title: A functional 12T-insertion polymorphism in the ATP1A1 promoter confers decreased susceptibility to hypertension in a male Sardinian population.
abstract: Identification of susceptibility genes for essential hypertension in humans has been a challenge due to its multifactorial pathogenesis complicated by gene-gene and gene-environment interactions, developmental programing and sex specific differences. These concurrent features make identification of causal hypertension susceptibility genes with a single approach difficult, thus requiring multiple lines of evidence involving genetic, biochemical and biological experimentation to establish causal functional mutations. Here we report experimental evidence encompassing genetic, biochemical and in vivo modeling that altogether support ATP1A1 as a hypertension susceptibility gene in males in Sardinia, Italy. ATP1A1 encodes the α1Na,K-ATPase isoform, the sole sodium pump in vascular endothelial and renal tubular epithelial cells. DNA-sequencing detected a 12-nucleotide long thymidine (12T) insertion(ins)/deletion(del) polymorphism within a poly-T sequence (38T vs 26T) in the ATP1A1 5'-regulatory region associated with hypertension in a male Sardinian population. The 12T-insertion allele confers decreased susceptibility to hypertension (P = 0.035; OR = 0.50 [0.28-0.93]) accounting for 12.1 mmHg decrease in systolic BP (P = 0.02) and 6.6 mmHg in diastolic BP (P = 0.046). The ATP1A1 promoter containing the 12T-insertion exhibited decreased transcriptional activity in in vitro reporter-assay systems, indicating decreased α1Na,K-ATPase expression with the 12T-insertion, compared with the 12T-deletion ATP1A1 promoter. To test the effects of decreased α1Na,K-ATPase expression on blood pressure, we measured blood pressure by radiotelemetry in three month-old, highly inbred heterozygous knockout ATP1A1+/- male mice with resultant 58% reduction in ATP1A1 protein levels. Male ATP1A1+/- mice showed significantly lower blood pressure (P < 0.03) than age-matched male wild-type littermate controls. Concordantly, lower ATP1A1 expression is expected to lower Na-reabsorption in the kidney thereby decreasing sodium-associated risk for hypertension and sodium-induced endothelial stiffness and dysfunction. Altogether, data support ATP1A1 as a hypertension susceptibility gene in a male Sardinian population, and mandate further investigation of its involvement in hypertension in the general population.
authors.affiliation: Whitaker Cardiovascular Institute, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Herrera
authors.affiliation: Whitaker Cardiovascular Institute, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Khristine A
authors.initials: KA
authors.lastname: Pasion
authors.affiliation: Whitaker Cardiovascular Institute, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Ann Marie
authors.initials: AM
authors.lastname: Moran
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Zaninello
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Maria Francesca
authors.initials: MF
authors.lastname: Ortu
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fresu
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Daniela Antonella
authors.initials: DA
authors.lastname: Piras
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Argiolas
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Troffa
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Glorioso
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Wanda
authors.initials: W
authors.lastname: Masala
authors.affiliation: Hypertension and Related Diseases Center, AOU-Universita' di Sassari, Sassari, Sardinia, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Glorioso
authors.affiliation: Whitaker Cardiovascular Institute, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Nelson
authors.initials: N
authors.lastname: Ruiz-Opazo
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D004195:Disease Models, Animal; D000075222:Essential Hypertension; D020022:Genetic Predisposition to Disease; D006801:Humans; D006973:Hypertension / Q000235:genetics* / Q000517:prevention & control*; D054643:INDEL Mutation; D007558:Italy; D008297:Male; D051379:Mice; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D012737:Sex Factors; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D044465:White People / Q000235:genetics*
chemical_list: C499076:ATP1A1 protein, human; D000254:Sodium-Potassium-Exchanging ATPase; D013936:Thymidine