下调PHLPP1表达通过激活PI3K/AKT/mTOR通路改善高糖诱导的人足细胞自噬抑制和凋亡促进作用

目的 研究富含亮氨酸重复序列的普列克底物蛋白同源结构域蛋白磷酸酶1(PHLPP1)在糖尿病肾病(DN)肾组织的表达及其对足细胞自噬、凋亡的影响并初步探究其相关作用机制.方法 采用免疫组织化学检测DN肾组织及非糖尿病肾组织PHLPP1表达,免疫荧光组织化学染色检测肾病蛋白(nephrin)、PHLPP1的共表达以确定PH...     

微小RNA-193a调控Wilms瘤基因1促进小鼠糖尿病肾病足细胞凋亡

目的 探讨微小RNA（miR）-193a对糖尿病肾病（DN）足细胞凋亡的影响及作用机制。 方法 通过体外高糖培养足细胞和体内小鼠腹腔注射链脲佐菌素(STZ)复制DN模型,将细胞或60只小鼠随机分为空白对照组、模型对照组、miR-193a抑制阴性对照组、miR-193a抑制组、miR-193a过表达阴性对照组和miR-193a过表达组。使用流式细胞术、免疫组织化学、免疫荧光、TUNEL、Real-time PCR和Western blotting检测DN小鼠和小鼠足细胞凋亡情况。 结果 DN小鼠和高糖诱导的小鼠足细胞中Nephrin、Podocin表达减弱,细胞凋亡率显著升高,miR-193a高表达,小鼠肾脏和足细胞中cleaved-Caspase-3和Bax蛋白水平显著升高,Bcl-2蛋白水平显著下降,而miR-193a 抑制剂(inhibitor)可改善这一过程。DN小鼠和高糖培养的小鼠足细胞中Wilms瘤基因1（WT1） mRNA和蛋白表达水平显著降低,miR-193a inhibitor干预后WT1蛋白表达显著升高。上调WT1可降低miR-193a对高糖诱导的小鼠足细胞凋亡的影响。双荧光素酶报告实验证实了miR-193a和WT1之间的靶向关系。 结论 MiR-193a下调WT1的表达,促进DN足细胞凋亡。     

Mechanisms of angiotensin II signaling on cytoskeleton of podocytes

Podocytes are significant in establishing the glomerular filtration barrier. Sustained rennin–angiotensin system (RAS) activation is crucial in the pathogenesis of podocyte injury and causes proteinuria. This study demonstrates that angiotensin II (Ang II) caused a reactive oxygen species (ROS)-dependent rearrangement of cortical F-actin and a migratory phenotype switch in cultured mouse podocytes with stable Ang II type 1 receptor (AT1R) expression. Activated small GTPase Rac-1 and phosphorylated ezrin/radixin/moesin (ERM) proteins provoked Ang II-induced F-actin cytoskeletal remodeling. This work also shows increased expression of Rac-1 and phosphorylated ERM proteins in cultured podocytes, and in glomeruli of podocyte-specific AT1R transgenic rats (Neph-hAT1 TGRs). The free radical scavenger DMTU eliminated Ang II-induced cell migration, ERM protein phosphorylation and cortical F-actin remodeling, indicating that ROS mediates the influence of Rac-1 on podocyte AT1R signaling. Heparin, a potent G-coupled protein kinase 2 inhibitor, was found to abolish ERM protein phosphorylation and cortical F-actin ring formation in Ang II-treated podocytes, indicating that phosphorylated ERM proteins are the cytoskeletal effector in AT1R signaling. Moreover, Ang II stimulation triggered down-regulation of α actinin-4 and reduced focal adhesion expression in podocytes. Signaling inhibitor assay of Ang II-treated podocytes reveals that Rac-1, RhoA, and F-actin reorganization were involved in expressional regulation of α actinin-4 in AT1R signaling. With persistent RAS activation, the Ang II-induced phenotype shifts from being dynamically stable to adaptively migratory, which may eventually exhaust podocytes with a high actin cytoskeletal turnover, causing podocyte depletion and focal segmental glomerulosclerosis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Angiotensin II contributes to podocyte injury by increasing TRPC6 expression via an NFAT-mediated positive feedback signaling pathway

