title: Degradation of p21Cip1 through anaphase-promoting complex/cyclosome and its activator Cdc20 (APC/CCdc20) ubiquitin ligase complex-mediated ubiquitylation is inhibited by cyclin-dependent kinase 2 in cardiomyocytes.
abstract: Cyclin-dependent kinase inhibitor p21Cip1 plays a crucial role in regulating cell cycle arrest and differentiation. It is known that p21Cip1 increases during terminal differentiation of cardiomyocytes, but its expression control and biological roles are not fully understood. Here, we show that the p21Cip1 protein is stabilized in cardiomyocytes after mitogenic stimulation, due to its increased CDK2 binding and inhibition of ubiquitylation. The APC/CCdc20 complex is shown to be an E3 ligase mediating ubiquitylation of p21Cip1 at the N terminus. CDK2, but not CDC2, suppressed the interaction of p21Cip1 with Cdc20, thereby leading to inhibition of anaphase-promoting complex/cyclosome and its activator Cdc20 (APC/CCdc20)-mediated p21Cip1 ubiquitylation. It was further demonstrated that p21Cip1 accumulation caused G2 arrest of cardiomyocytes that were forced to re-enter the cell cycle. Taken together, these data show that the stability of the p21Cip1 protein is actively regulated in terminally differentiated cardiomyocytes and plays a role in inhibiting their uncontrolled cell cycle progression. Our study provides a novel insight on the control of p21Cip1 by ubiquitin-mediated degradation and its implication in cell cycle arrest in terminal differentiation.
authors: Laboratory of Genome Structure and Regulation, School of Biomedical Science, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510.
authors: Kazuhiko
authors: K
authors: Yamada
authors: Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510; Department of Biochemistry, Teikyo University School of Medicine, 2-11-1, Kaga, Itabashi-ku, Tokyo, 173-8605. Electronic address: madachi@med.teikyo-u.ac.jp.
authors: Mimi
authors: M
authors: Tamamori-Adachi
authors: Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510.
authors: Ikuko
authors: I
authors: Goto
authors: Department of Biochemistry, Teikyo University School of Medicine, 2-11-1, Kaga, Itabashi-ku, Tokyo, 173-8605.
authors: Masayoshi
authors: M
authors: Iizuka
authors: Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku City, Kochi, 783-8505, Japan.
authors: Takashi
authors: T
authors: Yasukawa
authors: Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku City, Kochi, 783-8505, Japan.
authors: Teijiro
authors: T
authors: Aso
authors: Department of Biochemistry, Teikyo University School of Medicine, 2-11-1, Kaga, Itabashi-ku, Tokyo, 173-8605.
authors: Tomoki
authors: T
authors: Okazaki
authors: Laboratory of Genome Structure and Regulation, School of Biomedical Science, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510; Department of Biochemical Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8510.
authors: Shigetaka
authors: S
authors: Kitajima
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D064199:Cdc20 Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000166:cytology; D017434:Protein Structure, Tertiary; D012323:RNA Processing, Post-Transcriptional; D051381:Rats; D017207:Rats, Sprague-Dawley; D025801:Ubiquitin / Q000737:chemistry; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
chemical_list: D064199:Cdc20 Proteins; C577494:Cdc20 protein, rat; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D025801:Ubiquitin; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome