Introduction:Glomerular structural-functional relationships in diabetes were tested, stratifying by glomerular basement membrane (GBM) thickness, an approach not previously explored. Methods:Research kidney biopsies were performed in 30 people with type 2 diabetes (T2D) and any of the following baseline characteristics: moderate/severe albuminuria (urine albumin:creatinine ratio [UACR]: >30 µg/mg), low estimated glomerular filtration rate (eGFR) (45-60 mL/min/1.73 m2, with and without albuminuria), or severe/proliferative retinopathy. Stereologic analyses were performed, and participants were stratified by the presence of GBM thickening. Standard light microscopy (LM) for glomerular, vascular, and tubulointerstitial lesions was performed in a subset (N = 19) with available paraffin-embedded tissue. Creatinine values were collected, and the eGFR slope was calculated. Results:Thickening of the GBM was present in 21 of 30 participants. Clinically, the GBM-thickened group differed numerically from the normal GBM group only in having a higher HbA1c (7.9% vs. 6.6%) and greater prevalence of albuminuria (67% vs. 22%). Correlations with eGFR slope were not present in the full cohort, but were present in the group with GBM thickening: fractional volume of mesangium per glomerulus (R = -0.4; p = 0.03), fractional volume of mesangial matrix per glomerulus (R = -0.5; p = 0.04), and podocyte foot process width (R = -0.5; p = 0.03). Results were unchanged after excluding two participants with normal UACR and eGFR. Of the six members of the subgroup without GBM thickening who had available LM, two had hypertensive nephrosclerosis, three had significant vascular lesions but no interstitial fibrosis, and one had mild vascular and interstitial lesions. Conclusion:This study highlights the need for further work to better categorize renal structural phenotypes in patients with T2D to facilitate kidney disease prognostication, novel biomolecular target discovery and therapies, and renal structural endpoints for clinical trials.

Despite recent progress in the identification of mediators of podocyte injury, mechanisms underlying podocyte loss remain poorly understood, and cell-specific therapy is lacking. We previously reported that kidney and brain expressed protein (KIBRA), encoded by WWC1, promotes podocyte injury in vitro through activation of the Hippo signaling pathway. KIBRA expression is increased in the glomeruli of patients with focal segmental glomerulosclerosis, and KIBRA depletion in vivo is protective against acute podocyte injury. Here, we tested the consequences of transgenic podocyte-specific WWC1 expression in immortalized human podocytes and in mice, and we explored the association between glomerular WWC1 expression and glomerular disease progression. We found that KIBRA overexpression in immortalized human podocytes promoted cytoplasmic localization of Yes-associated protein (YAP), induced actin cytoskeletal reorganization, and altered focal adhesion expression and morphology. WWC1-transgenic (KIBRA-overexpressing) mice were more susceptible to acute and chronic glomerular injury, with evidence of YAP inhibition in vivo. Of clinical relevance, glomerular WWC1 expression negatively correlated with renal survival among patients with primary glomerular diseases. These findings highlight the importance of KIBRA/YAP signaling to the regulation of podocyte structural integrity and identify KIBRA-mediated injury as a potential target for podocyte-specific therapy in glomerular disease.

Human specific and mouse specific primers were validated using human pheochromocytoma-derived peri-adrenal fat and mouse brown adipose tissue respectively.

Human breast tumors used in this study were according to the stage/grade

Sequence of various mouse and human primers used in this study.

Images of xenografts, osmium stained sections, quantitation of lipids and immunohistochemistry.

Upregulation of the markers of beige/brown adipocytes were not dependent on site of cancer cell injection.