The transient receptor potential channel C6 (TRPC6) is a slit diaphragm-associated protein in podocytes involved in regulating glomerular filter function. Gain-of-function mutations in TRPC6 cause hereditary focal segmental glomerulosclerosis (FSGS), and several human acquired proteinuric diseases show increased glomerular TRPC6 expression. Angiotensin II (AngII) is a key contributor to glomerular disease and may regulate TRPC6 expression in nonrenal cells. We demonstrate that AngII regulates TRPC6 mRNA and protein levels in cultured podocytes and that AngII infusion enhances glomerular TRPC6 expression in vivo. In animal models for human FSGS (doxorubicin nephropathy) and increased renin-angiotensin system activity (Ren2 transgenic rats), glomerular TRPC6 expression was increased in an AngII-dependent manner. TRPC6 expression correlated with glomerular damage markers and glomerulosclerosis. We show that the regulation of TRPC6 expression by AngII and doxorubicin requires TRPC6-mediated Ca(2+) influx and the activation of the Ca(2+)-dependent protein phosphatase calcineurin and its substrate nuclear factor of activated T cells (NFAT). Accordingly, calcineurin inhibition by cyclosporine decreased TRPC6 expression and reduced proteinuria in doxorubicin nephropathy, whereas podocyte-specific inducible expression of a constitutively active NFAT mutant increased TRPC6 expression and induced severe proteinuria. Our findings demonstrate that the deleterious effects of AngII on podocytes and its pathogenic role in glomerular disease involve enhanced TRPC6 expression via a calcineurin/NFAT positive feedback signaling pathway.     

保护素D1 通过抑制肾脏炎症及足突细胞上皮-间充质转化而抑制早期 糖尿病肾病小鼠肾纤维化

 目的：保护素D1 (PD1) 是一个潜在的抗炎症脂蛋白分子,本实验探讨其治疗早期糖尿病肾病（DN）肾纤维化的作用及机制。方法：用链脲佐菌素125 mg/kg 2次腹腔注射C57BL/6J雌性小鼠,建立早期DN小鼠模型。糖尿病模型成功后,用PD1（0.08 mg·kg-1·d-1）腹腔注射治疗,设正常鼠及DN鼠为对照。治疗8周后检测各组小鼠24 h尿蛋白及尿白蛋白定量、体重、肾重、肾重/体重比、血清及尿肌酐和肌酐清除率;用PAS染色法检测肾小球系膜区基质/肾小球面积比,用免疫荧光染色法检测肾皮质中巨噬细胞的数量,用Western blotting检测肾小球纤连蛋白（FN）和α-平滑肌肌动蛋白（α-SMA）的表达,以及肾小球足突细胞特异性上皮标志蛋白zonula occludens-1(ZO-1)和P-cadherin的表达;同时,体外用高糖刺激小鼠巨噬细胞株RAW264.7,检测PD1对其分泌肿瘤坏死因子α（TNF-α）和白细胞介素1β（IL-1β）的抑制作用。体外用转化生长因子β1（TGF-β1）刺激小鼠足突细胞株,用Western blotting检测PD1对其诱导足突细胞上皮-间充质转化(EMT)中上皮细胞标志蛋白P-cadherin 和ZO-1减少的恢复作用,及间充质细胞标志蛋白成纤维细胞特异性蛋白1（FSP1） 和α-SMA过表达的抑制作用。结果：PD1能减少DN小鼠肾小球系膜基质的积聚、24 h尿蛋白及尿白蛋白定量、体重、肾重和肾重/体重比,抑制异常增高的肌酐清除率。PD1能减少DN小鼠肾皮质中巨噬细胞的数量,抑制DN小鼠肾小球FN和α-SMA的表达,恢复足突细胞特异性上皮标志蛋白ZO-1和P-cadherin的表达。PD1能抑制高糖诱导RAW264.7分泌TNF-α和IL-1β,能抑制TGF-β1诱导足突细胞FSP1和α-SMA表达的增加以及ZO-1和P-cadherin表达的减少。结论：PD1能减轻早期DN小鼠肾纤维化,其部分机制可能通过抑制肾脏的炎症及足突细胞EMT。     

Permselective dysfunction of podocyte-podocyte contact upon angiotensin II unravels the molecular target for renoprotective intervention

Ameliorating the function of the glomerular barrier to circulating proteins by blocking angiotensin II (Ang II) translates into less risk of progression toward end-stage renal failure in diabetic and nondiabetic nephropathies. However, the mechanisms underlying this barrier protection are not clear. Specialized contacts between adjacent podocytes are major candidate targets, and the actin cytoskeleton is emerging as a regulatory element. Here, we present data demonstrating that Ang II induced reorganization of F-actin fibers and redistribution of zonula occludens-1 (ZO-1) that is physically associated with actin in murine podocytes. These effects were paralleled by increased albumin permeability across podocyte monolayers. The F-actin stabilizer jasplakinolide prevented both ZO-1 redistribution and albumin leakage, suggesting that actin cytoskeleton rearrangement is instrumental to podocyte permselective dysfunction induced by Ang II. Changes in both F-actin and ZO-1 patterns were confirmed in glomeruli of rat isolated perfused kidneys on short infusion of Ang II, leading to increased protein excretion. Podocyte dysfunction was mediated by Ang II type 1 receptor and was partly dependent on Src kinase-phospholipase C activation. These data demonstrate that strategies aimed at stabilizing podocyte-podocyte contacts and targeting the relevant intracellular signal transduction are crucial to renoprotection.     

罗格列酮对2型糖尿病大鼠血浆resistin的影响及对肾小球硬化的干预研究

目的： 研究罗格列酮对糖尿病大鼠血清巨噬细胞因子resistin水平的影响,探讨该药物对糖尿病肾小球硬化的干预及可能的作用机制。方法： 20只10周龄Wistar大鼠随机分为糖尿病肾病（DN）模型组和罗格列酮干预组(DN+RSG),另取10只Wistar大鼠作为正常对照组(NC)。DN和罗格列酮干预组大鼠右肾切除后经过阴茎背静脉注射35 mg/kg链脲菌素（STZ）,罗格列酮组按照10 mg·kg-1·d-1的剂量给予罗格列酮灌胃,DN组及正常对照组喂饲普通饮食。STZ注射20周后留取静脉血和24h尿,后处死大鼠并取肾组织。ELISA法检测血浆白细胞介素-1(IL-1)、肿瘤坏死因子-α (TNF-α)及resistin水平,免疫比浊法测定高敏C反应蛋白(hs-CRP),并测定24 h尿微量白蛋白、空腹血糖及肾功能水平。光镜下观察肾组织的病理改变情况,免疫组化检测肾小球转化生长因子-β1(TGF-β1) 的表达,Western blotting检测Smad2磷酸化水平。 结果： 与NC组比较,DN组大鼠血浆炎症因子IL-1、TNF-α、hs-CRP及resistin的水平均显著升高;罗格列酮干预后血浆中上述指标含量均显著低于模型组。与DN组比较,罗格列酮干预组的空腹血糖无明显变化,但24 h尿微量白蛋白定量及肾功能水平均明显下降。罗格列酮干预后肾小球内TGF-β1蛋白表达及Smad2磷酸化水平较DN组显著降低,并且其肾小球系膜增生程度也较DN组明显减轻。结论： 罗格列酮具有延缓及改善糖尿病肾小球硬化的作用,该作用可能与其降低resistin及其它炎症相关因子的表达有关。针对炎症有望控制DN的发生发展。     

Focal and segmental glomerulosclerosis in murine models: a histological and ultrastructural characterization with immunohistochemistry correlation of glomerular CD44 and WT1 expression

