Development of Genetically Engineered Mice Lacking All Three Nitric Oxide Synthases

Abstract

Abstract. Nitric oxide (NO) is produced in almost all tissues and organs, exerting multiple biological actions under both physiological and pathological conditions. NO is synthesized by three different isoforms of NO synthase (NOS): neuronal, inducible, and endothelial NOSs. Due to the substantial compensatory interactions among the NOS isoforms, the ultimate roles of endogenous NO in our body still remain to be fully elucidated. To address this point, we have successfully developed mice in which all three NOS genes are completely disrupted. NOS expression and activities were totally absent in the triply n / i / eNOS −/ − mice before and after treatment with lipopolysaccharide. While the triply n / i / eNOS −/ − mice were viable, their survival and fertility rates were markedly reduced as compared with wild-type mice. The phenotypes of those mice that we first noticed were polyuria, polydipsia, and renal unresponsiveness to vasopressin, characteristics consistent with nephrogenic diabetes insipidus. We subsequently observed that in those mice, arteriosclerosis is spontaneously developed with a clustering of cardiovascular risk factors. These results provide the first evidence that the systemic deletion of all three NOSs causes a variety of cardiovascular diseases in mice, demonstrating a critical role of the endogenous NOSs system in maintaining cardiovascular homeostasis.

Diabetic eNOS knockout mice develop distinct macro- and microvascular complications

“…Clinically, some but not all patients develop diabetic nephropathy and our data suggest that endogenous availability of eNOS may be a key determinant for the development of nephropathy. Renal structural changes have been reported in triply NOSÀ/À mice; 27 however, in our model, the depletion of eNOS alone resulted in significant glomerular and tubulointerstitial injury suggesting that there is no appreciable compensation from other NOS isoforms.…”

“…26 In our injury model, we have also provided direct evidence for the impaired re-endothelialization, which could be due to impaired migration of endothelial cells from adjacent uninjured regions into the denuded areas of the aorta or due to a decline in the rate of endothelial proliferation. It should be noted that the triply NOS À/À knockout mouse model, 27 unlike the DKO model, presented with significant wall thickening and perivascular fibrosis in large epicardial coronary arteries and coronary microvessels in the absence of deliberate injury. This could be due to the depletion of all three isoforms of NOS, indicating the participation of other NOS isoforms in addition to eNOS in maintaining macrovascular health.…”

Expression and localization of nitric oxide synthase isoforms during porcine oocyte growth and acquisition of meiotic competence

“…The amounts of proteins increased and the localization underwent important changes during growth which can be related to the process of acquisition of meiotic competence. This presumption is also strengthened by the demonstrated significant role of NOS and NO in meiotic maturation, fertilization and pre-implantation embryo development Olson, 1998, 2000;Abe et al, 1999;Nishikimi et al, 2001;Tranguch and Huet-Hudson, 2003;Petr et al, 2005Petr et al, , 2007bTsutsui et al, 2006).…”

Contributions of Nitric Oxide Synthases, Dietary Nitrite/Nitrate, and Other Sources to the Formation of NO Signaling Products

“…These findings have most commonly been attributed to compensatory pathways, including upregulation of remaining NOS isoforms, soluble guanylate cyclase activity, and endothelial-derived hyperpolarizing factor (12). Of particular interest was the development of triple NOS knockouts (33). The realization that these animals are viable is surprising given that total deletion of the major downstream target of NO, soluble guanylyl cyclase, is known to be associated with dramatically reduced life expectancy (19).…”