Zfra is a small wizard in the mitochondrial apoptosis

Zfra (zinc finger-like protein that regulates apoptosis) is a naturally occurring short peptide consisting of 31 amino acids, which regulates tumor necrosis factor (TNF)-mediated cell death by interacting with receptor adaptor protein TRADD (TNF receptorassociated death domain protein) and downstream JNK (c-Jun N-terminal kinase), NF-κB (Nuclear factor kappa B) and WWOX/WOX1 (WW domain-containing oxidoreductase). Cytochrome c release is generally considered as a pivotal step in apoptosis. Remarkably, overexpressed Zfra induces apoptosis via the mitochondrial pathway, which involves suppression of Bcl-2 and Bcl-xL expression (without causing cytochrome c release), counteracting the apoptotic function of tumor suppressor p53 and WWOX, and dissipation of mitochondrial membrane potential for ultimately leading to cell death. Control of cellular aging and apoptosis by Zfra, p53 and WWOX is discussed.