Modulation of Sp1 activity by a cyclin A/CDK complex

• Published in: Journal of molecular biology Vol. 306; no. 2; pp. 201 - 212
• Main Authors: Haidweger, Eva, Novy, Michael, Rotheneder, Hans
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 16.02.2001
• Subjects: Animals; Binding Sites; CDC2 Protein Kinase - antagonists & inhibitors; CDC2-CDC28 Kinases; Cell Cycle; Cell Line; Cyclin A - chemistry; Cyclin A - genetics; Cyclin A - metabolism; cyclin dependent kinase; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinases - antagonists & inhibitors; Cyclin-Dependent Kinases - metabolism; DNA - genetics; DNA - metabolism; DNA-Binding Proteins - metabolism; Gene Expression Regulation - drug effects; Genes, Reporter - genetics; Histones - metabolism; Humans; Kinetin; Phosphorylation; Precipitin Tests; Promoter Regions, Genetic - genetics; Protein Binding - drug effects; Protein Kinases - metabolism; Protein Structure, Tertiary; protein-protein interaction; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Purines - pharmacology; Response Elements - genetics; Sp1; Sp1 Transcription Factor - chemistry; Sp1 Transcription Factor - metabolism; Sp3 Transcription Factor; transcription factor; Transcription Factors - metabolism; Zinc Fingers; CKI; transcription factor; GST; CDK; FACS; cyclin dependent kinase; Sp1; EMSA; TK; HA; protein-protein interaction; phosphorylation; wt
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1006/jmbi.2000.4406

Transcription factors of the Sp1 family are targets of several regulatory pathways and can induce or inhibit gene expression. Here we show that Sp1 is associated with a histone 1 kinase activity. This activity is growth regulated and correlates with the expression of cyclin A. Co-immunoprecipitation experiments demonstrate, that Sp1 interacts with cyclin A and can be phosphorylated by a cyclin A associated kinase. The interaction is direct and requires the zinc-finger region of Sp1 and the amino-terminal domain of cyclin A. Over-expression of cyclin A enhances the expression of a reporter gene controlled by an Sp1 responsive promoter. Addition of olomoucine, a specific inhibitor of CDK2 and CDC2 activity on the other hand reduces the expression of the reporter. Electrophoretic mobility shift assays suggest that this is due to a reduction of the DNA-binding ability of Sp1 family members. Our results indicate that phosphorylation of Sp1 and other members of the family by a cyclin A/CDK complex may play a role in the growth and cell cycle regulation of its transcriptional activity.