Semaphorin3a signaling,podocyte shape,and glomerular disease

Semaphorin3a (sema3a), a member of class 3 semaphorins, is a guidance protein that regulates angiogenesis, branching morphogenesis, axon growth, and cell migration, and has pleiotropic roles on organogenesis, immune response, and cancer. Sema3a is secreted by podocytes and is required for normal kidney patterning and glomerular filtration barrier development. We recently discovered that after completion of kidney development, Sema3a gain-of-function in podocytes leads to proteinuric glomerular disease in mice. Excess sema3a causes foot process effacement, glomerular basement lamination, and endothelial damage in vivo, and disrupts cell autonomously podocyte shape by down-regulating nephrin and inhibiting αvβ3 integrin. We identified a novel direct interaction between nephrin and plexinA₁, the sema3a signaling receptor. Nephrin–plexinA₁ interaction links the slit-diaphragm signaling complex to extracellular sema3a signals. Hence, sema3a functions as an extracellular negative regulator of the structure and function of the glomerular filtration barrier.     

Differential expression of nephrin according to glomerular size in early diabetic kidney disease

Diabetic nephropathy (DN) is clinically characterized by proteinuria. Many studies tried to demonstrate a relationship between proteinuria and changes in nephrin in various forms of glomerular diseases including DN, but the results are not consistent. Glomerular hypertrophy occurs in DN, yet hypertrophy does not develop in all glomeruli concurrently. For investigation of the differences in nephrin expression according to glomerular size, glomeruli were isolated from 10 control and 10 streptozotocin-induced diabetic rats at 6 wk after the induction of diabetes by a sieving technique using sieves with pore sizes of 250, 150, 125, and 75 microm. Glomeruli then were classified into large glomeruli (LG; on the 125-microm sieve) and small glomeruli (SG; on the 75-microm sieve) groups. Glomerular volumes were determined using an image analyzer, and mRNA and protein expression was determined by real-time PCR and Western blot, respectively. The mean volumes of diabetic LG (1.51 +/- 0.06 x 10(6) microm(3)) and control LG (1.37 +/- 0.05 x 10(6) microm(3)) were significantly higher than those of diabetic SG (0.94 +/- 0.03 x 10(6) microm(3)) and control SG (0.87 +/- 0.03 x 10(6) microm(3); P < 0.01). Nephrin mRNA expression was significantly reduced in the diabetic LG group compared with the diabetic SG and control glomeruli groups (P < 0.05). In contrast, nephrin mRNA expression was significantly higher in the diabetic SG group compared with the diabetic LG and control glomeruli groups (P < 0.05). Even after correction for 18s rRNA and Wilms' tumor-1 mRNA expression, the differences in nephrin mRNA expression remained significant. The expression of nephrin protein showed a similar pattern to the mRNA expression. In conclusion, these data suggest that the nephrin gene is differentially expressed according to glomerular size. Furthermore, more hypertrophied glomeruli with lesser nephrin expression may be responsible for albuminuria in the early stage of DN.     

Molecular response of human glioblastoma multiforme cells to ionizing radiation: cell cycle arrest,modulation of the expression of cyclin-dependent kinase inhibitors,and autophagy

OBJECT: Ionizing radiation is the gold-standard adjuvant treatment for glioblastoma multiforme (GBM), the most aggressive primary brain tumor. The mechanisms underlying neoplastic glial cell growth inhibition after administration of ionizing radiation, however, remain largely unknown. In this report, the authors characterize the response of GBM cells to ionizing radiation and elucidate factors that correlate with the radiosensitivity of these tumors. METHODS: Six human GBM cell lines were subjected to increasing doses of radiation. Each demonstrated a dose-dependent suppression of cell proliferation. In the most radiosensitive cell line, the authors demonstrated a transient increase in the expression of the cyclin-dependent kinase inhibitors (CDKIs) p21 and p27, which corresponded with a G1 cell-cycle arrest. In contrast, the most radioresistant cell line demonstrated a decrease in p21 and p27 expression levels, which correlated with a failure to arrest. Apoptosis did not occur in any cell line following irradiation. Instead, autophagic cell changes were observed following administration of radiation, regardless of the relative radiosensitivity of the cell line. CONCLUSIONS: These findings elucidate some of the molecular responses of GBMs to irradiation and suggest novel targets for future therapy.     

