) is a local regulator in the brain and vascular wall. We present data to demonstrate the production and action of CNP in the osteoblast. CNP increased cGMP production, far more potently than atrial natriuretic peptide (ANP) in an osteoblastic cell line, MC3T3-E1. Since ANP and CNP are the ligands for two particulate guanylate cyclases, guanylate cyclase-A (GC-A) and guanylate cyclase-B (GC-B), respectively, these results reveal the expression of GC-B in MC3T3-E1. In addition, CNP mRNA and CNP-like immunoreactivity were detected in cell extracts from MC3T3-E1 and its culture medium, respectively. Both CNP and 8-bromo cGMP dose-dependently decreased [3H]thymidine uptake, without affecting alkaline phosphatase activity. These results indicate that CNP is a novel autocrine/paracrine regulator of osteoblast and suggest the presence of "bone natriuretic peptide system."
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PMID:C-type natriuretic peptide as an autocrine/paracrine regulator of osteoblast. Evidence for possible presence of bone natriuretic peptide system. 866 Mar 52

The effects of natriuretic peptides on the proliferation and differentiation of osteoblast-like cells from rat calvariae were examined. Natriuretic peptides are physiological agonists that activate receptor guanylate cyclases, namely, natriuretic peptide receptor (NPR)-A and NPR-B. Exposure of cells to atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) resulted in large increases in the rate of intracellular production of guanosine 3',5'-cyclic monophosphate (cGMP). Moreover, CNP-like immunoreactivity was detected in the conditioned medium from osteoblast-like cells, while ANP was undetectable. In cells exposed to natriuretic peptides, a dose-dependent reduction in the rate of DNA synthesis was observed. Natriuretic peptides also stimulated the activity of alkaline phosphatase (ALPase) and the expression of mRNA for ALPase and osteocalcin and the mineralization of nodules by the cultured cells. These results could be reproduced by treating cells with 8-bromo-cGMP. Endothelin-1, whose physiological functions are the opposite of those of natriuretic peptides, decreased the ALPase activity and the mineralization of nodules. In the present study, natriuretic peptides were demonstrated to promote bone formation via the action of cGMP in a signal-transduction pathway mediated by specific receptors in osteoblast-like cells.
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PMID:cGMP produced in response to ANP and CNP regulates proliferation and differentiation of osteoblastic cells. 896 30

The C-type natriuretic peptide (10(-7) M) and atrial natriuretic peptide (10(-7) M) enhanced cGMP accumulation by 418 and 83 times the control value, respectively, in osteoblast-like MC3T3-E1 cells. The natriuretic peptide B receptor was assumed to be the major natriuretic peptide receptor. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) activated alkaline phosphatase doubled the activity versus the control value on day 15. Phosphodiesterase activity was not stimulated by the addition of cGMP (1 MicroM). cGMP-dependent protein kinase (G kinase) activity of the supernatant fraction was 25.5 pmol/min/mg protein. The 42 kDa protein band was detected to be phosphorylated by G kinase on SDS-PAGE. These results supported the hypothesis that natriuretic peptides regulate the differentiation of MC3T3-E1 cells through a cGMP-dependent pathway.
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PMID:Effect of cyclic GMP produced by natriuretic peptides on osteoblast-like MC3T3-E1 cells. 898 37

There is recent evidence that natriuretic peptides are important regulators of bone and cartilage, although they were originally identified as the cardiac hormones causing natriuresis and hypotension. Three members of natriuretic peptide family are known: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). The biologically active receptors for these peptides are particulate guanylate cyclases; the two known types are GC-A and GC-B. ANP and BNP have high affinities for GC-A, and CNP is the preferred ligand for GC-B. In this paper we report the results of our study of the expression and possible role(s) of natriuretic peptides in the ROB-C26 cell, which is an osteogenic cell line with multiple potentials for differentiating into myoblast, osteoblast, and adipocyte. ROB-C26 cells produced cGMP in response to natriuretic peptides at both their basal state and after enhanced differentiation into osteoblast which was induced by bone morphogenetic protein [(BMP)-2]. CNP was far more potent than ANP in cGMP production. In contrast, enhanced differentiation into adipocyte by dexamethasone resulted in the marked decrease in their responsiveness to natriuretic peptides. Although the messages for GC-A and GC-B were demonstrated by Northern blot analysis at both the basal stage and after BMP treatment, they were down-regulated after dexamethasone treatment. The presence of CNP was shown by RT-PCR and immunohistochemistry in ROB-C26 cells. C3H10T1/2, which is another and more primitive mesenchymal cell line, also produced cGMP in response to CNP, and less potently to ANP. Culturing ROB-C26 cells with CNP or 8-bromo cGMP decreased [(3)H]thymidine uptake and slightly increased the message for alkaline phosphatase, which is a marker for osteoblast differentiation. These results suggest that the CNP/GC-B system is preferentially expressed in the cells of osteogenic lineage and their expression is down-regulated with differentiation into adipocyte lineage. The CNP/GC-B system is likely to be an autocrine/paracrine regulator of osteoblast growth and differentiation.
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PMID:C-Type natriuretic peptide/guanylate cyclase B system in rat osteogenic ROB-C26 cells and its down-regulation by dexamethazone. 1059 67

