Highly Regulated Cell Type-restricted Expression of Human Renin in Mice Containing 140- or 160-Kilobase Pair P1 Phage Artificial Chromosome Transgenes

Abstract

We generated transgenic mice with two P1 artificial chromosomes, each containing the human renin (HREN) gene and extending to ؊35 and ؊75 kilobase pairs, respectively. HREN protein production was restricted to juxtaglomerular cells of the kidney, and its expression was tightly regulated by angiotensin II and sodium. The magnitude of the up-and down-regulation in HREN mRNA caused by the stimuli tested was identical to the endogenous renin gene, suggesting tight physiological regulation. P1 artificial chromosome mice were mated with transgenic mice overexpressing human angiotensinogen to determine if there was a chronic compensatory down-regulation of the transgene. Despite a 3-fold down-regulation of HREN mRNA, plasma angiotensin II and blood pressure was modestly elevated in the double transgenic mice. Nevertheless, this elevation was significantly less than a different double transgenic model containing a poorly regulated HREN transgene. The increase in blood pressure, despite the decrease in HREN mRNA, suggests that the HREN gene can partially, but not completely, compensate for excess circulating angiotensinogen. These data suggest the possibility that increases in circulating or tissue angiotensinogen may cause an increase in blood pressure in humans, even in the presence of a functionally active servo-mechanism to downregulate HREN expression.

Glia- and Neuron-specific Expression of the Renin-Angiotensin System in Brain Alters Blood Pressure, Water Intake, and Salt Preference

“…We recently examined the cellular localization of renin in the brain of transgenic mice containing the hREN gene encoded on a large P1 artificial chromosome. This transgene, because it contains extensive amounts of 5Ј-and 3Ј-flanking DNA exhibits a tightly regulated and highly specific cell type-restricted expression of hREN (31). In these mice, hREN immunoreactivity was observed in glial cells and neurons in the brain stem, hypothalamus, and cerebrum (19).…”

Granulation Rescue and Developmental Marking of Juxtaglomerular Cells Using “Piggy-BAC” Recombination of the Mouse RenLocus

“…Following captopril administration, expression of each renin gene was derepressed. A 45-kb human renin transgene including 25 kb of upstream sequences was reported to exhibit appropriate regulation of expression and secretion in transgenic mice (31), whereas more recently, 140-and 160-kb human renin PAC transgenes (containing 35 and 75 kb of upstream sequences, respectively) were expressed in the kidney at levels equivalent to the endogenous mouse renin gene and were upregulated by captopril administration (32).…”

The Renin Angiotensin System and the Metabolic Syndrome~!2010-02-12~!2010-04-19~!2010-06-25~!

“…BP and plasma Ang II levels in hREN Tg mice are indistinguishable from wild-type mice, while double transgenic mice harboring both hREN Tg and hAGT Tg, have high BP and Ang II levels [39], suggesting that human renin does not generate Ang I from mouse AGT. Indeed, when incubated with plasma from our Ren1c−/− mice, which contains high levels of mouse AGT, exogenous recombinant human renin (10 −12~−8 M) does not cause Ang I production even at a concentration 10,000 times higher than normal physiological levels of mouse renin, although both human and mouse renin equally activates ERK1/2 in mouse vascular smooth muscle cells (Fig.…”