IgA肾病患者尿足细胞数及肾组织podocalyxin表达与临床病理的相关分析

目的 探讨尿足细胞数和肾组织中足细胞顶膜区的特异性标记蛋白podocalyxin（PCX）的表达与IgA肾病(IgAN)患者临床和病理改变的关系。 方法 收集50例IgAN患者活检前3 d的每天晨尿和20例体检健康对照者的晨尿各100 ml,离心去上清于TXD3细胞离心涂片机上制成涂片。用抗人PCX单克隆抗体分别对尿沉渣涂片和肾组织切片进行免疫组化染色,于光学显微镜下计数尿足细胞排泄数,以及用计算机图像分析系统测量和计算肾小球PCX平均吸光度值。IgAN按Lee分级分成5组,并用Katafuchi半定量积分法记分。比较各组尿足细胞数和肾组织PCX平均吸光度值,并与各项病理指标评分和临床生化指标进行相关性分析。 结果 IgAN组尿中足细胞数显著高于健康对照组（P < 0.01）。IgAN Lee分级各组组间尿足细胞中位数两两比较,Ⅰ-Ⅱ级组低于Ⅲ、Ⅳ、Ⅴ级组（P < 0.05）;Ⅲ级组显著低于Ⅴ级组（P < 0.05）;Ⅲ级组低于Ⅳ级组和Ⅳ级组低于Ⅴ级组,但差异无统计学意义。尿足细胞阳性率在Ⅳ、Ⅴ级组最高（100%）,在LeeⅠ-Ⅱ级组最低（55%）。IgAN患者随着Lee分级升高,肾小球足细胞PCX表达下调,两两比较结果显示,Ⅰ-Ⅱ级组显著高于Ⅲ、Ⅳ、Ⅴ级组（P < 0.05）;Ⅲ、Ⅳ级组显著高于Ⅴ级组（P < 0.05）;Ⅲ级组稍高于Ⅳ级组（P > 0.05）。IgAN患者尿足细胞排泄数与肾小球PCX表达量呈负相关（r = -0.702,P < 0.01);与24 h尿蛋白量呈正相关（r = 0.465,P < 0.01）;与肾小球和肾小管病理积分均呈正相关（r = 0.233,r = 0.307,均P < 0.05）。肾小球PCX表达量分别与肾小球和肾小管病理积分呈负相关（r = -0.560,r = -0.377,均P < 0.05）;与24 h尿蛋白量呈负相关（r = -0.367,P < 0.05）。 结论 IgAN患者尿足细胞排泄量可反映肾组织足细胞缺失程度,肾小球足细胞损伤脱落可能参与IgAN的发生发展,其尿足细胞数有可能作为反映疾病进展的重要指标。     

Essential role of integrin-linked kinase in podocyte biology: Bridging the integrin and slit diaphragm signaling

Integrin-linked kinase (ILK) has been implicated in the pathogenesis of proteinuria and congenital nephrotic syndrome. However, the function of ILK in glomerular podocyte in a physiologic setting remains unknown. In this study, a mouse model was generated in which ILK gene was selectively disrupted in podocytes by using the Cre-LoxP system. Podocyte-specific ablation of ILK resulted in heavy albuminuria, glomerulosclerosis, and kidney failure, which led to animal death beginning at 10 wk of age. Podocyte detachment and apoptosis were not observed at 4 wk of age, when albuminuria became prominent, indicating that they are not the initial cause of proteinuria. Electron microscopy revealed an early foot process effacement, as well as morphologic abnormality, in ILK-deficient podocytes. ILK deficiency caused an aberrant distribution of nephrin and alpha-actinin-4 in podocytes, whereas the localization of podocin and synaptopodin remained relatively intact. Co-immunoprecipitation demonstrated that ILK physically interacted with nephrin to form a ternary complex, and alpha-actinin-4 participated in ILK/nephrin complex formation. Therefore, ILK plays an essential role in specifying nephrin and alpha-actinin-4 distribution and in maintaining the slit diaphragm integrity and podocyte architecture. These results also illustrate that the integrin and slit diaphragm signals in podocytes are intrinsically coupled through an ILK-dependent mechanism.     

Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss

Background: Podocyte loss plays an important role in the pathogenesis of diabetic nephropathy, but counting the number of glomerular podocyte in renal biopsy specimen is a labor-intensive task. We study whether intra-renal and urinary messenger RNA expression of podocyte-associated molecules could be used to estimate glomerular podocyte number in patients with diabetic nephropathy. Method: We studied 21 consecutive patients with biopsy-proven diabetic nephropathy. The intra-renal and urinary mRNA expression of nephrin, podocin, and synaptopodin were measured by real-time quantitative polymerase chain reaction. Podocyte number was determined in micro-dissected glomerulus. The degree of histological scarring was quantified by morphometric analysis. Results: Glomerular podocyte number correlated with intra-renal expression of nephrin (r = 0.510, p = 0.044), podocin (r = 0.605, p = 0.013), and synaptopodin (r = 0.480, p = 0.060). Glomerular podocyte number also significantly correlated with urinary expression of synaptopodin (r = 0.595, p = 0.019) but not other targets. Baseline renal function correlated with intra-renal expression of nephrin (r = 0.617, p = 0.005), synaptopodin (r = 0.474, p = 0.040), and podocin (r = 0.443, p = 0.057). The degree of tubulointerstitial scarring also inversely correlated with intra-renal expression of nephrin (r = ?0.462, p = 0.047), podocin (r = ?0.458, p = 0.049), and synaptopodin (r = ?0.500, p = 0.029) but not with urinary gene expression. Conclusion: Intra-renal expression of podocyte-associated molecules correlated with glomerular podocyte number, renal function, and tubulointerstitial scarring. The results suggest that intra-renal, but not urinary expression of podocyte-associated molecules, might be used to assess the degree of podocyte loss in diabetic nephropathy.     

Differential gene expression in human abdominal aorta: aneurysmal versus occlusive disease

OBJECTIVE: Inflammation and atherosclerosis are present in both abdominal aortic aneurysm (AAA) and arterial occlusive disease (AOD). Changes in gene expression that underlie the development of AAA versus AOD are poorly defined. This study evaluated differences in gene expression in AAA, AOD, and control aortic tissue with human gene array technology. METHODS: RNA was isolated from human aortic specimens (seven AAA, five AOD, and five control), and complementary DNA (cDNA) probes were generated. The cDNA probes were hybridized to a human cell interaction array of 265 genes and quantitated with phosphorimaging. The data were corrected for background and were standardized to housekeeping genes. Statistical differences in individual gene expression were determined with the Kruskal-Wallis test. RESULTS: Of 265 genes studied, 11 showed statistically different expression in diseased aorta as compared with control. The following three genes were downregulated in AAA: collagen VI alpha1 (P <.037), glycoprotein IIIA (P <.006), and alpha2-macroglobulin (P <.020). The following two genes were upregulated in AOD: laminin alpha4 (P <.034) and insulin-like growth factor 2 receptor (P <.049). The following three genes were upregulated in both AAA and AOD: matrix metalloproteinase-9 (MMP-9; P <.005), intercellular adhesion molecule-1 (P <.012), and tumor necrosis factor--beta receptor (P <.022). The following three genes were downregulated in both AAA and AOD: integrin alpha5 (P <.012), ephrin A5 (P <.037), and rho/rac guanine nucleotide exchange factor (P <.028). Of 16 MMPs evaluated, only MMP-9 was significantly (P <.005) upregulated in both AAA and AOD. Evaluation results of four tissue inhibitors of metalloproteinases showed no significant difference in expression for all tissue types, although tissue inhibitor of metalloproteinase-1 trended toward upregulation in AAA (P =.053). Eight of the fifteen most highly expressed genes in all the groups were extracellular matrix or secreted proteins. Of these, only collagen VI alpha1 (P <.037) showed a significant change, although biglycan trended toward downregulation in AAA (P =.076). CONCLUSION: This study used cDNA array technology in the comparison of human control and pathologic aortic tissue. Six genes had similar differential expression in both AAA and AOD as compared with control. Even more interesting were differences between AAA and AOD in the expression of five genes. These data suggest a similarity in genetic expression for both AAA and AOD, with altered expression of several genes playing a role in disease differentiation.     

