Cardiovascular and Craniofacial Defects in Crk-Null Mice

Abstract

The Crk adaptor protein, which is encoded by two splice variants termed CrkI and CrkII, 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 no Crk-knockout mouse model has been available. Therefore, we generated a complete null allele of Crk in mice by using the Cre-loxP recombination approach. The majority of Crk-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.

The authors would like to thank the following: St. Jude Children's Research Hospital shared core facilities for their help, the Cancer Center Core Cytogenetics Laboratory for karyotyping, the Transgenic Gene Knockout Facility for ES cell injection and germ line transmission, the Animal Resources Center for mouse husbandry, and Biomedical Communications for imaging of embryos. We also thank Michele Connelly and Jennifer DeBeauchamp for their technical assistance and Curran lab members and Angela J. McArthur for critical reading of the manuscript. Plasmids for Cre and NeoTk cassettes were kindly provided by Peter McKinnon.

This work was supported in part by grant 5R37NS036558 from NINDS, Cancer Center Support CA21765 from NCI, and the American Lebanese Syrian Associated Charities.