scholarly journals Cross-Talk between Fibroblast Growth Factor and Bone Morphogenetic Proteins Regulates Gap Junction-mediated Intercellular Communication in Lens Cells

2008 ◽  
Vol 19 (6) ◽  
pp. 2631-2641 ◽  
Author(s):  
Bruce A. Boswell ◽  
Pamela J. Lein ◽  
Linda S. Musil
Keyword(s):  
Growth Factor ◽  
Gap Junction ◽  
Fibroblast Growth Factor ◽  
Cross Talk ◽  
Primary Cultures ◽  
Vitreous Body ◽  
Equatorial Region ◽  
Bmp Signaling ◽  
Fibroblast Growth ◽  
Lens Cells

Homeostasis in the lens is dependent on an extensive network of cell-to-cell gap junctional channels. Gap junction-mediated intercellular coupling (GJIC) is higher in the equatorial region of the lens than at either pole, an asymmetry believed essential for lens transparency. Primary cultures of embryonic chick lens epithelial cells up-regulate GJIC in response to purified fibroblast growth factor (FGF)1/2 or to medium conditioned by vitreous bodies, the major reservoir of factors (including FGF) for the lens equator. We show that purified bone morphogenetic protein (BMP)2, -4, and -7 also up-regulate GJIC in these cultures. BMP2, -4, or both are present in vitreous body conditioned medium, and BMP4 and -7 are endogenously expressed by lens cells. Remarkably, lens-derived BMP signaling is required for up-regulation of GJIC by purified FGF, and sufficient for up-regulation by vitreous humor. This is the first demonstration of an obligatory interaction between FGF and BMPs in postplacode lens cells, and of a role for FGF/BMP cross-talk in regulating GJIC in any cell type. Our results support a model in which the angular gradient in GJIC in the lens, and thus proper lens function, is dependent on signaling between the FGF and BMP pathways.

scholarly journals Folliculostellate Cells Determine the Susceptibility of Lactotropes to Estradiol’s Mitogenic Action

Endocrinology ◽  
2004 ◽  
Vol 145 (3) ◽  
pp. 1473-1480 ◽  
Author(s):  
Souichi Oomizu ◽  
Kirti Chaturvedi ◽  
Dipak K. Sarkar
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Primary Cultures ◽  
Human Populations ◽  
Fibroblast Growth ◽  
Estradiol Treatment ◽  
Sd Rats ◽  
Mitogenic Action ◽  
F344 Rats

Abstract Estradiol is known to increase lactotropic cell proliferation, but estradiol susceptibility varies among human populations and among various strains of rats. We had reported that folliculostellate (FS) cells regulate estradiol’s mitogenic action on lactotropes; therefore, we studied their role in determining the susceptibility to estradiol in a high estradiol-responsive rat strain, Fischer 344 (F344), and in a low-responsive strain, Sprague Dawley (SD). Determination of total S-100-positive FS cells in the pituitary revealed that F344 rats have significantly more FS cells than do SD rats. Estradiol treatment did not change the number of FS cells in both F344 and SD rats. When cotransplanted with F344 pituitaries under the kidney capsule or cocultured with F344-derived lactotropes in vitro, FS cells derived from F344 rats increased estradiol’s mitogenic action. They also increased estradiol’s mitogenic action on SD-derived lactotropes in primary cultures. However, SD-derived FS cells failed to increase estrogen’s action on F344- or SD-derived lactotropes. The levels of basic fibroblast growth factor production and secretion by TGF-β3 and estradiol were much higher in F344-derived FS cells than in SD-derived FS cells. However, the lactotropes’ growth response to basic fibroblast growth factor was similar in both strains. These data suggest that cell-cell interaction between FS cells and lactotropes regulates estradiol’s mitogenic action on lactotropes and also determines lactotrope susceptibility to the steroid.

scholarly journals Fibroblast Growth Factor 4 Directs Gap Junction Expression in the Mesenchyme of the Vertebrate Limb Bud

1997 ◽  
Vol 138 (5) ◽  
pp. 1125-1137 ◽  
Author(s):  
H. Makarenkova ◽  
D.L. Becker ◽  
C. Tickle ◽  
A.E. Warner
Keyword(s):  
Growth Factor ◽  
Gap Junctions ◽  
Gap Junction ◽  
Fibroblast Growth Factor ◽  
Connexin 43 ◽  
Limb Bud ◽  
Functional Coupling ◽  
Fibroblast Growth ◽  
Mesenchyme Cells

Pattern in the developing limb depends on signaling by polarizing region mesenchyme cells, which are located at the posterior margin of the bud tip. Here we address the underlying cellular mechanisms. We show in the intact bud that connexin 43 (Cx43) and Cx32 gap junctions are at higher density between distal posterior mesenchyme cells at the tip of the bud than between either distal anterior or proximal mesenchyme cells. These gradients disappear when the apical ectodermal ridge (AER) is removed. Fibroblast growth factor 4 (FGF4) produced by posterior AER cells controls signaling by polarizing cells. We find that FGF4 doubles gap junction density and substantially improves functional coupling between cultured posterior mesenchyme cells. FGF4 has no effect on cultured anterior mesenchyme, suggesting that any effects of FGF4 on responding anterior mesenchyme cells are not mediated by a change in gap junction density or functional communication through gap junctions. In condensing mesenchyme cells, connexin expression is not affected by FGF4. We show that posterior mesenchyme cells maintained in FGF4 under conditions that increase functional coupling maintain polarizing activity at in vivo levels. Without FGF4, polarizing activity is reduced and the signaling mechanism changes. We conclude that FGF4 regulation of cell–cell communication and polarizing signaling are intimately connected.

