Podocyte-derived soluble RARRES1 drives kidney disease progression through direct podocyte and proximal tubular injury.

Retinoic acid receptor responder protein-1 (RARRES1) is a podocyte-enriched transmembrane protein whose increased expression correlates with human glomerular disease progression. RARRES1 promotes podocytopenia and glomerulosclerosis via p53-mediated podocyte apoptosis. Importantly, the cytopathic actions of RARRES1 are entirely dependent on its proteolytic cleavage into a soluble protein (sRARRES1) and subsequent podocyte uptake by endocytosis, as a cleavage mutant RARRES1 exerted no effects in vitro or in vivo. As RARRES1 expression is upregulated in human glomerular diseases, here we investigated the functional consequence of podocyte-specific overexpression of RARRES1 in mice in the experimental focal segmental glomerulosclerosis and diabetic kidney disease. We also examined the effects of long-term RARRES1 overexpression on slowly developing aging-induced kidney injury. As anticipated, the induction of podocyte overexpression of RARRES1 (Pod-RARRES1WT) significantly worsened glomerular injuries and worsened kidney function in all three models, while overexpression of RARRES1 cleavage mutant (Pod-RARRES1MT) did not. Remarkably, direct uptake of sRARRES1 was also seen in proximal tubules of injured Pod-RARRES1WT mice and associated with exacerbated tubular injuries, vacuolation, and lipid accumulation. Single-cell RNA sequence analysis of mouse kidneys demonstrated RARRES1 led to a marked deregulation of lipid metabolism in proximal tubule subsets. We further identified matrix metalloproteinase 23 (MMP23) as a highly podocyte-specific metalloproteinase and responsible for RARRES1 cleavage in disease settings, as adeno-associated virus 9-mediated knockdown of MMP23 abrogated sRARRES1 uptake in tubular cells in vivo. Thus, our study delineates a previously unrecognized mechanism by which a podocyte-derived protein directly facilitates podocyte and tubular injury in glomerular diseases and suggests that podocyte-specific functions of RARRES1 and MMP23 may be targeted to ameliorate glomerular disease progression in vivo.

Chronic kidney disease in a murine model of non-alcoholic steatohepatitis (NASH).

Clinical studies suggest that non-alcoholic steatohepatitis (NASH) is an independent risk factor for chronic kidney disease (CKD), but causality and mechanisms linking these two major diseases are lacking. To assess whether NASH can induce CKD, we have characterized kidney function, histological features, transcriptomic and lipidomic profiles in a well-validated murine NASH model. Mice with NASH progressively developed significant podocyte foot process effacement, proteinuria, glomerulosclerosis, tubular epithelial cell injury, lipid accumulation, and interstitial fibrosis. The progression of kidney fibrosis paralleled the severity of the histologic NASH-activity score. Significantly, we confirmed the causal link between NASH and CKD by orthotopic liver transplantation, which attenuated proteinuria, kidney dysfunction, and fibrosis compared with control sham operated mice. Transcriptomic analysis of mouse kidney cortices revealed differentially expressed genes that were highly enriched in mitochondrial dysfunction, lipid metabolic process, and insulin signaling pathways in NASH-induced CKD. Lipidomic analysis of kidney cortices further revealed that phospholipids and sphingolipids were the most significantly changed lipid species. Notably, we found similar kidney histological changes in human NASH and CKD. Thus, our results confirm a causative role of NASH in the development of CKD, reveal potential pathophysiologic mechanisms of NASH-induced kidney injury, and established a valuable model to study the pathogenesis of NASH-associated CKD. This is an important feature of fatty liver disease that has been largely overlooked but has clinical and prognostic importance.

A large-scale retrospective study enabled deep-learning based pathological assessment of frozen procurement kidney biopsies to predict graft loss and guide organ utilization.