Apoptosis and myofibroblast expression in human glomerular disease: a possible link with transforming growth factor-beta-1

BACKGROUND/AIMS: The pathophysiological pathways involved in the pathogenesis and evolution of renal fibrosis, have not been fully elucidated. Transforming growth factor-beta(1) (TGF-beta(1)) is involved in the development of renal scarring. Apoptosis is responsible for intrinsic cell deletion observed in end-stage kidney disease. Myofibroblasts are involved in the development of renal fibrosis. This study investigates whether there is a potential relationship between apoptosis, myofibroblast infiltration and TGF-beta(1) expression in the kidney of patients with glomerulonephritis (GN). METHODS: Forty patients with various types of GN were included in the study. Myofibroblasts and TGF-beta(1) positive cells were detected in kidney biopsies by immunohistochemistry, while apoptotic cells were detected by the in situ end labelling of fragmented DNA. RESULTS: Myofibroblasts were identified in the glomeruli of some patients with severe mesangioproliferative GN and glomerulosclerosis but a more intensive myofibroblast expression was found in the renal interstitium. TGF-beta(1) was expressed in the cytoplasm of tubular epithelial cells, in the renal interstitium and in the glomeruli of patients with GN. Apoptotic cells were mainly detected in the tubules and interstitium and were present in areas with intense myofibroblast infiltration. Positive correlations were observed between the intensity of myofibroblast expression in the interstitium and apoptosis in the tubulointerstitial area (r = 0.521, p < 0.01) as well as TGF-beta(1) expression (r = 0.462, p < 0.05) and degree of renal impairment (r = 0.430, p < 0.05). CONCLUSIONS: These observations suggest that myofibroblast infiltration and apoptosis along with TGF-beta(1) expression are associated with the development of interstitial fibrosis in patients with glomerular disease.     

人肠癌RKO细胞周期依赖性激抑制因子基因启动子区甲基化状态的研究

目的 探讨人结肠癌RKO细胞周期依赖性激酶抑制因子(CKIs)家族启动子区CpG岛甲基化状态及其甲基化可逆性特征.方法 应用特异性DNA甲基转移酶(DNMTs)抑制剂5-Aza-2]-deoxycytidine(5-Aza-CdR)处理肠癌细胞,甲基特异性聚合酶链反应(Methylation-Specific PCR,MSP)、T-A克隆及DNA测序法分析RKO细胞CKIs家族抑癌基因p15ink4b、p16ink4a/CDKN2、p21/cip、p27/kip启动子CpG岛甲基化状态.结果 未经5-Aza-CdR作用的肠癌RKO细胞,其p15ink4b、p16ink4a/CDKN2基因组DNA胞嘧啶(C)保持不变,这提示在其单链DNA中胞嘧啶呈甲基化状态;而经5-Aza-CdR作用的肠癌RKO细胞,其p15ink4b、p16ink4a/CDKN2、p21/cip和p27/kip基因组DNA胞嘧啶均已变为胸腺嘧啶,表明在DNA单链中胞嘧啶已呈去甲基化状态.结论 肠癌RKO细胞周期INK4家族(p15ink4b和p16ink4a/CDKN2)基因的启动子区处于异常的高甲基化状态,而KIP/CIP家族(p21/cip和p27/kip)基因未处于高甲基化状态;5-Aza-CdR能较好地逆转肿瘤细胞INK4家族基因DNA高甲基化状态.     

Combining inhibitors of Brd4 and cyclin-dependent kinase can decrease tumor growth in neuroblastoma with MYCN amplification

IntroductionHigh-risk neuroblastoma is a deadly disease; poor prognosticators are MYCN-amplification and TERT-overexpression. We hypothesized that Gene Set Enrichment Analysis (GSEA) could identify pathways associated with MYCN-amplification and that inhibition of these pathways could decrease tumor growth.MethodsWe analyzed the Neuroblastoma-Kocak dataset (GSE45547, n = 649) and identified pathways associated with MYCN-amplification. Inhibitors were selected from upregulated gene sets for in vitro cytotoxicity testing using ST16-patient-derived primary neuroblastoma cells and in vivo testing using orthotopic ST16-patient-derived xenografts (PDX) in mice. Tumor volume was measured with ultrasound and tumor sections examined after H&E staining.ResultsGSEA identified significantly overexpressed gene sets in MYCN-amplified tumors including MYC targets, cell cycle mitotic genes, TERT associated genes, loss of RB1 gene sets, and E2Fs targets. Several genes were potential Bromodomain-containing protein 4 (Brd4) targets, making Brd4 inhibitors - JQ1, AZD5153 - and cyclin-dependent kinase (Brd4’s binding partner) inhibitors – dinaciclib - potential therapeutic agents. JQ1 and dinaciclib were synergistic in inducing cytotoxicity in vitro. Dinaciclib-AZD5153 in vivo decreased tumor size compared to control, and increased tumor lymphocyte infiltration and necrosis on histology.ConclusionsGSEA is a powerful approach to identify upregulated genes and potential therapeutic targets. Dinaciclib-AZD5153 combination therapy can be effective against MYCN-amplified and TERT-overexpressing neuroblastoma tumors.     