Morphometric estimates of mean or individual glomerular volume (MGV, IGV) have biological implications, over and above qualitative histologic data. However, morphometry is time‐consuming and requires expertise limiting its utility in clinical cases. We evaluated MGV and IGV using plastic‐ and paraffin‐embedded tissue from 10 control and 10 focal segmental glomerulosclerosis (FSGS) mice (aging and 5/6th nephrectomy models) using the gold standard Cavalieri (Cav) method versus the 2‐profile and Weibel–Gomez (WG) methods and a novel 3‐profile method. We compared accuracy, bias and precision, and quantified results obtained when sampling differing numbers of glomeruli. In both FSGS and controls, we identified an acceptable precision for MGV of 10‐glomerular sampling versus 20‐glomerular sampling using the Cav method, while 5‐glomerular sampling was less precise. In plastic tissue, 2‐ or 3‐profile MGVs showed greater concordance with MGV when using Cav, versus MGV with WG. IGV comparisons using the same glomeruli reported a consistent underestimation bias with both 2‐ or 3‐profile methods versus the Cav method. FSGS glomeruli showed wider variations in bias estimation than controls. Our 3‐profile method offered incremental benefit to the 2‐profile method in both IGV and MGV estimation (improved correlation coefficient, Lin's concordance and reduced bias). In our control animals, we quantified a shrinkage artifact of 52% from tissue processed for paraffin‐embedded versus plastic‐embedded tissue. FSGS glomeruli showed overall reduced shrinkage albeit with variable artifact signifying periglomerular/glomerular fibrosis. A novel 3‐profile method offers slightly improved concordance with reduced bias versus 2‐profile. Our findings have implications for future studies using glomerular morphometry.

Sections of xenografts were analyzed for co-expression of collagen and adiponectin.

Background: Podocyte foot process effacement is a key histologic finding in proteinuric kidney disease. We previously showed that 3-week old CD2AP-deficient mice have significant proteinuria, glomerular hypertrophy and mesangial expansion. The goal of this study is to use morphometry to establish the temporal sequence of podocyte foot process effacement, glomerular volume expansion and albuminuria in Cd2ap−/− mice by measuring these parameters at the 2-week time point.Methods: Wild-type mice age 14 ± 1 days with the Cd2ap gene (WT, N = 5) and mice deficient for Cd2ap (Cd2ap KO, N = 5) were generated. Kidneys were harvested and fixed in 2.5% glutaraldehyde and processed for examination by light and electron microscopy. An average of 415.2 (range 268–716) grid points were counted for all the glomeruli, and quantification of glomerular volume from each kidney. Urine was collected the day prior to sacrifice for urine albumin-to-creatinine ratio (ACR) measurements.Results: There was no difference in albuminuria [median (range) mg/g] between WT [212.2 (177.6–388.4) mg/g] vs. Cd2ap KO mice [203.3 (164.7–910.2) mg/g], P = 0.89; or glomerular volume 68,307[10,931] vs. 66,844[13,022] μm3, p = 0.92. The volume densities of glomerular components of the podocyte, capillary lumen and mesangium were not different for the two groups, P = 0.14, 0.14 and 0.17 respectively. However, foot process width was increased in Cd2ap KO 1128[286] vs. WT [374 ± 42] nm, P = 0.02.Conclusion: Here we show that while 2-week old WT and Cd2ap KO mice have similar levels of albuminuria, glomerular and mesangial volume, Cd2ap KO mice have more extensive podocyte foot process effacement. The data suggests that podocyte injury is the initiating event leading to mesangial expansion and albuminuria in this model.

AIMS:Mitochondrial cardiomyopathy (MCM) is difficult to make a definite diagnosis because of various cardiovascular phenotypes and no diagnostic criteria in the pathology examination. We aim to add myocardial pathology to the diagnostic criteria for mitochondrial respiratory chain disorders.METHODS:Quantitative analysis of mitochondria using electron microscopy and immunohistopathological analysis with respiratory chain enzyme antibodies were performed in 11 patients with hypertrophic or restrictive cardiomyopathy who underwent endomyocardial biopsy for possible MCM . Respiratory chain enzymatic assay in biopsied myocardium and genetic studies were also performed in all the subjects to define MCM.RESULTS:Four patients were diagnosed with MCM according to the recent criteria of mitochondrial respiratory chain disorders. Using electron microscopy with quantitative analysis, the volume density of mitochondria within cardiac muscle cells was significantly increased in the MCM group compared with the non-MCM group (p=0.007). Immunohistopathological results were compatible with the result of the respiratory chain enzymatic assay.CONCLUSIONS:Pathological diagnosis of MCM could be confirmed by a quantitative study of electron microscopy and immunohistopathological analysis using the mitochondrial respiratory chain enzyme subunit antibody.