Lesion scores on procurement donor biopsies are commonly used to guide organ utilization for deceased-donor kidneys. However, frozen sections present challenges for histological scoring, leading to inter- and intra-observer variability and inappropriate discard. Therefore, we constructed deep-learning based models to recognize kidney tissue compartments in hematoxylin & eosin-stained sections from procurement needle biopsies performed nationwide in years 2011-2020. To do this, we extracted whole-slide abnormality features from 2431 kidneys and correlated with pathologists' scores and transplant outcomes. A Kidney Donor Quality Score (KDQS) was derived and used in combination with recipient demographic and peri-transplant characteristics to predict graft loss or assist organ utilization. The performance on wedge biopsies was additionally evaluated. Our model identified 96% and 91% of normal/sclerotic glomeruli respectively; 94% of arteries/arterial intimal fibrosis; 90% of tubules. Whole-slide features of Sclerotic Glomeruli (GS)%, Arterial Intimal Fibrosis (AIF)%, and Interstitial Space Abnormality (ISA)% demonstrated strong correlations with corresponding pathologists' scores of all 2431 kidneys, but had superior associations with post-transplant estimated glomerular filtration rates in 2033 and graft loss in 1560 kidneys. The combination of KDQS and other factors predicted one- and four-year graft loss in a discovery set of 520 kidneys and a validation set of 1040 kidneys. By using the composite KDQS of 398 discarded kidneys due to "biopsy findings", we suggest that if transplanted, 110 discarded kidneys could have had similar survival to that of other transplanted kidneys. Thus, our composite KDQS and survival prediction models may facilitate risk stratification and organ utilization while potentially reducing unnecessary organ discard.

Puerarin attenuates diabetic kidney injury through interaction with Guanidine nucleotide-binding protein Gi subunit alpha-1 (Gnai1) subunit.

Radix puerariae, a traditional Chinese herbal medication, has been used to treat patients with diabetic kidney disease (DKD). Our previous studies demonstrated that puerarin, the active compound of radix puerariae, improves podocyte injury in type 1 DKD mice. However, the direct molecular target of puerarin and its underlying mechanisms in DKD remain unknown. In this study, we confirmed that puerarin also improved DKD in type 2 diabetic db/db mice. Through RNA-sequencing odf isolated glomeruli, we found that differentially expressed genes (DEGs) that were altered in the glomeruli of these diabetic mice but reversed by puerarin treatment were involved mostly in oxidative stress, inflammatory and fibrosis. Further analysis of these reversed DEGs revealed protein kinase A (PKA) was among the top pathways. By utilizing the drug affinity responsive target stability method combined with mass spectrometry analysis, we identified guanine nucleotide-binding protein Gi alpha-1 (Gnai1) as the direct binding partner of puerarin. Gnai1 is an inhibitor of cAMP production which is known to have protection against podocyte injury. In vitro, we showed that puerarin not only interacted with Gnai1 but also increased cAMP production in human podocytes and mouse diabetic kidney in vivo. Puerarin also enhanced CREB phosphorylation, a downstream transcription factor of cAMP/PKA. Overexpression of CREB reduced high glucose-induced podocyte apoptosis. Inhibition of PKA by Rp-cAMP also diminished the effects of puerarin on high glucose-induced podocyte apoptosis. We conclude that the renal protective effects of puerarin are likely through inhibiting Gnai1 to activate cAMP/PKA/CREB pathway in podocytes.

Deep learning identified pathological abnormalities predictive of graft loss in kidney transplant biopsies.

Interstitial fibrosis, tubular atrophy, and inflammation are major contributors to kidney allograft failure. Here we sought an objective, quantitative pathological assessment of these lesions to improve predictive utility and constructed a deep-learning-based pipeline recognizing normal vs. abnormal kidney tissue compartments and mononuclear leukocyte infiltrates. Periodic acid- Schiff stained slides of transplant biopsies (60 training and 33 testing) were used to quantify pathological lesions specific for interstitium, tubules and mononuclear leukocyte infiltration. The pipeline was applied to the whole slide images from 789 transplant biopsies (478 baseline [pre-implantation] and 311 post-transplant 12-month protocol biopsies) in two independent cohorts (GoCAR: 404 patients, AUSCAD: 212 patients) of transplant recipients to correlate composite lesion features with graft loss. Our model accurately recognized kidney tissue compartments and mononuclear leukocytes. The digital features significantly correlated with revised Banff 2007 scores but were more sensitive to subtle pathological changes below the thresholds in the Banff scores. The Interstitial and Tubular Abnormality Score (ITAS) in baseline samples was highly predictive of one-year graft loss, while a Composite Damage Score in 12-month post-transplant protocol biopsies predicted later graft loss. ITASs and Composite Damage Scores outperformed Banff scores or clinical predictors with superior graft loss prediction accuracy. High/intermediate risk groups stratified by ITASs or Composite Damage Scores also demonstrated significantly higher incidence of estimated glomerular filtration rate decline and subsequent graft damage. Thus, our deep-learning approach accurately detected and quantified pathological lesions from baseline or post-transplant biopsies and demonstrated superior ability for prediction of post-transplant graft loss with potential application as a prevention, risk stratification or monitoring tool.

