Dissecting complex traits: recent advances in hypertension genomics

Genome-wide association scans are beginning to identify risk alleles for a number of complex diseases and traits. Essential hypertension looked as though it would be an exception to this trend after the Wellcome Trust Case Control Consortium data were published in 2007. However, more recent scans and meta-analyses have reversed the fortunes of essential hypertension. A number of loci have been identified, including a new antihypertensive drug target in the guise of the serine/threonine kinase SPAK. This kinase forms part of a novel kinase cascade that regulates the NCCT (Na+/Cl- co-transporter; SLC12A3) in the kidney and is defective in a rare Mendelian hypertension syndrome (Gordon's syndrome). Genome-wide scans are also being used to look for alleles to predict individual response to antihypertensive drugs and their risk of causing side-effects. The results of these are expected in the near future and may finally deliver the long-awaited goal of personalized drug therapy for hypertensive patients

Serial extractions versus late premolar extractions

The purpose of this study was to compare treatment times for serial extractions (SE) and late premolar extractions (LPE) for a cost-effectiveness analysis. A retrospective chart review identified 51 SE and 49 LPE patients. PAR scores were obtained at the initiation (PAR T1) and completion (PAR T2) of active orthodontic treatment. PAR T1 scores for the SE patients were significantly less than that for the LPE patients (p<0.001) whereas PAR T2 scores were not significantly different. Active-treatment time was significantly less for the SE group as compared to the LPE group (p<0.001). Total time (mos. pre-active + active-treatment) and total number of visits was significantly greater for the SE group as compared to the LPE group (p<0.001). Total chair time (min.) was not significantly different between groups. Serial extractions may reduce active-treatment time for severe crowding but a significant time and effort precedes active-treatment

ROMK expression remains unaltered in a mouse model of familial hyperkalemic hypertension caused by the CUL3Δ403-459 mutation.

Familial hyperkalemic hypertension (FHHt) is a rare inherited form of salt-dependent hypertension caused by mutations in proteins that regulate the renal Na(+)-Cl(-) cotransporter NCC Mutations in four genes have been reported to cause FHHt including CUL3 (Cullin3) that encodes a component of a RING E3 ligase. Cullin-3 binds to WNK kinase-bound KLHL3 (the substrate recognition subunit of the ubiquitin ligase complex) to promote ubiquitination and proteasomal degradation of WNK kinases. Deletion of exon 9 from CUL3 (affecting residues 403-459, CUL3(Δ403-459)) causes a severe form of FHHt (PHA2E) that is recapitulated closely in a knock-in mouse model. The loss of functionality of CUL3(Δ403-459) and secondary accumulation of WNK kinases causes substantial NCC activation. This accounts for the hypertension in FHHt but the origin of the hyperkalemia is less clear. Hence, we explored the impact of CUL3(Δ403-459) on expression of the distal secretory K channel, ROMK, both in vitro and in vivo. We found that expressing wild-type but not the CUL3(Δ403-459) mutant form of CUL3 prevented the suppression of ROMK currents by WNK4 expressed in Xenopus oocytes. The mutant CUL3 protein was also unable to affect ROMK-EGFP protein expression at the surface of mouse M-1 cortical collecting duct (CCD) cells. The effects of CUL3 on ROMK expression in both oocytes and M-1 CCD cells was reduced by addition of the neddylation inhibitor, MLN4924. This confirms that neddylation is important for CUL3 activity. Nevertheless, in our knock-in mouse model expressing CUL3(Δ403-459) we could not show any alteration in ROMK expression by either western blotting whole kidney lysates or confocal microscopy of kidney sections. This suggests that the hyperkalemia in our knock-in mouse and human PHA2E subjects with the CUL3(Δ403-459) mutation is not caused by reduced ROMK expression in the distal nephron.British Heart Foundation. Grant Number: PG/13/89/30577This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.14814/phy2.1285

ROMK expression remains unaltered in a mouse model of familial hyperkalemic hypertension caused by the CUL3Δ403‐459mutation

