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

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Query: EC:3.1.1.34 (lipoprotein lipase)
7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study, we investigated the role of the phytoestrogen genistein and 17beta-estradiol in human bone marrow stromal cells, undergoing induced osteogenic or adipogenic differentiation. Profiling of estrogen receptors (ERs)-alpha, -beta1, -beta2, -beta3, -beta4, -beta5, and aromatase mRNAs revealed lineage-dependent expression patterns. During osteogenic differentiation, the osteoblast-determining core binding factor-alpha1 showed a progressive increase, whereas the adipogenic regulator peroxisome proliferator-activated receptor gamma (PPARgamma) was sequentially decreased. This temporal regulation of lineage-determining marker genes was strongly enhanced by genistein during the early osteogenic phase. Moreover, genistein increased alkaline phosphatase mRNA levels and activity, the osteoprotegerin:receptor activator of nuclear factor-kappaB ligand gene expression ratio, and the expression of TGFbeta1. During adipogenic differentiation, down-regulation in the mRNA levels of PPARgamma and CCAAT/enhancer-binding protein-alpha at d 3 and decreased lipoprotein lipase and adipsin mRNA levels at d 21 were observed after genistein treatment. This led to a lower number of adipocytes and a reduction in the size of their lipid droplets. At d 3 of adipogenesis, TGFbeta1 was strongly up-regulated by genistein in an ER-dependent manner. Blocking the TGFbeta1 pathway abolished the effects of genistein on PPARgamma protein levels and led to a reduction in the proliferation rate of precursor cells. Overall, genistein enhanced the commitment and differentiation of bone marrow stromal cells to the osteoblast lineage but did not influence the late osteogenic maturation markers. Adipogenic differentiation and maturation, on the other hand, were reduced by genistein (and 17beta-estradiol) via an ER-dependent mechanism involving autocrine or paracrine TGFbeta1 signaling.
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PMID:The phytoestrogen genistein enhances osteogenesis and represses adipogenic differentiation of human primary bone marrow stromal cells. 1460 6

Interconversion of bone marrow osteoblasts and adipocytes has been reported previously. However, the osteogenic potential of extramedullary adipocytes is not known. Thus, we incubated a pure culture of human subcutaneous adipocytes in control medium for 1-2 weeks. Afterward, the cells were incubated in either osteoblast medium (OB medium) containing various combinations of calcitriol, dexamethasone, ascorbic acid, and beta-glycerophosphate or in adipocyte medium (AD medium) containing HEPES, biotin, pantothenate, insulin, triiodothyronine, dexamethasone, and isobutylmethylxanthine for 4 weeks. Expression of osteoblastic and adipocytic phenotypes was examined by determination of lineage-specific mRNA markers and in vitro adipocyte and osteoblast formation. Cells were also implanted, mixed with hydroxyapatite-tricalcium phosphate powder, in the subcutaneous tissue of immunodeficient mice in order to assess in vivo bone formation potential. One week after incubation in control medium, cells formed fusiform elongated fibroblast-like cells. In OB medium, cells stained positive for alkaline phosphatase (AP) and expressed mRNAs encoding Cbfa1/Runx2, AP, and osteocalcin. In AD medium cells reacquired adipocyte morphology with multilocular lipid-filled cells. Also, the cells expressed adipocyte-specific mRNA markers: lipoprotein lipase and peroxisome proliferator-activated receptor gamma2. Bone was formed only in the in vivo implants of cells incubated in OB medium. In conclusion, extramedullary adipocytes can transdifferentiate to bone-forming cells. Because of their ease of isolation, adipocytes may be good candidates for tissue-engineering protocols aimed at creating bone tissue for the repair of nonunion fractures and large bone defects.
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PMID:Subcutaneous adipocytes can differentiate into bone-forming cells in vitro and in vivo. 1516 55

Bone marrow stromal cells (BMSCs) are multipotent progenitor cells with a capacity to form bone tissue in vivo, and to differentiate into the osteoblastic lineage in vitro. Drawing on evidence that bone is mechanosensitive and mechanical stimuli are anabolic, we postulate that proliferation and osteoblastic differentiation of BMSCs may be stimulated by mechanical forces. In this study, BMSCs cultured in the presence of osteogenic factors (dexamethasone, beta-glycerophosphate, and ascorbate) were stimulated repeatedly (every second day) with shearing flow (1.6 dyn/cm(2)) for 5, 30, or 120 min, and assayed for systematic changes in cell number and phenotypic markers of osteoblastic differentiation. Cells exposed to fluid flow on days 2 and 4 after the addition of osteogenic factors and assayed at day 6 exhibited a modest decrease in cell number and increase in normalized alkaline phosphatase activity, suggesting the detachment of a non-osteogenic subpopulation. Cells exposed to fluid flow on days 6, 8, 10, and 12 and assayed at day 20 demonstrated maximal expression of osteopontin and bone sialoprotein mRNA with 30 min duration of flow. Concurrently, at day 20 expression of the adipogenic marker, lipoprotein lipase, was minimal with a 120-min duration of flow. These results indicate that repeated application of shear stress stimulates late phenotypic markers of osteoblastic differentiation of BMSCs in a manner that depends on the duration of stimulus. Finally, accumulation of prostaglandin E(2) in culture medium in response to shearing flow systematically decreased with repeated exposure to 30 and 120 min of shear stress (from day 6 to day 12), suggesting an adaptation of the cells to fluid flow.
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PMID:Fluid flow stimulates expression of osteopontin and bone sialoprotein by bone marrow stromal cells in a temporally dependent manner. 1586 16