Fibroblast Growth Factor-2 and Epidermal Growth Factor Modulate Prolactin Responses to TRH and Dopamine in Primary Cultures

Endocrine ◽  
2006 ◽  
Vol 29 (2) ◽  
pp. 317-324 ◽  
Author(s):  
Carlos Spuch ◽  
Yolanda Diz-Chaves ◽  
Diego Pérez-Tilve ◽  
Federico Mallo
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Fibroblast Growth Factor ◽  
Primary Cultures ◽  
Fibroblast Growth Factor 2 ◽  
Fibroblast Growth ◽  
Epidermal Growth

scholarly journals Involvement of Protein Kinase C-Dependent Mitogen-Activated Protein Kinase p44/42 Signaling Pathway for Cross-Talk between Estradiol and Transforming Growth Factor-β3 in Increasing Basic Fibroblast Growth Factor in Folliculostellate Cells

Endocrinology ◽  
2004 ◽  
Vol 145 (2) ◽  
pp. 706-715 ◽  
Author(s):  
Kirti Chaturvedi ◽  
Dipak K. Sarkar
Keyword(s):  
Protein Kinase C ◽  
Growth Factor ◽  
Protein Kinase ◽  
Fibroblast Growth Factor ◽  
Basic Fibroblast Growth Factor ◽  
Cross Talk ◽  
Mapk Pathway ◽  
Dominant Negative Mutant ◽  
Fibroblast Growth ◽  
Kinase C

Abstract We have recently shown that TGF-β3, in the presence of estradiol, increases the release of basic fibroblast growth factor (bFGF) from folliculostellate (FS) cells in the pituitary. We determined the interactive effects of TGF-β3 and estradiol on bFGF production and release from FS cells, and the role of the MAPK pathway in TGF-β3 and estradiol interaction. We found that TGF-β3 and estradiol alone moderately increased cell content and release of bFGF from FS cells; but together, they markedly increased the peptide. Estradiol and TGF-β3 alone moderately activated MAPK p44/42; together they produced marked activation of MAPK p44/42. Pretreatment of FS cells with an MAPK kinase 1/2 inhibitor or with protein kinase C inhibitors suppressed the activation of MAPK p44/42, bFGF release, and protein level increases, all of which were induced by TGF-β3 and estradiol. Estradiol and TGF-β3, either alone or in combination, increased the levels of active Ras. Furthermore, bFGF induction by TGF-β3 and estradiol was blocked by overexpression of Ras N17, a dominant negative mutant of Ras p21. Estrogen receptor blocker ICI 182,780 failed to prevent estrogen’s and TGF-β3’s effects on bFGF. These data suggest that an estradiol receptor-independent protein kinase C- activated Ras-dependent MAPK pathway is involved in the cross-talk between TGF-β3 and estradiol to increase bFGF production and/or release from FS cells.

scholarly journals Synergistic interaction between the fibroblast growth factor and bone morphogenetic protein signaling pathways in lens cells

2015 ◽  
Vol 26 (13) ◽  
pp. 2561-2572 ◽  
Author(s):  
Bruce A. Boswell ◽  
Linda S. Musil
Keyword(s):  
Gene Expression ◽  
Signaling Pathways ◽  
Bone Morphogenetic Protein ◽  
Primary Cultures ◽  
Bmp Signaling ◽  
Fibroblast Growth ◽  
Lens Development ◽  
Morphogenetic Protein ◽  
Lens Cells ◽  
And Function

Fibroblast growth factors (FGFs) play a central role in two processes essential for lens transparency—fiber cell differentiation and gap junction–mediated intercellular communication (GJIC). Using serum-free primary cultures of chick lens epithelial cells (DCDMLs), we investigated how the FGF and bone morphogenetic protein (BMP) signaling pathways positively cooperate to regulate lens development and function. We found that culturing DCDMLs for 6 d with the BMP blocker noggin inhibits the canonical FGF-to-ERK pathway upstream of FRS2 activation and also prevents FGF from stimulating FRS2- and ERK-independent gene expression, indicating that BMP signaling is required at the level of FGF receptors. Other experiments revealed a second type of BMP/FGF interaction by which FGF promotes expression of BMP target genes as well as of BMP4. Together these studies reveal a novel mode of cooperation between the FGF and BMP pathways in which BMP keeps lens cells in an optimally FGF-responsive state and, reciprocally, FGF enhances BMP-mediated gene expression. This interaction provides a mechanistic explanation for why disruption of either FGF or BMP signaling in the lens leads to defects in lens development and function.

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