PARPaktivaation

PARP activation, or Poly(ADP-ribose) polymerase activation, is a biological process that plays a crucial role in DNA repair and cellular stress response. Poly(ADP-ribose) polymerases (PARPs) are a family of enzymes that catalyze the addition of ADP-ribose units to various proteins, including histones and PARP itself. This process is known as ADP-ribosylation.

PARP activation is typically triggered by DNA damage, such as single-strand breaks, double-strand breaks, or base damage. Upon activation, PARP enzymes use NAD+ as a substrate to synthesize ADP-ribose, which is then attached to target proteins. This modification can alter the function of these proteins, leading to various cellular responses.

One of the primary functions of PARP activation is DNA repair. By ADP-ribosylating histones, PARP enzymes can recruit DNA repair proteins to the site of damage, facilitating the repair process. Additionally, PARP activation can induce cell cycle arrest, apoptosis, or senescence, depending on the extent and type of DNA damage.

PARP inhibitors are a class of drugs that target PARP enzymes, particularly PARP-1. These inhibitors have shown promise in cancer therapy, as they can sensitize cancer cells to DNA-damaging agents, leading to increased cell death. However, the use of PARP inhibitors is not without controversy, as they may also induce PARP-independent off-target effects.

In summary, PARP activation is a vital process in DNA repair and cellular stress response. It plays a significant role in cancer therapy, but further research is needed to fully understand its mechanisms and potential applications.