Aim: Focal segmental glomerulosclerosis (FSGS) is a common progressive chronic renal disease. Podocyte injury and loss are the postulated pivotal events that trigger FSGS. In this study, the authors aim to examine the evolution of FSGS in murine models histologically, ultrastructurally and immunohistochemically with special emphasis on podocytes and parietal epithelial cells (PECs). Material and methods: FSGS resembling primary FSGS in humans was initiated in Wistar rats using intravenous Adriamycin injections. Blood and urine analysis were performed at 0, 8, and 12 weeks. Both the control kidneys and the test kidneys were harvested at 8 and 12 weeks, examined histologically and ultrastructurally and the findings correlated with the glomerular expression of immunostains specific for podocytes (WT-1) and for activated PECs (CD44). Results: FSGS developed in both 8 and 12 weeks test groups showing progressive proteinuria, podocytopathy and segmental glomerular scarring. There was a decrease in the glomerular expression of WT-1 with a concurrent increase in the glomerular expression of CD44, indicating podocyte loss with synchronous increase in activated PECs. The evolving FSGS correlated negatively with podocytes and positively with activated PECs. Conclusion: Our study shows that with podocyte injury there is podocyte effacement and loss, proteinuria, glomerular segmental adhesion and scarring, all culminating in FSGS. In addition, there is activation, hyperplasia and hypertrophy of PECs. This demonstrates that both podocyte loss and PEC activation promote FSGS. Our findings are consistent with recent investigations. More studies are required to further understand the role of these cells in the evolution of FSGS and subsequently introduce new targeted treatment modalities.     

Urinary excretion of IGFBP-1 and -3 correlates with disease activity and differentiates focal segmental glomerulosclerosis and minimal change disease

The glomerular microenvironment is influenced by circulating growth factors that are filtered from the blood stream and pass the glomerular filtration barrier. In this study, we wanted to explore the role of IGF-binding proteins (IGFBPs) in two diseases that concern podocytes. We analyzed glomerular expression and urinary excretion of IGFBP-1, -2, and -3 in patients with focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). We found that patients with active FSGS excrete high amounts of podocalyxin positive cells as well as IGFBP-1 and -3. In human podocytes, we can induce mRNA expression of IGFBP-3 in response to TGF-β and in human microvascular endothelial cells expression of IGFBP-1 and -3 in response to TGF-β and Bradykinin. We conclude that the local expression of IGFBPs in podocytes and endothelial cells might contribute to the pathogenesis of glomerular disease and that IGFBP-1 and -3 are potential non-invasive markers of FSGS.     

The effects of angiotensin-II receptor blockers on podocyte damage and glomerular apoptosis in a rat model of experimental streptozotocin-induced diabetic nephropathy

The aim of the study was to determine in a rat model of streptozotocin-induced diabetic nephropathy the expression of: WT-1 (for podocyte loss in the glomerulus), TGF-beta 1 (for tissue damage), caspase-3 and bax (for glomerular apoptosis) and the possible protective effects of an angiotensin II type 1 receptor blocker. Three groups of male Wistar albino rats were used. The first group consisted of non-diabetic control rats. The second group was the untreated diabetic rats. The third group consisted of diabetic rats treated with Irbesartan, which is an angiotensin II receptor antagonist, widely used in treatment for hypertension. Immunohistochemical stainings for TGF-beta 1, bax, caspase-3 and WT-1 were performed. The microalbuminuria levels of the Irbesartan-treated diabetic group were lower than those of the untreated diabetic group (P < 0.01). The immunostaining of TGF-beta 1, bax and caspase-3 was decreased in glomeruli of the Irbesartan-treated diabetic group compared to the untreated diabetic group. WT-1 immunopositive podocyte numbers were found to be significantly lower in the untreated diabetic group than in the other groups (P < 0.01). In the Irbesartan-treated diabetic group, the WT-1 immunopositive cell numbers were higher compared to the untreated diabetic group (P < 0.01). We conclude that the decrease in the number of podocytes is an early marker of diabetic nephropathy, AT1 receptor blocker has renoprotective effects on the regulation of renal hemodynamics and on the control of tissue damage by preventing podocyte loss, which leads to decrease of bax and caspase-3 expressions of apoptosis related proteins, and may prevent glomerular cell apoptosis via angiotensin II.     

