Detection of targeted GFP-Hox gene fusions during mouse embryogenesis

Detection of targeted GFP-Hox gene fusions during mouse embryogenesis

Howard Hughes Medical Institute, Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112

Contributed by Mario R. Capecchi

Abstract

The ability to use a vital cell marker to study mouse embryogenesis will open new avenues of experimental research. Recently, the use of transgenic mice, containing multiple copies of the jellyfish gene encoding the green fluorescent protein (GFP), has begun to realize this potential. Here, we show that the fluorescent signals produced by single-copy, targeted GFP in-frame fusions with two different murine Hox genes, Hoxa1 and Hoxc13, are readily detectable by using confocal microscopy. Since Hoxa1 is expressed early and Hoxc13 is expressed late in mouse embryogenesis, this study shows that single-copy GFP gene fusions can be used through most of mouse embryogenesis. Previously, targeted lacZ gene fusions have been very useful for analyzing mouse mutants. Use of GFP gene fusions extends the benefits of targeted lacZ gene fusions by providing the additional utility of a vital marker. Our analysis of the Hoxc13 ^GFPneo embryos reveals GFP expression in each of the sites expected from analysis of Hoxc13 ^lacZneo embryos. Similarly, Hoxa1 ^GFPneo expression was detected in all of the sites predicted from RNA in situ analysis. GFP expression in the foregut pocket of Hoxa1 ^GFPneo embryos suggests a role for Hoxa1 in foregut-mediated differentiation of the cardiogenic mesoderm.

gene targeting/Hoxa1/Hoxc13

Footnotes

↵ * A.R.G. and H.S.S. contributed equally to this manuscript.
↵ † Present address: Department of Biological Chemistry, University of California, Los Angeles, CA 90095.
↵ ‡ To whom reprint requests should be addressed at: Howard Hughes Medical Institute, University of Utah, 15 North 2030 East, Suite 5400, Salt Lake City, UT 84112-5331. e-mail: mario.capecchi{at}genetics.utah.edu.
ABBREVIATIONS:

GFP,

green fluorescent protein;

E,

embryonic day;

ES cell,

embryonic stem cell;

Hox,

homeobox containing;

HSV,

herpes simplex virus;

β-gal,

β-galactosidase