Developmental origins for kidney disease due to Shroom3 deficiency

CKD is a significant health concern with an underlying genetic component. Multiple genome-wide association studies (GWASs) strongly associated CKD with the shroomfamilymember 3 (SHROOM3) gene, which encodes an actin-associated protein important in epithelial morphogenesis. However, the role of SHROOM3 in kidney development and function is virtually unknown. Studies in zebrafish and rat showed that alterations in Shroom3 can result in glomerular dysfunction. Furthermore, human SHROOM3 variants can induce impaired kidney function in animal models. Here, we examined the temporal and spatial expression of Shroom3 in the mammalian kidney. We detected Shroom3 expression in the condensing mesenchyme, Bowman\u27s capsule, and developing and mature podocytes in mice. Shroom3 null (Shroom3Gt/Gt) mice showed marked glomerular abnormalities, including cystic and collapsing/degenerating glomeruli, and marked disruptions in podocyte arrangement and morphology. These podocyte-specific abnormalities are associated with altered Rho-kinase/myosin II signaling and loss of apically distributed actin. Additionally, Shroom3 heterozygous (Shroom3Gt/+) mice showed developmental irregularities that manifested as adult-onset glomerulosclerosis and proteinuria. Taken together, our results establish the significance of Shroom3 in mammalian kidney development and progression of kidney disease. Specifically, Shroom3 maintains normal podocyte architecture in mice via modulation of the actomyosin network, which is essential for podocyte function. Furthermore, our findings strongly support the GWASs that suggest a role for SHROOM3 in human kidney disease

Genome-wide analysis identifies 12 loci influencing human reproductive behavior.

The genetic architecture of human reproductive behavior-age at first birth (AFB) and number of children ever born (NEB)-has a strong relationship with fitness, human development, infertility and risk of neuropsychiatric disorders. However, very few genetic loci have been identified, and the underlying mechanisms of AFB and NEB are poorly understood. We report a large genome-wide association study of both sexes including 251,151 individuals for AFB and 343,072 individuals for NEB. We identified 12 independent loci that are significantly associated with AFB and/or NEB in a SNP-based genome-wide association study and 4 additional loci associated in a gene-based effort. These loci harbor genes that are likely to have a role, either directly or by affecting non-local gene expression, in human reproduction and infertility, thereby increasing understanding of these complex traits

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

Stromal β-catenin overexpression contributes to the pathogenesis of renal dysplasia.

Renal dysplasia, the leading cause of renal failure in children, is characterized by disrupted branching of the collecting ducts and primitive tubules, with an expansion of the stroma, yet a role for the renal stroma in the genesis of renal dysplasia is not known. Here, we demonstrate that expression of β-catenin, a key transcriptional co-activator in renal development, is markedly increased in the expanded stroma in human dysplastic tissue. To understand its contribution to the genesis of renal dysplasia, we generated a mouse model that overexpresses β-catenin specifically in stromal progenitors, termed β-cat(GOF-S) . Histopathological analysis of β-cat(GOF) (-S) mice revealed a marked expansion of fibroblast cells surrounding primitive ducts and tubules, similar to defects observed in human dysplastic kidneys. Characterization of the renal stroma in β-cat(GOF) (-S) mice revealed altered stromal cell differentiation in the expanded renal stroma demonstrating that this is not renal stroma but instead a population of stroma-like cells. These cells overexpress ectopic Wnt4 and Bmp4, factors necessary for endothelial cell migration and blood vessel formation. Characterization of the renal vasculature demonstrated disrupted endothelial cell migration, organization, and vascular morphogenesis in β-cat(GOF) (-S) mice. Analysis of human dysplastic tissue demonstrated a remarkably similar phenotype to that observed in our mouse model, including altered stromal cell differentiation, ectopic Wnt4 expression in the stroma-like cells, and disrupted endothelial cell migration and vessel formation. Our findings demonstrate that the overexpression of β-catenin in stromal cells is sufficient to cause renal dysplasia. Further, the pathogenesis of renal dysplasia is one of disrupted stromal differentiation and vascular morphogenesis. Taken together, this study demonstrates for the first time the contribution of stromal β-catenin overexpression to the genesis of renal dysplasia. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd

Stromally Expressed β-Catenin Modulates Wnt9b Signaling in the Ureteric Epithelium

