Cardiovascular and Craniofacial Defects in Crk-Null Mice

The Crk adaptor protein, which is encoded by two splice variants termedCrkI andCrkII , contains both SH2 and SH3 domains but no catalytic region. It is thought to function in signal transduction processes involved in growth regulation, cell transformation, cell migration, and cell adhesion. Although the function of Crk has been studied in considerable detail in cell culture, its biological role in vivo is still unclear, and noCrk -knockout mouse model has been available. Therefore, we generated a complete null allele ofCrk in mice by using the Cre-loxP recombination approach. The majority ofCrk -null mice die at late stages of embryonic development, and the remainder succumb shortly after birth. Embryos lacking both CrkI and CrkII exhibited edema, hemorrhage, and cardiac defects. Immunohistochemical examination suggested that defects in vascular smooth muscle caused dilation and rupturing of blood vessels. Problems in nasal development and cleft palate were also observed. These data indicate that Crk is involved in cardiac and craniofacial development and that it plays an essential role in maintaining vascular integrity during embryonic development.