Podocyte injury promotes progressive nephropathy in zucker diabetic fatty rats.

The zucker diabetic fatty (ZDF-fa/fa) rat is one of the attractive models for type II diabetes based on impaired glucose tolerance caused by the inherited insulin-resistance gene fa. Characterization of nephropathy in this model may provide useful insights into the mechanism of the progression of diabetic nephropathy. The present study analyzed the pathophysiology of diabetes and nephropathy, including the process of glomerulosclerosis in this model by biochemical and morphometric analyses. In addition, we conducted studies in podocytes in culture to examine the direct effects of high glucose on podocytes. ZDF-fa/fa rats showed overt diabetes despite hyperinsulinemia as early as 3 months of age. Blood glucose levels increased further with a considerable decrease of insulin levels at 5 months. Glomerular filtration rate (GFR) was significantly elevated until 3 months, but fell to the level seen in lean rats by 7 months. Proteinuria started to rise during the period of increased GFR, and increased further after GFR had fallen to within the normal range. Renal fibronectin, collagen iv, and vascular endothelial growth factor mRNA levels were increased at 7 months. Glomerulosclerosis commenced as early as 5 months of age, and was associated with glomerular hypertrophy and mild mesangial expansion with evidence of accentuated podocyte injury, as revealed by increased expression of desmin. Electron microscopy suggested that degeneration of podocytes and the development of tuft adhesions were responsible for the glomerular sclerosis in this model. In addition, glomeruli from the diabetic rats showed up-regulation of the cyclin kinase inhibitors, p21 and p27. Further studies suggested that the increase in p27 expression was predominantly caused by podocytes, because predominant immunolocalization of p27 in podocytes in diabetic rats and high glucose medium induced cell hypertrophy accompanied by p27 up-regulation in differentiated podocyte cell lines. In conclusion, progressive diabetic nephropathy in ZDF-fa/fa rats is associated with evidence of podocyte injury. High concentrations of ambient glucose induced podocyte hypertrophy and stress in vitro, suggesting that the podocyte is a likely target of the diabetic milieu.     

Rituximab targets podocytes in recurrent focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerular disease characterized by proteinuria, progression to end-stage renal disease, and recurrence of proteinuria after kidney transplantation in about one-third of patients. It has been suggested that rituximab might treat recurrent FSGS through an unknown mechanism. Rituximab not only recognizes CD20 on B lymphocytes, but might also bind sphingomyelin phosphodiesterase acid-like 3b (SMPDL-3b) protein and regulate acid sphingomyelinase (ASMase) activity. We hypothesized that rituximab prevents recurrent FSGS and preserves podocyte SMPDL-3b expression. We studied 41 patients at high risk for recurrent FSGS, 27 of whom were treated with rituximab at time of kidney transplant. SMPDL-3b protein, ASMase activity, and cytoskeleton remodeling were studied in cultured normal human podocytes that had been exposed to patient sera with or without rituximab. Rituximab treatment was associated with lower incidence of posttransplant proteinuria and stabilization of glomerular filtration rate. The number of SMPDL-3b(+) podocytes in postreperfusion biopsies was reduced in patients who developed recurrent FSGS. Rituximab partially prevented SMPDL-3b and ASMase down-regulation that was observed in podocytes treated with the sera of patients with recurrent FSGS. Overexpression of SMPDL-3b or treatment with rituximab was able to prevent disruption of the actin cytoskeleton and podocyte apoptosis induced by patient sera. This effect was diminished in cultured podocytes where SMPDL-3b was silenced. Our study suggests that treatment of high-risk patients with rituximab at time of kidney transplant might prevent recurrent FSGS by modulating podocyte function in an SMPDL-3b-dependent manner.     

