MOLECULAR CELL BIOLOGY SIXTH EDITION CHAPTER 20 Regulating the Eukaryotic Cell Cycle Copyright 2008 © W. H. Freeman and Company

V. Replication at Each Origin is Initiated Only Once during the Cell Cycle *1 Multiple replication origin *2 Only once initiation Yeast Replication origin a. 11-base-pair conserved core sequence b. Origin recognition complex (ORC) c. Initiation factors d. Prereplicatiom complex Regulation of prereplication complexs a. Phosphorylated initiation factor b. S-phase cyclin-CDK and DDK c. B-type cyclin-CDK d. Cdc14

20.6 Cell-Cycle Control in Mammalian Cells Extracellular signal Signal transduction Intracellular cues I. Mammalian Restriction Point Growth factors (mitogen) Restriction point II. Mammalian CDKs and Cyclins Cyclin-dependent kinase (CDK) a. 적어도 4개가 확인 b. 각 phase마다 작동하는 CDKs가 다름: * G1; CDK4, 6 * mid G1 to S; CDK2 * G2 to M; CDK1

(2) Cyclins ( Two major group : G1 cyclins & B type ) a. Ability to complement yeast mutant로 확인 b. Mid- G1 : D c. Late- G1 : E d. S-phase : A e. Mitotic : B, A f. Destruction box (3) Cyclin D is essential for passage a. Anti-Cyclin D Ab microinjection b. Before 14 h c. After 14h (4) G0 cells

III. Regulated Expression of Two Classes of Genes Return G0 mammalian cells to the cell cycle Early-response genes a. Activation of preexisting TF b. Induction of gene expression : c-Jun, C-Fos (2) Delayed-response genes a. Early gene product 에 의한 gene expression이 조절됨 b. Mid-G1 cyclin, Late-G1 cyclins , CDKs, E2F factors c. Growth factor를 restriction point passage 직전에 제거 시 d. Cyclin D mRNA의 translation 조절 IV. Passage though the Restriction Point (1) E2F factors : Activation of cyclin E, A expression (2) RB protein : Tumor-suppressor (3) Regulation of Rb and E2F activity

V. Cyclin A: for DNA synthesis CDK1: for Mitosis Entry (1) Cyclin A-CDK2 complex (S-phase complex) (2) CDK inhibitory proteins (CKIs): p27KIP1, p57KIP2, p21CIP a. Sic1과 기능이 유사 b. p27KIP1 (3) Cyclin-CDK2 function의 조절( MPF 와 유사) a. Cdc25A phosphtase b. G1 to S transition c. Activation in late G1 (4) Initiation of DNA replication a. Phosphorylation of preinitiation complex : IFs b. Geminin c. Cdc14 phosphatase

VI. Two Types of Cyclin-CDK inhibitors (5) CDK1: G2 & Mitosis에서 주된 역할 a. Cyclin A & B 와 association b. Cdc25C Phosphatase (6) Cyclin B a. Synthesis b. Cyclin B shuttles between the cytosol and nucleus c. Removal by APC/C-Cdh1 VI. Two Types of Cyclin-CDK inhibitors CKI type : S- phase 로 entry전에 제거 a. Inhibition of CDK2 b. p21CIP : DNA Damage 시 작동 c. p27KIP1 knockouts d. p57KIP2 knockouts INK4 type a. Binding to CDK4 & CDK6 b. Tumor suppressor

20.7 Checkpoints in Cell-Cycle Regulation *1 Fundamental processes in the eukaryotic cell cycle DNA prereplication complexs assemble at origin G1 cyclin-CDK inactivate Cdh1 G1 C-C activates expression of S-phase C-C component G1 C-C phosphorylates S-phase inhibitor SCF/proteasome degrades phosphorylated S-phase C-C inhibitor S cyclin-CDK activates prereplication complex Cdc25 phosphatase activates Mitotic cyclin-CDKs APC/C-Cdc20 degrade securin Cdc14 phosphatase activates Cdh1

*2 Checkpoints in Cell-Cycle Regulation Intra S phase checkpoint : Inhibition of Cdc25C Spindle-assembly checkpoint : Inhibition of Cdc20 Spindle-position checkpoint : Prevention of Cdc14 DNA-damage checkpoint : Inhibition of Cdc25A I . Intra S phase checkpoint Association of ATR with replication fork Chk1 kinase Cdc25 phosphatase Checkpoint controller II. Spindle-assembly checkpoint Mad2 (Mitotic arrest defective 2) p31comet

III. Proper Segregation checkpoint The spindle-position checkpoint (2) Mitotic exit network a. Tem1 : GTPase superfamily b. Releasing of Cdc14 (3) Checkpoint인 이유 a. Telophase initiation b. Kin4 kinase

IV. DNA-damage checkpoint a. Chemical agents b. Irradiation c. G1 arrest or G2 arrest (2) Tumor-suppressor gene products, ATM & Chk2 ATM or Chk2 mutation Encode protein kinase Inactivation of Cdc25A (3) p53 protein (Tumor-suppressor) DNA damage Transcription factor Degradation by Mdm2 ATM & ATR Activation of p21CIP p53 induced apoptosis

I. Key Features Distinguish Meiosis from Mitosis Comparison of mitosis and meiosis Chiasmata II. Repression of G1 Cyclins and a Meiosis-specific Protein Kinase Promote Premeiotic S phase S. cerevisiae and S. pombe 의 meiosis Nitrogen and Carbon source 부족 시 Ime2 의 Induction Meiosis I 과 II 사이에 DNA replication의 suppression MPF activity 2nd rise in MPF activity Cdc20 activity is increased Separase is activated

III. Two Physical links: Recombination Meiosis-specific cohesin subunit Homologous chromosome사이에 physical links Recombination Cohesin function during mitosis and meiosis Meiotic chromosome 와 cohesin IV. Rec 8 Stability Meiosis I Meiosis II

V. The Monopolin Complex Co-orient Sister Kinetochores in Meiosis I (1) MAMI (2) Monopolin complex VI. Tension on Spindle Microtubles Contributes to Proper Spindle Attachment (1) Mitosis 에서 (2) Meiosis I 에서