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The transcriptional corepressor NAB2 inhibits NGF-induced differentiation of PC12 cells.

Qu Z, Wolfraim LA, Svaren J, Ehrengruber MU, Davidson N, Milbrandt J - J. Cell Biol. (1998)

Bottom Line: We found that stably transfected PC12 cells expressing high levels of NAB2 do not differentiate, but rather continue to proliferate in response to NGF.Inhibition of PC12 differentiation by NAB2 overexpression was confirmed using two additional experimental approaches, transient transfection, and adenoviral infection.Cotransfection with p21(WAF1) restored the ability of NAB2-overexpressing PC12 cells to differentiate in response to NGF.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

ABSTRACT
The PC12 pheochromocytoma cell line responds to NGF by undergoing growth arrest and proceeding to differentiate toward a neuronal phenotype. Among the early genetic events triggered by NGF in PC12 cells are the rapid activation of the zinc finger transcription factor Egr1/NGFI-A, and a slightly delayed induction of NAB2, a corepressor that inhibits Egr1 transcriptional activity. We found that stably transfected PC12 cells expressing high levels of NAB2 do not differentiate, but rather continue to proliferate in response to NGF. Inhibition of PC12 differentiation by NAB2 overexpression was confirmed using two additional experimental approaches, transient transfection, and adenoviral infection. Early events in the NGF signaling cascade, such as activation of MAP kinase and induction of immediate-early genes, were unaltered in the NAB2-overexpressing PC12 cell lines. However, induction of delayed NGF response genes such as TGF-beta1 and MMP-3 was inhibited. Furthermore, NAB2 overexpression led to downregulation of p21(WAF1), a molecule previously shown to play a pivotal role in the ability of PC12 cells to undergo growth arrest and commit to differentiation in response to NGF. Cotransfection with p21(WAF1) restored the ability of NAB2-overexpressing PC12 cells to differentiate in response to NGF.

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NAB2-overexpressing cells do not undergo growth arrest in response to NGF. Wild-type PC12 cells and the NAB2 stably transfected cell lines, N2-8 and N2-64, were plated at 5,000  cells/well in a 24-well plate. NGF was added to each culture at  day 4. Medium was changed every other day and cell counts were  performed on four wells from each cell line at the indicated time  points. Error bars indicate the standard deviation.
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Figure 3: NAB2-overexpressing cells do not undergo growth arrest in response to NGF. Wild-type PC12 cells and the NAB2 stably transfected cell lines, N2-8 and N2-64, were plated at 5,000 cells/well in a 24-well plate. NGF was added to each culture at day 4. Medium was changed every other day and cell counts were performed on four wells from each cell line at the indicated time points. Error bars indicate the standard deviation.

Mentions: To determine whether NAB2 overexpression affects proliferation of PC12 cells, equivalent numbers of cells were plated and cell counts were performed at various times for ≤10 d in the presence of NGF. NAB2-overexpressing cell lines divide at a rate that is similar to wild-type PC12 cells in the absence of NGF (data not shown). However, whereas wild-type PC12 cells cease proliferation 3 to 4 d after exposure to NGF, the growth rate of NAB2-overexpressing cells was not altered by NGF (Fig. 3). These results suggest that NAB2 overexpression prevents cell cycle arrest, a prerequisite for NGF-induced differentiation (Mark and Storm, 1997).


The transcriptional corepressor NAB2 inhibits NGF-induced differentiation of PC12 cells.

Qu Z, Wolfraim LA, Svaren J, Ehrengruber MU, Davidson N, Milbrandt J - J. Cell Biol. (1998)

NAB2-overexpressing cells do not undergo growth arrest in response to NGF. Wild-type PC12 cells and the NAB2 stably transfected cell lines, N2-8 and N2-64, were plated at 5,000  cells/well in a 24-well plate. NGF was added to each culture at  day 4. Medium was changed every other day and cell counts were  performed on four wells from each cell line at the indicated time  points. Error bars indicate the standard deviation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132876&req=5

Figure 3: NAB2-overexpressing cells do not undergo growth arrest in response to NGF. Wild-type PC12 cells and the NAB2 stably transfected cell lines, N2-8 and N2-64, were plated at 5,000 cells/well in a 24-well plate. NGF was added to each culture at day 4. Medium was changed every other day and cell counts were performed on four wells from each cell line at the indicated time points. Error bars indicate the standard deviation.
Mentions: To determine whether NAB2 overexpression affects proliferation of PC12 cells, equivalent numbers of cells were plated and cell counts were performed at various times for ≤10 d in the presence of NGF. NAB2-overexpressing cell lines divide at a rate that is similar to wild-type PC12 cells in the absence of NGF (data not shown). However, whereas wild-type PC12 cells cease proliferation 3 to 4 d after exposure to NGF, the growth rate of NAB2-overexpressing cells was not altered by NGF (Fig. 3). These results suggest that NAB2 overexpression prevents cell cycle arrest, a prerequisite for NGF-induced differentiation (Mark and Storm, 1997).

Bottom Line: We found that stably transfected PC12 cells expressing high levels of NAB2 do not differentiate, but rather continue to proliferate in response to NGF.Inhibition of PC12 differentiation by NAB2 overexpression was confirmed using two additional experimental approaches, transient transfection, and adenoviral infection.Cotransfection with p21(WAF1) restored the ability of NAB2-overexpressing PC12 cells to differentiate in response to NGF.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

ABSTRACT
The PC12 pheochromocytoma cell line responds to NGF by undergoing growth arrest and proceeding to differentiate toward a neuronal phenotype. Among the early genetic events triggered by NGF in PC12 cells are the rapid activation of the zinc finger transcription factor Egr1/NGFI-A, and a slightly delayed induction of NAB2, a corepressor that inhibits Egr1 transcriptional activity. We found that stably transfected PC12 cells expressing high levels of NAB2 do not differentiate, but rather continue to proliferate in response to NGF. Inhibition of PC12 differentiation by NAB2 overexpression was confirmed using two additional experimental approaches, transient transfection, and adenoviral infection. Early events in the NGF signaling cascade, such as activation of MAP kinase and induction of immediate-early genes, were unaltered in the NAB2-overexpressing PC12 cell lines. However, induction of delayed NGF response genes such as TGF-beta1 and MMP-3 was inhibited. Furthermore, NAB2 overexpression led to downregulation of p21(WAF1), a molecule previously shown to play a pivotal role in the ability of PC12 cells to undergo growth arrest and commit to differentiation in response to NGF. Cotransfection with p21(WAF1) restored the ability of NAB2-overexpressing PC12 cells to differentiate in response to NGF.

Show MeSH
Related in: MedlinePlus