scholarly journals Increased KCNJ18 promoter activity as a mechanism in atypical normokalemic periodic paralysis

2018 ◽  
Vol 4 (5) ◽  
pp. e274 ◽  
Author(s):  
Muhidien Soufi ◽  
Volker Ruppert ◽  
Susanne Rinné ◽  
Tobias Mueller ◽  
Bilgen Kurt ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Gene Mutations ◽  
Periodic Paralysis ◽  
Hek293 Cells ◽  
Luciferase Assay ◽  
Candidate Gene Approach ◽  
Causative Gene ◽  
Outward Currents ◽  
Promoter Construct ◽  
Health Situation

ObjectiveTo identify the genetic basis of a patient with symptoms of normokalemic sporadic periodic paralysis (PP) and to study the effect of KCNJ18 mutations.MethodsA candidate gene approach was used to identify causative gene mutations, using Sanger sequencing. KCNJ18 promoter activity was analyzed in transfected HEK293 cells with a luciferase assay, and functional analysis of Kir2.6 channels was performed with the two-electrode voltage-clamp technique.ResultsAlthough we did not identify harmful mutations in SCN4A, CACNA1S, KCNJ2 and KCNE3, we detected a monoallelic four-fold variant in KCNJ18 (R39Q/R40H/A56E/I249V), together with a variant in the respective promoter of this channel (c.-542T/A). The exonic variants in Kir2.6 did not alter the channel function; however, luciferase assays revealed a 10-fold higher promoter activity of the c.-542A promoter construct, which is likely to cause a gain-of-function by increased expression of Kir2.6. We found that reducing extracellular K+ levels causes a paradoxical reduction in outward currents, similar to that described for other inward rectifying K+ channels. Thus, reducing the extracellular K+ levels might be a therapeutic strategy to antagonize the transcriptionally increased KCNJ18 currents. Consistently, treatment of the patient with K+ reducing drugs dramatically improved the health situation and prevented PP attacks.ConclusionsWe show that a promoter defect in the KCNJ18 gene is likely to cause periodic paralysis, as the observed transcriptional upregulation will be linked to increased Kir2.6 function. This concept is further supported by our observation that most of the PP attacks in our patient disappeared on medical treatment with K+ reducing drugs.

The transcription factor E2F-1 mediates the autoregulation of RB gene expression

1994 ◽  
Vol 14 (1) ◽  
pp. 299-309
Author(s):  
B Shan ◽  
C Y Chang ◽  
D Jones ◽  
W H Lee
Keyword(s):  
Promoter Region ◽  
Promoter Activity ◽  
Cell Cycle Progression ◽  
Gene Mutations ◽  
Suppressor Gene ◽  
Recognition Sequence ◽  
Cycle Progression ◽  
Rb Gene ◽  
Transcription Factor E2f ◽  
Stimulation Of

The retinoblastoma (RB) gene is the prototype tumor suppressor gene. Mutations in this gene are often associated with the occurrence of various tumors. Several mutations have been found in the promoter region of the gene, suggesting that inappropriate transcriptional regulation of the RB gene contributes to tumorigenesis. Sequence analysis of the RB promoter has revealed a potential E2F recognition site within a region critical for RB gene transcription. By using the cloned E2F-1 gene, here we report that (i) RB expression is negatively regulated by its own gene product, (ii) E2F-1 binds specifically to an E2F recognition sequence in the RB promoter and transactivates the RB promoter, (iii) overexpression of RB suppresses E2F-1-mediated stimulation of RB promoter activity, and (iv) the expression of the RB gene is paralleled by the expression of the E2F-1 gene during cell cycle progression. These results demonstrate that expression of RB is negatively autoregulated through E2F-1.

scholarly journals Genetics of multiple endocrine neoplasia type 1 syndrome: what's new and what's old

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 73 ◽  
Author(s):  
Alberto Falchetti
Keyword(s):  
Multiple Endocrine Neoplasia ◽  
Multiple Endocrine Neoplasia Type ◽  
Hot Spot ◽  
Gene Mutations ◽  
Causative Gene ◽  
Endocrine Neoplasia ◽  
Endocrine Neoplasia Type ◽  
Main Gene ◽  
Clinical Surveillance

Despite its identification in 1997, the functions of the MEN1 gene—the main gene underlying multiple endocrine neoplasia type 1 syndrome—are not yet fully understood. In addition, unlike the RET—MEN2 causative gene—no hot-spot mutational areas or genotype–phenotype correlations have been identified. More than 1,300 MEN1 gene mutations have been reported and are mostly "private” (family specific). Even when mutations are shared at an intra- or inter-familial level, the spectrum of clinical presentation is highly variable, even in identical twins. Despite these inherent limitations for genetic counseling, identifying MEN1 mutations in individual carriers offers them the opportunity to have lifelong clinical surveillance schemes aimed at revealing MEN1-associated tumors and lesions, dictates the timing and scope of surgical procedures, and facilitates specific mutation analysis of relatives to define presymptomatic carriers.

scholarly journals Cold-induced urticarial autoinflammatory syndrome related to factor XII activation

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jörg Scheffel ◽  
Niklas A. Mahnke ◽  
Zonne L. M. Hofman ◽  
Steven de Maat ◽  
Jim Wu ◽  
...  
Keyword(s):  
Interleukin 1 ◽  
Gene Mutations ◽  
Coagulation Factor ◽  
Hek293 Cells ◽  
Receptor Protein ◽  
Local Source ◽  
Factor Xii ◽  
Mutant Proteins ◽  
Hereditary Autoinflammatory Diseases ◽  
Immune Pathway

AbstractHereditary autoinflammatory diseases are caused by gene mutations of the innate immune pathway, e.g. nucleotide receptor protein 3 (NLRP3). Here, we report a four-generation family with cold-induced urticarial rash, arthralgia, chills, headache and malaise associated with an autosomal-dominant inheritance. Genetic studies identify a substitution mutation in gene F12 (T859A, resulting in p.W268R) which encodes coagulation factor XII (FXII). Functional analysis reveals enhanced autocatalytic cleavage of the mutated protein and spontaneous FXII activation in patient plasma and in supernatant of transfected HEK293 cells expressing recombinant W268R-mutated proteins. Furthermore, we observe reduced plasma prekallikrein, cleaved high molecular weight kininogen and elevated plasma bradykinin. Neutrophils are identified as a local source of FXII. Interleukin-1β (IL-1β) is upregulated in lesional skin and mononuclear donor cells exposed to recombinant mutant proteins. Treatment with icatibant (bradykinin-B2-antagonist) or anakinra (interleukin-1-antagonist) reduces disease activity in patients. In conclusion, our findings provide a link between contact system activation and cytokine-mediated inflammation.

scholarly journals SAT-718 Inhibition of Androgen Receptor Activity by DDE Is Affected by Mutations in the BF3 Site

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Andrea Lozano ◽  
Evangelia Kotsikorou ◽  
Frank B Dean
Keyword(s):  
Androgen Receptor ◽  
Ligand Binding ◽  
Binding Domain ◽  
Ligand Binding Domain ◽  
Hek293 Cells ◽  
Luciferase Assay ◽  
Breakdown Product ◽  
Reporter System ◽  
Surface Binding ◽  
Endocrine Disrupting

Abstract The androgen receptor (AR) plays an important role in the development of the male phenotype and traits. Some diphenyl compounds inhibit AR activity by binding to a hydrophobic surface binding site, BF3. A similar diphenyl structure is found in 4,4’ DDT and its breakdown product 4,4’ DDE. Previous results showed that DDT and DDE induced the release of bound dihydrotestosterone from the AR ligand binding domain, with IC50 values ranging from 54 to 82uM. This suggested that DDT and related compounds may act as endocrine disrupting chemicals by binding to the BF3 site and inducing allosteric changes in the AR structure, disrupting binding of the steroid to the ligand binding domain. Here, an AR reporter system was transiently transfected into HEK293 cells and AR activity was measured using a dual luciferase assay. The system was used to measure the response of the AR protein to varying concentrations of dihydrotestosterone in the presence and absence of DDE. DDE inhibited the activation of AR by dihydrotestosterone under these conditions. Five mutant AR genes with amino acid changes in the BF3 site were tested for alterations in the ability of DDE to disrupt AR activity. The five mutations tested were F673K, F673W, G724R, G724M, and L830D. The ability of DDE to inhibit AR activity was reduced by the mutations in the BF3 site. These results suggest that DDE acts as an endocrine disrupting chemical (EDC) by binding to the BF3 site and allosterically regulating AR activity.

scholarly journals Axenfeld-Rieger Syndrome Associated with Congenital Glaucoma and Cytochrome P4501B1 Gene Mutations

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Mukesh Tanwar ◽  
Tanuj Dada ◽  
Rima Dada
Keyword(s):  
Clinical Manifestations ◽  
Gene Mutations ◽  
Corneal Opacity ◽  
North India ◽  
Congenital Glaucoma ◽  
Causative Gene ◽  
Nasal Bridge ◽  
Rieger Syndrome ◽  
Cytochrome P4501b1 ◽  
Outflow Pathway

Developmental anomalies of the ocular anterior chamber angle may lead to an incomplete development of the structures that form the conventional aqueous outflow pathway. Thus, disorders that present with such dysfunction tend to be associated with glaucoma. Among them, Axenfeld-Rieger (ARS) malformation is a rare clinical entity with an estimated prevalence of one in every 200,000 individuals. The changes in eye morphogenesis in ARS are highly penetrant and are associated with 50% risk of development of glaucoma. Mutations in the cytochrome P4501B1 (CYP1B1) gene have been reported to be associated with primary congenital glaucoma and other forms of glaucoma and mutations in pituitary homeobox 2 (PITX2) gene have been identified in ARS in various studies. This case was negative forPITX2mutations and compound heterozygote forCYP1B1mutations. Clinical manifestations of this patient include bilateral elevated intraocular pressure (>40 mmHg) with increased corneal diameter (>14 mm) and corneal opacity. Patient also had iridocorneal adhesions, anteriorly displaced Schwalbe line, anterior insertion of iris, broad nasal bridge and protruding umbilicus. This is the first study from north India reportingCYP1B1mutations in Axenfeld-Rieger syndrome with bilateral buphthalmos and early onset glaucoma. Result of this study supports the role ofCYP1B1as a causative gene in ASD disorders and its role in oculogenesis.

scholarly journals Does thyrotoxic periodic paralysis have a genetic predisposition? A case report

2018 ◽  
Vol 55 (6) ◽  
pp. 713-716 ◽  
Author(s):  
E Rasheed ◽  
J Seheult ◽  
J Gibney ◽  
G Boran
Keyword(s):  
Thyroid Hormone ◽  
Clinical Presentation ◽  
Normal Population ◽  
Rare Complication ◽  
Gene Mutations ◽  
Periodic Paralysis ◽  
Acute Onset ◽  
Nucleotide Polymorphisms ◽  
Thyrotoxic Periodic Paralysis ◽  
Inwardly Rectifying Potassium Channel

Thyrotoxic periodic paralysis is a rare complication of hyperthyroidism where increased influx of potassium into skeletal muscle cells leads to profound hypokalaemia and paralysis. Most cases arise sporadically in Asians; however, it is being increasingly reported in Caucasians. It is regarded as a channelopathy where a genetic and/or acquired defect in the sodium-potassium (Na/K-ATPase) pump renders it more sensitive to excess thyroid hormone in susceptible individuals. Because the clinical presentation is similar to familial hypokalaemic periodic paralysis, genes implicated in this autosomal-dominant condition became candidates for thyrotoxic periodic paralysis, particularly if they were known to have thyroid hormone-responsive elements. These include the voltage-gated calcium (CACNA1S) and sodium (SCN4A) channel genes, KCNJ18 which encodes the inwardly rectifying potassium channel Kir2.6, and subunits of the Na/K-ATPase genes. Although no single pathogenetic mutation has been identified in thyrotoxic periodic paralysis, several single-nucleotide polymorphisms in these genes have been associated with it. We describe a 27-year-old Caucasian Irish male who presented with acute onset limb paralysis and severe hypokalaemia. He was diagnosed as having thyrotoxic periodic paralysis secondary to Graves’ disease based on clinical presentation, biochemical findings and rapid response to intravenous potassium. Genetic analysis identified heterozygous variants in three candidate genes: KCNJ18 (c.576G>C), SCN4A (c.2341G>A) and CACNA1S (c.1817G>A). Since these variants are not disease causing and occur at high prevalences of 50%, 2–3% and 1%, respectively, in the normal population, they do not explain the clinical phenotype in our patient suggesting that acquired environmental triggers or as-yet unidentified gene mutations remain as leading pathogenetic co-factors in thyrotoxic periodic paralysis.

scholarly journals Comparative Genomics, Infectivity and Cytopathogenicity of American Isolates of Zika Virus that Developed Persistent Infections in Human Embryonic Kidney (HEK293) Cells

2019 ◽  
Vol 20 (12) ◽  
pp. 3035 ◽  
Author(s):  
Hebing Liu ◽  
Hsiao-Mei Liao ◽  
Bingjie Li ◽  
Shien Tsai ◽  
Guo-Chiuan Hung ◽  
...  
Keyword(s):  
Cell Line ◽  
Zika Virus ◽  
Hek293 Cell ◽  
Clonal Selection ◽  
Gene Mutations ◽  
Host Cells ◽  
Hek293 Cells ◽  
Specific Gene ◽  
Human Embryonic Kidney ◽  
Hek293 Cell Line

Zika virus (ZIKV) transmission can cause serious fetal neurological abnormalities. ZIKV persistence in various human cells and tissues can serve as infectious reservoirs and post serious threats to public health. The human embryonic kidney (HEK293) cell line with known neuronal developmental properties was readily infected by ZIKV in a strain-dependent fashion. Significant cytopathic effect in HEK293 cells infected by the prototype MR 766 strain of ZIKV resulted in complete loss of cells, while small numbers of HEK293 cells infected by contemporary ZIKV isolates (PRV or FLR strain) continued to survive and regrow to confluency in the culture around two months after initial infection. Most, if not all, of the cells in the two resulting persistently ZIKV-infected HEK293 cell lines tested positive for ZIKV antigen. Compared to HEK293 control cells, the persistently ZIKV-infected HEK293 cells had slower growth rates with some cells undergoing apoptosis in culture. The “persistent ZIKVs” produced constitutively by both PRV and FLR strains ZIKV-infected HEK293 cells had significantly attenuated cell infectivity and/or cytopathogenicity. Comparative genome sequence analyses between the persistent ZIKVs and the original inoculum ZIKVs showed no clonal selection with specific gene mutations in the prolonged process of establishing persistently PRV strain ZIKV-infected HEK293 cells; while selection of ZIKV subclones with mutations in the envelope, protein pr and multiple NS genes was evident in developing persistently FLR strain ZIKV-infected HEK293 cell line. Our study provides molecular insights into the complex interplays of ZIKV and human host cells in establishing ZIKV persistence.

A Novel Loss of Function Melanocortin-4-Receptor Mutation (MC4R-F313Sfs*29) in Morbid Obesity

2020 ◽  
Author(s):  
Elisabetta Trevellin ◽  
Marnie Granzotto ◽  
Cristina Host ◽  
Francesca Grisan ◽  
Diego De Stefani ◽  
...  
Keyword(s):  
Early Onset ◽  
Functional Characterization ◽  
Gene Mutations ◽  
Melanocortin Receptor ◽  
Hek293 Cells ◽  
Intracellular Camp ◽  
Loss Of Function ◽  
Mc4r Gene ◽  
Melanocortin 4 Receptor

Abstract Context Melanocortin receptor-4 (MC4R) gene mutations are associated with early-onset severe obesity, and the identification of potential pathological variants is crucial for the clinical management of patients with obesity. Objective To explore whether and how a novel heterozygous MC4R variant (MC4R-F313Sfs*29), identified in a young boy (body mass index [BMI] 38.8 kg/m2) during a mutation analysis conducted in a cohort of patients with obesity, plays a determinant pathophysiological role in the obesity development. Design Setting and Patients The genetic screening was carried out in a total of 209 unrelated patients with obesity (BMI ≥ 35 kg/m2). Structural and functional characterization of the F313Sfs*29-mutated MC4R was performed using computational approaches and in vitro, using HEK293 cells transfected with genetically encoded biosensors for cAMP and Ca2+. Results The F313Sfs*29 was the only variant identified. In vitro experiments showed that HEK293 cells transfected with the mutated form of MC4R did not increase intracellular cAMP or Ca2+ levels after stimulation with a specific agonist in comparison with HEK293 cells transfected with the wild type form of MC4R (∆R/R0 = -90% ± 8%; P < 0.001). In silico modeling showed that the F313Sfs*29 mutation causes a major reorganization in the cytosolic domain of MC4R, thus reducing the affinity of the putative GalphaS binding site. Conclusions The newly discovered F313Sfs*29 variant of MC4R may be involved in the impairment of α-MSH-induced cAMP and Ca2+ signaling, blunting intracellular G protein-mediated signal transduction. This alteration might have led to the dysregulation of satiety signaling, resulting in hyperphagia and early onset of obesity.

Evidence that estrogen receptor β enhances MMP-13 promoter activity in HIG-82 cells and that this enhancement can be influenced by ligands and involves specific promoter sites

2007 ◽  
Vol 85 (3) ◽  
pp. 326-336 ◽  
Author(s):  
Ting Lu ◽  
Yamini Achari ◽  
Jerome B. Rattner ◽  
David A. Hart
Keyword(s):  
Estrogen Receptor ◽  
Promoter Activity ◽  
Estrogen Receptor Β ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Connective Tissues ◽  
Matrix Metalloproteinase 13 ◽  
Promoter Construct ◽  
The Impact ◽  
Dose Dependent

Degradation of articular cartilage is characteristic of osteoarthritis, and matrix metalloproteinase-13 (MMP-13) has been implicated in this condition. Estrogen receptors (ERs) are present in connective tissues, indicating these tissues' potential responsiveness to estrogen. We based this study on the hypothesis that estrogen receptor β (ERβ) can modulate MMP-13 promoter activity. Transfection of cells with ERβ constructs led to the induction of the endogenous MMP-13 gene, as evidenced by increased mRNA levels. The results also indicated that MMP-13 promoter construct activity in the HIG-82 cell line significantly increased when ERβ was present, and that estrogen downregulated this response in a dose-dependent manner. ERβ was shown to enhance MMP-13 expression somewhat more strongly than ERα, and the impact of a number of selective ER modulators (tamoxifen, raloxifene, and ICI 182,780) on ERβ enhancement of promoter activity was found to be significantly less than that of estrogen. Furthermore, transcription regulatory sites in the MMP-13 promoter, specifically AP-1 and PEA-3, were shown to act in conjunction to mediate ERβ effects. Thus, ERβ likely influences MMP-13 promoter expression in normal and disease processes.

Sign in / Sign up

Export Citation Format

Share Document