CARP is a novel caspase recruitment domain containing pro-apoptotic protein

Many CARD-containing caspase mediators interact with CARD-containing caspases and participate in activation or suppression of caspases. We cloned a novel CARD-containing protein from our EST database, named CARP. Computational characterization revealed that CARP encoded 445 amino acids with predicted MW 49.7 kDa, localized at chromosome 10p13 with 15 exons, and four putative function domains, one CARD domain (aa 160-243), one nuclear receptor-binding motif, two EF-hand motifs, and 42% alpha-helix content. Stable transfection of CARP into lung carcinoma A549 and HEK293S cells leads to 23% of the cells undergoing apoptosis, but only 3% in the cells transfected with empty control vector. The cell proliferation was significantly inhibited by 1.2-5 folds (P<0.02) in seven CARP-transfected tumor cell lines-lung carcinoma A549 and PG, melanoma WM451, prostate cancer PC-3 and PC-3M, liver cancer H7402, and bladder cancer BIU87. Our results suggest that CARP is a novel CARD-containing pro-apoptotic protein.