Cell cycle regulation presentation by me and my colleagues. Not the Best work but still it will give a general idea about DNA damage checkpoints, roles of Cdk-Cyclin complexes, Rb proteins, ATM&ATR kinases, p51, etc. Reference : Nature reviews & The Cell a molecular approach. (cooper)

1. Regulation Of Cell Cycle
Shubhankar Ambike
Bhushan Nikam
Kiran Ghayal
National Institute of Virology, Pune

2. Cell Cycle & Regulation
• Sequence of events by which cell duplicates
its genome and divides into two daughter
cells
• Two main phases:
Interphase (G1,S and G2 phases)
M-phase (Mitosis phase) /Meosis

4. Regulation of cell cycle by Cdk cyclin
• Cdks are the catalytic subunits of heterodimeric
serine/threonine protein kinases
• Best-characterized in controlling progression
through the cell cycle.
• Cyclins regulate the cell cycle by binding to Cdk and
activating cyclin-dependent kinases (Cdks) by
Phosphorylation of specific groups on Cdk
• Common classes of cyclins include G1-phase cyclins,
G1/S-phase cyclins, S-phase cyclins, and M-phase
cyclins.

5. Regulation of cell cycle processes by CDK–cyclin
complexes.

6. The classical and minimal model of cell cycle
control

7. Regulation of Cdk by phosphorylation and
proteolysis

8. Cell Cycle Checkpoints

9. Spindle Assembly Checkpoint

10. PREVENTING RE-REPLICATION
OF CHROMOSOMAL DNA

11. Role of Rb Protein in Cell Cycle Regulation

12. Protein Kinases and Cell Cycle
Regulation
Protein kinases are involved in Regulation of cell cycle progression by
Regulating DNA DAMAGE CHECKPOINTS.
They are involved in various proteins which are Associated with DNA
replication.
MPF i.e. Maturation Promoting Factors present in cells, induces
entry into the M phase. Eg: Progesterone in frog oocytes, CdK
proteins.

13. Masui and Markert Experiment :
It showed that the oocytes Arrested
in G2 phase could be induced to
enter M phase by Microinjection of
Cytoplasm from oocytes that passed
the phase i.e. Hormonally
stimulated.

14. WHAT ARE DNA DAMAGE CHECKPOINTS
These ensures that Damaged DNA is not replicated and passed
on to the next generation.
They play a critical role in maintaining integrity of genome by
arresting cell cycle progression in response to the damaged or
non-replicated DNA.
Well studied examples are :
ATM and ATR Protein Kinases.

15. Cell Cycle Arrest Mediated by ATM
and ATR

16. Role of P53 in G1 Arrest

17. Role of p53 continued…
Intrestingly, the gene encoding for p53 is frequently mutated in
human cancers.
Loss of p53 function, PREVENTS G1 ARREST in response to the DNA
DAMAGE.
Results in INCREASED FREQUENCY OF MUTATIONS and general
instability of the genome, which CONTRIBUTE TO THE CANCER
DEVELOPMENT.
‘P53 GENE THEREPY’