Dachshund homolog 1 (DACH1), a key cell-fate determinant, regulates transcription by DNA sequence-specific binding. We identified diminished Dach1 expression in a large-scale screen for mutations that convert injury-resistant podocytes into injury-susceptible podocytes. In diabetic kidney disease (DKD) patients, podocyte DACH1 expression levels are diminished, a condition that strongly correlates with poor clinical outcomes. Global Dach1 KO mice manifest renal hypoplasia and die perinatally. Podocyte-specific Dach1 KO mice, however, maintain normal glomerular architecture at baseline, but rapidly exhibit podocyte injury after diabetes onset. Furthermore, podocyte-specific augmentation of DACH1 expression in mice protects from DKD. Combined RNA sequencing and in silico promoter analysis reveal conversely overlapping glomerular transcriptomic signatures between podocyte-specific Dach1 and Pax transactivation-domain interacting protein (Ptip) KO mice, with upregulated genes possessing higher-than-expected numbers of promoter Dach1-binding sites. PTIP, an essential component of the activating histone H3 lysine 4 trimethylation (H3K4Me3) complex, interacts with DACH1 and is recruited by DACH1 to its promoter-binding sites. DACH1-PTIP recruitment represses transcription and reduces promoter H3K4Me3 levels. DACH1 knockdown in podocytes combined with hyperglycemia triggers target gene upregulation and increases promoter H3K4Me3. These findings reveal that in DKD, diminished DACH1 expression enhances podocyte injury vulnerability via epigenetic derepression of its target genes.

Herein, we report that Shroom3 knockdown, via Fyn inhibition, induced albuminuria with foot process effacement (FPE) without focal segmental glomerulosclerosis (FSGS) or podocytopenia. Interestingly, knockdown mice had reduced podocyte volumes. Human minimal change disease (MCD), where podocyte Fyn inactivation was reported, also showed lower glomerular volumes than FSGS. We hypothesized that lower glomerular volume prevented the progression to podocytopenia. To test this hypothesis, we utilized unilateral and 5/6th nephrectomy models in Shroom3-KD mice. Knockdown mice exhibited less glomerular and podocyte hypertrophy after nephrectomy. FYN-knockdown podocytes had similar reductions in podocyte volume, implying that Fyn was downstream of Shroom3. Using SHROOM3 or FYN knockdown, we confirmed reduced podocyte protein content, along with significantly increased phosphorylated AMPK, a negative regulator of anabolism. AMPK activation resulted from increased cytoplasmic redistribution of LKB1 in podocytes. Inhibition of AMPK abolished the reduction in glomerular volume and induced podocytopenia in mice with FPE, suggesting a protective role for AMPK activation. In agreement with this, treatment of glomerular injury models with AMPK activators restricted glomerular volume, podocytopenia, and progression to FSGS. Glomerular transcriptomes from MCD biopsies also showed significant enrichment of Fyn inactivation and Ampk activation versus FSGS glomeruli. In summary, we demonstrated the important role of AMPK in glomerular volume regulation and podocyte survival. Our data suggest that AMPK activation adaptively regulates glomerular volume to prevent podocytopenia in the context of podocyte injury.