Differential glycosylation of polymeric and monomeric IgA: a possible role in glomerular inflammation in IgA nephropathy

IgA nephropathy (IgAN) is characterized by mesangial deposition of polymeric IgA1 (pIgA1) and complement. Complement activation via mannose-binding lectin and the lectin pathway is associated with disease progression. Furthermore, recent studies have indicated a possible role for secretory IgA. IgAN is associated with abnormalities in circulating IgA, including aberrant O-linked glycosylation. This study characterized and compared functional properties and N-linked glycosylation of highly purified monomeric IgA (mIgA) and pIgA from patients with IgAN and control subjects. Total serum IgA was affinity-purified from patients (n = 11) and control subjects (n = 11) followed by size separation. pIgA but not mIgA contained secretory IgA, and its concentration was significantly higher in patients with IgAN than in control subjects. Both in patients with IgAN and in control subjects, IgA binding to the GalNAc-specific lectin Helix Aspersa and to mannose-binding lectin was much stronger for pIgA than for mIgA. Furthermore, binding of IgA to mesangial cells largely was restricted to polymeric IgA. Binding of pIgA to mesangial cells resulted in increased production of IL-8, predominantly with IgA from patients with IgAN. Quantitative analysis of N-linked glycosylation of IgA heavy chains showed significant differences in glycan composition between mIgA and pIgA, including the presence of oligomannose exclusively on pIgA. In conclusion, binding and activation of mesangial cells, as well as lectin pathway activation, is a predominant characteristic of pIgA as opposed to mIgA. Furthermore, pIgA has different N-glycans, which may recruit lectins of the inflammatory pathway. These results underscore the role of pIgA in glomerular inflammation in IgAN.     

血管生成素的异常表达与大鼠肾小球毛细血管损失的关系及其意义

目的 探讨足细胞损伤后，肾小球内血管生成素（Ang）1和Ang-2的表达改变与肾小球毛细血管丧失的关系及其意义。方法 100只健康雄性Wistar大鼠，随机分为假手术（Sham）组30只、单侧肾切除（UNX）组30只和单侧肾切除＋柔红霉素（DRB）组加只。DRB组大鼠，切除左肾后的第7、14天，从尾静脉各注射柔红霉素5mg／kg 1次。Sham组和UNX组亦同时以等量生理盐水尾静脉注射。完成上述处理后的第1、2、4、6、8周，随机取各组大鼠6只，采血和24h尿液检测Ccr。用PAS染色、免疫组化和原位杂交进行肾组织学分析，并用TUNEL法和透射电镜检测细胞凋亡。结果 与Sham组及UNX组比较，DRB组的Ang-1 mRNA和蛋白表达量呈显著下降的趋势；Ang-2 mRNA和蛋白表达量呈逐渐增高的趋势；Fas、FasL和caspase-3蛋白在肾小球内的表达也呈逐渐增高的趋势；肾小球凋亡指数（GAI）和肾小球硬化指数（GSI）呈逐步增高的趋势，而肾小球毛细血管密度（GCD）和Ccr呈逐步下降的趋势；透射电镜下可见到凋亡的内皮细胞。相关分析显示，Ang-1 mRNA和蛋白分别与Fas、FasL和caspase-3蛋白表达呈负相关，与GCD、Ccr呈正相关，与GAI、GSI呈负相关。Ang-2 mRNA和蛋白分别与Fas、FasL和caspase-3蛋白表达呈正相关，与GCD、Ccr呈负相关，与GAI、GSI呈正相关。结论 肾小球足细胞损伤后，局部Ang-1和Ang-2表达的平衡发生改变。这种变化与Fas／FasL及caspase-3凋亡途径的活化相关，并可能通过促进肾小球内皮细胞的凋亡，导致肾小球毛细血管的减损，进而促进肾小球硬化的发展。