scholarly journals Bone Morphogenetic Protein Regulation of Early Osteoblast Genes in Human Marrow Stromal Cells Is Mediated by Extracellular Signal-Regulated Kinase and Phosphatidylinositol 3-Kinase Signaling

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3428-3437 ◽  
Author(s):  
Anna M. Osyczka ◽  
Phoebe S. Leboy
Keyword(s):  
Alkaline Phosphatase ◽  
Stromal Cells ◽  
Marrow Stromal Cells ◽  
Phosphatidylinositol 3 Kinase ◽  
Serum Free ◽  
Igf I ◽  
Erk Activity ◽  
Osteoblast Genes ◽  
Erk Kinase ◽  
Phosphatidylinositol 3

Abstract Bone marrow stromal cells (MSC) are the major source of osteoblasts for bone remodeling and repair in postnatal animals. Rodent MSC cultured with bone morphogenetic proteins (BMPs) differentiate into osteoblasts, but most human MSC show a poor osteogenic response to BMPs. In this study we demonstrate that BMP-induced osteogenesis in poorly responsive human MSC requires modulation of ERK and phosphatidylinositol 3-kinase (PI3-K) pathways. Either treating human MSC cultures with the MAPK/ERK kinase inhibitor PD98059 or transferring them to serum-free medium with insulin or IGF-I permits BMP-dependent increases in the expression of the early osteoblast-associated genes, alkaline phosphatase and osteopontin. Increased expression of these genes in BMP-treated, serum-free cultures correlates with increased nuclear levels of activated Smads, whereas serum-free cultures of human MSC expressing constitutively active MAPK/ERK kinase show decreased expression of early osteoblast genes and decreased nuclear translocation of BMP-activated Smads. Inhibiting ERK activity in human MSC also elevates the expression of Msx2, a transcription factor that is directly regulated by Smad-binding elements in its promoter. Therefore, growth factor stimulation leading to high levels of ERK activity in human MSC results in suppressed BMP-induced transcription of several early osteoblast genes, probably because levels of BMP-activated nuclear Smads are decreased. In contrast, inhibiting the insulin/IGF-I-activated PI3-K/AKT pathway decreases BMP-induced alkaline phosphatase and osteopontin expression in serum-free cultures of human MSC, but increases BMP activation of Smads; thus, PI3-K signaling is required for BMP-induced expression of early osteoblast genes in human MSC either downstream or independent of the BMP-activated Smad signaling pathway.

Therapeutic Impact of Human Bone Marrow Stromal Cells Expanded by Animal Serum–Free Medium for Cerebral Infarct in Rats

Neurosurgery ◽  
2011 ◽  
Vol 68 (6) ◽  
pp. 1733-1742 ◽  
Author(s):  
Taku Sugiyama ◽  
Satoshi Kuroda ◽  
Yukari Takeda ◽  
Mitsufumi Nishio ◽  
Masaki Ito ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Marrow Stromal Cells ◽  
Human Bone ◽  
Human Bone Marrow ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Therapeutic Impact

IGF-I does not affect the proliferation or early osteogenic differentiation of human marrow stromal cells

Bone ◽  
2003 ◽  
Vol 33 (1) ◽  
pp. 80-89 ◽  
Author(s):  
S Walsh ◽  
C.M Jefferiss ◽  
K Stewart ◽  
J.N Beresford
Keyword(s):  
Osteogenic Differentiation ◽  
Stromal Cells ◽  
Marrow Stromal Cells ◽  
Igf I

scholarly journals Parallel Phosphatidylinositol-3 Kinase and p42/44 Mitogen-Activated Protein Kinase Signaling Pathways Subserve the Mitogenic and Antiapoptotic Actions of Insulin-Like Growth Factor I in Osteoblastic Cells

Endocrinology ◽  
2003 ◽  
Vol 144 (11) ◽  
pp. 4886-4893 ◽  
Author(s):  
Andrew Grey ◽  
Qi Chen ◽  
Xin Xu ◽  
Karen Callon ◽  
Jill Cornish
Keyword(s):  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Osteoblastic Cells ◽  
Phosphatidylinositol 3 Kinase ◽  
P70s6 Kinase ◽  
Igf I ◽  
Convergence Point ◽  
Phosphatidylinositol 3

Abstract IGF-I is an endocrine and paracrine regulator of skeletal homeostasis, principally by virtue of its anabolic effects on osteoblastic cells. In the current study, we examined the intracellular signaling pathways by which IGF-I promotes proliferation and survival in SaOS-2 human osteoblastic cells. Inhibition of each of the phosphatidylinositol-3 kinase (PI-3 kinase), p42/44 MAPK, and p70s6 kinase pathways partially inhibited the ability of IGF-I to stimulate osteoblast proliferation and survival. Because activation of p70s6 kinase is downstream of both PI-3 kinase and p42/44 MAPK activation in osteoblasts treated with IGF-I, this ribosomal kinase represents a convergence point for IGF-I-induced PI-3 kinase and p42/44 MAPK signaling in osteoblastic cells. In addition, abrogation of PI-3 kinase-dependent Akt signaling, which does not inhibit IGF-I-induced p70s6 kinase phosphorylation, also inhibited the antiapoptotic effects of IGF-I in osteoblasts. Finally, interruption of Gβγ signaling partially abrogated the ability of IGF-I to promote osteoblast survival, without inhibiting signaling through PI-3 kinase/Akt, p42/44 MAPKs, or p70s6 kinase. These data suggest that IGF-I signals osteoblast mitogenesis and survival through parallel, partly overlapping intracellular pathways involving PI-3 kinase, p42/44 MAPKs, and Gβγ subunits.

scholarly journals Lysophosphatidic acid stimulates glucose transport in Xenopus oocytes via a phosphatidylinositol 3′-kinase with distinct properties

1996 ◽  
Vol 316 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Fiona J. THOMSON ◽  
Colin MOYES ◽  
Pamela H. SCOTT ◽  
Robin PLEVIN ◽  
Gwyn W. GOULD
Keyword(s):  
Phosphatidic Acid ◽  
Glucose Transport ◽  
Lysophosphatidic Acid ◽  
Xenopus Oocytes ◽  
Kinase Activity ◽  
Sugar Transport ◽  
Phosphatidylinositol 3 Kinase ◽  
Marked Contrast ◽  
Igf I ◽  
Phosphatidylinositol 3

Lysophosphatidic acid (LPA) stimulated the transport of deoxyglucose into oocytes isolated from Xenopus laevis. This stimulation was accounted for entirely by an increase in the Vmax for transport. Various LPAs with different acyl groups in the sn-1 position and phosphatidic acid stimulated deoxyglucose (deGlc) transport in these cells with a rank order potency of 1-oleoyl-LPA > 1-palmitoyl-LPA > phosphatidic acid = 1-stearoyl-LPA > 1-myristoyl-LPA. The phosphatidylinositol 3´-kinase inhibitor LY294002 completely blocked LPA-stimulated deoxyglucose uptake (IC50 ~2 μM). In marked contrast, wortmannin, which can completely block both insulin-like growth factor-I (IGF-I)-stimulated deGlc uptake in oocytes and phosphatidylinositol 3´-kinase activation at concentrations as low as 20 nM [Gould, Jess, Andrews, Herbst, Plevin and Gibbs (1994) J. Biol. Chem. 269, 26622–26625], was a relatively poor inhibitor of LPA-stimulated deGlc transport, even at concentrations as high as 100 nM. We further show that LPA stimulates phosphatidylinositol 3´-kinase activity(s) that can phosphorylate both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate, and that this stimulation is inhibited by LY294002 but is relatively insensitive to wortmannin, again in marked contrast to IGF-I-stimulated phosphatidylinositol 3´-kinase activity. Antibodies against the p85 regulatory subunit of phosphatidylinositol 3´-kinase or antiphosphotyrosine antibodies immunoprecipitated IGF-I-stimulated but not LPA-stimulated phosphatidylinositol 3´-kinase activity. We conclude that LPA stimulates glucose uptake in Xenopus oocytes by a mechanism that may involve activation of a form of phosphatidylinositol 3´-kinase that is distinguished from other isoforms by its resistance to wortmannin and by its substrate specificity. Since the LPA-activated form of phosphatidylinositol 3´-kinase is pharmacologically and immunologically distinct from that which is involved in IGF-I-stimulated glucose transport in these cells, we suggest that distinct isoforms of this enzyme are able to function with the same biological effect, at least in the regulation of sugar transport.

scholarly journals Dexamethasone recruitment of self-renewing osteoprogenitor cells in chick bone marrow stromal cell cultures

Blood ◽  
1992 ◽  
Vol 79 (2) ◽  
pp. 320-326
Author(s):  
N Kamalia ◽  
CA McCulloch ◽  
HC Tenebaum ◽  
H Limeback
Keyword(s):  
Bone Marrow ◽  
Alkaline Phosphatase ◽  
Stromal Cells ◽  
Bone Marrow Stromal Cells ◽  
Cellular Proliferation ◽  
Marrow Stromal Cells ◽  
Mineralized Tissue ◽  
Osteoprogenitor Cells ◽  
Osteogenic Lineage ◽  
Population Doublings

Bone marrow stromal cells are a mixed population that contribute to the formation of the hematopoietic microenvironment. The osteogenic lineage includes populations of cells that, in culture, form discrete nodules of mineralized tissue when grown in the presence of ascorbic acid and sodium beta-glycerophosphate. We have used nodule formation to assay for the self-renewal capacity of osteoprogenitor cells in chick bone marrow cultures. To examine the regulatory influence of dexamethasone (Dx), first subcultures were grown continuously or split 1:1 at repeated subculture. Cells in continuous culture exhibited less than two population doublings, while cellular proliferation and alkaline phosphatase area were inhibited by 10(-8) mol/L Dx. Cells in split (redistributed) cultures exhibited up to 14 population doublings and cellular proliferation was also inhibited by Dx. In contrast with continuous cultures, redistributed cultures treated with Dx had increased alkaline phosphatase area and 15-fold larger amounts of mineralized tissue formation than controls. Osteogenesis was sustained for up to four subcultures and the ratio of mineralized tissue area to alkaline phosphotase positive cell area was at most 0.55. These data indicate that the osteogenic lineage of bone marrow stromal cells contains self-renewing progenitors that are recruited by Dx in culture and that at a maximum, only 55% of the alkaline phosphatase-positive cell population contributes to osteogenesis.

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