Mechanisms of pathogenicity and the quest for genetic modifiers of kidney disease in branchiootorenal syndrome.

Backgound: Branchiootorenal (BOR) syndrome is an autosomal dominant disorder caused by pathogenic EYA1 variants and clinically characterized by auricular malformations with hearing loss, branchial arch anomalies, and congenital anomalies of the kidney and urinary tract. BOR phenotypes are highly variable and heterogenous. While random monoallelic expression is assumed to explain this phenotypic heterogeneity, the potential role of modifier genes has not yet been explored. Methods: Through thorough phenotyping and exome sequencing, we studied one family with disease presentation in at least four generations in both clinical and genetic terms. Functional investigation of the single associated EYA1 variant c.1698+1G>A included splice site analysis and assessment of EYA1 distribution in patient-derived fibroblasts. The candidate modifier gene CYP51A1 was evaluated by histopathological analysis of murine Cyp51+/- and Cyp51-/- kidneys. As the gene encodes the enzyme lanosterol 14α-demethylase, we assessed sterol intermediates in patient blood samples as well. Results: The EYA1 variant c.1698+1G>A resulted in functional deletion of the EYA domain by exon skipping. The EYA domain mediates protein-protein interactions between EYA1 and co-regulators of transcription. EYA1 abundance was reduced in the nuclear compartment of patient-derived fibroblasts, suggesting impaired nuclear translocation of these protein complexes. Within the affected family, renal phenotypes spanned from normal kidney function in adulthood to chronic kidney failure in infancy. By analyzing exome sequencing data for variants that potentially play roles as genetic modifiers, we identified a canonical splice site alteration in CYP51A1 as the strongest candidate variant. Conclusion: In this study, we demonstrate pathogenicity of EYA1 c.1698+1G>A, propose a mechanism for dysfunction of mutant EYA1, and conjecture CYP51A1 as a potential genetic modifier of renal involvement in BOR syndrome.

Towards understanding policy design through text-as-data approaches: The policy design annotations (POLIANNA) dataset.

Despite the importance of ambitious policy action for addressing climate change, large and systematic assessments of public policies and their design are lacking as analysing text manually is labour-intensive and costly. POLIANNA is a dataset of policy texts from the European Union (EU) that are annotated based on theoretical concepts of policy design, which can be used to develop supervised machine learning approaches for scaling policy analysis. The dataset consists of 20,577 annotated spans, drawn from 18 EU climate change mitigation and renewable energy policies. We developed a novel coding scheme translating existing taxonomies of policy design elements to a method for annotating text spans that consist of one or several words. Here, we provide the coding scheme, a description of the annotated corpus, and an analysis of inter-annotator agreement, and discuss potential applications. As understanding policy texts is still difficult for current text-processing algorithms, we envision this database to be used for building tools that help with manual coding of policy texts by automatically proposing paragraphs containing relevant information.

Defective claudin-10 causes a novel variation of HELIX syndrome through compromised tight junction strand assembly.

Formation of claudin-10 based tight junctions (TJs) is paramount to paracellular Na+ transport in multiple epithelia. Sequence variants in CLDN10 have been linked to HELIX syndrome, a salt-losing tubulopathy with altered handling of divalent cations accompanied by dysfunctional salivary, sweat, and lacrimal glands. Here, we investigate molecular basis and phenotypic consequences of a newly identified homozygous CLDN10 variant that translates into a single amino acid substitution within the fourth transmembrane helix of claudin-10. In addition to hypohidrosis (H), electrolyte (E) imbalance with impaired urine concentrating ability, and hypolacrimia (L), phenotypic findings include altered salivary electrolyte composition and amelogenesis imperfecta but neither ichthyosis (I) nor xerostomia (X). Employing cellular TJ reconstitution assays, we demonstrate perturbation of cis- and trans-interactions between mutant claudin-10 proteins. Ultrastructures of reconstituted TJ strands show disturbed continuity and reduced abundance in the mutant case. Throughout, both major isoforms, claudin-10a and claudin-10b, are differentially affected with claudin-10b showing more severe molecular alterations. However, expression of the mutant in renal epithelial cells with endogenous TJs results in wild-type-like ion selectivity and conductivity, indicating that aberrant claudin-10 is generally capable of forming functional paracellular channels. Thus, mutant proteins prove pathogenic by compromising claudin-10 TJ strand assembly. Additional ex vivo investigations indicate their insertion into TJs to occur in a tissue-specific manner.

Claudin-10a Deficiency Shifts Proximal Tubular Cl- Permeability to Cation Selectivity via Claudin-2 Redistribution.

BACKGROUND: The tight junction proteins claudin-2 and claudin-10a form paracellular cation and anion channels, respectively, and are expressed in the proximal tubule. However, the physiologic role of claudin-10a in the kidney has been unclear. METHODS: To investigate the physiologic role of claudin-10a, we generated claudin-10a-deficient mice, confirmed successful knockout by Southern blot, Western blot, and immunofluorescence staining, and analyzed urine and serum of knockout and wild-type animals. We also used electrophysiologic studies to investigate the functionality of isolated proximal tubules, and studied compensatory regulation by pharmacologic intervention, RNA sequencing analysis, Western blot, immunofluorescence staining, and respirometry. RESULTS: Mice deficient in claudin-10a were fertile and without overt phenotypes. On knockout, claudin-10a was replaced by claudin-2 in all proximal tubule segments. Electrophysiology showed conversion from paracellular anion preference to cation preference and a loss of paracellular Cl- over HCO3- preference. As a result, there was tubular retention of calcium and magnesium, higher urine pH, and mild hypermagnesemia. A comparison with other urine and serum parameters under control conditions and sequential pharmacologic transport inhibition, and unchanged fractional lithium excretion, suggested compensative measures in proximal and distal tubular segments. Changes in proximal tubular oxygen handling and differential expression of genes regulating fatty acid metabolism indicated proximal tubular adaptation. Western blot and immunofluorescence revealed alterations in distal tubular transport. CONCLUSIONS: Claudin-10a is the major paracellular anion channel in the proximal tubule and its deletion causes calcium and magnesium hyper-reabsorption by claudin-2 redistribution. Transcellular transport in proximal and distal segments and proximal tubular metabolic adaptation compensate for loss of paracellular anion permeability.

