Cyclin A2

Cyclin A2

Cyclin A2 is a member of the cyclin family, which is a group of proteins that are crucial regulators of the cell cycle. Cyclin A2 is involved in the control of the cell cycle at two critical points: the S phase and the G2/M transition. It is encoded by the CCNA2 gene in humans.

Structure

Cyclin A2 is a protein that contains a conserved region known as the cyclin box, which is responsible for its interaction with cyclin-dependent kinases (CDKs). The protein structure allows it to bind to CDK1 and CDK2, forming active complexes that are essential for cell cycle progression.

Function

Cyclin A2 plays a dual role in the cell cycle:

• S Phase: Cyclin A2 binds to CDK2, forming a complex that is necessary for the initiation and progression of DNA replication. This complex phosphorylates various substrates that are involved in the replication machinery.

• G2/M Transition: Cyclin A2 also associates with CDK1, facilitating the transition from the G2 phase to mitosis. This complex is involved in the activation of proteins required for mitotic entry.

Regulation

The expression and activity of Cyclin A2 are tightly regulated throughout the cell cycle. Cyclin A2 levels are low in the G1 phase, increase during the S phase, and peak in the G2 phase. The degradation of Cyclin A2 is mediated by the anaphase-promoting complex/cyclosome (APC/C), which targets it for ubiquitination and subsequent proteasomal degradation.

Clinical Significance

Abnormal regulation of Cyclin A2 has been implicated in various cancers. Overexpression of Cyclin A2 can lead to uncontrolled cell proliferation, a hallmark of cancer. Studies have shown that Cyclin A2 is overexpressed in several types of tumors, including breast, lung, and colorectal cancers.

Research

Research on Cyclin A2 continues to explore its role in cancer biology and its potential as a therapeutic target. Inhibitors of Cyclin A2-CDK complexes are being investigated for their ability to halt the proliferation of cancer cells.

See Also

• Cyclin B1
• Cyclin D1
• Cell cycle
• Cyclin-dependent kinase

References

• Sherr, C. J. (1996). "Cancer cell cycles." Science, 274(5293), 1672-1677.
• Pagano, M., & Draetta, G. (1992). "Cyclin A is required at two points in the human cell cycle." The EMBO Journal, 11(3), 961-971.

External Links

• CCNA2 Gene - NCBI
• Cyclin A2 - UniProt