The Ron/STK receptor tyrosine kinase is essential for peri-implantation development in the mouse
Rebecca S. Muraoka, … , Jay L. Degen, Sandra J. Friezner Degen
Rebecca S. Muraoka, … , Jay L. Degen, Sandra J. Friezner Degen
Published May 1, 1999
Citation Information: J Clin Invest. 1999;103(9):1277-1285. https://doi.org/10.1172/JCI6091.
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Article

The Ron/STK receptor tyrosine kinase is essential for peri-implantation development in the mouse

Abstract

The Ron/STK receptor tyrosine kinase is a member of the c-Met family of receptors and is activated by hepatocyte growth factor–like protein (HGFL). Ron activation results in a variety of cellular responses in vitro, such as activation of macrophages, proliferation, migration, and invasion, suggesting a broad biologic role in vivo. Nevertheless, HGFL-deficient mice grow to adulthood with few appreciable phenotypic abnormalities. We report here that in striking contrast to the loss of its only known ligand, complete loss of Ron leads to early embryonic death. Embryos that are devoid of Ron (Ron–/–) are viable through the blastocyst stage of development but fail to survive past the peri-implantation period. In situ hybridization analysis demonstrates that Ron is expressed in the trophectoderm at embryonic day (E) 3.5 and is maintained in extraembryonic tissue through E7.5, compatible with an essential function at this stage of development. Hemizygous mice (Ron+/–) grow to adulthood; however, these mice are highly susceptible to endotoxic shock and appear to be compromised in their ability to downregulate nitric oxide production. These results demonstrate a novel role for Ron in early mouse development and suggest that Ron plays a limiting role in the inflammatory response.

Authors

Rebecca S. Muraoka, William Y. Sun, Melissa C. Colbert, Susan E. Waltz, David P. Witte, Jay L. Degen, Sandra J. Friezner Degen

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Figure 1

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Disruption of the mouse Ron gene in embryonic stem (ES) cells and mice. ...
Disruption of the mouse Ron gene in embryonic stem (ES) cells and mice. (a) Schematic representation and partial restriction map of the targeting vector (top) used to disrupt the endogenous mouse Ron gene (middle). The predicted organization of the targeted mouse Ron gene following homologous recombination is also shown (bottom). The targeting vector contains sequences homologous to the endogenous Ron gene (gray bars) flanking the HPRT expression cassette (white bar). The HSV-tk gene flanks the targeting vector at the 3′ end (dark gray bar). The exons of the endogenous Ron gene are numbered (1–19, black boxes). The primers used for PCR genotyping are indicated with arrows and are numbered 1–6. The probe used for Southern blot analysis is shown below the endogenous Ron gene. The BamHI fragments of genomic DNA that are complementary to the probe are indicated with the expected sizes (4.7 kb and 3.6 kb). B, BamHI. H, HindIII. S, SalI Sm, SmaI. X, XbaI. (b) Southern blot analysis of BamHI–digested DNA from selection-resistant ES cell clones. The wild-type allele (WT) is represented by a 4.7-kb fragment, while the targeted allele (Tg) is represented by a 3.6-kb fragment. ES9 was included as a wild-type control. (c) Southern blot analysis of BamHI–digested DNA from a single litter generated from a Ron+/– intercrossing. Offspring were genotyped at 7 days postnatal. Of the 12 littermates shown, 8 are Ron+/– (+/–) and 4 are Ron+/+ (+/+). (d) Genotype analysis by PCR of a single litter of E3.5 blastocysts generated from a Ron+/– intercrossing. The wild-type allele is represented by a 523-bp product generated from primers 1 and 2 (see a); the targeted allele is represented by a 274-bp product generated from primers 5 and 6.