Genome-wide non-HLA donor-recipient genetic differences influence renal allograft survival via early allograft fibrosis.

Donor-recipient (D-R) differences at human leukocyte antigen (HLA) loci are currently incorporated into organ sharing, allocation and immunosuppression decisions. However, while acute rejection episodes have substantially diminished, progressive histologic damage occurs in allografts and improved long-term survival remains an unrealized goal among kidney recipients. Here we tested the hypothesis that non-HLA dependent, genome-wide D-R genetic differences could contribute to unchecked alloimmunity with histologic and functional consequences, culminating in long-term allograft failure. Genome-wide single nucleotide polymorphism (SNP) array data, excluding the HLA region, was utilized from 385 transplants to study the role of D-R differences upon serial histology and allograft survival. ADMIXTURE analysis was performed to quantitatively estimate ancestry in each D-R pair and PLINK was used to estimate the proportion of genome-shared identity-by-descent (pIBD) between D-R pairs. Subsequently, quantitative measures of recipient ancestry based on non-HLA SNPs was associated with death-censored allograft survival in adjusted Cox models. In D-R pairs of similar ancestry, pIBD was significantly associated with allograft survival independent of HLA mismatches in 224 transplants. Surprisingly, pIBD and recipient ancestry were not associated with clinical or subclinical rejection at any time post-transplant. Significantly, in multivariable analysis, pIBD inversely correlated with vascular intimal fibrosis in 160 biopsies obtained less than one year which in turn was significantly associated with allograft survival. Thus, our novel data show that non-HLA D-R differences associate with early vascular intimal fibrosis and allograft survival.

A Peripheral Blood Gene Expression Signature to Diagnose Subclinical Acute Rejection.

BACKGROUND: In kidney transplant recipients, surveillance biopsies can reveal, despite stable graft function, histologic features of acute rejection and borderline changes that are associated with undesirable graft outcomes. Noninvasive biomarkers of subclinical acute rejection are needed to avoid the risks and costs associated with repeated biopsies. METHODS: We examined subclinical histologic and functional changes in kidney transplant recipients from the prospective Genomics of Chronic Allograft Rejection (GoCAR) study who underwent surveillance biopsies over 2 years, identifying those with subclinical or borderline acute cellular rejection (ACR) at 3 months (ACR-3) post-transplant. We performed RNA sequencing on whole blood collected from 88 individuals at the time of 3-month surveillance biopsy to identify transcripts associated with ACR-3, developed a novel sequencing-based targeted expression assay, and validated this gene signature in an independent cohort. RESULTS: Study participants with ACR-3 had significantly higher risk than those without ACR-3 of subsequent clinical acute rejection at 12 and 24 months, faster decline in graft function, and decreased graft survival in adjusted Cox analysis. We identified a 17-gene signature in peripheral blood that accurately diagnosed ACR-3, and validated it using microarray expression profiles of blood samples from 65 transplant recipients in the GoCAR cohort and three public microarray datasets. In an independent cohort of 110 transplant recipients, tests of the targeted expression assay on the basis of the 17-gene set showed that it identified individuals at higher risk of ongoing acute rejection and future graft loss. CONCLUSIONS: Our targeted expression assay enabled noninvasive diagnosis of subclinical acute rejection and inflammation in the graft and may represent a useful tool to risk-stratify kidney transplant recipients.

Smad4 deficiency impairs chondrocyte hypertrophy via the Runx2 transcription factor in mouse skeletal development.