Regenerative dental pulp strategies require the identification of precursors able to differentiate into odontoblast-like cells that secrete reparative dentin after injury. Pericytes have the ability to give rise to osteoblasts, chondrocytes, and adipocytes, a feature that has led to the suggestion that odontoblast-like cells could derive from these perivascular cells. In order to gain new insights into this hypothesis, we investigated the effects of dexamethasone (Dex), a synthetic glucocorticoid employed to induce osteogenic differentiation in vitro, in a previously reported model of human dental pulp cultures containing pericytes as identified by their expression of smooth muscle actin (SMA) and their specific ultrastructural morphology. Our data indicated that Dex (10(-8) M) significantly inhibited cell proliferation and markedly reduced the proportion of SMA-positive cells. Conversely, Dex strongly stimulated alkaline phosphatase (ALP) activity and induced the expression of the transcript encoding the major odontoblastic marker, dentin sialophosphoprotein. Nevertheless, parathyroid hormone/parathyroid hormone-related peptide receptor, core-binding factor a1/osf 2, osteonectin, and lipoprotein lipase mRNA levels were not modified by Dex treatment. Dex also increased the proportion of cells expressing STRO-1, a marker of multipotential mesenchymal progenitor cells. These observations indicate that glucocorticoids regulate the commitment of progenitors derived from dental pulp cells to form odontoblast-like cells, while reducing the proportion of SMA-positive cells. These results provide new perspectives in deciphering the cellular and molecular mechanisms leading to reparative dentinogenesis.
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PMID:Dexamethasone stimulates differentiation of odontoblast-like cells in human dental pulp cultures. 1598 17

Functional engineering of musculoskeletal tissues generally involves rapid expansion of progenitor cells in vitro while retaining their potential for further differentiation and then induction in specific culture conditions. The autologous adipose-derived stromal cells (ASCs) are considered to contain pluripotent mesenchymal stem cells. Imaging with expression of green fluorescent protein (GFP) facilitates the detailed research on ASCs physiological behavior during differentiation into a variety of cell lineages both in vitro and in vivo. In this study, we aimed to confirm the trans-germ plasticity of homogeneously marked ASCs from GFP transgenic mice. Simultaneously, the term and intensity of GFP expression in ASCs were also focused on during variant inductions, when cells were incubated with multiple growth factors and adjuvant. ASCs were harvested from inguinal fat pads of transgenic nude mice, passaged 3 times in monolayer cultures, and then transferred to osteogenic, adipogenic, neurogenic, and myogenic medium. The morphological characterization of inductive cells was observed using phase-contrast microscopy and histological staining such as alizarin red for mineralization nodules and oil red O for lipid accumulation. The expression of marker genes or proteins was measured using RT-PCR and immunocytochemical analysis. Collagen type I, osteopontin (OPN), and osteocalcin (OCN) were positive in osteogenic lineages, peroxisome proliferator-activated receptor(PPAR)-gamma2 and lipoprotein lipase (LPL) were positive in adipogenic ones, glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE) were positive in neurogenic ones, and alpha-smooth muscle actin (alpha-SMA) was positive in myogenic ones. Moreover, the results of fluorescence microscopic imaging suggested that there was no significant decline of GFP expression during ASCs differentiation and the level of GFP maintained stable till differentiated ASCs showed apoptotic phenotype. So the endogenous GFP and multilineage potential of transgenic ASCs had no influences on each other. Since the population of GFP ASCs can be easily identified, it is proposed that they may be promising candidate seed cells for further studies on ASCs tissue engineering, especially the study on engineered tissues formed in vivo.
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PMID:Multilineage differentiation of adipose-derived stromal cells from GFP transgenic mice. 1647 77

