Multiple forms of SppI (secreted phosphoprotein, osteopontin) synthesized by normal and transformed rat bone cell populations: Regulation by TGF-β

Kubota, Takao; Zhang, Qi; Wrana, Jeffrey L.; Ber, R.; Aubin, Jane E.; Butler, William T.; Sodek, Jaro

doi:10.1016/0006-291x(89)90837-1

Cited by 97 publications

(50 citation statements)

References 15 publications

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“…Although phosphorylation of OPN and BSP is believed to occur intracellularly, as demonstrated previously in bone cell cultures with $#PO % $− as a substrate [12,15], our previous studies of purinergic receptors in bone cells, including the UMR 106.06 cell line (L. C. Luo, H. Yu and J. Ferrier, unpublished work), have indicated the presence of ectokinase activity. Similarly, ectokinase activity has been demonstrated in neonatal rat calvarial bone cell populations [18], confirming an earlier observation of an extracellular enzyme in bone that could catalyse the transfer of phosphoryl groups from ATP to protein within the bone matrix [50].…”

Section: Discussionsupporting

confidence: 57%

“…In comparison, OPN, which is expressed later than BSP, binds rapidly to pre-existing crystals [12,13] and will inhibit crystal growth, the efficacy of the inhibition being dependent on the presence of phosphate groups [14]. Previous studies using $#PO % $− labelling have shown that phosphorylation of BSP and OPN occurs intracellularly [12,13,15], primarily through a casein kinase II-like enzyme [16].…”

Section: Introductionmentioning

confidence: 99%

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Evidence of ectokinase-mediated phosphorylation of osteopontin and bone sialoprotein by osteoblasts during bone formation in vitro

Zhu

Luo

Ferrier

et al. 1997

Biochemical Journal

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Section: Discussionsupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Evidence of ectokinase-mediated phosphorylation of osteopontin and bone sialoprotein by osteoblasts during bone formation in vitro

Zhu

Luo

Ferrier

et al. 1997

Biochemical Journal

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“…Breast milk has also been shown to contain highly phosphorylated OPN (37). OPN is usually secreted in both nonphosphorylated and phosphorylated forms (5,16,35,37). In the present study, we did not elucidate which form of OPN was secreted from P. marneffei-stimulated PBMCs, because the ELISA used recognizes both.…”

Section: Fig 4 Failure Of Anti-tnf-␣ and -Il-1rimentioning

confidence: 79%

Penicillium marneffeiCauses Osteopontin-Mediated Production of Interleukin-12 by Peripheral Blood Mononuclear Cells

et al. 2002

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We investigated the role of osteopontin (OPN) in interleukin-12 (IL-12) production from peripheral blood mononuclear cells (PBMCs) stimulated with Penicillium marneffei. Kinetic studies showed that OPN synthesis preceded that of IL-12 at both mRNA and protein levels when PBMCs were cocultured with P. marneffei. Treatment with anti-OPN monoclonal antibodies (MAb) significantly suppressed IL-12 secretion. Furthermore, native OPN induced a profound level of synthesis of IL-12 from noninfected PBMCs. The major cellular source of OPN was monocytes, because depletion of CD14 ؉ cells resulted in the abrogation of such production. We also examined the regulatory role of granulocyte-macrophage colony-stimulating factor (GM-CSF) in OPN secretion from P. marneffei-stimulated PBMCs. Neutralizing anti-GM-CSF MAb significantly reduced OPN secretion, and treatment with this cytokine induced OPN production from both infected and noninfected PBMCs. Finally, antagonists against the mannose receptor but not the ␤-glucan receptor almost completely abrogated the production of OPN. Our results demonstrated that OPN secreted from monocytes is involved in the production of IL-12 from PBMCs after stimulation with P. marneffei and that OPN production is regulated by GM-CSF. Our results also indicated the possible involvement of the mannose receptor as a signaltransducing receptor for triggering the secretion of OPN by P. marneffei-stimulated PBMCs.Penicillium marneffei, an opportunistic fungal pathogen, causes a life-threatening deep-seated systemic infection in patients with AIDS in Southeast Asian countries. The incidence of P. marneffei infection has been increasing among AIDS patients in Thailand since a decade ago (8,12,40). As predicted by the high incidence in these patients, cellular immunity is a central mechanism that mediates host resistance against infection with P. marneffei (18), and CD4 ϩ T cells play an important role in eradicating the microorganisms from infected sites (19). Interleukin-12 (IL-12) protects mice against this infection (17). Furthermore, gamma interferon, generated during the progression of cellular immunity, renders murine macrophages highly active in killing P. marneffei yeast cells, a form usually detected in biological samples from infected patients, by promoting the release of nitric oxide (20).Osteopontin (OPN), a phosphoprotein originally isolated from bone, contains an RGD sequence similar to that of other extracellular matrix and serum proteins, including fibronectin, vitronectin, collagen, thrombospondin, and fibrinogen (7,30,42). OPN promotes integrin-and CD44-mediated cell adhesion and chemotaxis of osteoclasts, smooth muscle cells, macrophages, and T cells (30). OPN production is elevated in various pathophysiological conditions, such as atherosclerosis, nephritis, malignancy, pulmonary fibrosis, wound healing, and bone remodeling (6,9,13,21,28,35,41). OPN is also abundantly produced by T cells and macrophages during the formation of granulomatous lesions in sarcoidosis and tuberculosis (4,25...

