Cooperation of Sp1 and p300 in the induction of the CDK inhibitor p21WAF1/CIP1 during NGF-mediated neuronal differentiation

Abstract

Addition of nerve growth factor (NGF) to PC12 cells promotes neuronal di erentiation while inhibiting cell proliferation. In order to understand how NGF exerts its antimitogenic e ect during di erentiation, we have studied the mechanism by which this factor activates the promoter of the CDK inhibitor p21 WAF1/CIP1 . The minimal region of the p21 promoter required for the NGF-induction was mapped to a contiguous stretch of 10 bp located 83 bases upstream of the transcription initiation site. This GC-rich region was shown to interact speci®cally with the transcription factor Sp1 and the related protein Sp3, in either exponentiallygrowing or NGF-treated PC12 cells. The addition of NGF resulted in an accumulation of the transcriptional co-activator p300 in complexes associated with the NGF-responsive region. Transcriptional activity of Sp1, Sp3 and p300 was speci®cally induced by NGF in a Gal4-fusion assay, indicating that induction of p21 during neuronal di erentiation may involve regulation of the activity of these factors by NGF. Furthermore, p300 was able to act as a co-activator for Sp1-mediated transcriptional activation in PC12 cells, suggesting that p300 and Sp1 may cooperate in activating p21 transcription during the withdrawal of neuronal precursors from the cell cycle. This hypothesis is supported by experiments showing that p300 and Sp1 form complexes in PC12 cells.

Regulation of interaction of the acetyltransferase region of p300 and the DNA‐binding domain of Sp1 on and through DNA binding

“…A recent study which addressed the cooperation of Sp1 and p300 in the induction of the cyclin-dependent kinase inhibitor p21 WAF/CIP1 gene during nerve growth factor (NGF)-mediated neuronal differentiation showed that p300 and Sp1 associate in PC12 cells, and for this association of p300 and Sp1 on the promoter to be induced by NGF stimulation to likely form a transcriptional activation complex, consistent with results of cotransfection transcription assays (Billon et al 1999). Others have suggested that the progesterone receptor may act as a bridging factor to form a multiprotein complex containing Sp1 and p300 for the progesterone regulation of the p21 WAF/CIP1 promoter through Sp1-binding sites (Owen et al 1998).…”

Unique induction of p21WAF1/CIP1expression by vinorelbine in androgen-independent prostate cancer cells

“…Several important biological modifiers have been shown to activate p21 transcription through different Spl binding sites (Cartel and Tyner, 1999). For example, phorbol ester and okadaic acid induce p21 expression through Spl-1 and Spl-2 sites (Biggs et al, 1996), whereas the Spl-3 site in the promoter of p21 has been shown to be required for p21 induction by transforming growth factor-b, histone deacetylase inhibitors such as TSA and butyrate, lovastatin, nerve growth factor (NGF) as well as calcium (Datto et al, 1995;Nakano et al, 1997;Prowse et al, 1997;Sowa et al, 1997;Lee et al, 1998;Billon et al, 1999). In this report, we demonstrated that Spl-3 and Spl-4 in the promoter of human p21 gene are required for vinorelbinemediated transcriptional restoration of p21 in the p21-deficient Al cells, which may provide a new mechanism in drug-mediated p21 regulation.…”

Activation of the p21WAF1/CIP1 promoter independent of p53 by the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) through the Sp1 sites

“…The standard deviations from three independent experiments were shown 1997; Sowa et al, 1997). Interestingly, the region containing the responsive elements for HDAC inhibitors also mediates p21 transcriptional activation regulated by TGF-b (Datto et al, 1995), the protein kinase C activator phorbol esters (Biggs et al, 1996), the phosphatases 1 and 2A inhibitor okadaic acid (Biggs et al, 1996), the geranylgeranyltransferase I inhibitor GGTI-298 (Adnane et al, 1998), progesterone (Owen et al, 1998), and nerve growth factor (Billon et al, 1999). We have then demonstrated that Sp1 and Sp3 transcription factors bind speci®cally to the Sp1-3 site of the p21 promoter, the primary SAHA-responsive element.…”