The purpose of this paper is to investigate the osteogenesis and adipogenesis in bone marrow mesenchymal stem cells (MSCs) isolated from normal rats and osteoporotic rats by ovariectomy. Osteoporotic animal model was established in 3 month-old and 6 month-old female Sprague-Dawley (SD) rats by ovariectomy. Animal experiments were divided into 4 groups: 1) control-3 group; 2) ovx-3 group; 3) control-6 group and 4) ovx-6 group. MSCs were isolated by means of the density-gradient centrifugation method from each group, respectively. Colony-forming unit-fibroblast (CFU-Fs ) number, CFU-Fs size distribution and cell density in CFU-Fs of primary passage MSCs were measured at the inverted phase contrast microscope. The cell cycle and proliferation index (PI) as well as apoptosis idex (AI) of MSCs were studied by (FCM). After osteogenic induction (OSI), calcium nodes of MSCs were marked by alizarin red staining (ARS); The expression level of alkaline phosphatase(ALP) was detected by dynamics method with substrate of phosphoric acid para-Nitro benzene and the content of osteocalcin (OCN) was detected with the isotope labelling method. After adipogenic induction (ADI), lipid droplet in MSCs were detected by oil red O staining and the mRNA level of lipoprotein lipase (LPL) was measured by RT-PCR. The results showed that CFU-Fs and PI are obviously decresed and AI are increased of MSCs in OVX-3 and OVX-6 groups (P<0.05). The secretory volume of ALP and BGP of MSCs and the content of calcium nods of MSCs are lower in OVX-3 and OVX-6 groups than that in control-3 and control-6 groups after osteogenic induction (P<0.05). The number of lipid droplet and the expression level of LPL mRNA are higher in OVX-3 and OVX-6 groups than that in control-3 and control-6 (P<0.05). The result in our study suggested that depress of osteogenesis and the up-regulation of adipogenesis of MSCs in osteoporotic rats by ovariectomy may be relate close to the pathogenesis of osteoporosis.
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PMID:[A potential role for the bone marrow mesenchymal stem cell in the pathogenesis of osteoporosis by ovariectomy in rat]. 1653 27

Musculoskeletal tissues regeneration requires rapid expansion of seeding cells both in vitro and in vivo while maintaining their multilineage differentiation ability. Human adipose-derived stem cells (ASCs) are considered to contain multipotent mesenchymal stem cells. Monolayer cultures of human ASCs were isolated from human lipoaspirates and passaged 3 times and then infected with replication-incompetent adenoviral vectors carrying green fluorescent protein (Ad/GFP) genes. Then, Ad/GFP infected human ASCs were transferred to osteogenic, chondrogenic, adipogenic, and myogenic medium. The morphological characterization of induced cells was observed using phase-contrast microscopy and fluorescence microscopy. The expression of marker proteins or genes was measured by immunocytochemical and RT-PCR analysis. Osteopontin (OPN), and osteocalcin (OCN) were positive in osteogenic lineages, aggrecan and SOX9 were positive in chondrogenic ones, peroxisome proliferator-activated receptor (PPAR-gamma2) and lipoprotein lipase (LPL) were positive in adipogenic ones, and myogenin and myod1 was positive in myogenic ones. At the same time, the results of fluorescence microscopic imaging proved that the high level of GFP expression during ASCs differentiation maintained stable nearly 2 months. So the exogenous GFP and multilineage potential of human ASCs had no severe influences on each other. Since the human ASCs can be easily obtained and abundant, it is proposed that they may be promising candidate cells for further studies on tissue engineering. Imaging with expression of GFP facilitates the research on ASCs physiological behavior and application in tissue engineering during differentiation both in vitro and in vivo.
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PMID:Pluripotency potential of human adipose-derived stem cells marked with exogenous green fluorescent protein. 1671 63

Whereas continuous PTH infusion increases bone resorption and bone loss, intermittent PTH treatment stimulates bone formation, in part, via reactivation of quiescent bone surfaces and reducing osteoblast apoptosis. We investigated the possibility that intermittent and continuous PTH treatment also differentially regulates osteogenic and adipocytic lineage commitment of bone marrow stromal progenitor/mesenchymal stem cells (MSC). The MSC were cultured under mildly adipogenic conditions in medium supplemented with dexamethasone, insulin, isobutyl-methylxanthine and troglitazone (DIIT), and treated with 50 nM human PTH(1-34) for either 1 h/day or continuously (PTH replenished every 48 h). After 6 days, cells treated with PTH for 1 h/day retained their normal fibroblastic appearance whereas those treated continuously adopted a polygonal, irregular morphology. After 12-18 days numerous lipid vacuole and oil red O-positive adipocytes had developed in cultures treated with DIIT alone, or with DIIT and continuous PTH. In contrast, adipocyte number was reduced and alkaline phosphatase staining increased in the cultures treated with DIIT and 1 h/day PTH, indicating suppression of adipogenesis and possible promotion of early osteoblastic differentiation. Furthermore, intermittent but not continuous PTH treatment suppressed markers of differentiated adipocytes such as mRNA expression of lipoprotein lipase and PPARgamma as well as glycerol 3-phosphate dehydrogenase activity. All of these effects of intermittent PTH were also produced by a 1 h/day treatment with AH3960 (30 microM), a small molecule, non-peptide agonist of the PTH1 receptor. AH3960, like PTH, activates both the cAMP and calcium signaling pathways. Treatment with the adenylyl cyclase activator forskolin for 1 h/day, mimicked the anti-adipogenic effect of intermittent PTH, whereas pretreatment with the protein kinase-A inhibitor H89 prior to intermittent PTH resulted in almost complete conversion to adipocytes. In contrast, the MAP kinase inhibitor PD 98059 failed to prevent the anti-adipocytic effect of intermittent PTH, suggesting that the inhibitory effect of PTH on adipocyte differentiation is predominantly cAMP-dependent. These results demonstrate a differential effect of PTH1 receptor agonists on the adipocytic commitment and differentiation of adult human bone marrow mesenchymal stem cells. This response may represent an additional mechanism that contributes to the overall bone anabolic action of intermittent PTH.
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PMID:Intermittent treatment with parathyroid hormone (PTH) as well as a non-peptide small molecule agonist of the PTH1 receptor inhibits adipocyte differentiation in human bone marrow stromal cells. 1690 89

