BACKGROUNDLiddle's syndrome is a rare autosomal-dominant monogenic form of salt-sensitive hypertension. This study aimed to screen the gene mutation in β and γ subunits of the epithelial sodium channel (ENaC) of a Chinese family with Liddle's syndrome, an autosomal dominant form of hypertension.

METHODSDNA samples from the proband with early-onset, treatment-resistant hypertension and suppressed plasma renin activity were initially screened for mutations in the C-terminal exons of the ENaC β or γ subunit genes, using amplification by polymerase chain reaction and direct DNA sequencing. We also screened the C-terminus of SCNN1B and SCNN1G in family members, and screened for the mutation in 150 controls.

RESULTSGenetic analysis of the β ENaC gene revealed a missense mutation of CCC to TCC at codon 616 in the proband, her mother and her grandmother. One hundred and fifty randomly selected controls had not the mutation, indicating that this is not a common genetic polymorphism. There was no mutation of the γ ENaC gene in any of the individuals examined.

CONCLUSIONSThrough direct DNA sequencing analysis, we established the diagnosis of Liddle's syndrome for the proband and her families, and provided tailored therapies to this abnormality. These results provide further evidence that Pro616Ser is a critical amino acid that has a key role in the inhibition of sodium channel activity.

Adolescent ; DNA Mutational Analysis ; Epithelial Sodium Channels ; genetics ; Female ; Humans ; Liddle Syndrome ; genetics ; Male ; Mutation, Missense ; Pedigree

OBJECTIVETo investigate the epithelial sodium channel (ENaC) subunit mRNA expression in acutely isolated rat alveolar type II (ATII) cells.

METHODSAcutely isolated ATII cells from 20 SD rats were purified and ENaC alpha, beta, gamma-subunit mRNA levels were determined by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTSmRNA expressions of all the subunits were detected in the ATII cells, and ENaC alpha-subunit mRNA showed significantly higher expression than beta- and gamma-subunit mRNAs, and the expressions of the latter two mRNAs were comparable.

CONCLUSIONAs the predominant ENaC subunit expressed at the mRNA level in rat ATII cells, the alpha-subunit of ENAC plays an important role in alveolar fluid clearance.

Animals ; Cells, Cultured ; Epithelial Sodium Channels ; genetics ; metabolism ; Male ; Pulmonary Alveoli ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley

PURPOSE: Although it is well known thatmortality and morbidity due to cardiovascular diseases are higher in salt-sensitive subjects than in salt-resistant subjects, their underlying mechanisms related to obesity remain unclear. Here, we focused on salt-sensitive gene variants unrelated to monogenic obesity that interacted with sodium intake in humans. METHODS: This review was written based on the modified 3(rd) step of Khans' systematic review. Instead of the literature, subject genes were based on candidate genes screened from our preliminary Genome-Wide Association Study (GWAS). Finally, literature related to five genes strongly associated with salt sensitivity were analyzed to elucidate the mechanism of obesity. RESULTS: Salt sensitivity is a measure of how blood pressure responds to salt intake, and people are either salt-sensitive or salt-resistant. Otherwise, dietary sodium restriction may not be beneficial for everyone since salt sensitivity may be associated with inherited susceptibility. According to our previous GWAS studies, 10 candidate genes and 11 single nucleotide polymorphisms (SNPs) associated with salt sensitivity were suggested, including angiotensin converting enzyme (ACE), α-adducin1 (ADD1), angiotensinogen (AGT), cytochrome P450 family 11-subfamily β-2 (CYP11β-2), epithelial sodium channel (ENaC), G-protein b3 subunit (GNB3), G protein-coupled receptor kinases type 4 (GRK4 A142V, GRK4 A486V), 11β-hydroxysteroid dehydrogenase type-2 (HSD 11β-2), neural precursor cell-expressed developmentally down regulated 4 like (NEDD4L), and solute carrier family 12(sodium/chloride transporters)-member 3 (SLC 12A3). We found that polymorphisms of salt-sensitive genes such as ACE, CYP11β-2, GRK4, SLC12A3, and GNB3 may be positively associated with human obesity. CONCLUSION: Despite gender, ethnic, and age differences in genetics studies, hypertensive obese children and adults who are carriers of specific salt-sensitive genes are recommended to reduce their sodium intake. We believe that our findings can contribute to the prevention of early-onset of chronic diseases in obese children by facilitating personalized diet-management of obesity from childhood to adulthood.
Adult ; Angiotensinogen ; Blood Pressure ; Cardiovascular Diseases ; Child ; Chronic Disease ; Cytochrome P-450 Enzyme System ; Epithelial Sodium Channels ; Genetics ; Genome-Wide Association Study ; GTP-Binding Proteins ; Humans ; Hypertension ; Obesity* ; Oxidoreductases ; Peptidyl-Dipeptidase A ; Phosphotransferases ; Polymorphism, Single Nucleotide ; Sodium ; Sodium, Dietary

OBJECTIVETo explore the relationship between G2139A,G3091A, T663A, and T3593C single nucleotide polymorphisms (SNPs), which are located at the promoter region,13th exon, and 2nd intron of epithelial sodium channel (ENaC) gene, and their haplotypes with essential hypertension (EH) in Kazakhs in Xinjiang.