We reported previously that C-type natriuretic peptide (CNP) promotes the differentiation and mineralization of osteoblast-like cells. However, little information is available about the mechanism of action of CNP in differentiating osteoblastic cells. In this study, using the technique known as differential display-polymerase chain reaction, we identified a novel cDNA fragment that corresponded to a transcript whose level was increased by CNP in mouse clonal preosteoblastic MC3T3-E1 cells. Northern blotting analysis revealed transcripts of 1.3 kb and 2.3 kb in MC3T3-E1 cells. Both these transcripts were also expressed at high levels in the heart and stomach. We isolated a full-length cDNA (2,135 bp) from a cDNA library derived from MC3T3-E1 cells using the original cDNA fragment. Analysis of the sequence and of products of transcription and translation in vitro indicated that the transcript of the gene did not include any extensive open reading frames. Enhanced expression, after transfection, of transcript in MC3T3-E1 cells stimulated the deposition of calcium of these cells and the formation of mineralized nodules, but did not affect the activity of alkaline phosphatase. Our results suggest that CNP promotes the expression of a novel transcript, which might stimulate the mineralization of MC3T3-E1 cells.
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PMID:Identification of a novel osteoblastic gene, inducible by C-type natriuretic peptide, whose transcript might function in mineralization as a noncoding RNA. 1187 Apr 17

Altered chondrocyte differentiation, including development of chondrocyte hypertrophy, mediates osteoarthritis and pathologic articular cartilage matrix calcification. Similar changes in endochondral chondrocyte differentiation are essential for physiologic growth plate mineralization. In both articular and growth plate cartilages, chondrocyte hypertrophy is associated with up-regulated expression of certain protein-crosslinking enzymes (transglutaminases (TGs)) including the unique dual-functioning TG and GTPase TG2. Here, we tested if TG2 directly mediates the development of chondrocyte hypertrophic differentiation. To do so, we employed normal bovine chondrocytes and mouse knee chondrocytes from recently described TG2 knockout mice, which are phenotypically normal. We treated chondrocytes with the osteoarthritis mediator IL-1 beta, with the all-trans form of retinoic acid (ATRA), which promotes endochondral chondrocyte hypertrophy and pathologic calcification, and with C-type natriuretic peptide, an essential factor in endochondral development. IL-1 beta and ATRA induced TG transamidation activity and calcification in wild-type but not in TG2 (-/-) mouse knee chondrocytes. In addition, ATRA induced multiple features of hypertrophic differentiation (including type X collagen, alkaline phosphatase, and MMP-13), and these effects required TG2. Significantly, TG2 (-/-) chondrocytes lost the capacity for ATRA-induced expression of Cbfa1, a transcription factor necessary for ATRA-induced chondrocyte hypertrophy. Finally, C-type natriuretic peptide, which did not modulate TG activity, comparably promoted Cbfa1 expression and hypertrophy (without associated calcification) in TG2 (+/+) and TG2 (-/-) chondrocytes. Thus, distinct TG2-independent and TG2-dependent mechanisms promote Cbfa1 expression, articular chondrocyte hypertrophy, and calcification. TG2 is a potential site for intervention in pathologic calcification promoted by IL-1 beta and ATRA.
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PMID:Distinct transglutaminase 2-independent and transglutaminase 2-dependent pathways mediate articular chondrocyte hypertrophy. 1260 40

