Abrogation of the Cripto gene in mouse leads to failure of postgastrulation morphogenesis and lack of differentiation of cardiomyocytes

• Type of Material: Article
• Authors: Chunhui Xu, Emory University; Giovanna Liguori, Instituto Internationale di Genetica e Biofisica; M. Graziella Persico, Instituto Internationale di Genetica e Biofisica; Eileen D. Adamson, La Jolla Cancer Research Center
• Language: English
• Date: 1999-02-01
• Publisher: Company of Biologists: Development
• Publication Version: Final Published Version
• Copyright Statement: © The Company of Biologists Limited 1999.
• Title of Journal or Parent Work: Development
• ISSN: 0950-1991
• Volume: 126
• Issue: 3
• Start Page: 483
• End Page: 494
• Grant/Funding Information: This work was done during the tenure of a research fellowship (97-71) from the Americal Heart Association, California Affiliate (to C. X).; Grant support from the Department of Defense, grant number DAMD17-94-J-4286 (to E.D.A.) and from the Italian Association for Cancer (AIRC) (to M.G.P.) is gratefully acknowledged.
• Keywords: Developmental Biology; Science & Technology; neuroepithelium; IDENTIFICATION; mesoderm; EMBRYONIC STEM-CELLS; TRANSCRIPTION FACTOR; gene targeting; homologous recombination; CHAMBER SPECIFICATION; EXPRESSION; VASCULOGENESIS; cardiac myosin; gastrulation; IN-VITRO; Life Sciences & Biomedicine; mouse; visceral endoderm; HEART TUBE FORMATION; CARDIOGENESIS
• Research Categories: Biology, General; Biology, Genetics

Abstract

Cripto-1 (Cr1) protein encoded by the tdgf1 gene, is a secreted growth factor that is expressed early in embryonic development and is re-expressed in some tumors of the breast and colon. During embryonic development, Cr1 is expressed in inner cell mass cells and the primitive streak, and later is restricted to the developing heart. To investigate the role of Cr1 during mouse development, mice were generated that contain a null mutation of both Cr1 genes, derived from homologous recombination in embryonic stem cells. No homozygous Cr1(-/-) mice were born, indicating that Cr1 is necessary for embryonic development. Embryos initiated gastrulation and some embryos produced mesoderm up to day E7.5. Increasingly aberrant morphogenesis gave rise to disordered neuroepithelium that failed to produce a recognizable neural tube, or head-fold. Although some biochemical markers of differentiating ectoderm, mesoderm and endoderm were expressed, all the cardiac-specific markers were absent from day E8.7 embryos: αMHC, βMHC, MLC2A, MLC2V and ANF, whereas they were expressed in wild-type embryos. The yolk sac and placental tissues continued development in the absence of the embryo until day E9.5 but lacked large yolk sac blood vessels. Chimeric mice were constructed by microinjection of double targeted Cr1(-/-) embryonic stem cells into normal C57BL/6 blastocysts. The Cr1 produced by the normal C57BL/6 cells fully rescued the phenotype of Cr1(-/-) cells, indicating that Cr1 protein acted in a paracrine manner. Cells derived from the embryo proliferated and migrated poorly and had different adhesion properties compared to wild type. Therefore, lethality in the absence of Cr1, likely resulted largely from defective precardiac mesoderm that was unable to differentiate into functional cardiomyocytes.