Chondrocyte hypertrophy is the terminal step in chondrocyte differentiation and is crucial for endochondral bone formation. How signaling pathways regulate chondrocyte hypertrophic differentiation remains incompletely understood. In this study, using a Tbx18:Cre (Tbx18Cre/+) gene-deletion approach, we selectively deleted the gene for the signaling protein SMAD family member 4 (Smad4f/f ) in the limbs of mice. We found that the Smad4-deficient mice develop a prominent shortened limb, with decreased expression of chondrocyte differentiation markers, including Col2a1 and Acan, in the humerus at mid-to-late gestation. The most striking defects in these mice were the absence of stylopod elements and failure of chondrocyte hypertrophy in the humerus. Moreover, expression levels of the chondrocyte hypertrophy-related markers Col10a1 and Panx3 were significantly decreased. Of note, we also observed that the expression of runt-related transcription factor 2 (Runx2), a critical mediator of chondrocyte hypertrophy, was also down-regulated in Smad4-deficient limbs. To determine how the skeletal defects arose in the mouse mutants, we performed RNA-Seq with ChIP-Seq analyses and found that Smad4 directly binds to regulatory elements in the Runx2 promoter. Our results suggest a new mechanism whereby Smad4 controls chondrocyte hypertrophy by up-regulating Runx2 expression during skeletal development. The regulatory mechanism involving Smad4-mediated Runx2 activation uncovered here provides critical insights into bone development and pathogenesis of chondrodysplasia.

Anabolic actions of Notch on mature bone.

Notch controls skeletogenesis, but its role in the remodeling of adult bone remains conflicting. In mature mice, the skeleton can become osteopenic or osteosclerotic depending on the time point at which Notch is activated or inactivated. Using adult EGFP reporter mice, we find that Notch expression is localized to osteocytes embedded within bone matrix. Conditional activation of Notch signaling in osteocytes triggers profound bone formation, mainly due to increased mineralization, which rescues both age-associated and ovariectomy-induced bone loss and promotes bone healing following osteotomy. In parallel, mice rendered haploinsufficient in γ-secretase presenilin-1 (Psen1), which inhibits downstream Notch activation, display almost-absent terminal osteoblast differentiation. Consistent with this finding, pharmacologic or genetic disruption of Notch or its ligand Jagged1 inhibits mineralization. We suggest that stimulation of Notch signaling in osteocytes initiates a profound, therapeutically relevant, anabolic response.

Protein S Protects against Podocyte Injury in Diabetic Nephropathy.

Background Diabetic nephropathy (DN) is a leading cause of ESRD in the United States, but the molecular mechanisms mediating the early stages of DN are unclear.Methods To assess global changes that occur in early diabetic kidneys and to identify proteins potentially involved in pathogenic pathways in DN progression, we performed proteomic analysis of diabetic and nondiabetic rat glomeruli. Protein S (PS) among the highly upregulated proteins in the diabetic glomeruli. PS exerts multiple biologic effects through the Tyro3, Axl, and Mer (TAM) receptors. Because increased activation of Axl by the PS homolog Gas6 has been implicated in DN progression, we further examined the role of PS in DN.Results In human kidneys, glomerular PS expression was elevated in early DN but suppressed in advanced DN. However, plasma PS concentrations did not differ between patients with DN and healthy controls. A prominent increase of PS expression also colocalized with the expression of podocyte markers in early diabetic kidneys. In cultured podocytes, high-glucose treatment elevated PS expression, and PS knockdown further enhanced the high-glucose-induced apoptosis. Conversely, PS overexpression in cultured podocytes dampened the high-glucose- and TNF-α-induced expression of proinflammatory mediators. Tyro3 receptor was upregulated in response to high glucose and mediated the anti-inflammatory response of PS. Podocyte-specific PS loss resulted in accelerated DN in streptozotocin-induced diabetic mice, whereas the transient induction of PS expression in glomerular cells in vivo attenuated albuminuria and podocyte loss in diabetic OVE26 mice.Conclusions Our results support a protective role of PS against glomerular injury in DN progression.

SHROOM3-FYN Interaction Regulates Nephrin Phosphorylation and Affects Albuminuria in Allografts.

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.

Transcriptomic analysis uncovers novel synergistic mechanisms in combination therapy for lupus nephritis.

