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).
While known for their role in programmed cell death, caspases are also essential for mediating inflammatory responses and innate immunity. Binding of microbial molecules by pattern recognition receptors triggers the formation of the multiprotein inflammasome complex and the activation of caspase-1 (1). Caspase-1 is then able to mediate the activation and secretion of proinflammatory cytokines including interleukin-1. In addition to caspase-1, caspase-11 also plays an important role during the inflammatory response.
Microtubule-associated protein-1 light chain 3 (LC3/LC3B) is a ubiquitin-like protein involved in the formation of the autophagosome. It is homologous to the yeast Atg8 protein. Autophagosomes are important for the degradation and recycling of intracellular cargo such as misfolded proteins or damaged organelles. Upon induction of autophagy, LC3 is conjugated to the lipid phosphatidylethanolamine (PE) by the Atg12-Atg5-Atg16 protein complex.
The D4-GDI protein is a negative regulator of the Ras-related Rho family of small molecule "molecular switch" GTPases. The Rho GTPases modify cell structure and architecture via rapid changes to the actin cytoskeleton and cell membrane. Many of these physiological processes are associated with apoptotic cell death, thus the in vivo removal of D4-GDI inhibitory block is critical for proper induction and progression of apoptosis in cells.
