ABSTRACT
The renin-angiotensin system has always been viewed as an endocrine system involved in the feedback regulation of blood pressure and fluid-electrolyte homeostasis. It has also been viewed as an atypical endocrine system, because the biologically active peptide, angiotensin II (AngII), is generated in the plasma. The cell and organ phenotype is due to the selective expression of a subset of available genes in the genome. This cell-specific regulation of gene expression is to a large extent regulated at the point of gene transcription. A prototypic eukaryotic gene would consist structurally of multiple coding regions of DNA, called exons, interspersed with noncoding pieces of DNA, called introns. The structural regions contain the information that will be transcribed into mRNA and subsequently translated into protein. Microinjection of recombinant DNA into the pronucleus of a fertilized mouse egg has been the most widely and successfully used technique for obtaining transgenic animals.