METHODSA case-control study was conducted including 252 EH patients (EH group) and 254 normotensive subjects (NT group) among Kazakhs in Xinjiang. The four genetic polymorphisms were identified by polymerase chain reaction - restriction fragment length polymorphism. The distribution of the genotypes and alleles in all subjects and the different frequency of these four SNPs between EH group and NT group were analyzed. The linkage disequilibrium and haplotypes of these four SNPs were analyzed.

RESULTSThese four SNPs of alpha ENaC gene existed in Xinjiang Kazakhs. In all subjects, the distribution frequencies of genotypes AA, AG, and GG at G2139A were 26.2%, 52.3%, and 21.5%, respectively, and those of alleles (A, G) were 52.37% and 47.63%. The distribution frequencies of genotypes AA, AG, and GG at G3091A were 19.0%, 52.5%, and 28.5%, respectively, and those of and alleles (A, G) were 45.56% and 59.44%. The distribution frequencies of genotypes AA, AG, and GG at T663A were 15.6%, 49.9%, and 34.5%, respectively, and those of alleles (A, G) were 40.53% and 59.47%. The distribution frequencies of genotypes TT, TC, and CC at T3593C were 88.5%, 10.5%, and 1.0%, respectively, and those of alleles (T, C) were 93.77% and 6.23%. The distribution of genotypes at these four SNPs were all consistent with Hardy-Weinberg equilibrium in this population (P0.05). The distribution frequencies of genotypes and alleles about these four genetic polymorphisms were not significantly different between the EH group and NT group (P0.05). However, the frequencies of two haplotypes were found to be significantly different between these two groups (P0.05). The haplotype frequency which included 2139G, 3091A, 663G, and 3593T alleles was significantly increased in EH group (P0.01), while the haplotype frequency which included 2139A, 3091A, 663A, and 3593C alleles was significantly increased in NT group (P0.05).

CONCLUSIONSThe haplotypes that are composed of G2139A, G3091A, T663A, and T3593C polymorphisms of alphaENaC gene may play an important role in the development of EH among Kazakhs in Xinjiang. The haplotypes that are composed of 2139G, 3091A, 663G, and 3593T alleles may aggravate the development of EH. The haplotypes that composed of 2139A, 3091A, 663A, and 3593C alleles may decrease the risk of EH among Kazakhs.

Adult ; Asian Continental Ancestry Group ; genetics ; Case-Control Studies ; China ; Epithelial Sodium Channels ; genetics ; Exons ; genetics ; Humans ; Hypertension ; genetics ; Introns ; genetics ; Middle Aged ; Polymorphism, Single Nucleotide ; Promoter Regions, Genetic ; genetics

Adult ; Azoospermia/pathology* ; Carbonic Anhydrases/genetics* ; Congenital Abnormalities/genetics* ; Epithelial Sodium Channels/genetics* ; Gene Expression Regulation/genetics* ; Genome, Human ; Humans ; Infertility, Male/genetics* ; Male ; Male Urogenital Diseases/genetics* ; Mutation ; Vas Deferens/abnormalities*

OBJECTIVETo screen the mutation of the beta and gamma subunits of epithelial sodium channel gene SCNN1 in two families with Liddle's syndrome.

METHODSTwo patients clinically diagnosed as Liddle's syndrome and their family members were enrolled. Peripheral blood samples were collected and total genomic DNA was prepared. Polymerase chain reaction (PCR) was used to amplify the exon 13 of the SCNN1B and SCNN1G gene. PCR products were purified and subjected to direct DNA sequencing.

RESULTSA heterozygous nonsense mutation at codon 564 of the SCNN1B gene from CGA(Arg) to stop codon(TGA) was detector in the proband of family 1. More importantly, a novel heterozygous nonsense mutation of CAG(Gln) to stop codon TAG at codon 567 of the SCNN1G gene was detected in the proband and another two members of family 2.

CONCLUSIONScreening for specific mutations of the SCNN1 gene in relatives of patients with Liddle's syndrome can be used to identify the previously unrecognized cases within the family. A new nonsense mutation(Q567X) of the SCNN1G gene is likely the cause of Liddle's syndrome in family 2.

Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Case-Control Studies ; DNA Mutational Analysis ; Epithelial Sodium Channels ; genetics ; Female ; Humans ; Liddle Syndrome ; genetics ; Male ; Mutation ; genetics ; Pedigree ; Young Adult

OBJECTIVETo explore the association of epithelial sodium channel alpha subunit (alphaENaC) with terbutaline-induced transient enhancement of pulmonary edema clearance in adult rats with acute lung injury (ALI).

