G protein-coupled inward rectifier K(+) channel 4(GIRK4) is a G protein-coupled inward rectifier potassium channel family member. Encoded by the KCNJ5, it is widely distributed in the mammalian heart, brain, and other tissues and organs. Recent studies have demonstrated that the abnormal expression of GIRK4 gene is associated with atrial fibrillation, and meanwhile may be closely related to obesity, metabolic syndrome, and many other clinical conditions. Further research on the role the GIRK4 gene in the pathophysiology of these clinical conditions will definitely facilitate their clinical diagnosis and treatment.
Atrial Fibrillation ; genetics ; G Protein-Coupled Inwardly-Rectifying Potassium Channels ; genetics ; Humans ; Metabolic Syndrome ; genetics

Diabetes Mellitus ; genetics ; Humans ; Infant, Newborn ; Male ; Mutation ; Potassium Channels, Inwardly Rectifying ; genetics

OBJECTIVEE23K polymorphism in KCNJ11 gene is associated with cardiovascular disease and diabetes. In order to explore the mechanism of E23K correlation to related diseases, the effect of E23K polymorphism in KCNJ11 gene on membrane current was investigated.

METHODSThe exon of KCNJ11 was obtained by PCR amplification and the G-->A mutation was completed by overlap extension PCR. The sequences of KCNJ11 exon contained 23E or 23K was inserted into pcDNA3.1/CT-GFP vector respectively. The recombinant plasmid, pcDNA3.1-KCNJ11(E) and pcDNA3.1-KCNJ11(K), were transfected into HEK293T cells by lipofectamine and the membrane current density was determined by whole-cell patch clamp technique.

RESULTS1,173 bp sequences of KCNJ11 gene's exon were amplified by PCR and the recombinant expression plasmid, pcDNA3.1-KCNJ11(E) and pcDNA3.1-KCNJ11(K), were constructed successful. Positive and negative currents were detected in HEK293T cells transfected with difference plasmid by whole-cell patch clamp technique. Results showed that the reversed voltage was 50mV. The current in HEK293T cells with pcDNA3.1-KCNJ11(E) was significantly greater than that with pcDNA3.1-KCNJ11(K) (P < 0.05, n = 10).

CONCLUSIONThe polymorphism of E23K in exon of KCNJ11 gene changed the membrane currents in HEK293T cells. It could be an experiment support for the possible mechanism between the locus and related diseases.

Exons ; HEK293 Cells ; Humans ; Membrane Potentials ; Patch-Clamp Techniques ; Polymorphism, Genetic ; Potassium Channels, Inwardly Rectifying ; genetics

OBJECTIVETo assess the association between polymorphisms of rs3740835(C/A) and rs2604204(A/C) in KCNJ5 gene with the susceptibility to unilateral and bilateral primary aldosteronism (PA).

METHODSA total of 1043 subjects were studied, which included 83 unilateral PA patients,142 bilateral PA patients and 818 essential hypertensive(EH) patients. The polymorphism of KCNJ5 gene at rs3740835(C/A) and rs2604204(A/C) position were analyzed with a TaqMan genotyping technique.

RESULTSFrequencies of A allele and AA+AC genotype at rs3740835(C/A) in unilateral PA group were significantly higher than EH group (P < 0.05). However, the above frequencies did not show a statistical significance between bilateral PA group and EH group (P > 0.05). No statistical difference was detected in the distribution of alleles or genotypes at rs2604204 (A/C) between unilateral PA and EH group or between bilateral PA and EH group. Haplotypic frequencies of C-A and A-A in unilateral PA group were significantly higher and lower than EH group, respectively. However, there was no statistical difference in the haplotype distribution between bilateral PA and EH groups.

CONCLUSIONRs3740835(C/A) polymorphism may be associated with unilateral PA but not with bilateral PA. rs2604204(A/C) polymorphism is not associated with either unilateral or bilateral PA. Haplotype C-A and A-A may respectively be susceptibility factor and protective factor for unilateral PA. No haplotype has been found to associate with bilateral PA.

Adult ; Female ; G Protein-Coupled Inwardly-Rectifying Potassium Channels ; genetics ; Haplotypes ; Humans ; Hyperaldosteronism ; genetics ; Male ; Middle Aged ; Polymorphism, Genetic

OBJECTIVETo investigate the expression of GIRK4 gene in the kidney tissues of obese rats.

METHODSObese rat models were established using diet-induced method. The GIRK4 protein expression in kidney tissues was determined in 20 obese rats and 10 normal rats using Western blot analysis.

RESULTSThe relative expression level of GIRK4 protein in the kidney tissues of obese rat (1.75±0.42) was significantly lower than that in normal rats (3.37±0.68, P<0.05).

CONCLUSIONGIRK4 has a low protein expression in the kidney tissues of obese rat.

Animals ; Female ; Gene Expression ; Kidney ; metabolism ; Male ; Obesity ; genetics ; metabolism ; Potassium Channels, Inwardly Rectifying ; genetics ; metabolism ; Rats

OBJECTIVESTo construct the expression vector pGenesil-3-shRNA that can express the short hairpin RNAs (shRNA) silencing Kir6.2 gene and to study its influence on the proliferation and invasion of HepG2 cells.

METHODSTwo shRNA silencing Kir6.2 genes were transcript synthesized intracellularly by expressed templates of plasmid vector pSilence-3, and the target sequence of Kir6.2 gene was inserted into the upstream of the reporter gene in order to construct the recombinant plasmid vector pGenesil-3. Plasmids containing 2 different sequences of human Kir6.2 mRNA coding region were constructed and transfected into HepG2 cells by using lipofectamine 2000 methods. The experiment was divided into 4 groups: SK (normal), SK-HK (negative control), SK-K1 (transfected with the interfering sequence 1) and SK-K2 (transfected with the interfering sequence 2) groups. A selected single clone was cultured after screening by G418. The expression of Kir6.2 protein was detected by Western blot. MTT assay and Transwell system were used to observe the proliferation and invasion of HepG2 cells.

RESULTSThe recombinant expression plasmid pGenesil-3 was successfully constructed and underexpression of Kir6.2 gene in HepG2 cells was detected by Western blot. Underexpression of Kir6.2 gene significantly decreased the proliferation and invasion of the HepG2 cells.

CONCLUSIONshRNA can inhibit the expression of Kir6.2 gene in the HepG2 cells, and underexpression of Kir6.2 gene decreased the proliferation and invasion of the HepG2 cells.

Cell Proliferation ; Genetic Vectors ; Hep G2 Cells ; Humans ; Neoplasm Invasiveness ; Plasmids ; Potassium Channels, Inwardly Rectifying ; genetics ; RNA, Small Interfering ; genetics

OBJECTIVETo investigate the relationship between the G protein-gated inward rectifier K+ channel subunit 4 (GIRK4) gene polymorphism and the dyslipidemia among Uyghur residents in Xinjiang.

METHODSThe polymorphisms of rs2604204, rs4937391, rs6590357, and rs11221497 among the Uyghur residents were genotyped using Taqman polymerase chain reaction (PCR). Lipid levels were measured by conventional methods and were analyzed.

RESULTSIn the less-than-50-years population, the genotype distributions of the rs6590357 was statistically significant different in subjects with or without abnormal triglycerides (P=0.005). Aslo, the the genotype distributions of the rs11221497 also significantly differed in subjects with normal compared or abnormal TG (P=0.011). Logistic regression analysis suggested that rs6590357 still had positive association with TG abnormalities in subjects under 50 years (P=0.014). rs11221497 also had positive association with TC abnormalities. The TG levels of CT+TT genotypes were significantly higher than the CC group (P=0.006). Haplotype analysis found that the differences of H3 haplotype frequencies between the TG abnormal and normal groups were statistically significant (P=0.007).

CONCLUSIONThe polymorphisms of rs11221497 and rs6590357 of GIRK4 gene may play a role in the development of dyslipidemia in Uygur population.

China ; epidemiology ; Dyslipidemias ; epidemiology ; metabolism ; Genotype ; Humans ; Polymerase Chain Reaction ; Polymorphism, Single Nucleotide ; Potassium Channels, Inwardly Rectifying ; genetics ; Triglycerides

Inwardly rectifying potassium (Kir) channels exhibit an asymmetrical conductance at hyperpolarization (high conductance) compared to depolarization (low conductance). The KCNJ10 gene which encodes an inwardly rectifying K+ channel Kir4.1 subunit plays an essential role in the inner ear and hearing. Mutations or deficiency of KCNJ10 can cause hearing loss with epilepsy, ataxia, sensorineural deafness, and renal tubulopathy (EAST) or SeSAME (seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance) syndromes. In this review, we mainly focus on the expression and function of Kir4.1 channels in the inner ear and mutation-induced EAST/SeSAME syndromes to provide insight for understanding the pathogenesis of deafness induced by KCNJ10 deficiency.
Deafness ; genetics ; metabolism ; Ear, Inner ; metabolism ; Hearing Loss, Sensorineural ; genetics ; metabolism ; Humans ; Intellectual Disability ; genetics ; metabolism ; Mutation ; Potassium Channels, Inwardly Rectifying ; genetics ; metabolism ; Seizures ; genetics ; metabolism

OBJECTIVETo compare the changes of both inward rectifying K(+) (Kir) current(I(k1)) density and mRNA expression level of Kir2.1, a major subfamily of Kir in chronic human atrial fibrillation (CAF) with those in normal sinus rhythm (NSR).

METHODSI(k1) density was measured with whole-cell patch clamp technique in single myocyte isolated by an enzymatic dissociation method from right atrial appendages in patients with CAF (n = 8) and those with NSR (n = 12). The mRNA expression levels of Kir2.1 was determined in right atrial appendages from CAF (n = 19) and NSR (n = 18) by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR).

RESULTThe average resting membrane potentials were similar between CAF and NSR (-78.95 mV +/- 4.67 mV and -70.22 mV +/- 11.08 mV, P>0.05). I(k1) density in single myocyte significantly increased at hyperpolarized potential level (-100 mV) in CAF compared to that in NSR (-9.59 pA/pF +/- 2.47 pA/pF vs. -5.58 pA/pF +/- 2.52 pA/pF, P<0.01). The mRNA level of Kir2.1 was also significantly higher in CAF than that of NSR (0.50+/-0.16 vs. 0.34+/-0.09, P<0.05).

CONCLUSIONThe data suggest that Kir2.1 up-regulation and I(k1) current increase might contribute to the electrical remodeling in CAF patients.

Atrial Fibrillation ; genetics ; metabolism ; physiopathology ; Gene Expression ; Humans ; Myocytes, Cardiac ; metabolism ; physiology ; Patch-Clamp Techniques ; Potassium Channels, Inwardly Rectifying ; genetics ; metabolism ; RNA, Messenger ; genetics

OBJECTIVE: To investigate the clinical characteristics and genetic basis for a child with Keppen-Lubinsky syndrome (KPLBS). METHODS: Trio-whole exome sequencing (Trio-WES) was carried out for the proband and her parents. Candidate variant was verified by Sanger sequencing and bioinformatic analysis. RESULTS: The child has featured peculiar facies including large eyes, alar hypoplasia, microretrognathia, premature aging appearance in addition with growth delay and mental retardation. Trio-WES has identified that she has carried a de novo variant of the KCNJ6 gene, namely c.460G>C (p.Gly154Arg). The variant has not been recorded in the database. Prediction of protein structure indicated that the variant may affect the potassium ion selective filtration structure channel in the transmembrane region of KCNJ6 protein, which may result in up regulation of the function of the channel. CONCLUSION The de novo c.460G>C (p.Gly154Arg) variant of the KCNJ6 gene probably underlay the KPLBS in this child. Above finding has enriched the genotypic and phenotype spectrum of this syndrome.
Cataract ; China ; Female ; G Protein-Coupled Inwardly-Rectifying Potassium Channels/genetics* ; Humans ; Hypogonadism/congenital* ; Intellectual Disability/genetics* ; Mutation ; Whole Exome Sequencing