Neither the New Zealand Genetically Hypertensive Strain nor Dahl Salt-Sensitive Strain Has an A1079T Transversion in the α1 Isoform of the Na ⁺ ,K ⁺ -ATPase Gene

Abstract

Abstract-A putative 1079A3 T mutation in the ␣1 isoform of the Na ϩ , K ϩ -ATPase (Atp1a1) gene of the Dahl salt-sensitive rat inbred by John Rapp (SS/Jr) strain was projected to cause a conformation change in the membrane hydrophobic region of the protein product, possibly resulting in hypertension. The existence of the mutation was challenged, but the challenge was apparently rebutted. The New Zealand genetically hypertensive (GH) rat is known to have a blood pressure quantitative trait locus on chromosome 2 containing the gene for the ATPase. Thus, we sought to determine whether the GH rat carried the 1079A3 T transversion. We chose a method, first nucleotide change analysis, that can detect point mutations in a mixed population of polymerase chain reaction (PCR) products, even in the presence of PCR bias, and confirmed our analysis by restriction enzyme digestion of PCR products. To ensure the validity of our analyses, we used site-directed mutagenesis to create positive controls containing the mutation. Surprisingly, we found that neither the GH nor the SS/Jr strain had the A1079T transversion. Indeed, the transversion was not found in any strain tested. As an incidental observation, we have sequenced the intron preceding the exon containing the putative A1079T transversion. Within this intron, a single-base C/T polymorphism was observed at base 132. Our results definitively eliminate the putative A1079T transversion in Atp1a1 as a causative factor underlying hypertension in the GH, spontaneously hypertensive, and SS/Jr rat strains and indicate that alternative candidate genes in the region defined by the chromosome 2 hypertension quantitative trait locus should be examined.

Relationships between membrane lipids and ion transport in red blood cells of Dahl rats

“…Moreover, these experiments revealed significant association of ion transport parameters with total plasma cholesterol (Zicha et al, 2001), which is in agreement with findings that salt hypertension of Dahl rats is accompanied by pronounced hypercholesterolemia (Dahl, 1960;O'Donnell et al, 1992). Some studies indicate that enhanced activity of the Na + -K + pump results from a mutation of gene for a 1 -isoform of the Na + -K + ATPase (Herrera and Ruiz-Opazo, 1990;Canessa et al, 1993), but other studies did not confirm this thesis (Simonet et al, 1991;Barnard et al, 2001;Orlov et al, 2001;Zicha et al, 2001).…”

Corroboration of Dahl S Q276L α1Na,K-ATPase protein sequence: impact on affinities for ligands and on E1 conformation

“…Altered E1-E2 conformational equilibrium has been implicated in functional differences between a1 and a2Na, K-ATPase isoforms [23] concordant with the functional alteration induced by the Q276L substitution detected in Dahl S a1Na,K-ATPase. These data are supported by the altered ion pore predicted by computational modeling of the Q276L substitution compared with wild-type Q276 a1Na,K-ATPase [6].…”

“…In retrospect, analysis of reported data by others and us reveals that A1079T is not detected whenever DNA amplification precedes detection of said mutation regardless of detection methodology [5][6][7]. The most likely hypothesis accounting for these observations is that the T 1079 mutation induces a more thermodynamically stable 4-bp hairpin loop structure rather than the wild-type sequencing resulting in the bias towards A 1079 at nt 1079 during PCR amplification.…”

Functional Genomic Assessment of Phosgene-Induced Acute Lung Injury in Mice

“…The Dahl salt-sensitive (Dahl S) rat (67,68) was thought to have a genetic variant in Atp1a1, and transgenic Dahl S rats bearing the Dahl salt-resistant Atp1a1 exhibited less salt-sensitive hypertension, less hypertensive renal disease, and longer life span when compared with nontransgenic Dahl S control rats (69)(70)(71). However, these findings are controversial (72,73). In dairy cattle, an ATP1A1 polymorphism has been associated with heat tolerance and with respiratory rate (74).…”