A large proportion of recessive non-syndromic hearing loss is due to mutations in the GJB2 gene encoding connexin 26 (Cx26), a component of a gap junction. Within different ethnic groups there are specific common recessive mutations each with a relatively high carrier frequency suggesting a possibility of heterozygous advantage. Carriers of the R143W GJB2 allele, the most prevalent in the African population, present with a thicker epidermis than non-carriers. In this study, we show (R143W)Cx26 expressing keratinocytes form a significantly thicker epidermis in an organotypic co-culture skin model. In addition, we show increased migration of cells expressing (R143W)Cx26 compared to (WT)Cx26 overexpressing cells. We also demonstrate that cells expressing (R143W)Cx26 are significantly less susceptible to cellular invasion by the enteric pathogen Shigella flexneri than (WT)Cx26 expressing cells. These in vitro studies suggest an advantageous effect of (R143W)Cx26 in epithelial cells.

Summary Endogenous PIEZO1 channels of native endothelium lack the hallmark inactivation often seen when these channels are overexpressed in cell lines. Because prior work showed that the force of shear stress activates sphingomyelinase in endothelium, we considered if sphingomyelinase is relevant to endogenous PIEZO1. Patch clamping was used to quantify PIEZO1-mediated signals in freshly isolated murine endothelium exposed to the mechanical forces caused by shear stress and membrane stretch. Neutral sphingomyelinase inhibitors and genetic disruption of sphingomyelin phosphodiesterase 3 (SMPD3) cause PIEZO1 to switch to profoundly inactivating behavior. Ceramide (a key product of SMPD3) rescues non-inactivating channel behavior. Its co-product, phosphoryl choline, has no effect. In contrast to ceramide, sphingomyelin (the SMPD3 substrate) does not affect inactivation but alters channel force sensitivity. The data suggest that sphingomyelinase activity, ceramide, and sphingomyelin are determinants of native PIEZO gating that enable sustained activity.

This is a repository copy of Biallelic inheritance of hypomorphic PKD1 variants is highly prevalent in very early onset polycystic kidney disease.

Birth weight is an important indicator of both perinatal and adult health, but little is known about the genetic factors contributing to its variability. Intrauterine growth restriction is a leading cause of perinatal morbidity and mortality and is also associated with adult disease. A significant correlation has been reported between lower birth weight and increased expression of the maternal PHLDA2 allele in term placenta (the normal imprinting pattern was maintained). However, a mechanism that explains the transcriptional regulation of PHLDA2 on in utero growth has yet to be described. In this study, we sequenced the PHLDA2 promoter region in 263 fetal DNA samples to identify polymorphic variants. We used a luciferase reporter assay to identify in the PHLDA2 promoter a 15 bp repeat sequence (RS1) variant that significantly reduces PHLDA2-promoter efficiency. RS1 genotyping was then performed in three independent white European normal birth cohorts. Meta-analysis of all three (total n = 9,433) showed that maternal inheritance of RS1 resulted in a significant 93 g increase in birth weight (p = 0.01; 95% confidence interval [CI] = 22-163). Moreover, when the mother was homozygous for RS1, the influence on birth weight was 155 g (p = 0.04; 95% CI = 9-300), which is a similar magnitude to the reduction in birth weight caused by maternal smoking.

Piezo1 forms a mechanically activated calcium-permeable nonselective cation channel that is functionally important in many cell types. Structural data exist for C-terminal regions, but we lack information about N-terminal regions and how the entire channel interacts with the lipid bilayer. Here, we use computational approaches to predict the three-dimensional structure of the full-length Piezo1 and simulate it in an asymmetric membrane. A number of novel insights are suggested by the model: 1) Piezo1 creates a trilobed dome in the membrane that extends beyond the radius of the protein, 2) Piezo1 changes the lipid environment in its vicinity via preferential interactions with cholesterol and phosphatidylinositol 4,5-bisphosphate (PIP 2 ) molecules, and 3) cholesterol changes the depth of the dome and PIP 2 binding preference. In vitro alteration of cholesterol concentration inhibits Piezo1 activity in a manner complementing some of our computational findings. The data suggest the importance of N-terminal regions of Piezo1 for dome structure and membrane cholesterol and PIP 2 interactions.

14 Piezo1 is a critical mechanical sensor in many cells. It is activated by mechanical force thus 15 allowing cells to sense the physical environment and respond to stress. Structural data have 16suggested that Piezo1 has a curved shape. Here, we use computational approaches to model, 17for the first time, the 3D structure of the full-length Piezo1 in an asymmetric membrane. A 18 number of novel insights emerge: (i) Piezo1 creates a dome in the membrane with a trilobed 19 topology that extends beyond the radius of the protein, (ii) Piezo1 changes the lipid 20 environment in its vicinity via specific interactions with cholesterol and PIP2 molecules, (iii) 21 changes in cholesterol concentration that change the membrane stiffness result in changes in 22 the depth of the dome created by Piezo1, and iv) modelling of the N-terminal region that is 23 missing from current structures modifies Piezo1 membrane footprint, suggesting the 24 importance of this region in Piezo1 function. 25

The first clinical descriptions of autosomal dominant polycystic kidney disease (ADPKD) go back at least 500 years to the late 16 th century. Advances in understanding disease presentation and pathophysiology have mirrored the progress of clinical medicine in anatomy, pathology, physiology, cell biology, and genetics. The identification of PKD1 and PKD2, the major genes mutated in ADPKD, has stimulated major advances, which in turn have led to the first approved drug for this disorder and a fresh reassessment of patient management in the 21 st century. In this commentary, we consider how clinical management is likely to change in the coming decade.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is thought to affect about 1 in 1000 people in the UK. ADPKD causes a progressive decline in kidney function, with kidney failure tending to occur in middle age. Children and young people with ADPKD may not have any symptoms. However they may have high blood pressure, which may accelerate progression to later stages of chronic kidney disease. There is uncertainty and variation in how health professionals manage children and young people with confirmed or a family history of ADPKD, because of a lack of evidence. For example, health professionals may be unsure about when to test children’s blood pressure and how often to monitor it in the hospital clinic or at the GP. They may have different approaches in recommending scanning or genetic testing for ADPKD in childhood, with some recommending waiting until the young person is mature enough to make this decision his or herself. This guideline is intended to help families affected by ADPKD by making sure that: health professionals with specialist knowledge in ADPKD offer you information on inheritance and potential benefits and harms of testing for ADPKD. the decision to test and the method of testing for ADPKD in children and young people is shared between you or your family and the health professionals blood pressure assessment is undertaken regularly in children and young people at risk of developing ADPKD