Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Osteoblast maturation is partly controlled by the interaction of 1alpha,25(OH)(2)D(3) (D3), an active metabolite of Vitamin D, with other growth factors. The first reports describing the in vitro effect of D3 on human osteoblast differentiation performed experiments in the presence of serum. One potentially exciting candidate that might help explain the D3 responses observed for osteoblasts cultured with serum is lysophosphatidic acid (LPA). Drawn to the possibility that D3 and serum borne LPA might interact to induce osteoblast maturation we co-treated human cells with D3 and serum in the presence of Ki16425, an LPA receptor antagonist. Ki16425 inhibited osteoblast maturation as determined by markedly reduced alkaline phosphatase (ALP) expression. We subsequently found that LPA and D3 acted synergistically in generating mature osteoblasts and that this differentiation response could be inhibited using pertussis toxin, implying an important role of Galphai signal transduction. Furthermore, we found evidence for a dependency on both mitogen activated protein kinase kinase (MEK) and Rho associated coiled kinase (ROCK) for LPA and D3 stimulated maturation.
...
PMID:Lysophosphatidic acid cooperates with 1alpha,25(OH)2D3 in stimulating human MG63 osteoblast maturation. 1684 86

Statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, were originally developed to lower cholesterol. Their pleiotropic (or cholesterol-independent) effects at the cellular and molecular levels are highly related to numerous cellular functions, such as proliferation and differentiation. However, they are hardly studied in embryonic stem cells. In this study, we evaluated the effects of statins on mouse ESCs (J1, D3, and RW.4) to enhance our understanding of the molecular basis of ESC self-renewal. Treatment of ESCs with simvastatin, mevastatin, atorvastatin, or pravastatin induced morphological change and decreased cell proliferation. We observed that the use of simvastatin was most effective in all three ESCs. Loss of ESC self-renewal by simvastatin was determined by marked downregulation of ESC markers alkaline phosphatase, Oct4, Nanog, Rex-1, and SSEA-1. Simvastatin effects were selectively reversed by either mevalonate or its metabolite geranylgeranyl pyrophosphate (GGPP) but not by cholesterol or farnesyl pyrophosphate. These results suggest that simvastatin effects were mainly derived from depletion of intracellular pools of GGPP, the substrate required for the geranylgeranylation. Using this approach, we found that GGPP, a derivative of the mevalonate pathway, is critical for ESC self-renewal. Furthermore, we identified that simvastatin selectively blocked cytosol-to-membrane translocalization of RhoA small guanosine triphosphate-binding protein, known to be the major target for geranylgeranylation, and lowered the levels of Rho-kinase (ROCK)2 protein in ESCs. In addition, simvastatin downregulated the ROCK activity, and this effect was reversed by addition of GGPP. Our data suggest that simvastatin, independently of its cholesterol-lowering properties, impairs the ESC self-renewal by modulating RhoA/ROCK-dependent cell-signaling.
...
PMID:Simvastatin suppresses self-renewal of mouse embryonic stem cells by inhibiting RhoA geranylgeranylation. 1746 88

Here, we identified human myogenic progenitor cells coexpressing Pax7, a marker of muscle satellite cells and bone-specific alkaline phosphatase, a marker of osteoblasts, in regenerating muscle. To determine whether human myogenic progenitor cells are able to act as osteoprogenitor cells, we cultured both primary and immortalized progenitor cells derived from the healthy muscle of a nondystrophic woman. The undifferentiated myogenic progenitors spontaneously expressed two osteoblast-specific proteins, bone-specific alkaline phosphatase and Runx2, and were able to undergo terminal osteogenic differentiation without exposure to an exogenous inductive agent such as bone morphogenetic proteins. They also expressed the muscle lineage-specific proteins Pax7 and MyoD, and lost their osteogenic characteristics in association with terminal muscle differentiation. Both myoblastic and osteoblastic properties are thus simultaneously expressed in the human myogenic cell lineage prior to commitment to muscle differentiation. In addition, C3 transferase, a specific inhibitor of Rho GTPase, blocked myogenic but not osteogenic differentiation of human myogenic progenitor cells. These data suggest that human myogenic progenitor cells retain the capacity to act as osteoprogenitor cells that form ectopic bone spontaneously, and that Rho signaling is involved in a critical switch between myogenesis and osteogenesis in the human myogenic cell lineage.
...
PMID:Osteogenic properties of human myogenic progenitor cells. 1816 86

During maturation, chondrocytes undergo changes in morphology, matrix production, and gene expression; however, it remains unclear whether these are interrelated. In this study, we examined whether Rho GTPases were involved in these regulatory interplays. Levels of active Rho GTPases were assayed in immature and mature primary chondrocytes. We found that activation of Rac-1 and Cdc42 increased with maturation, whereas RhoA levels remained unchanged. GFP-tagged Rho GTPases tracked cellular localization. Rac-1 was enriched at the cell membrane where it co-localized with cortical actin, while RhoA and Cdc42 were cytoplasmic. To test the roles of Rac-1 in chondrocyte maturation, we force-expressed constitutively active or dominant negative forms of Rac-1 and assessed phenotypic consequences in primary chondrocytes. Activated Rac-1 expression induced chondrocyte enlargement and increased matrix metalloproteinase expression, which are characteristic of mature chondrocytes. Conversely, Rac-1 inactivation diminished adhesion, decreased alkaline phosphatase activity, and stimulated functions typical of immature chondrocytes. Exposure to a pro-maturation factor, Wnt3A, induced a flattened and enlarged morphology accompanied by peripheral Rac-1 re-arrangement. Wnt3A stimulated Tiam1 expression and Rac-1 activation, while DN-Rac-1 inhibited Wnt3A-induced cell spreading. Our data provide strong evidence that Rac-1 coordinates changes in chondrocyte phenotype and function and stimulates the maturation process essential for skeletal development.
...
PMID:Small GTPase protein Rac-1 is activated with maturation and regulates cell morphology and function in chondrocytes. 1826 26

Recent studies have shown that the mevalonate pathway plays an important role in skeletal metabolism. Statins stimulate bone morphogenetic proteins-2 (BMP-2) production in osteoblasts, implicating a possible beneficial role for statins in promoting anabolic effects on bone. Here, we investigated the effects of a lipophilic simvastatin on osteoblast differentiation using mouse myoblast C2C12 cells, in the presence of tumor necrosis factor-alpha (TNF-alpha), an inflammatory cytokine that inhibits osteogenesis. The addition of TNF-alpha to C2C12 cells suppressed the BMP-2-induced expression of key osteoblastic markers including Runx2 and alkaline phosphatase (ALP) activity. Simvastatin had no independent effects on Runx2 and alkaline phosphatase activity; however, it reversed the suppressive effects of TNF-alpha. The ability of simvastatin to reverse TNF-alpha inhibition of BMP-induced Smad1,5,8 phosphorylation and Id-1 promoter activity suggests the involvement of Smad signaling pathway in simvastatin action. In addition, cDNA array analysis revealed that simvastatin increased expression levels of Smads in C2C12 cells exposed to TNF-alpha that also activated mitogen-activated protein kinase (MAPK) signaling pathways, including extracellular signal-regulated kinase 1/2 (ERK1/2), P38, and stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK). Simvastatin potently suppressed TNF-alpha-induced phosphorylation of ERK1/2 and SAPK/JNK by inhibiting TNF-alpha-induced membrane localization of Ras and RhoA. Farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) reversed the simvastatin effects on TNF-alpha-induced activation of Ras/Rho/MAPK pathways. FPP and GGPP also restored the simvastatin effects on TNF-alpha-induced suppression of Runx2 and ALP activity. In addition, simvastatin decreased the expression levels of TNF type-1 and -2 receptor mRNAs. Collectively, simvastatin supports BMP-induced osteoblast differentiation through antagonizing TNF-alpha-to-Ras/Rho/MAPK pathway and augmenting BMP-Smad signaling, suggesting a potential usage of statins to ameliorate inflammatory bone damage.
...
PMID:Simvastatin antagonizes tumor necrosis factor-alpha inhibition of bone morphogenetic proteins-2-induced osteoblast differentiation by regulating Smad signaling and Ras/Rho-mitogen-activated protein kinase pathway. 1831 Apr 56

We examined the effect of liver X receptor (LXR) agonists on vascular calcification, prevalent in atherosclerotic lesions. T0901317, an LXR agonist, augmented protein kinase A (PKA)-induced mineralization and alkaline phosphatase (ALP) activity in aortic smooth muscle cells isolated from wild-type, but not from Lxrbeta(-/-)mice. A six-hour T0901317 treatment augmented the PKA-induced expression of the phosphate transporter Pit-1, a positive regulator of mineralization, suggesting a direct role. A ten-day T0901317 treatment attenuated PKA-induced expression of mineralization inhibitors, osteopontin and ectonucleotide pyrophosphatase/phosphodiesterase-1, suggesting an indirect role. The effects of T0901317 were attenuated by inhibition of ALP, Pit-1 and Rho-associated kinase, but not by inhibition of PKA. These results suggest that T0901317-augmented mineralization occurs downstream of PKA, involving both direct and indirect LXR-mediated pathways.
...
PMID:T0901317, an LXR agonist, augments PKA-induced vascular cell calcification. 1932 57

Medial artery calcification, which does not accompany lipid or cholesterol deposit, preferentially occurs in elderly population, but its underlying mechanisms remain unclear. In the present study, we investigated the potential role of senescent vascular smooth muscle cells (VSMCs) in the formation of senescence-associated medial calcification. Replicative senescence was induced by the extended passages (until passages 11-13) in human primary VSMCs, and cells in early passage (passage 6) were used as control young cells. VSMC calcification was markedly enhanced in the senescent cells compared with that in the control young cells. We identified that genes highly expressed in osteoblasts, such as alkaline phosphatase (ALP) and type I collagen, were significantly upregulated in the senescent VSMCs, suggesting their osteoblastic transition during the senescence. Knockdown of either ALP or type I collagen significantly reduced the calcification in the senescent VSMCs. Of note, runt-related transcription factor-2 (RUNX-2), a core transcriptional factor that initiates the osteoblastic differentiation, was also upregulated in the senescent VSMCs. Knockdown of RUNX-2 significantly reduced the ALP expression and calcification in the senescent VSMCs, suggesting that RUNX-2 is involved in the senescence-mediated osteoblastic transition. Furthermore, immunohistochemistry of aorta from the klotho(-/-) aging mouse model demonstrated in vivo emergence of osteoblast-like cells expressing RUNX-2 exclusively in the calcified media. We also found that statin and Rho-kinase inhibitor effectively reduced the VSMC calcification by inhibiting P(i)-induced apoptosis and potentially enhancing matrix Gla protein expression in the senescent VSMCs. These findings strongly suggest an important role of senescent VSMCs in the pathophysiology of senescence-associated medial calcification, and the inhibition of osteoblastic transition could be a new therapeutic approach for the prevention of senescence-associated medial calcification.
...
PMID:Replicative senescence of vascular smooth muscle cells enhances the calcification through initiating the osteoblastic transition. 1974 65

Rho-kinase (ROK), downstream of the mevalonate pathway, is detrimental to vessels, and suppressing its activity is a target for the treatment of human disease such as coronary artery disease and pulmonary hypertension. Recent studies have shown that ROK has a crucial role in bone metabolism. However, the role of ROK in stromal cells is still unclear. The present study was undertaken to investigate the effect of a ROK inhibitor, fasudil hydrochloride, on stromal cell lines, C3H10T1/2 and ST2. In both cells, Fasudil significantly stimulated alkaline phosphatase activity and enhanced cell mineralization. Moreover, fasudil significantly increased the mRNA expression of collagen-I, osteocalcin, and bone morphogenetic protein-2 (BMP-2). Supplementation of noggin, a BMP-2 antagonist, significantly reversed the fasudil-induced collagen-I and osteocalcin mRNA expression in both cells. These findings suggest that fasudil induces the osteoblastic differentiation of stromal cells via enhancing BMP-2 expression, and that this drug might be beneficial for not only atherosclerosis but also osteoporosis by promoting bone formation.
...
PMID:Fasudil hydrochloride induces osteoblastic differentiation of stromal cell lines, C3H10T1/2 and ST2, via bone morphogenetic protein-2 expression. 2015 8