Familial hyperkalemic hypertension (FHHt) is a rare inherited form of salt‐dependent hypertension caused by mutations in proteins that regulate the renal Na+‐Cl‐ cotransporter NCC. Mutations in four genes have been reported to cause FHHt including CUL3 (Cullin3) that encodes a component of a RING E3 ligase. Cullin‐3 binds to WNK kinase‐bound KLHL3 (the substrate recognition subunit of the ubiquitin ligase complex) to promote ubiquitination and proteasomal degradation of WNK kinases. Deletion of exon 9 from CUL3 (affecting residues 403‐459, CUL3Δ403‐459) causes a severe form of FHHt (PHA2E) that is recapitulated closely in a knock‐in mouse model. The loss of functionality of CUL3Δ403‐459 and secondary accumulation of WNK kinases causes substantial NCC activation. This accounts for the hypertension in FHHt but the origin of the hyperkalemia is less clear. Hence, we explored the impact of CUL3Δ403‐459 on expression of the distal secretory K channel, ROMK, both in vitro and in vivo. We found that expressing wild‐type but not the CUL3Δ403‐459 mutant form of CUL3 prevented the suppression of ROMK currents by WNK4 expressed in Xenopus oocytes. The mutant CUL3 protein was also unable to affect ROMK‐EGFP protein expression at the surface of mouse M‐1 cortical collecting duct (CCD) cells. The effects of CUL3 on ROMK expression in both oocytes and M‐1 CCD cells was reduced by addition of the neddylation inhibitor, MLN4924. This confirms that neddylation is important for CUL3 activity. Nevertheless, in our knock‐in mouse model expressing CUL3Δ403‐459 we could not show any alteration in ROMK expression by either western blotting whole kidney lysates or confocal microscopy of kidney sections. This suggests that the hyperkalemia in our knock‐in mouse and human PHA2E subjects with the CUL3Δ403‐459 mutation is not caused by reduced ROMK expression in the distal nephron

WNK signalling pathways in blood pressure regulation.

Hypertension (high blood pressure) is a major public health problem affecting more than a billion people worldwide with complications, including stroke, heart failure and kidney failure. The regulation of blood pressure is multifactorial reflecting genetic susceptibility, in utero environment and external factors such as obesity and salt intake. In keeping with Arthur Guyton's hypothesis, the kidney plays a key role in blood pressure control and data from clinical studies; physiology and genetics have shown that hypertension is driven a failure of the kidney to excrete excess salt at normal levels of blood pressure. There is a number of rare Mendelian blood pressure syndromes, which have shed light on the molecular mechanisms involved in dysregulated ion transport in the distal kidney. One in particular is Familial hyperkalemic hypertension (FHHt), an autosomal dominant monogenic form of hypertension characterised by high blood pressure, hyperkalemia, hyperchloremic metabolic acidosis, and hypercalciuria. The clinical signs of FHHt are treated by low doses of thiazide diuretic, and it mirrors Gitelman syndrome which features the inverse phenotype of hypotension, hypokalemic metabolic alkalosis, and hypocalciuria. Gitelman syndrome is caused by loss of function mutations in the thiazide-sensitive Na/Cl cotransporter (NCC); however, FHHt patients do not have mutations in the SCL12A3 locus encoding NCC. Instead, mutations have been identified in genes that have revealed a key signalling pathway that regulates NCC and several other key transporters and ion channels in the kidney that are critical for BP regulation. This is the WNK kinase signalling pathway that is the subject of this review.KMO and MM would like to thank the British Heart Foundation for support in some of their work cited in this review (PG/13/89/30577)

Modified HEK cells simulate DCT cells in their sensitivity and response to changes in extracellular K.

A potassium (K+ ) rich diet is known to have an antihypertensive effect that has been embodied by the NHLBI in the DASH diet. However, the molecular basis for this blood pressure-lowering effect has been unclear, until a recent study proposed a model in which the DCT cells of the kidney regulate their salt transport in response to variations in intracellular chloride ([Cl- ]i ), which are directly regulated by serum K+ . With the knowledge that WNK proteins are Cl- sensors, and are a part of the WNK/SPAK/NCC signaling cascade which regulates the NCC, the main salt transporter in the distal nephron, we examined the effect of serum K+ on the ([Cl- ]i ) and, in turn its effect on the WNK4 signaling pathway in a "modified HEK 293T" cell line. Using a fluorescence-based approach in this cell line, we have shown that the membrane potential of the cell membrane is sensitive to the small changes in external KCl within the physiological range (2-5 mM), thus functioning as a K+ electrode. When the extracellular K+ was progressively increased (2-5 mM), the membrane depolarization lead to a subsequent increase in [Cl- ]i measured by fluorescence quenching of an intracellular chloride sensor. Increase in extracellular [K] resulted in a decrease in the phosphorylation of the WNK4 protein and its downstream targets, SPAK and NCC. This confirms that small changes in serum K can affect WNK4/SPAK/NCC signaling and transcellular Na+ flux through the DCT and provide a possible mechanism by which a K-rich DASH diet could reduce blood pressure

Comment on “Effects of Arsenite during Fetal Development on Energy Metabolism and Susceptibility to Diet-Induced Fatty Liver Diseases in Male Mice” and “Mechanisms Underlying Latent Disease Risk Associated with Early-Life Arsenic Exposure: Current Trends and Scientific Gaps”

Peer reviewedPublisher PD

Targeted disruption of the Kcnj5 gene in the female mouse lowers aldosterone levels.

Aldosterone is released from adrenal zona glomerulosa (ZG) cells and plays an important role in Na and K homoeostasis. Mutations in the human inwardly rectifying K channel CNJ type (KCNJ) 5 (KCNJ5) gene encoding the G-coupled inwardly rectifying K channel 4 (GIRK4) cause abnormal aldosterone secretion and hypertension. To better understand the role of wild-type (WT) GIRK4 in regulating aldosterone release, we have looked at aldosterone secretion in a Kcnj5 knockout (KO) mouse. We found that female but not male KO mice have reduced aldosterone levels compared with WT female controls, but higher levels of aldosterone after angiotensin II (Ang-II) stimulation. These differences could not be explained by sex differences in aldosterone synthase (Cyp11B2) gene expression in the mouse adrenal. Using RNAseq analysis to compare WT and KO adrenals, we showed that females also have a much larger set of differentially expressed adrenal genes than males (395 compared with 7). Ingenuity Pathway Analysis (IPA) of this gene set suggested that peroxisome proliferator activated receptor (PPAR) nuclear receptors regulated aldosterone production and altered signalling in the female KO mouse, which could explain the reduced aldosterone secretion. We tested this hypothesis in H295R adrenal cells and showed that the selective PPARα agonist fenofibrate can stimulate aldosterone production and induce Cyp11b2. Dosing mice in vivo produced similar results. Together our data show that Kcnj5 is important for baseline aldosterone secretion, but its importance is sex-limited at least in the mouse. It also highlights a novel regulatory pathway for aldosterone secretion through PPARα that may have translational potential in human hyperaldosteronism

Good intentions in universal design: A global challenge for higher education

It is not often that a high-level edict requires higher education centres to promote universal design through their programmes; however the recent United Nations Beijing Declaration and Action Plan (UNESCAP 2017) expressly states that, “academic institutions should provide training programmes on universal design for policymakers, building inspectors and contractors, as well as integrating universal design and accessibility into curricula related to architecture, urban planning, transport, civil engineering and other relevant academic branches”. This is particularly timely in the Asia-Pacific region, where economies continue to show massive expansion of their built environments. This imperative to future-proof any development therefore is vital, especially considering the growing percentile of older people with their needs for safe and accessible living. Achieving these ends clearly implies a need both to educate professionals and to enact appropriate codes and standards, which in turn require the training of personnel to carry them out. Anticipating this need, Goal 3 of the United Nations Incheon Strategy (UNESCAP 2012) optimistically calls for “civil society involvement in conducting accessibility audits, creating guidelines and advocacy work to promote universal design” and “to enhance mechanisms for tracking its progress”. While such good intentions are admirable, they will require radical steps to be achieved. The paper describes examples, including those from the writers' own experiences, outlining a range of practical methods which academics and teachers involved in inculcating universal design principles in both European and Asian centres, through their teaching, training and technology transfer, can positively support continued cooperation towards a more inclusive World for everyone

The dark side of political marketing

Purpose This article discusses exploratory research into the perceptions of British Muslims towards Islamist ideological messaging to contribute to the general debate on ‘radicalisation'. The article discusses the findings of discussion groups in the light of research previously undertaken in the propaganda/psychology fields, from the perspective of Reversal Theory. Methodology/approach Four focus groups were undertaken with a mixture of Bangladeshi and Pakistani British Muslims who were shown a selection of Islamist propaganda media clips, garnered from the internet. The research is intended to provide exploratory indications of how British Muslims receive Islamist communication messages in order to provoke further research in this critical field. Findings We propose that Islamist communications focus on eliciting change in emotional states, specifically inducing the paratelic-excitement mode, by focusing around a meta-narrative of Muslims as a unitary grouping self- defined as victim to Western aggression. Early indicators are that some genres of Islamist propaganda may be more effective than others in generating these emotional change states (e.g. cartoons) and some groupings appear to be more susceptible than others. We conclude that our British Muslim respondents were unsympathetic to the Islamist ideological messaging contained in our sample of propaganda clips. Research limitations/implications The research highlights the difficulties in undertaking research in such a sensitive field. We propose a series of four testable propositions to guide future research looking specifically at whether those subjects who are more likely to be excited by Islamist communication include those with weakly held identities, younger males, those feeling contempt for Western culture, and the use of specific media genre formats. Originality/value of paper The article provides an insight into how British Muslims might respond to Islamist communications, indicating that whilst most are not susceptible to inducement of paratelic-excitement, others are likely to be, dependent on which genre of clip is used, the messages contained therein, and who that clip is targeted at