Limits...
Fgf9 inhibition of meiotic differentiation in spermatogonia is mediated by Erk-dependent activation of Nodal-Smad2/3 signaling and is antagonized by Kit Ligand.

Tassinari V, Campolo F, Cesarini V, Todaro F, Dolci S, Rossi P - Cell Death Dis (2015)

Bottom Line: Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process.We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway.Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Biomedicina e Prevenzione, Università degli Studi di Roma Tor Vergata, Rome, Italy.

ABSTRACT
Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process. To understand the molecular mechanisms that might underlie this difference, we tried to dissect the intracellular signaling elicited by these two growth factors. We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway. Sustained Erk1/2 activity promoted by Fgf9 is required for induction of the autocrine Cripto-Nodal-Smad2/3 signaling loop in these cells. Nodal signaling, in turn, is essential to mediate Fgf9 suppression of the meiotic program, including inhibition of Stra8 and Scp3 expression and induction of the meiotic gatekeeper Nanos2. On the contrary, sustained activation of the Pi3k-Akt pathway is required for the induction of Stra8 expression elicited by Kl and retinoic acid. Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells.

Show MeSH

Related in: MedlinePlus

Fgf9 stimulates proliferation of spermatogonia. Top panel: cell count analysis of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both. Bottom panels: analysis of [3H]-thymidine incorporation (left panel) and cell viability measured by MTS assay (right panel) of in vitro cultured purified Kit+ spermatogonia treated overnight with Kl, Fgf9 or both factors. Data are expressed as the average fold increase with respect to untreated cells in three independent experiments. Bars represent the mean ±S.D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385934&req=5

fig2: Fgf9 stimulates proliferation of spermatogonia. Top panel: cell count analysis of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both. Bottom panels: analysis of [3H]-thymidine incorporation (left panel) and cell viability measured by MTS assay (right panel) of in vitro cultured purified Kit+ spermatogonia treated overnight with Kl, Fgf9 or both factors. Data are expressed as the average fold increase with respect to untreated cells in three independent experiments. Bars represent the mean ±S.D.

Mentions: Fgfs lead primarily to cell proliferation although cell differentiation or cell migration can also be observed.17, 18 To understand whether Fgf9 could induce spermatogonia proliferation, we first performed cell counts of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both (Figure 2, top panel). We found that both Kl and Fgf9 induced a significant increase of cell numbers, but they did not show any additive effect. The same results were obtained by [3H]-thymidine incorporation and, MTS assays on Kit+ cells, which are the cells committed to enter meiosis. As shown in Figure 2, bottom panels, an increase of DNA synthesis and cell viability were induced by Fgf9 treatment. As expected, also Kl induced an increase of both parameters, although the proliferation rate was twice that found in Fgf9-treated samples. Also in Kit+ cells, no additive effect was found when both factors were added together, suggesting that Kl and Fgf9 might converge on common pathways to signal mitogenic stimuli on Kit+ cells.


Fgf9 inhibition of meiotic differentiation in spermatogonia is mediated by Erk-dependent activation of Nodal-Smad2/3 signaling and is antagonized by Kit Ligand.

Tassinari V, Campolo F, Cesarini V, Todaro F, Dolci S, Rossi P - Cell Death Dis (2015)

Fgf9 stimulates proliferation of spermatogonia. Top panel: cell count analysis of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both. Bottom panels: analysis of [3H]-thymidine incorporation (left panel) and cell viability measured by MTS assay (right panel) of in vitro cultured purified Kit+ spermatogonia treated overnight with Kl, Fgf9 or both factors. Data are expressed as the average fold increase with respect to untreated cells in three independent experiments. Bars represent the mean ±S.D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385934&req=5

fig2: Fgf9 stimulates proliferation of spermatogonia. Top panel: cell count analysis of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both. Bottom panels: analysis of [3H]-thymidine incorporation (left panel) and cell viability measured by MTS assay (right panel) of in vitro cultured purified Kit+ spermatogonia treated overnight with Kl, Fgf9 or both factors. Data are expressed as the average fold increase with respect to untreated cells in three independent experiments. Bars represent the mean ±S.D.
Mentions: Fgfs lead primarily to cell proliferation although cell differentiation or cell migration can also be observed.17, 18 To understand whether Fgf9 could induce spermatogonia proliferation, we first performed cell counts of total spermatogonia after 24 h of culture in the presence or absence of Kl, Fgf9 or both (Figure 2, top panel). We found that both Kl and Fgf9 induced a significant increase of cell numbers, but they did not show any additive effect. The same results were obtained by [3H]-thymidine incorporation and, MTS assays on Kit+ cells, which are the cells committed to enter meiosis. As shown in Figure 2, bottom panels, an increase of DNA synthesis and cell viability were induced by Fgf9 treatment. As expected, also Kl induced an increase of both parameters, although the proliferation rate was twice that found in Fgf9-treated samples. Also in Kit+ cells, no additive effect was found when both factors were added together, suggesting that Kl and Fgf9 might converge on common pathways to signal mitogenic stimuli on Kit+ cells.

Bottom Line: Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process.We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway.Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Biomedicina e Prevenzione, Università degli Studi di Roma Tor Vergata, Rome, Italy.

ABSTRACT
Both fibroblast growth factor 9 (Fgf9) and Kit Ligand (Kl) signal through tyrosine kinase receptors, yet they exert opposite effects on meiotic differentiation in postnatal spermatogonia, Fgf9 acting as a meiosis-inhibiting substance and Kl acting as a promoter of the differentiation process. To understand the molecular mechanisms that might underlie this difference, we tried to dissect the intracellular signaling elicited by these two growth factors. We found that both Fgf9 and Kl stimulate Erk1/2 activation in Kit+ (differentiating) spermatogonia, even though with different time courses, whereas Kl, but not Fgf9, elicits activation of the Pi3k-Akt pathway. Sustained Erk1/2 activity promoted by Fgf9 is required for induction of the autocrine Cripto-Nodal-Smad2/3 signaling loop in these cells. Nodal signaling, in turn, is essential to mediate Fgf9 suppression of the meiotic program, including inhibition of Stra8 and Scp3 expression and induction of the meiotic gatekeeper Nanos2. On the contrary, sustained activation of the Pi3k-Akt pathway is required for the induction of Stra8 expression elicited by Kl and retinoic acid. Moreover, we found that Kl treatment impairs Nodal mRNA expression and Fgf9-mediated Nanos2 induction, reinforcing the antagonistic effect of these two growth factors on the meiotic fate of male germ cells.

Show MeSH
Related in: MedlinePlus