Cyclin E Flashcards
What is the primary role of Cyclin E in the cell cycle?
Regulating the transition from the G1 phase to the S phase.
How does Cyclin E influence the G1/S checkpoint?
By forming a complex with CDK2, driving the cell into the S phase.
Which proteins are phosphorylated by the Cyclin E-CDK2 complex to promote S phase entry?
The retinoblastoma (Rb) protein.
What is the consequence of Cyclin E-CDK2 phosphorylating the Rb protein?
Release of E2F transcription factors that initiate DNA replication.
How does overexpression of Cyclin E affect cancer progression?
It leads to unscheduled CDK2 activation, bypassing normal cell cycle checkpoints and promoting uncontrolled proliferation.
Why is Cyclin E considered a potential therapeutic target in cancer treatment?
Because its dysregulation is associated with poor prognosis and resistance to therapies.
What happens to Cyclin E when it undergoes proteolytic processing in cancer cells?
It generates low molecular weight (LMW) isoforms that are more stable and can contribute to tumorigenesis.
What is the role of Cyclin E in the formation of pre-replication complexes?
It ensures the cell is prepared for DNA synthesis by forming these complexes at origins of replication.
How does Cyclin E-CDK2 activity relate to therapy resistance in cancer?
Cells may resist CDK4/6 inhibitors as Cyclin E-CDK2 can compensate for the loss of Cyclin D-CDK4/6 activity.
What is the clinical relevance of low molecular weight (LMW) isoforms of Cyclin E?
Their presence often indicates a poor prognosis in cancers like breast cancer.
How does abnormal Cyclin E activity contribute to genomic instability?
By causing incomplete or improper DNA replication, leading to mutations and chromosomal aberrations.
