PARP

By Natalia Gurule, PhD

By Natalia Gurule, PhD

Apoptosis is a form of programmed cell death which is mediated by cysteine proteases called caspases. It is an essential phenomenon in the maintenance of homeostasis and growth of tissues, and it also plays a critical role in immune response. The cytomorphological alterations and the key features of apoptosis are listed below:

PARPs (poly ADP ribose polymerases) are DNA repair enzymes that promote single stranded break (SSB) repair by binding to DNA at the sites of SSBs and recruiting repair machinery. In humans, the PARP superfamily consists of 17 members, of which five play known roles in SSB repair. PARP-1, the most well-studied family member, is required for base excision repair and is thought to be responsible for 90% of PARP activity (5).

Caspase-3 is one of the most important players in apoptosis signaling. It is synthesized as an inactive 32 kDa pro-enzyme and upon direct activation by Caspase-8, -9 or -10, it gets processed into its active forms, the p17-20 and p10-12 subunits. The latter are responsible for the cleavage of PARP (poly ADP-ribose polymerase), actin and SREBP, which are associated with apoptosis [1].

Caspase-7 is an effector caspase with important roles in mediating cell death signaling. As an effector caspase, caspase-7 is cleaved and activated by initiator caspases such as caspase-1 (1). Like other caspase family proteins, caspase-7 contains a catalytic cysteine residue in its active site. This allows caspase-7 to cleave various substrates, such as PARP, to aid in the degradation and destruction of the cell (2).

Caspase 7 (also known as CASP7, Mch3, ICE-LAP3, CMH-1) is a member of caspase family of cysteine proteases. It is an apoptosis-related cystein peptidase encoded by the CASP7 gene in humans. CASP7 homologous sequences have been identified in nearly all mammals. Similar to Caspase 3, Caspase-7 is an effector caspase and plays a key role in apoptotic execution.

The PARP (Poly(ADP-ribose) polymerase) protein is a zinc-dependant nuclear enzyme whose main role is to detect and repair DNA single-strand breaks (SSB). However, PARP antibody research has revealed there are at least 17 PARP proteins, which also play a major role in apoptosis (programmed cell death) and post-translational modification. We at Novus Biologicals have an extensive range of PARP antibody products in our antibody catalogu.