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“…In addition to osteoblasts, preosteoblasts, osteocytes as well as other haemopoietic cells, also synthesise Opn within the BM (Mark et al, 1987a(Mark et al, ,b, 1988Swanson et al, 1989). Opn does not appear to be synthesised by mesenchymal cells or fibroblasts in vivo (Butler, 1989). Opn is thought to be a single protein coded by a single gene (Smith & Denhardt, 1987;Swanson et al, 1989), but through phosphorylation, glycosylation and proteolytic cleavage, various molecular masses of Opn can be detected, ranging from 25 to 75 kDa.…”

Section: Osteopontinmentioning

confidence: 99%

“…Opn is secreted in non-phosphorylated (Kubota et al, 1989;Chambers et al, 1992;Chang & Prince, 1993;Barber et al, 1999) and phosphorylated (Salih et al, 1995(Salih et al, , 1997Sorensen et al, 1994) forms, which contains up to 28 phosphate residues and are differentially induced by cytokines. Phosphorylation appears to be functionally important in determining whether Opn binds to cell surface receptors or the extracellular matrix (Nemir et al, 1989;Ek-Rylander et al, 1994).…”

Section: Osteopontinmentioning

confidence: 99%

Osteopontin: a bridge between bone and blood

2006

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SummaryThe production of mature blood cells within the bone marrow (BM) is attributed to a pool of haemopoietic stem cells (HSC). It is now evident that HSC reside preferentially at the endosteal region within the BM where bone-lining osteoblasts are a key cellular component of the HSC niche that directly regulates HSC fate. Osteoblasts synthesise proteins that stimulate and inhibit HSC proliferation. In addition to angiopoietin 1 (Ang-1), osteoblasts synthesise and express the highly acidic glycoprotein, osteopontin (Opn), which, like Ang-1, acts as a potent constraining factor on HSC proliferation. Overexpression of Opn is a feature of haemopoietic malignancies, such as multiple myeloma and chronic myeloid leukaemia, although its exact role in the aetiology and progression of these diseases remains unclear. Through osteoblasts and their cell surface and expressed proteins including Opn, bone is able to regulate the tissue that resides within it. In doing so, Opn can be considered a bridge between bone and blood.

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Multiple forms of SppI (secreted phosphoprotein, osteopontin) synthesized by normal and transformed rat bone cell populations: Regulation by TGF-β

Cited by 97 publications

References 15 publications

Evidence of ectokinase-mediated phosphorylation of osteopontin and bone sialoprotein by osteoblasts during bone formation in vitro

Evidence of ectokinase-mediated phosphorylation of osteopontin and bone sialoprotein by osteoblasts during bone formation in vitro

Penicillium marneffeiCauses Osteopontin-Mediated Production of Interleukin-12 by Peripheral Blood Mononuclear Cells

Osteopontin: a bridge between bone and blood

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