The presence of multiple cell types in bone marrow and their varying proportions from isolation to isolation may count for the considerable variation in the outcome of different experiments. The presence of these multiple subpopulations suggests a need for a method that can purify the osteogenic component, i.e. osteoprogenitors, from other components. The availabilities of monoclonal antibodies recognizing subpopulations of osteoblasts are providing means for antibody-based methods. The cell surface antigens STRO-1, ALP and HOP-26 were used for cell sorting experiments with fluorescence activated cell sorting (FACS). These cell populations were analyzed on differential gene expression, cell proliferation and differentiation into the osteoblastic lineage. The oligo-microarray results showed that only the ALP positive cell population expressed genes of the extracellular matrix; like different collagens, ECM-1 and matrix protease MMP-14. The real-time polymerase chain reaction (QPCR) results showed that STRO-1 and ALP positive cells had an upregulation in expression of lipoprotein lipase, osteocalcin, and collagen type I. Integrin beta-3 was only upregulated for ALP positive cells, while for these cells downregulation occurred for the genes myosine, alkaline phosphatase and integrin beta-1. HOP-26 positive cells showed an upregulation in collagen type I compared to control group. The DNA analysis revealed that the cells of the control group and the HOP-26 positive cells showed a 5 times higher cell growth compared to the STRO-1 and ALP positive cells. The alkaline phosphatase activity showed no activity for the control group. The STRO-1 and ALP positive cells had a higher activity compared to the HOP-26 positive. The calcium measurements revealed only for the control group calcium at day 24. Based on the results of our study, we conclude that the FACS method had no negative effect on the proliferating as well as differentiating response of the cells. Further, we conclude that by using an antibody-based cell selection method, different cell populations with different mRNA expression profiles and different osteogenic characteristics can be obtained.
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PMID:Enrichment of osteogenic cell populations from rat bone marrow stroma. 1696 17

Ectomesenchymal cells isolated from the first branchial arch have the potential to differentiate into a variety of cell lineages both in vitro and in vivo. This study was aimed to confirm the plasticity of multilineage differentiation with molecular and cellular characterization. Monolayer cultures of ectomesenchymal cells harvested from the first branchial arch primordia in embryonic day 9.5 BALB/c mice were passaged 3 times before analysis. Staining with antibodies against S-100, p75 and vimentin suggested that the population of stem cells originated from ectomesenchyme, with few contaminating cells stained for cytokeratin. Then, cells were transferred to adipogenic, osteogenic, chondrogenic and odontogenic media. The initiation of controlled differentiation was determined with histological assays, and the expression of tissue-specific genes was detected using immunocytochemical staining and reverse transcription polymerase chain reaction. The adipogenic ectomesenchymal cells showed accumulation of lipid vacuoles and expression of lipoprotein lipase and peroxisome proliferator-activated receptor gamma(2). Following osteoinduction, the fibroblast-like cells became cuboidal and formed mineralized nodules. In addition, the expression of mRNA encoding osteocalcin and osteopontin proved osteogenesis at the molecular level. Chondrogenic lineage expressed collagen type II, aggrecan and Sox9 with a low level of collagen type I in monolayer culture. Odontogenesis was determined by dentin sialophosphoprotein, collagen type I and dentin matrix protein 1 expression. Therefore, we have demonstrated that ectomesenchymal cells from the first branchial arch are capable of extensive multilineage differentiation in vitro, controllable by the culture environment. This makes them a relevant and valuable source of stem cells for research of craniofacial development and tissue engineering of restoration.
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PMID:Characterization of ectomesenchymal cells isolated from the first branchial arch during multilineage differentiation. 1710 83


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