TopII

TopII, also known as topoisomerase II, is a vital enzyme found in all living organisms. Its primary function is to manage the complex topology of DNA. DNA, the molecule that carries genetic information, is a double helix, and during cellular processes like replication, transcription, and recombination, this helix can become entangled, overwound, or underwound. Topoisomerase II resolves these topological problems by creating transient breaks in one or both DNA strands, allowing the DNA to pass through itself, and then resealing the breaks. This action is crucial for maintaining the integrity and accessibility of the genome.

There are several types of topoisomerase II, with TopIIα and TopIIβ being the major isoforms in eukaryotes. TopIIα is generally more abundant and is particularly active during cell division. TopIIβ, on the other hand, plays roles in neuronal development and differentiation, as well as in DNA repair. Topoisomerase II inhibitors are an important class of anticancer drugs. By trapping the enzyme in a complex with DNA, these drugs prevent the resealing of DNA breaks, leading to DNA damage and ultimately programmed cell death (apoptosis) in rapidly dividing cancer cells. Examples of such drugs include etoposide and doxorubicin.