A recent clinical study showed that combination therapy consisting of mycophenolate mofetil, tacrolimus and steroids was shown to be more effective in achieving complete remission in patients with severe forms of lupus nephritis than conventional therapy consisting of intravenous cyclophosphamide and steroids. To explore the underlying molecular and cellular mechanisms of increased efficacy of the combination therapy regimen, we employed a mouse model of lupus nephritis, MRL/lpr mice, and treated them with monotherapies of prednisone, mycophenolate mofetil, or tacrolimus, or with their combination. Consistent with previous clinical findings, combination therapy markedly improved renal outcome compared to the monotherapies in mice with lupus nephritis. Transcriptomic analysis of their kidneys revealed distinct molecular pathways that were differentially regulated in combination therapy versus monotherapies. Combination therapy not only provided additive immunosuppressive effects, but also induced gene expression and molecular pathways to confer enhanced renoprotection. Specifically, combination therapy inhibited TLR7 expression in the kidneys of mice with lupus nephritis; combination of tacrolimus and mycophenolate mofetil led to better stabilization of the podocyte actin cytoskeleton through the reciprocal regulation of RhoA and Rac1 activities. Combination therapy strongly suppressed the IL-6/Stat3 pathway. These findings were further validated in renal biopsy samples from patients with lupus nephritis before and after treatments with mycophenolate mofetil, tacrolimus or combination therapy. Thus, our study further supports the earlier clinical finding and further provides insights into the molecular basis for increased efficacy of combination therapy.

Gene expression profiles of glomerular endothelial cells support their role in the glomerulopathy of diabetic mice.

Endothelial dysfunction promotes the pathogenesis of diabetic nephropathy (DN), which is considered to be an early event in disease progression. However, the molecular changes associated with glomerular endothelial cell (GEC) injury in early DN are not well defined. Most gene expression studies have relied on the indirect assessment of GEC injury from isolated glomeruli or renal cortices. Here, we present transcriptomic analysis of isolated GECs, using streptozotocin-induced diabetic wildtype (STZ-WT) and diabetic eNOS-null (STZ-eNOS-/-) mice as models of mild and advanced DN, respectively. GECs of both models in comparison to their respective nondiabetic controls showed significant alterations in the regulation of apoptosis, oxidative stress, and proliferation. The extent of these changes was greater in STZ-eNOS-/- than in STZ-WT GECs. Additionally, genes in STZ-eNOS-/- GECs indicated further dysregulation in angiogenesis and epigenetic regulation. Moreover, a biphasic change in the number of GECs, characterized by an initial increase and subsequent decrease over time, was observed only in STZ-eNOS-/- mice. This is consistent with an early compensatory angiogenic process followed by increased apoptosis, leading to an overall decrease in GEC survival in DN progression. From the genes altered in angiogenesis in STZ-eNOS-/- GECs, we identified potential candidate genes, Lrg1 and Gpr56, whose function may augment diabetes-induced angiogenesis. Thus, our results support a role for GEC in DN by providing direct evidence for alterations of GEC gene expression and molecular pathways. Candidate genes of specific pathways, such as Lrg1 and Gpr56, can be further explored for potential therapeutic targeting to mitigate the initiation and progression of DN.

Genomic Analysis of Kidney Allograft Injury Identifies Hematopoietic Cell Kinase as a Key Driver of Renal Fibrosis.

Renal fibrosis is the common pathway of progression for patients with CKD and chronic renal allograft injury (CAI), but the underlying mechanisms remain obscure. We performed a meta-analysis in human kidney biopsy specimens with CAI, incorporating data available publicly and from our Genomics of Chronic Renal Allograft Rejection study. We identified an Src family tyrosine kinase, hematopoietic cell kinase (Hck), as upregulated in allografts in CAI. Querying the Kinase Inhibitor Resource database revealed that dasatinib, a Food and Drug Administration-approved drug, potently binds Hck with high selectivity. In vitro, Hck overexpression activated the TGF-ß/Smad3 pathway, whereas HCK knockdown inhibited it. Treatment of tubular cells with dasatinib reduced the expression of Col1a1 Dasatinib also reduced proliferation and α-SMA expression in fibroblasts. In a murine model with unilateral ureteric obstruction, pretreatment with dasatinib significantly reduced the upregulation of profibrotic markers, phosphorylation of Smad3, and renal fibrosis observed in kidneys pretreated with vehicle alone. Dasatinib treatment also improved renal function, reduced albuminuria, and inhibited expression of profibrotic markers in animal models with lupus nephritis and folic acid nephropathy. These data suggest that Hck is a key mediator of renal fibrosis and dasatinib could be developed as an antifibrotic drug.