Diminished met signaling in podocytes contributes to the development of podocytopenia in transplant glomerulopathy

Transplant glomerulopathy (TxG) can show secondary focal and segmental glomerulosclerosis (FSGS). FSGS in native kidneys is caused by podocytopenia. This study examines podocytopenia and the role of decreased paracrine Met activation on podocytes by decreased glomerular hepatocyte growth factor (HGF) levels in the development of podocytopenia in TxG. Podocytes were counted in 10 zero-hour biopsies and 10 specimens each with and without TxG. HGF/Met was examined with immunostains and quantitative RT-PCR in a set of three consecutive biopsies from 10 patients with TxG, including the diagnostic biopsy (DiagnBx) and the two previous biopsies (1stPrevBx and 2ndPrevBx). Antiapoptotic effects of HGF on podocytes were examined in vitro. Mean podocyte numbers per glomerulus were lower and glomerular volume higher in TxG. Fewer of the two preceding biopsies of the patients than of the controls contained phospho-Met(Tyr1349)-positive podocytes (2 of 8 versus 7 of 7, P = 0.0070; 4 of 9 versus 9 of 9, P = 0.0294). Glomerular HGF mRNA levels were lower in the 1stPrevBx of the patients (0.049 ± 0.083 versus 0.284 ± 0.331; P = 0.0155). In vitro, HGF stimulation of podocytes resulted in antiapoptotic phosphorylation of AKT and extracellular signal-regulated kinase (ERK) and induction of X-linked inhibitor of apoptosis protein (XIAP). Decreased antiapoptotic Met signaling in podocytes, probably due to decreased HGF secretion by glomerular epithelial cells, could contribute to podocyte loss and FSGS in TxG.     

APPL1 acts as a protective factor against podocytes injury in high glucose environment

APPL1, an intracellular adaptor protein, takes part in numerous metabolic reactions. Although APPL1 plays a key role in glucose metabolism via adiponectin pathway and has been proved associated with type 2 diabetes, little is known about its role in diabetic nephropathy. To explore the role of APPL1 in diabetic nephropathy, we upregulated the expression of APPL1 in cultured mouse podocytes by adenovirus infection and tested the effects of APPL1 overexpression in podocytes treated with high glucose. Here, a mouse podocyte cell line (generated from H-2Kb-tsA58 immortmouse) was cultured and divided into four groups: Group 1 (normal glucose, NG), Group 2 (high glucose, HG), Group 3 (HG and infected with control adenovirus) and Group 4 (HG and infected with Ad-APPL1). Cell vitality of Group 4 is significantly higher than Group 2, but notably lower than Group 1 (P<0.01). The apoptosis rate of Group 4 was much lower (P<0.01) than Group 2 and Group 3. A decrease in phase G0/G1 and an increase in phase S was observed in Group 4 compared with Group 2 (P<0.01). These data suggested the protective role of APPL1 overexpression in high glucose condition. Moreover, the levels of Nephrin, AMPK and p-AMPK were decreased by high-glucose treatment, but increased by APPL1 overexpression. In conclusion, in the experimental high glucose condition, APPL1 acts as a protective factor against podocytes injury through regulating AMPK signaling, and may be a new therapy target for diabetic nephropathy.     

血糖波动对糖尿病大鼠肾小球内皮细胞和肾小管上皮细胞凋亡的影响

目的:观察血糖波动和持续高血糖对糖尿病大鼠肾小球血管内皮细胞和肾小管上皮细胞凋亡和Bax、Bcl-2表达的影响。方法:SD大鼠24只,均分为正常对照组、糖尿病持续高血糖组、糖尿病血糖波动组。采用链脲佐菌素（STZ）60 mg/kg腹腔注射诱发糖尿病，血糖波动组每天定时腹腔注射超短效胰岛素类似物诺和锐，并错时给予葡萄糖，造成1 d中血糖浓度大幅度波动模型。制模4周后，免疫组化法检测肾组织Bcl-2和Bax蛋白表达，原位缺口末端标记法（TUNEL）检测肾小球血管内皮细胞和肾小管上皮细胞凋亡。结果:糖尿病血糖波动组的肾脏凋亡细胞明显多于、肾小球Bcl-2蛋白表达少于、肾小管Bax表达明显多于糖尿病持续高血糖组。结论:糖尿病大鼠血糖明显波动可加速肾小管上皮细胞凋亡。     