BACKGROUND:We previously showed that the presence of a CKD-associated locus in SHROOM3 in a donor kidney results in increased expression of SHROOM3 (an F-actin-binding protein important for epithelial morphogenesis, via rho-kinase [ROCK] binding); this facilitates TGF-b signaling and allograft fibrosis. However, other evidence suggests Shroom3 may have a protective role in glomerular development.METHODS:We used human data, Shroom3 knockdown podocytes, and inducible shRNA-mediated knockdown mice to study the role of Shroom3 in adult glomeruli.RESULTS:Expression data from the Nephroseq database showed glomerular and nonglomerular SHROOM3 had opposing associations with renal function in CKD biopsy samples. In human allografts, homozygosity at rs17319721, the SHROOM3 locus linked with lower GFR, was associated with reduced albuminuria by 2 years after transplant. Although our previous data showed reduced renal fibrosis with tubular Shroom3 knockdown, this study found that glomerular but not tubular Shroom3 knockdown induced albuminuria. Electron microscopy revealed diffuse foot process effacement, and glomerular RNA-sequencing showed enrichment of tyrosine kinase signaling and podocyte actin cytoskeleton pathways in knockdown mice. Screening SHROOM3-interacting proteins identified FYN (a src-kinase) as a candidate.We confirmed the interaction of endogenous SHROOM3 with FYN in human podocytes via a critical Src homology 3-binding domain, distinct from its ROCK-binding domain. Shroom3-Fyn interaction was required in vitro and in vivo for activation of Fyn kinase and downstream nephrin phosphorylation in podocytes. SHROOM3 knockdown altered podocyte morphology, cytoskeleton, adhesion, and migration.CONCLUSIONS:We demonstrate a novel mechanism that may explain SHROOM3's dichotomous associations in glomerular versus nonglomerular compartments in CKD.

Progressive kidney diseases are often associated with scarring of the kidney’s filtration unit, a condition called focal segmental glomerulosclerosis (FSGS). This scarring is due to loss of podocytes, cells critical for glomerular filtration, and leads to proteinuria and kidney failure. Inherited forms of FSGS are caused by Rac1-activating mutations, and Rac1 induces TRPC5 ion channel activity and cytoskeletal remodeling in podocytes. Whether TRPC5 activity mediates FSGS onset and progression is unknown. We identified a small molecule, AC1903, that specifically blocks TRPC5 channel activity in glomeruli of proteinuric rats. Chronic administration of AC1903 suppressed severe proteinuria and prevented podocyte loss in a transgenic rat model of FSGS. AC1903 also provided therapeutic benefit in a rat model of hypertensive proteinuric kidney disease. These data indicate that TRPC5 activity drives disease and that TRPC5 inhibitors may be valuable for the treatment of progressive kidney diseases.

Abstract The initiation and progression of breast cancer is a complex process that is influenced by heterogeneous cell populations within the tumor microenvironment. Although adipocytes have been shown to promote breast cancer development, adipocyte characteristics involved in this process remain poorly understood. In this study, we demonstrate enrichment of beige/brown adipose markers, contributed from the host as well as tumor cells, in the xenografts from breast cancer cell lines. In addition to uncoupling protein-1 (UCP1) that is exclusively expressed in beige/brown adipocytes, gene expression for classical brown (MYF5, EVA1, and OPLAH) as well as beige (CD137/TNFRSF9 and TBX1) adipocyte markers was also elevated in the xenografts. Enrichment of beige/brown characteristics in the xenografts was independent of the site of implantation of the breast tumor cells. Early stages of xenografts showed an expansion of a subset of mammary cancer stem cells that expressed PRDM16, a master regulator of brown adipocyte differentiation. Depletion of UCP1+ or Myf5+ cells significantly reduced tumor development. There was increased COX2 (MT-CO2) expression, which is known to stimulate formation of beige adipocytes in early xenografts and treatment with a COX2 inhibitor (SC236) reduced tumor growth. In contrast, treatment with factors that induce brown adipocyte differentiation in vitro led to larger tumors in vivo. A panel of xenografts derived from established breast tumor cells as well as patient tumor tissues were generated that expressed key brown adipose tissue–related markers and contained cells that morphologically resembled brown adipocytes. Implications: This is the first report demonstrating that beige/brown adipocyte characteristics could play an important role in breast tumor development and suggest a potential target for therapeutic drug design. Mol Cancer Res; 14(1); 78–92. ©2015 AACR.