<div><p>The mammalian kidney undergoes cell interactions between the epithelium and mesenchyme to form the essential filtration unit of the kidney, termed the nephron. A third cell type, the kidney stroma, is a population of fibroblasts located in the kidney capsule, cortex and medulla and is ideally located to affect kidney formation. We found β-catenin, a transcriptional co-activator, is strongly expressed in distinctive intracellular patterns in the capsular, cortical, and medullary renal stroma. We investigated β-catenin function in the renal stroma using a conditional knockout strategy that genetically deleted β-catenin specifically in the renal stroma cell lineage (β-cat^s-/-). <i>β-cat^s-/-</i> mutant mice demonstrate marked kidney abnormalities, and surprisingly we show β-catenin in the renal stroma is essential for regulating the condensing mesenchyme cell population. We show that the population of induced mesenchyme cells is significantly reduced in <i>β-cat^s-/-</i> mutants and exhibited decreased cell proliferation and a specific loss of Cited 1, while maintaining the expression of other essential nephron progenitor proteins. <i>Wnt9b</i>, the key signal for the induction of nephron progenitors, was markedly reduced in adjacent ureteric epithelial cells in <i>β-cat^s-/-</i>. Analysis of Wnt9b-dependent genes in the neighboring nephron progenitors was significantly reduced while Wnt9b-independent genes remained unchanged. In contrast mice overexpressing β-catenin exclusively in the renal stroma demonstrated massive increases in the condensing mesenchyme population and <i>Wnt9b</i> was markedly elevated. We propose that β-catenin in the renal stroma modulates a genetic program in ureteric epithelium that is required for the induction of nephron progenitors.</p></div

β-catenin is expressed in distinctive patterns in the renal stroma.

<p>(A-I) Immunofluorescence demonstrating β-catenin spatial and temporal expression in stromal cells. (A) At E11.5 Pbx1 is expressed in the nucleus of stromal cells (arrow head-inset) surrounding the condensing mesenchyme. Some Pbx1 positive stromal cells locate within the condensing mesenchyme, directly adjacent to epithelial cells (arrows). (B,C) At E11.5 β-catenin is expressed in the condensing mesenchyme and ureteric epithelium, and co-localizes with Pbx1 demonstrating expression in the renal stroma. At E11.5, some Pbx1 cells co-localize with β-catenin in the nuclear compartment of stromal cells (arrowhead-inset). (D) At E13.5, Pbx1 is expressed in capsular and cortical stroma surrounding the condensing mesenchyme. (E, F) At E13.5, β-catenin co-localizes in the cytoplasm of capsular stromal cells. The stromal cells located between developing nephrons express β-catenin in the cytoplasmic (arrow-inset) and nuclear compartment (arrowhead-inset). (G) At E17.5, Pbx1 marks the capsular, cortical, and medullary stroma. (H-I) β-catenin is expressed in the medullary stroma and co-localizes strongly with Pbx1 in the nuclear compartment (arrowhead-inset). (scale bar = 100μm, s = stroma, cm = condensing mesenchyme, ub = ureteric epithelium, rc = renal capsule, ms = medullary stroma, rp = renal pelvis).</p

The condensing mesenchyme cell population is reduced in <i>β-cat</i>^<i>S-/</i>- mutant kidneys.

<p>(A,B) As compared to <i>WT</i>, which demonstrates 3–4 cell layers of aggregated condensing mesenchyme, <i>β-cat</i>^<i>S-/</i>- kidneys display a reduced, single cell layer of loosely aggregated condensing mesenchyme. (C-H) Analysis of cell proliferation in the condensing mesenchyme was performed using Brdu cell proliferation assay. (C-E) As compared to <i>WT</i>, <i>β-cat</i>^<i>S-/</i>- mutants demonstrated a 6.46% reduction in condensing mesenchyme cell proliferation at E14.5 (<i>WT</i>, 34.56%±1.45, n = 28 versus <i>β-cat</i>^<i>S-/</i>-, 28.02%±1.05, n = 27, p = 0.0006). (F-G) At E15.5 <i>β-cat</i>^<i>S-/</i>- mutants demonstrated a 7.35% reduction in condensing mesenchyme cell proliferation when compared to <i>WT</i> (<i>WT</i>, 34.09%±1.65, n = 17 versus <i>β-cat</i>^<i>S-/</i>-, 26.73%±2.21, n = 15, p = 0.01). (I,J) A TUNEL assay at E15.5 did not reveal any changes in apoptosis in the condensing mesenchyme between <i>WT</i> and <i>β-cat</i>^<i>S-/</i>-. Scale Bar = 50μm</p