METHODSThe effect of 1-h intratracheal terbutaline treatment on pulmonary edema clearance in adult rats with experimental ALI was observed by blood gas analysis, lung tissue HE staining, and extravascular lung water (EVLW) content measurement. The mRNA and protein expressions of alphaENaC in the lung tissues were detected by fluorescence quantitative real-time RT-PCR and Western blotting, respectively.

RESULTTerbutaline treatment of the rats with ALI resulted in significant differences in PaO2, oxygenation index, and EVLW from those in ALI group without treatment. No significant differences in pulmonary alphaENaC mRNA and protein expressions were noted between the normal control, ALI, and terbutaline-treated ALI groups.

CONCLUSIONSIntratracheal terbutaline administration for 1 h can significantly promote pulmonary edema clearance in adult rats with ALI, and this effect is not mediated by alphaENaC gene expression.

Acute Lung Injury ; chemically induced ; complications ; drug therapy ; genetics ; metabolism ; Animals ; Epithelial Sodium Channels ; genetics ; metabolism ; Female ; Male ; Oleic Acid ; Pulmonary Edema ; drug therapy ; etiology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Terbutaline ; therapeutic use

OBJECTIVETo investigate the role of interleukin-17 (IL-17) in alveolar fluid clearance in mice with acute lung injury (ALI) and explore the possible mechanism.

METHODSSixteen IL-17-knockout mice and 16 wild-type mice were both randomized for intratracheal instillation of PBS (control) on lipopolysaccharide (LPS) to induce ALI. Forty-eight hours after the treatments, the wet-dry ratio (W/D) of the lungs, IL-8 in the bronchoalveolar lavage fluid (BALF) and histopathological changes of the lung tissues were examined. The expressions of epithelial sodium channel α subunit (α-ENaC) was detected with Western blotting and liver kinase B1 (LKB1) was detected with immunohistochemistry.

RESULTSCompared with wild-type mice treated with LPS, IL-17 knockout mice showed significantly decreased W/D of the lungs (9.739∓3.3 vs 5.351∓0.56) and IL-8 level in the BALF (67.50∓7.33 vs 41.00∓3.16 pg/mL) following LPS challenge. Pathological examination revealed reduced alveolar edema fluid aggregations and lower lung injury score in IL-17 knockout mice with also higher expression levels of ENaC and LKB1 compared with the wild-type mice.

CONCLUSIONKnocking out IL-17 in mice not only alleviates inflammation of the lung tissue following ALI but also reduces the loss of ENaC protein and promotes alveolar fluid clearance, mechanism of which is probably associated with LKB1.

Acute Lung Injury ; metabolism ; Animals ; Bronchoalveolar Lavage Fluid ; chemistry ; Epithelial Sodium Channels ; metabolism ; Gene Knockout Techniques ; Interleukin-17 ; genetics ; metabolism ; Interleukin-8 ; metabolism ; Lipopolysaccharides ; Lung ; pathology ; Mice ; Protein-Serine-Threonine Kinases ; metabolism

BACKGROUNDThe amiloride-sensitive epithelial sodium channel α-subunit (α-ENaC) is an important factor for alveolar fluid clearance during acute lung injury. The relationship between adenosine receptor A(2a) (A(2a)AR) expressed in alveolar epithelial cells and α-ENaC is poorly understood. We targeted the A(2a)AR in this study to investigate its role in the expression of α-ENaC and in acute lung injury.

METHODSA549 cells were incubated with different concentrations of A(2a)AR agonist CGS-21680 and with 100 µmol/L CGS-21680 for various times. Rats were treated with lipopolysaccharide (LPS) after CGS-21680 was injected. Animals were sacrificed and tissue was harvested for evaluation of lung injury by analysis of the lung wet-to-dry weight ratio, lung permeability and myeloperoxidase activity. RT-PCR and Western blotting were used to determine the mRNA and protein expression levels of α-ENaC in A549 cells and alveolar type II epithelial cells.

RESULTSBoth mRNA and protein levels of α-ENaC were markedly higher from 4 hours to 24 hours after exposure to 100 µmol/L CGS-21680. There were significant changes from 0.1 µmol/L to 100 µmol/L CGS-21680, with a positive correlation between increased concentrations of CGS-21680 and expression of α-ENaC. Treatment with CGS-21680 during LPS induced lung injury protected the lung and promoted α-ENaC expression in the alveolar epithelial cells.

CONCLUSIONActivation of A(2a)AR has a protective effect during the lung injury, which may be beneficial to the prognosis of acute lung injury.

Acute Lung Injury ; metabolism ; Adenosine ; analogs & derivatives ; pharmacology ; Animals ; Blotting, Western ; Cell Line ; Epithelial Sodium Channels ; genetics ; metabolism ; Humans ; Male ; Phenethylamines ; pharmacology ; Pulmonary Alveoli ; cytology ; metabolism ; Purinergic P1 Receptor Agonists ; pharmacology ; Rats ; Receptors, Purinergic P1 ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction