What does the protein p21 do why is it important?
The protein p21 (also known as WAF1, CIP1 or SD11) regulates cell proliferation by inhibiting the cell cycle through the cyclin kinase pathway. It also has been shown to inhibit apoptosis induced by numerous stimuli.
Does p21 inhibit the cell cycle?
p21 inhibits cell cycle progression primarily through the inhibition of CDK2 activity, which is required not only for the phosphorylation of RB with the consequent release and activation of E2f-dependent gene expression, but also for the firing of replication origins and for the activity of proteins directly involved …
How does p21 inhibit apoptosis?
A, p21 may block apoptosis by interacting with proapoptotic molecules such as procaspase-3, caspase-8, and the kinase apoptosis signal-regulating kinase 1 (ASK1) or by inducing cell cycle arrest after binding to cyclin E/Cdk2 complexes or by binding to cyclin A/Cdk2 complexes.
Is p21 a tumor suppressor protein?
In 1994, p21 (also known as wildtype activating factor-1/cyclin-dependent kinase inhibitory protein-1 or WAF1/CIP1) was introduced as a tumor suppressor in brain, lung, and colon cancer cells; it was shown that p21 induces tumor growth suppression through wild type p53 activity [2].
What is p21 in cell cycle?
P21 is a well-known inhibitor of cell cycle and can arrest the cell cycle progression in G1/S and G2/M transitions by inhibiting CDK4,6/cyclin-D and CDK2/cyclin-E, respectively. It is believed that the regulation of cell growth by p21 is mediated by control of E2F activity [3], [4].
What is the function of p21 in the cell cycle?
What CDK p21 inhibits?
CDK inhibition The p21 (CIP1/WAF1) protein binds to and inhibits the activity of cyclin-CDK2, -CDK1, and -CDK4/6 complexes, and thus functions as a regulator of cell cycle progression at G1 and S phase.
What does p21 do in the cell cycle?
Summary. P21 is a cell cycle inhibitor that is involved in essential cellular processes such as cell cycle arrest, apoptosis, and transcriptional regulation, as well as differentiation, senescence, and DNA repair.
Where is p21 protein produced?
p21 represents a major target of p53 activity and thus is associated with linking DNA damage to cell cycle arrest. This protein is encoded by the CDKN1A gene located on chromosome 6 (6p21. 2) in humans.
What activates p21?
Upon DNA damage or other stressors, the tumor suppressor p53 is activated, leading to transient expression of the cyclin-dependent kinase inhibitor (CKI) p21. This either triggers momentary G1 cell cycle arrest or leads to a chronic state of senescence or apoptosis, a form of genome guardianship.
How is p21 related to cell cycle arrest?
Cyclin-dependent kinase (CDK) inhibitor p21 (also known as p21(WAF1/Cip1)) is one of these factors that promote cell cycle arrest in response to a variety of stimuli. The inhibitory effect of P21 on cell cycle progression co … An appropriate control over cell cycle progression depends on many factors.
How does p21 play a role in DNA repair?
In addition, p21 can play a role in DNA repair by interacting with proliferating cell nuclear antigen (PCNA). In this review, we will focus on the multiple functions of p21 in cell cycle regulation, apoptosis and gene transcription after DNA damage and briefly discuss the pathways and factors that have critical roles in p21 expression and activity.
What are the functions of p21 in the cell cycle?
P21 can be induced by both p53-dependent and p53-independent mechanisms. Some other important functions attributed to p21 include transcriptional regulation, modulation or inhibition of apoptosis. These functions are largely dependent on direct p21/protein interactions and also on p21 subcellular localizations.