Governing complex societal problems: The impact of private on public regulation through technological change.

When addressing complex societal problems, public regulation is increasingly complemented by private regulation. Extant literature has provided valuable insights into the effectiveness of such complex governance structures, with most empirical studies focusing on how public regulation influences private regulation. Conversely, the impact of private on public regulation is less well studied. Here, we investigate this impact with a focus on technological change as possible mechanism. Based on a case study of energy efficiency in buildings in Switzerland, we find evidence of a symbiotic interaction between public and private regulation that leads to ratcheting-up of regulatory stringency. We identify technological change as the mechanism linking private and public regulation. We discuss the relevance of our findings for governance literature and regulators.

Matching clinical and genetic diagnoses in autosomal dominant polycystic kidney disease reveals novel phenocopies and potential candidate genes.

PURPOSE: Autosomal dominant polycystic kidney disease (ADPKD) represents the most common hereditary nephropathy. Despite growing evidence for genetic heterogeneity, ADPKD diagnosis is still primarily based upon clinical imaging criteria established before discovery of additional PKD genes. This study aimed at assessing the diagnostic value of genetic verification in clinical ADPKD. METHODS: In this prospective, diagnostic trial, 100 families with clinically diagnosed ADPKD were analyzed by PKD gene panel and multiplex ligation-dependent probe amplification (MLPA); exome sequencing (ES) was performed in panel/MLPA-negative families. RESULTS: Diagnostic PKD1/2 variants were identified in 81 families (81%), 70 of which in PKD1 and 11 in PKD2. PKD1 variants of unknown significance were detected in another 9 families (9%). Renal survival was significantly worse upon PKD1 truncation versus nontruncation and PKD2 alteration. Ten percent of the cohort were PKD1/2-negative, revealing alternative genetic diagnoses such as autosomal recessive PKD, Birt-Hogg-Dubé syndrome, and ALG9-associated PKD. In addition, among unsolved cases, ES yielded potential novel PKD candidates. CONCLUSION: By illustrating vast genetic heterogeneity, this study demonstrates the value of genetic testing in a real-world PKD cohort by diagnostic verification, falsification, and disease prediction. In the era of specific treatment for fast progressive ADPKD, genetic confirmation should form the basis of personalized patient care.

Anodal transcranial direct current stimulation (tDCS) over supplementary motor area (SMA) but not pre-SMA promotes short-term visuomotor learning.

BACKGROUND: Non-invasive brain stimulation such as transcranial direct current stimulation (tDCS) has been shown to modulate cortical excitability and thereby influencing motor behaviour and learning. HYPOTHESIS: While there is increasing knowledge about the importance of the primary motor cortex (M1) in short- and long-term motor skill learning, little is known about the role of secondary motor areas such as the supplementary and pre-supplementary motor area (SMA/pre-SMA) especially in short-term motor performance. Since SMA but not pre-SMA is directly connected to M1, we hypothesize that anodal tDCS over SMA but not pre-SMA will facilitate visuomotor learning. METHODS: We applied anodal tDCS (tDCS(anodal)) over left SMA, pre-SMA or M1 (n=12 in each group) while subjects performed a visuomotor pinch force task (VPFT) with their right hand and compared VPFT performance relative to sham (tDCS(sham)). RESULTS: For the first time, we could show that apart from tDCS(anodal) over left M1 also SMA but not pre-SMA stimulation promotes short-term improvements in visuomotor learning relative to tDCS(sham). CONCLUSIONS: Our findings provide novel evidence about the role of SMA in short-term visuomotor performance. This knowledge might be beneficial in developing hypothesis-driven clinical studies in neurorehabilitation.

Enhancing the effect of repetitive I-wave paired-pulse TMS (iTMS) by adjusting for the individual I-wave periodicity.

BACKGROUND: Repeated application of paired-pulse TMS over the primary motor cortex (M1) in human subjects with an inter-pulse interval (IPI) of 1.5 ms (iTMS(1.5 ms)) has been shown to significantly increase paired-pulse MEP (ppMEP) amplitudes during the stimulation period and increased single-pulse MEP amplitudes for up to 10 minutes after termination of iTMS. RESULTS: Here we show in a cross-over design that a modified version of the iTMS(1.5 ms) protocol with an I-wave periodicity adjusted to the individual I1-peak wave latency (iTMS(adj)) resulted in a stronger effect on ppMEPs relative to iTMS(1.5 ms). CONCLUSIONS: Based on these findings, our results indicate that the efficiency of iTMS strongly depends on the individual choice of the IPI and that parameter optimization of the conventional iTMS(1.5 ms) protocol might improve the outcome of this novel non-invasive brain stimulation technique.