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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 overexpression blocks NGF-mediated differentiation of PC12 cells. Wild-type PC12 cells and PC12 cells overexpressing NAB2 (N2-8) were grown in the absence or presence of  NGF for 6 d. The morphology of the cells was examined using  phase-contrast microscopy. Note the contrast between the long,  slender neurites emanating from wild-type cells and the short,  stubby projections emanating from NAB2-overexpressing cells.
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Figure 2: NAB2 overexpression blocks NGF-mediated differentiation of PC12 cells. Wild-type PC12 cells and PC12 cells overexpressing NAB2 (N2-8) were grown in the absence or presence of NGF for 6 d. The morphology of the cells was examined using phase-contrast microscopy. Note the contrast between the long, slender neurites emanating from wild-type cells and the short, stubby projections emanating from NAB2-overexpressing cells.

Mentions: In the absence of NGF, the NAB2-overexpressing line contains a higher percentage of cells that develop small extensions from the cell surface, as compared with wild-type PC12 cells. However, the most dramatic difference is observed after addition of NGF. After growing in the presence of NGF for several days, wild-type PC12 cells undergo a series of dramatic phenotypic changes and acquire properties characteristic of sympathetic neurons (Allen and Heinrich, 1987). The cell bodies of differentiated PC12 cells enlarge and become flatter, and each cell generally extends several long neurites. In contrast, clonal PC12 lines overexpressing NAB2 fail to differentiate after exposure to NGF for 6 d (Fig. 2). NGF treatment of cells overexpressing NAB2 causes them to enlarge slightly and develop only very short, stubby projections from the cell surface. The average number of neurites per NAB2-overexpressing cell is 3.1 ± 1.1 (as compared with 3.5 ± 1.2 for wild-type PC12 cells), and the average length of the neurite is 38 ± 13 μm (compared with 223 ± 177 μm for wild-type PC12 cells).


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 overexpression blocks NGF-mediated differentiation of PC12 cells. Wild-type PC12 cells and PC12 cells overexpressing NAB2 (N2-8) were grown in the absence or presence of  NGF for 6 d. The morphology of the cells was examined using  phase-contrast microscopy. Note the contrast between the long,  slender neurites emanating from wild-type cells and the short,  stubby projections emanating from NAB2-overexpressing cells.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: NAB2 overexpression blocks NGF-mediated differentiation of PC12 cells. Wild-type PC12 cells and PC12 cells overexpressing NAB2 (N2-8) were grown in the absence or presence of NGF for 6 d. The morphology of the cells was examined using phase-contrast microscopy. Note the contrast between the long, slender neurites emanating from wild-type cells and the short, stubby projections emanating from NAB2-overexpressing cells.
Mentions: In the absence of NGF, the NAB2-overexpressing line contains a higher percentage of cells that develop small extensions from the cell surface, as compared with wild-type PC12 cells. However, the most dramatic difference is observed after addition of NGF. After growing in the presence of NGF for several days, wild-type PC12 cells undergo a series of dramatic phenotypic changes and acquire properties characteristic of sympathetic neurons (Allen and Heinrich, 1987). The cell bodies of differentiated PC12 cells enlarge and become flatter, and each cell generally extends several long neurites. In contrast, clonal PC12 lines overexpressing NAB2 fail to differentiate after exposure to NGF for 6 d (Fig. 2). NGF treatment of cells overexpressing NAB2 causes them to enlarge slightly and develop only very short, stubby projections from the cell surface. The average number of neurites per NAB2-overexpressing cell is 3.1 ± 1.1 (as compared with 3.5 ± 1.2 for wild-type PC12 cells), and the average length of the neurite is 38 ± 13 μm (compared with 223 ± 177 μm for wild-type PC12 cells).

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