Species specificity of renin kinetics in transgenic rats harboring the human renin and angiotensinogen genes.

Abstract

The renin-anglotensin system (RAS) is the most important regulatory system of electrolyte homeostasis and blood pressure. We report here the development of transgenic rats carrying the human angiotensinogen TGR-(hAOGEN) and human renin TGR(hREN) genes. The plasma levels and tissue distribution of the transcription and translation products from both genes are described. A unique species specificity of the enzyme kinetics was observed. The human RAS components in the transgenic rats did not interact with the endogenous rat RAS in vivo. Insead, infusions of exogenous human RAS components specifically interacted with human transgene translation products. Thus, iion of human renin in TGR(hAOGEN) led to an increase of angioensin H and an elevation of blood pressure, which could not be antagonized by the human-specific renin enzyme inhibitor Ro 42-5892. Rat renin also elevated blood pressure and angiotensin H in TGR(hAOGEN); however, this effect was not antagonized by the human renin inhibitor. Compared to mice, rats offer the advantage of chronic instrumentation and repetitive, sophisticated, hemodynamic, and endocrinological investigations. Thus, transgenic rat models with human-specific enzyme kinetics permit primate-specific analyses in non-primate in vivo and in vitro experimental systems.The successful incorporation of renin-angiotensin (RAS) genes into transgenic mice has been reported (1, 2). Rats, on the other hand, present specific technical problems with respect to the generation of transgenic animals. The transgenic rats TGR(mREN2)27, which harbor a mouse renin gene and exhibit fulminant hypertension, provided evidence for a monogenetic form of hypertension (3).Transgenic mice harboring the genes of mouse renin and angiotensinogen (2), rat renin and angiotensinogen (4), as well as human renin (1) have been described. Thus far, most ofthe RAS gene constructs used for the generation of transgenic animals interacted directly with the host RAS (2, 4).Since the genetic background for the transgenes appears to be of primary importance for the development of hypertension (5), we developed transgenic rats harboring the complete human renin TGR(hREN) and human angiotensinogen TGR(hAOGEN) genes. These rats allow studies into the regulation of human genes in non-primate animal models (6). In vitro, the species specificity of human renin and angiotensinogen is well known. Transgenic animals permit the study of specific interactions with the human transgene products in vivo, without interference from the host RAS.EXPERIMENTAL PROCEDURES Transgenic Techniques. Linear DNA fiagments consisting of either the entire human renin gene (1, 7) or the entire human angiotensinogen gene (8), as described elsewhere (1, 3), were injected into the male pronuclei offertilized, outbred Sprague-Dawley (SD) rat eggs.Immnnalyses of Renin and en. Human renin was immunologically measured in transgenic rat plasma. The direct and specific measurement of human renin used two pairs of monoclonal antibodies in an immunoradiometric assay. ...

New insights into the renoprotective actions of the renin inhibitor aliskiren in experimental renal disease

“…This issue can be circumvented by using a transgenic rat model with an activated RAAS. The so-called double transgenic rat 66 expresses the human genes for renin and Aogen, and thereby provides a model in which a human DRI can inhibit human renin in a rodent. A second model, the TG(mRen-2) 27 (mRen-2) rat expresses the mouse ren-2 gene, 67 and takes advantage of the capacity of mouse renin to cleave rat Aogen.…”

Angiotensin II Induces Connective Tissue Growth Factor Gene Expression via Calcineurin-Dependent Pathways

“…The dTGR are described elsewhere. 23,24 The protocols were approved by the Animal Experimentation Committee of the University of Helsinki, Finland, whose standards correspond to those of the American Physiological Society. The rats had free access to chow (NaCl 0.8%) and drinking water.…”

Transgenic rats as models for hypertension

“…Investigations that manipulate the RAS, such as alterations in sodium homeostasis, are necessary to elucidate the interacMerits of the model: The ACE transgenic rat model tion of human transgenes and its effect on BP develallows us a selective investigation of cardiac ACE in opment in this model. 21 cardiovascular pathophysiology. In another experiment, the homozygous human renin transgenic rat was crossbred with the homozygous human angiotensinogen rat.…”

“…15 This ANG II. 21 local ANG II formation may be a key factor for the changes in cardiovascular morphology that appear to be partially independent from BP. Even so, is the The human angiotensinogen transgenic rat, endothelial dysfunction, which is more severe in the TGR(hAOGEN) Ren-2 rat compared to the spontaneous hypertensive…”