Biopsy transcriptome expression profiling to identify kidney transplants at risk of chronic injury: a multicentre, prospective study.

BACKGROUND: Chronic injury in kidney transplants remains a major cause of allograft loss. The aim of this study was to identify a gene set capable of predicting renal allografts at risk of progressive injury due to fibrosis. METHODS: This Genomics of Chronic Allograft Rejection (GoCAR) study is a prospective, multicentre study. We prospectively collected biopsies from renal allograft recipients (n=204) with stable renal function 3 months after transplantation. We used microarray analysis to investigate gene expression in 159 of these tissue samples. We aimed to identify genes that correlated with the Chronic Allograft Damage Index (CADI) score at 12 months, but not fibrosis at the time of the biopsy. We applied a penalised regression model in combination with permutation-based approach to derive an optimal gene set to predict allograft fibrosis. The GoCAR study is registered with ClinicalTrials.gov, number NCT00611702. FINDINGS: We identified a set of 13 genes that was independently predictive for the development of fibrosis at 1 year (ie, CADI-12 ≥2). The gene set had high predictive capacity (area under the curve [AUC] 0·967), which was superior to that of baseline clinical variables (AUC 0·706) and clinical and pathological variables (AUC 0·806). Furthermore routine pathological variables were unable to identify which histologically normal allografts would progress to fibrosis (AUC 0·754), whereas the predictive gene set accurately discriminated between transplants at high and low risk of progression (AUC 0·916). The 13 genes also accurately predicted early allograft loss (AUC 0·842 at 2 years and 0·844 at 3 years). We validated the predictive value of this gene set in an independent cohort from the GoCAR study (n=45, AUC 0·866) and two independent, publically available expression datasets (n=282, AUC 0·831 and n=24, AUC 0·972). INTERPRETATION: Our results suggest that this set of 13 genes could be used to identify kidney transplant recipients at risk of allograft loss before the development of irreversible damage, thus allowing therapy to be modified to prevent progression to fibrosis. FUNDING: National Institutes of Health.

Genetic-epigenetic dysregulation of thymic TSH receptor gene expression triggers thyroid autoimmunity.

Graves disease (GD) is an autoimmune condition caused by interacting genetic and environmental factors. Genetic studies have mapped several single-nucleotide polymorphisms (SNPs) that are strongly associated with GD, but the mechanisms by which they trigger disease are unknown. We hypothesized that epigenetic modifications induced by microenvironmental influences of cytokines can reveal the functionality of GD-associated SNPs. We analyzed genome-wide histone H3 lysine 4 methylation and gene expression in thyroid cells induced by IFNα, a key cytokine secreted during viral infections, and overlapped them with known GD-associated SNPs. We mapped an open chromatin region overlapping two adjacent GD-associated SNPs (rs12101255 and rs12101261) in intron 1 of the thyroid stimulating hormone receptor (TSHR) gene. We then demonstrated that this region functions as a regulatory element through binding of the transcriptional repressor promyelocytic leukemia zinc finger protein (PLZF) at the rs12101261 site. Repression by PLZF depended on the rs12101261 disease susceptibility allele and was increased by IFNα. Intrathymic TSHR expression was decreased in individuals homozygous for the rs12101261 disease-associated genotype compared with carriers of the disease-protective allele. Our studies discovered a genetic-epigenetic interaction involving a noncoding SNP in the TSHR gene that regulates thymic TSHR gene expression and facilitates escape of TSHR-reactive T cells from central tolerance, triggering GD.

Comparison of Glomerular and Podocyte mRNA Profiles in Streptozotocin-Induced Diabetes.