Unchanged distribution density of anionic sites on the glomerular wall in rats with streptozotocin-induced diabetic nephropathy

As a cause of proteinuria in diabetic nephropathy, a decrease in anionic charge on the glomerular basement membrane (GBM) is considered to be related to protein leakage. However, the constancy of the anionic charge has been reported in several types of nephropathy. To elucidate the relation between glomerular protein leakage and anionic charge, we examined the distribution of anionic sites on the GBM and podocytes in diabetic rats induced by a single intravenous injection of 60 mg/kg of streptozotocin (STZ). Five months after the treatment with STZ, urinalysis for glucose and protein levels was conducted, and the kidneys were examined using electron microscopic cytochemistry for the assessment of anionic charge with two cationic probes. The distributions of anionic sites on the GBM demonstrated by two kinds of cationic markers in the diabetic rats were similar in density to those seen in the control animals. The distributions of anionic sites on the foot processes and cell membrane of podocytes were regular and also similar in density to that of the control group. From these results, we consider that the charge barrier of the GBM and podocytes is irrelevant to the protein leakage in diabetic rats.     

高糖状态下小鼠肾小球足细胞凋亡和组成型光形态建成1蛋白的表达

背景：组成型光形态建成1蛋白与细胞凋亡有关。 目的：观察高糖对体外培养的小鼠肾小球足细胞凋亡和组成型光形态建成1蛋白表达的影响。 方法：将不同浓度葡萄糖溶液分别加入体外培养的条件永生性小鼠肾小球足细胞株培养液中,培养不同时间后检测肾小球足细胞凋亡指数和死亡指数,以筛选最佳剂量效应葡萄糖浓度。用30 mmol/L葡萄糖溶液干预小鼠肾小球足细胞(高糖组),并设立对照组和采用30 mmol/L甘露醇干预的甘露醇组。 结果与结论：在一定浓度范围内,葡萄糖呈时间和剂量依赖性诱导肾小球足细胞凋亡和死亡(P < 0.05),随着葡萄糖浓度的进一步加大,肾小球足细胞死亡指数明显升高,而凋亡指数变化不大。与对照组比较,高糖组凋亡指数显著增加(P < 0.05),其COP1 mRNA及蛋白表达水平均明显下降(P < 0.05)。 结果证实,高糖可诱导肾小球足细胞的凋亡,其机制可能与其下调COP1的表达有关。     

Bone marrow-derived progenitor cells do not contribute to podocyte turnover in the puromycin aminoglycoside and renal ablation models in rats

A key event in the progression of glomerular disease is podocyte loss that leads to focal and segmental glomerulosclerosis (FSGS). Because adult podocytes are postmitotic cells, podocyte replacement by bone marrow-derived progenitors could prevent podocytopenia and FSGS. This study uses double immunofluorescence for Wilms' tumor-1 and enhanced green fluorescent protein (eGFP) to examine whether an eGFP-positive bone marrow transplant can replace podocytes under normal circumstances and in 3 different rat models of FSGS: puromycin aminoglycoside nephropathy, subtotal nephrectomy, and uninephrectomy. Bone marrow engraftment was successful, with more than 70% eGFP-positive cells and virtually normal histologic findings. No bone marrow transplant-derived podocytes were found in four control rats after transplantation, in nine rats at up to 10 weeks after puromycin aminoglycoside nephropathy induction, in three rats 23 days after subtotal nephrectomy, and in six rats up to 21 days after uninephrectomy. A total of 2200 glomeruli with 14,474 podocytes were evaluated in all groups. Thus, podocyte replacement by bone marrow-derived cells does not contribute to podocyte turnover in rats, even in models of podocyte damage. This is in contrast to previous studies in mice, in which bone marrow-derived podocytes were found. Further studies will address this discrepancy, which could be explained by species differences or by predominant podocyte regeneration from a parietal epithelial cell niche.