To clarify the regulating mechanism of vascular calcification, the investigators observed the effects of three vasoactive peptides, adrenomedullin (ADM), C-type natriuretic peptide (CNP), and parathyroid hormone-related peptide (PTHrP) on calcification in rat vascular smooth muscle cells (VSMCs). Beta-glycerophosphate stimulated growth and calcification in VSMCs. Adrenomedullin and CNP lowered beta-glycerophosphate-induced increase in VSMC growth. All three vasoactive peptides attenuated the increases of 45Ca accumulation, calcium content, and alkaline phosphatase activity in calcified VSMCs. As for comparing the inhibitory effects, the strongest was PTHrP. Both ADM and PTHrP increased cyclic adenosine monophosphate (cAMP) content in calcified VSMCs, but CNP upregulated cyclic guanosine monophosphate (cGMP) content. The PKA inhibitor PKAI completely reversed the inhibition of ADM on cell growth and all inhibitory effects of PTHrP on the parameters of calcification. The PKG inhibitor H8, however, strongly antagonized all the inhibitory effects of CNP on calcification. These data suggested that beta-glycerophosphate-induced calcification in VSMCs was inhibited by ADM, CNP, and PTHrP. Adrenomedullin and PTHrP inhibited VSMC calcification partially through the cAMP/PKA pathway, whereas CNP inhibited VSMC calcification through the cGMP/PKG pathway. This study could be of help in understanding the pathogenesis of vascular calcification, and providing new target for clinical treatment of cardiovascular diseases associated with vascular calcification.
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PMID:Effects of adrenomedullin, C-type natriuretic peptide, and parathyroid hormone-related peptide on calcification in cultured rat vascular smooth muscle cells. 1282 32

Recent evidence from rodents and humans shows that C-type natriuretic peptide (CNP) plays an essential role in endochondral bone growth. We recently identified a stable product of proCNP, amino-terminal proCNP (NT-proCNP), which unlike CNP is readily measurable in human and ovine plasma. Hypothesizing that plasma NT-proCNP concentrations reflect in part CNP synthesis within growth plates of rapidly growing cartilage, we studied levels of CNP forms in both children and lambs and related these to age, growth velocity, and biochemical markers of bone turnover. Plasma NT-proCNP levels were elevated at birth and fell progressively with age. Significant associations between plasma NT-proCNP and height velocity, alkaline phosphatase, and type 1 collagen C telopeptide were identified in children (aged 5-18 y). In longitudinal animal studies, elevated plasma concentration of NT-proCNP in 1-wk-old lambs fell progressively to mature adult levels at age 27 wk. Plasma NT-proCNP showed a highly significant association with alkaline phosphatase and metacarpal growth velocity. Glucocorticoids, a treatment known to inhibit cartilage proliferation, reduced metacarpal growth elongation in 4-wk-old lambs and markedly lowered circulating NT-proCNP levels during the treatment period. In summary, NT-proCNP levels in blood show a strong association with growth velocity and markers of bone formation and may well serve as a useful marker of growth plate activity in humans and other mammals.
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PMID:Amino-terminal proCNP: a putative marker of cartilage activity in postnatal growth. 1600 35

Using a novel marker of C-type natriuretic peptide (CNP) synthesis [amino-terminal pro-CNP (NT-proCNP)], we have recently shown that plasma NT-proCNP is strongly correlated with skeletal growth and markers of bone formation and is reversibly reduced by glucocorticoids. The effects on CNP of other catabolic or anabolic factors, known to affect skeletal growth, are unknown. Accordingly, we have studied the response of plasma CNP forms to acute catabolic (caloric restriction) and anabolic [growth hormone (GH) stimulation] interventions in lambs and related the findings to circulating IGF-I levels, growth velocity, and markers of bone formation. Lambs fed a reduced caloric intake (25% of normal) for 6 days exhibited reduced live weight, plasma urea, and IGF-I (P < 0.001 for all) compared with control lambs. Basal levels of NT-proCNP (40.1 +/- 0.9 pmol/l) fell promptly to a nadir (28.1 +/- 0.8 pmol/l, P < 0.001) on day 6, returning rapidly to basal levels upon refeeding. Although plasma alkaline phosphatase (ALP) fell (P < 0.001), reductions in metacarpal growth velocity were not significant within the 12-day period of study. In contrast to caloric restriction, long-acting bovine recombinant GH (2.5 mg/kg on days 0 and 6), as expected, increased plasma IGF-I more than twofold above control for 12 days (P < 0.001). Growth velocity did not differ during the 30 days of observation, and, consistent with unchanged growth velocity, plasma NT-proCNP and ALP were also unaffected. In conclusion, CNP synthesis and markers of bone formation are acutely sensitive to catabolism but unaffected by doses of GH that fail to stimulate skeletal growth.
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PMID:Response of plasma CNP forms to acute anabolic and catabolic interventions in growing lambs. 1722 62


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