CAZIP, a novel protein expressed in the developing heart and nervous system

Recently, we have performed a whole genome micro-array analysis on human embryonic stem cells differentiating toward cardiomyocytes, which resulted in the identification of novel genes that were highly up-regulated during differentiation. Here, we describe one of these novel genes annotated as KIAA0774. The predicted protein contains a leucine-zipper domain at the C-terminus and has at least two isoforms (358 and 1354 amino acids). Whole-mount in situ hybridization confirmed that the mRNA of both the mouse and chicken orthologs of KIAA0774 is expressed during early cardiac development. Hence, we named this protein CAZIP (cardiac zipper protein). Later during embryonic development, Cazip was also expressed in parts of the nervous system. Northern blot and real-time polymerase chain reaction analysis showed that Cazip is expressed in heart and brain in adult mice. These results suggest a role for CAZIP in development and function of the heart and nervous system in vertebrates.