Pomegranate (Punica granatum L.) has been used widely in the traditional medicine of various civilizations for more than 5000 years. The pomegranate tree has several parts; each part has useful medicinal effects. Previous studies have demonstrated the antibacterial, antioxidant, and anti-inflammatory properties of pomegranate. The aim of the present study was to determine whether administration of pomegranate extract could result in morphometric changes in the kidneys of rats. Eighteen male rats (180-200 g) were divided into three groups that received either: G1, distilled water; G2, 250 mg kg(-1) pomegranate extract; and G3, 500 mg kg(-1) pomegranate extract via oral gavages daily for eight weeks. At the end of eight weeks, the rats were euthanized and their kidneys were removed and processed for morphometric analyses. In rats received pomegranate extract, the kidney weight, kidney weight/body weight ratio, cortex v/lume and glomerular volume were increased (p < 0.05), while, medulla volume and the number of glomeruli per kidney did not change. No pathological lesions were observed in the kidney. Therefore, pomegranate hydro-alcoholic extract at doses of 250 and 500 (mg kg(-1)) increased the volume of some parts of the kidney; however, it did not cause any pathological changes in the kidney.

Podocyte loss is central to the progression of proteinuric kidney diseases leading to end-stage kidney disease (ESKD), requiring renal replacement therapy, such as dialysis. Despite modern tools and techniques, the 5-year mortality of some patients requiring dialysis remains at about 70% to 80%. Thus, there is a great unmet need for podocyte-specific treatments aimed at preventing podocyte loss and the ensuing development of ESKD. Here, we show that ablation of the podocyte death-promoting protein dendrin delays the onset of ESKD, thereby expanding the life span of mice lacking the adapter protein CD2AP. Ablation of dendrin delays onset and severity of proteinuria and podocyte loss. In addition, dendrin ablation ameliorates mesangial volume expansion and up-regulation of mesangial fibronectin expression, which is mediated by a podocyte-secreted factor. In conclusion, onset of ESKD and death can be markedly delayed by blocking the function of dendrin.

FSGS is the most common primary glomerular disease underlying ESRD in the United States and is increasing in incidence globally. FSGS results from podocyte injury, yet the mechanistic details of disease pathogenesis remain unclear. This has resulted in an unmet clinical need for cell-specific therapy in the treatment of FSGS and other proteinuric kidney diseases. We previously identified Yes-associated protein (YAP) as a prosurvival signaling molecule, the in vitro silencing of which increases podocyte susceptibility to apoptotic stimulus. YAP is a potent oncogene that is a prominent target for chemotherapeutic drug development. In this study, we tested the hypothesis that podocyte-specific deletion of Yap leads to proteinuric kidney disease through increased podocyte apoptosis. Yap was selectively silenced in podocytes using Cre-mediated recombination controlled by the podocin promoter. Yap silencing in podocytes resulted in podocyte apoptosis, podocyte depletion, proteinuria, and an increase in serum creatinine. Histologically, features characteristic of FSGS, including mesangial sclerosis, podocyte foot process effacement, tubular atrophy, interstitial fibrosis, and casts, were observed. In human primary FSGS, we noted reduced glomerular expression of YAP. Taken together, these results suggest a role for YAP as a physiologic antagonist of podocyte apoptosis, the signaling of which is essential for maintaining the integrity of the glomerular filtration barrier. These data suggest potential nephrotoxicity with strategies directed toward inhibition of YAP function. Further studies should evaluate the role of YAP in proteinuric glomerular disease pathogenesis and its potential utility as a therapeutic target.