Ron-mediated cytoplasmic signaling is dispensable for viability but is required to limit inflammatory responses
Susan E. Waltz, … , Klaus H. Kaestner, Sandra J.F. Degen
Susan E. Waltz, … , Klaus H. Kaestner, Sandra J.F. Degen
Published August 15, 2001
Citation Information: J Clin Invest. 2001;108(4):567-576. https://doi.org/10.1172/JCI11881.
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Article

Ron-mediated cytoplasmic signaling is dispensable for viability but is required to limit inflammatory responses

Abstract

Ron receptor activation induces numerous cellular responses in vitro, including proliferation, dissociation, and migration. Ron is thought to be involved in blood cell development in vivo, as well as in many aspects of the immune response including macrophage activation, antigen presentation, and nitric oxide regulation. In previous studies to determine the function of Ron in vivo, mice were generated with a targeted deletion of the extracellular and transmembrane regions of this gene. Mice homologous for this deletion appear to die early during embryonic development. To ascertain the in vivo function of Ron in more detail, we have generated mice with a germline ablation of the tyrosine kinase domain. Strikingly, our studies indicate that this domain of Ron, and therefore Ron cytoplasmic signaling, is not essential for embryonic development. While mice deficient in this domain are overtly normal, mice lacking Ron signaling have an altered ability to regulate nitric oxide levels and, in addition, have enhanced tissue damage following acute and cell-mediated inflammatory responses.

Authors

Susan E. Waltz, Laura Eaton, Kenya Toney-Earley, Karla A. Hess, Belinda E. Peace, Jeffrey R. Ihlendorf, Ming-Hai Wang, Klaus H. Kaestner, Sandra J.F. Degen

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HNF3αCre targeting strategy and characterization of the mutant mice. (a)...
HNF3αCre targeting strategy and characterization of the mutant mice. (a) The top line depicts the gene structure of the HNF3α gene. Exons are indicated as boxes; the gray box represents the winged helix domain. The targeting vector used for homologous recombination is shown in the middle line, while the structure of the targeted allele (HNF3αCre) is shown on the bottom. PGK neo PA was used for selection. The 5′ probe was used for the Southern blot analyses to identify targeted clones. B, BamHI; Bg, BglII; E, EcoRI; H, HindIII; N, NotI; Xh, XhoI. (b) Southern hybridization analysis was performed on DNA from the indicated organs of an experimental and a control mouse. Complete Cre-mediated recombination was seen in every tissue analyzed in the experimental animals (+Cre, Excised) compared with the control mice (–Cre, Floxed). (c) Ron expression was evaluated by RT-PCR from RNA from control (TK+/+; lanes 2, 4, 5, and 7) and experimental (TK–/–; lanes 1, 3, 6, and 8) mice. Expression of a RT-PCR product specific for exons 11 and 12 is shown in lanes 1 and 2. Primers specific for the tyrosine kinase domain of Ron is shown in lanes 3 and 4. Primers specific for a truncated Ron gene product (with primers in exons 11 and 19) are shown in lanes 7 and 8. GAPDH expression is shown in lanes 5 and 6. (d) Western blot analysis of Ron from resident peritoneal macrophages. A truncated form of Ron is expressed in the experimental animals.