Evaluating the mRNA profile of podocytes in the diabetic kidney may indicate genes involved in the pathogenesis of diabetic nephropathy. To determine if the podocyte-specific gene information contained in mRNA profiles of the whole glomerulus of the diabetic kidney accurately reflects gene expression in the isolated podocytes, we crossed Nos3(-/-) IRG mice with podocin-rtTA and TetON-Cre mice for enhanced green fluorescent protein labeling of podocytes before diabetic injury. Diabetes was induced by streptozotocin, and mRNA profiles of isolated glomeruli and sorted podocytes from diabetic and control mice were examined 10 weeks later. Expression of podocyte-specific markers in glomeruli was downregulated in diabetic mice compared with controls. However, expression of these markers was not altered in sorted podocytes from diabetic mice. When mRNA levels of glomeruli were corrected for podocyte number per glomerulus, the differences in podocyte marker expression disappeared. Analysis of the differentially expressed genes in diabetic mice also revealed distinct upregulated pathways in the glomeruli (mitochondrial function, oxidative stress) and in podocytes (actin organization). In conclusion, our data suggest reduced expression of podocyte markers in glomeruli is a secondary effect of reduced podocyte number, thus podocyte-specific gene expression detected in the whole glomerulus may not represent that in podocytes in the diabetic kidney.

Reduced Krüppel-like factor 2 expression may aggravate the endothelial injury of diabetic nephropathy.

Krüppel-like factor 2 (KLF2), a shear stress-inducible transcription factor, has endoprotective effects. In streptozotocin-induced diabetic rats, we found that glomerular Klf2 expression was reduced in comparison with nondiabetic rats. However, normalization of hyperglycemia by insulin treatment increased Klf2 expression to a level higher than that of nondiabetic rats. Consistent with this, we found that Klf2 expression was suppressed by high glucose but increased by insulin in cultured endothelial cells. To determine the role of KLF2 in streptozotocin-induced diabetic nephropathy, we used endothelial cell-specific Klf2 heterozygous knockout mice and found that diabetic knockout mice developed more kidney/glomerular hypertrophy and proteinuria than diabetic wild-type mice. Glomerular expression of Vegfa, Flk1, and angiopoietin 2 increased, but expression of Flt1, Tie2, and angiopoietin 1 decreased, in diabetic knockout mice compared with diabetic wild-type mice. Glomerular expression of ZO-1, glycocalyx, and eNOS was also decreased in diabetic knockout compared with diabetic wild-type mice. These data suggest knockdown of Klf2 expression in the endothelial cells induced more endothelial cell injury. Interestingly, podocyte injury was also more prominent in diabetic knockout compared with diabetic wild-type mice, indicating a cross talk between these two cell types. Thus, KLF2 may play a role in glomerular endothelial cell injury in early diabetic nephropathy.

Protein profiling of Helicobacter pylori-associated gastric cancer.

Helicobacter pylori infection is an initiating factor in the development of gastric cancer. Gastric cancer can be divided into two groups on the basis of H. pylori serological status; seropositive H. pylori status predicts favorable prognosis in patients with gastric cancer. By using the protein pathway array, we identified 20 differentially expressed proteins in primary gastric cancer tissues between the H. pylori-seropositive and H. pylori-seronegative groups. Our results indicate that both brassinosteroid insensitive 1-associated kinase 1 and calpastatin are favorable prognostic factors in H. pylori-seropositive gastric cancer patients. In contrast, dachshund homolog 1 is a favorable prognostic factor in H. pylori-seronegative gastric cancer patients. Different signaling pathways were found to be altered between H. pylori-seropositive and H. pylori-seronegative gastric cancer, which may account for the different tumorigenesis and outcomes between these two subsets of patients.

BRD4 inhibitor inhibits colorectal cancer growth and metastasis.

Post-translational modifications have been identified to be of great importance in cancers and lysine acetylation, which can attract the multifunctional transcription factor BRD4, has been identified as a potential therapeutic target. In this paper, we identify that BRD4 has an important role in colorectal cancer; and that its inhibition substantially wipes out tumor cells. Treatment with inhibitor MS417 potently affects cancer cells, although such effects were not always outright necrosis or apoptosis. We report that BRD4 inhibition also limits distal metastasis by regulating several key proteins in the progression of epithelial-to-mesenchymal transition (EMT). This effect of BRD4 inhibitor is demonstrated via liver metastasis in animal model as well as migration and invasion experiments in vitro. Together, our results demonstrate a new application of BRD4 inhibitor that may be of clinical use by virtue of its ability to limit metastasis while also being tumorcidal.