Pin1-mediated Sp1 phosphorylation by CDK1 increases Sp1 stability and decreases its DNA-binding activity during mitosis.
We have shown that Sp1 phosphorylation at Thr739 decreases its DNA-binding activity. In this study, we found that phosphorylation of Sp1 at Thr739 alone is necessary, but not sufficient for the inhibition of its DNA-binding activity during mitosis. We demonstrated that Pin1 could be recruited to the Thr739(p)-Pro motif of Sp1 to modulate the interaction between phospho-Sp1 and CDK1, thereby facilitating CDK1-mediated phosphorylation of Sp1 at Ser720, Thr723 and Thr737 during mitosis. Loss of the C-terminal end of Sp1 (amino acids 741-785) significantly increased Sp1 phosphorylation, implying that the C-terminus inhibits CDK1-mediated Sp1 phosphorylation. Binding analysis of Sp1 peptides to Pin1 by isothermal titration calorimetry indicated that Pin1 interacts with Thr739(p)-Sp1 peptide but not with Thr739-Sp1 peptide. X-ray crystallography data showed that the Thr739(p)-Sp1 peptide occupies the active site of Pin1. Increased Sp1 phosphorylation by CDK1 during mitosis not only stabilized Sp1 levels by decreasing interaction with ubiquitin E3-ligase RNF4 but also caused Sp1 to move out of the chromosomes completely by decreasing its DNA-binding activity, thereby facilitating cell cycle progression. Thus, Pin1-mediated conformational changes in the C-terminal region of Sp1 are critical for increased CDK1-mediated Sp1 phosphorylation to facilitate cell cycle progression during mitosis.
Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
Hang-Che
HC
Yang
The PhD Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
Jian-Ying
JY
Chuang
Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan.
Wen-Yih
WY
Jeng
Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei 110, Taiwan.
Chia-I
CI
Liu
Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
Andrew H-J
AH
Wang
Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, 138 Sheng-Li Road, Tainan 70403, Taiwan.
Pei-Jung
PJ
Lu
Graduate Institute of Medical Sciences, College of Medicine, and Center for Neurotrauma and Neuroregeneration, Taipei Medical University, Taipei 110, Taiwan.
Wen-Chang
WC
Chang
Institute of Bioinformatics and Biosignal Transduction, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei 110, Taiwan Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan Center for Infectious Disease and Signal Transduction Research, National Cheng Kung University, Tainan 701, Taiwan petehung@mail.ncku.edu.tw.
Jan-Jong
JJ
Hung
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008938:Mitosis / Q000235:genetics; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D055550:Protein Stability; D016329:Sp1 Transcription Factor / Q000737:chemistry / Q000378:metabolism*
D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D016329:Sp1 Transcription Factor; D004247:DNA; D016203:CDC2 Protein Kinase; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse