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GC box binding induces phosphorylation of Spl by a DNA-dependent protein kinase. Cell

Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Cell (Impact Factor: 33.12). 11/1990; 63(1):155-65. DOI: 10.1016/0092-8674(90)90296-Q
Source: PubMed

ABSTRACT Efficient transcription of SV40 early genes requires transcription factor Sp1. Here, we report that SV40 infection induces Sp1 phosphorylation. While characterizing this modification, we discovered that Sp1 becomes quantitatively phosphorylated in an in vitro transcription extract. Multiple processive phosphorylation of Sp1 depends on binding of Sp1 to GC box-containing DNA. Cell fractionation and column chromatography reveal that the Sp1 kinase is a nuclear DNA binding protein that corresponds to a previously identified DNA-dependent protein kinase. Because only some trans-activators are phosphorylated by this kinase, Sp1 belongs to a specific subgroup of factors that are phosphorylated upon binding to promoter sequences. Finally, efficient phosphorylation of Sp1 requires both a functional DNA binding domain and a region containing the transcriptional activation domains. Coupling of phosphorylation to DNA binding may represent a novel mechanism for regulating transcriptional initiation.

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    • "Studies further identified DNA-PKcs as a modulator of cancer-associated pathways distinct from DNA repair, including hypoxia, metabolism, inflammatory response, and transcriptional regulation (Goodwin and Knudsen, 2014). Notably, DNA-PKcs was originally discovered and characterized as part of SP1 transcriptional complexes (Jackson et al., 1990) and as a regulatory component of transcriptionally poised RNA polymerase II (RNAPII) (Dvir et al., 1992); accordingly, recent studies revealed that DNA-PKcs is recruited to active sites of transcription (Ju et al., 2006). DNA-PKcs can interact with the basal transcriptional machinery (Maldonado et al., 1996) and both binds and modulates the function of multiple sequence-specific transcription factors (e.g., AIRE, p53, and ERG) as well as select nuclear receptors (including the glucocorticoid, progesterone, estrogen [ER], and androgen receptors [AR]) (Goodwin and Knudsen, 2014). "
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    Cancer cell 07/2015; 28(1):97-113. DOI:10.1016/j.ccell.2015.06.004 · 23.89 Impact Factor
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    • "There is growing evidence that the Spfamily plays an important role in proliferation and differentiation and participates in the regulation of genes that are both ubiquitously expressed, as well as those expressed in a tissue specific manner [11] [12]. Sp1 can be phosphorylated, a modification that affects its binding to the DNA [13] [14] [15] and Oglycosilated [16], which confers resistance to proteosome dependent degradation [17]. The GC-rich boxes bound by Sp1 are also recognized by the Sp3 transcription factor, competing for DNA binding. "
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    • "It remains possible that other histone modifications or proteins localized to breaks before fixation are responsible for the observed in situ localized DNA-PK activity. Alternatively, it is possible that in situ reconstitution of γH2AX foci by DNA-PK result from local allosteric activation of DNA-PK via binding to DNA termini (34–36). We reasoned that if local kinase activation by DNA DSBs were responsible for γH2AX foci reconstitution, then introduction of new DSBs into the genome should alter γH2AX in situ phosphorylation patterns. "
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