Calponin h1 (CNh1) is an actin-binding protein originally isolated from vascular smooth muscle and has been reported to suppress bone formation. We are therefore curious how CNh1 is involved in bone loss that is caused by space flight in microgravity. We assessed the effects of tail suspension (TS) in C57BL/6J wild (CN+/+) and CNh1-deleted (CN-/-) mice to elucidate the role of CNh1 in bone loss under weightless conditions. Bone mineral density (BMD) of tibiae was measured by single energy X-ray absorptiometry, and bone volume fraction (BV/TV), mineral apposition rate (MAR), and bone formation rate (BFR/BS) were measured by bone histomorphometry. BMD, BV/TV, MAR, and BFR/BS were lower in CN+/+ mice with TS than in those without. In the CN-/- group, however, the decrease in each of these parameters by TS was ameliorated. Decreases in serum osteocalcin levels by TS in CN+/+ mice were attenuated in CN-/- mice. Furthermore, urinary deoxypyridinolin (DPD), an indicator of bone resorption, was increased in CN+/+ mice following TS, but not in CN-/- mice. In transfection experiments, the degree of induction of bone formation markers, alkaline phosphatase (ALP) activity and bone morphogenetic protein (BMP)-4 mRNA expression, under stimulation with BMP-2, was lower in MC3T3-E1 mouse osteoblast-like cells expressing CNh1 than that in mock transfected cells. Notably, the BMP-2-induced ALP activity was decreased by CNh1 expression, which was partially rescued by treatment with the Rho kinase inhibitor Y27632. Taken together, these results indicate that CNh1 is responsible for weightlessness-induced bone loss in part through Rho signaling pathway.
...
PMID:Tail-suspended mice lacking calponin H1 experience decreased bone loss. 2055 1

RhoA/Rho kinases (ROCK) play a critical role in vascular smooth muscle cell (VSMC) actin cytoskeleton organization, differentiation, and function and are implicated in the pathogenesis of cardiovascular disease. We have previously determined that an important step in the regulation of calcification is fetuin-A endocytosis, a process that is dependent on changes in the cytoskeleton, which, in turn, is known to be affected by the RhoA/ROCK signaling pathway. In the present study, bovine VSMC (BVSMC) were treated with the ROCK inhibitor Y-27632 or transfected with ROCK small interfering (si) RNA to knock down ROCK expression. Both conditions resulted in reduced actin stress fibers and increased Cy5-labeled fetuin-A uptake. Inhibition of ROCK by Y-27632 or siRNA also significantly increased BVSMC alkaline phosphatase (ALP) activity and calcification of BVSMC and rat aorta organ cultures. Cells were then incubated in calcification media in the presence or absence of Y-27632 and matrix vesicles (MV) isolated by collagenase digestion. These MV, isolated from BVSMC incubated with Y-27632, had increased ALP activity and increased ability of MV to subsequently calcify collagen by 66%. In contrast, activation of RhoA, which is upstream of ROCK, by transfecting plasmids encoding the dominant active Rho GTPase mutant (Rho-L63) led to decreased fetuin-A uptake and reduced calcification in BVSMC. These results demonstrate that the RhoA/ROCK signaling pathway is an important negative regulator of vascular calcification.
...
PMID:RhoA/Rho kinase (ROCK) alters fetuin-A uptake and regulates calcification in bovine vascular smooth muscle cells (BVSMC). 2061 May 33


<< Previous 1 2 3 4 5 Next >>

---