Generation of mice with a conditional allele of the p120 Ras GTPase‐activating protein

Abstract

p120 Ras GTPase-activating protein (RasGAP) encoded by the rasa1 gene in mice is a prototypical member of the RasGAP family of proteins involved in negative-regulation of the p21 Ras proto-oncogene. RasGAP has been implicated in signal transduction through a number of cell surface receptors. In humans, inactivating mutations in the coding region of the RASA1 gene cause capillary malformation arteriovenous malformation. In mice, generalized disruption of the rasa1 gene results in early embryonic lethality associated with defective vasculogenesis and increased apoptosis of neuronal cells. The early lethality in this mouse model precludes its use to further study the importance of RasGAP as a regulator of cell function. Therefore, to circumvent this problem, we have generated a conditional rasa1 knockout mouse. In this mouse, an exon that encodes a part of the RasGAP protein essential for catalytic activity has been flanked by loxP recognition sites. With the use of different constitutive and inducible Cre transgenic mouse lines, we show that deletion of this exon from the rasa1 locus results in effective loss of expression of catalytically-active RasGAP from a variety of adult tissues. The conditional rasa1 mouse will be useful for the analysis of the role of RasGAP in mature cell types.

Unbiased RNAi screen for hepcidin regulators links hepcidin suppression to proliferative Ras/RAF and nutrient-dependent mTOR signaling

“…60 Importantly, two of the identified hepcidin modifiers, RASA1 and RASAL2, directly connect to Ras protein inactivation. 41,61,62 Our observation that systemic loss of Rasa1 in the mouse affects liver hepcidin expression further indicates that regulators of Ras activity may function as modifiers of iron homeostasis in vivo. Of note, 2 similar syndromes hallmarked by vascular malformations are associated with mutations in SMAD4 or the Ras suppressor RASA1, 63,64 further corroborating a link between Ras-dependent signaling events and the SMAD pathway.…”

“…41 Seven-to eight-week-old Rasa1-floxed female mice with and without engineered Ert2Cre transgene were administered with tamoxifen (MP biochemicals) to induce nuclear translocation of the Ert2Cre protein and disruption of the Rasa1 gene. Mice were analyzed 6 weeks after tamoxifen injection.…”

Downregulation of Ras GTPase-activating protein 1 is associated with poor survival of breast invasive ductal carcinoma patients

“…functionally, the RASA1 gene encodes a p120-RasGTPase-activating protein, which switches the active GTP-bound Ras to the inactive GDP-bound form. In RASA1 knockout mice, the embryos exhibit abnormal vascular development (22,23). Subsequent studies have demonstrated that RASA1 is an important member of the RAS pathway and a putative tumor suppressor (24).…”

RASA1 regulates the function of lymphatic vessel valves in mice

“…Rasa1 fl/fl mice with and without Ub ert2cre or Prox1 ert2cre transgenes and Rasa1 fl/R780Q mice have been described (11,12,38 mice were generated through crossbreeding. All mice were on a mixed 129S6/SvEv × C57BL/6 genetic background.…”