Morphine modulates proliferation of kidney fibroblasts

Morphine modulates proliferation of kidney fibroblasts. Renal interstitial scarring is an important component of heroin-associated nephropathy. Kidney fibroblasts have been demonstrated to play a role in the development of renal scarring in a variety of renal diseases. We studied the effect of morphine, an active metabolite of heroin, on the proliferation of kidney fibroblasts. Morphine at a concentration of 10−12M enhanced (P < 0.001) the proliferation of kidney fibroblasts (control, 67.5 ± 2.0 vs. morphine, 112.2 ± 10.1 × 104 cells/well). [3H]thymidine incorporation studies further confirmed these results. Morphine at concentrations of 10−12M to 10−10M also modulated mRNA expression of early growth related genes (c-fos, c-jun and c-myc). Morphine at concentrations of 10−8 to 10−4M promoted apoptosis of kidney fibroblasts and also enhanced the synthesis of p53 by kidney fibroblasts. We speculate that morphine-induced kidney fibroblast proliferation may be mediated through the activation of early growth related genes, whereas morphine induced kidney fibroblast apoptosis may be mediated through the generation of p53. The present in vitro study provides a hypothetical basis for the role of morphine in the development of renal interstitial scarring in patients with heroin-associated nephropathy

Vitamin D Receptor Deficit Induces Activation of Renin Angiotensin System Via SIRT1 Modulation in Podocytes

Vitamin D receptor (VDR) deficient status has been shown to be associated with the activation of renin angiotensin system (RAS). We hypothesized that lack of VDR would enhance p53 expression in podocytes through down regulation of SIRT1; the former would enhance the transcription of angiotensinogen (Agt) and angiotensinogen II type 1 receptor (AT1R) leading to the activation of RAS. Renal tissues of VDR mutant (M) mice displayed increased expression of p53, Agt, renin, and AT1R. In vitro studies, VDR knockout podocytes not only displayed up regulation p53 but also displayed enhanced expression of Agt, renin and AT1R. VDR deficient podocytes also displayed an increase in mRNA expression for p53, Agt, renin, and AT1R. Interestingly, renal tissues of VDR-M as well as VDR heterozygous (h) mice displayed attenuated expression of deacetylase SIRT1. Renal tissues of VDR-M mice showed acetylation of p53 at lysine (K) 382 residues inferring that enhanced p53 expression in renal tissues could be the result of ongoing acetylation, a consequence of SIRT1 deficient state. Notably, podocytes lacking SIRT1 not only showed acetylation of p53 at lysine (K) 382 residues but also displayed enhanced p53 expression. Either silencing of SIRT1/VDR or treatment with high glucose enhanced podocyte PPAR-y expression, whereas, immunoprecipitation (IP) of their lysates with anti-Retinoid X receptor (RXR) antibody revealed presence of PPAR-y. It appears that either the deficit of SIRT1 has de-repressed expression of PPAR-y or enhanced podocyte expression of PPAR-y (in the absence of VDR) has contributed to the down regulation of SIRT1

sPLA2 IB induces human podocyte apoptosis via the M-type phospholipase A2 receptor

The M-type phospholipase A2 receptor (PLA2R) is expressed in podocytes in human glomeruli. Group IB secretory phospholipase A2 (sPLA2 IB), which is one of the ligands of the PLA2R, is more highly expressed in chronic renal failure patients than in controls. However, the roles of the PLA2R and sPLA2 IB in the pathogenesis of glomerular diseases are unknown. In the present study, we found that more podocyte apoptosis occurs in the kidneys of patients with higher PLA2R and serum sPLA2 IB levels. In vitro, we demonstrated that human podocyte cells expressed the PLA2R in the cell membrane. After binding with the PLA2R, sPLA2 IB induced podocyte apoptosis in a time- and concentration-dependent manner. sPLA2 IB-induced podocyte PLA2R upregulation was not only associated with increased ERK1/2 and cPLA2α phosphorylation but also displayed enhanced apoptosis. In contrast, PLA2R-silenced human podocytes displayed attenuated apoptosis. sPLA2 IB enhanced podocyte arachidonic acid (AA) content in a dose-dependent manner. These data indicate that sPLA2 IB has the potential to induce human podocyte apoptosis via binding to the PLA2R. The sPLA2 IB-PLA2R interaction stimulated podocyte apoptosis through activating ERK1/2 and cPLA2α and through increasing the podocyte AA content.</p

Sistema Solar: Planetas Clássicos

O conhecimento curricular de Astronomia para surdos, não pode ser empobrecido, subtraído, fragmentado, mas sim formulado para corresponder a sua identidade de cognição, sem distanciar-se, porém, do direito inalienável a tudo que devem conhecer. Métodos de ensino não podem ser únicos para todos e, um sistema educacional que não revela estas diferenças está fadado em provocar a exclusão destes educandos por considerá-los inaptos, intelectualmente. Sendo assim, ao organizar o conteúdo que será trabalhado em sala de aula, o professor terá sempre em mente o tema Sistema Solar /Planetas Clássicos. Este tema está diretamente ligado a outros temas, permitindo ao aluno surdo fazer parte desse todo tão complexo que é o Universo em que vivemo

Impact of APOL1 polymorphism and IL-1β priming in the entry and persistence of HIV-1 in human podocytes

Background Patients of African ancestry with untreated HIV-1 infection and carrying the G1 or G2 kidney disease risk variants (Vs) at the APOL1 gene have a tenfold higher risk of developing HIV-associated nephropathy (HIVAN) compared to those with the non-risk wild type (WT) G0 variant. However, the mechanistic contribution of the APOL1 allelic state to kidney injury in HIV-1 infection remains to be elucidated. Results Non-risk WT APOL1 is associated with lower intracellular levels of HIV-1 in conditionally immortalized human podocytes, while the over expression of G1 or G2 risk Vs significantly increases viral accumulation. The priming of podocytes with exogenous IL-1\u3b2 facilitates HIV-1 entry, via the up-regulation of DC-SIGN. The over expression of APOL1 G1 and G2 risk Vs in combination with an increase in IL-1\u3b2 levels causes a greater increase in viral concentration than either condition alone. In turn, HIV-1 and exogenous IL-1\u3b2 together induce a de novo secretion of endogenous IL-1\u3b2 and an increase of APOL1 gene expression. Conclusions Our findings indicate that the presence of risk Vs of APOL1 is permissive of HIV-1 persistence in human podocytes in synergy with IL-1\u3b2, a cytokine that characterizes the inflammatory milieu of acute and chronic phases of HIV-1 infection. The elucidation of these molecular mechanisms explains, at least in part, the higher frequency of HIVAN in populations carrying the risk polymorphic genetic variant of APOL1 gene

Full-length soluble urokinase plasminogen activator receptor down-modulates nephrin expression in podocytes

Increased plasma level of soluble urokinase-type plasminogen activator receptor (suPAR) was associated recently with focal segmental glomerulosclerosis (FSGS). In addition, different clinical studies observed increased concentration of suPAR in various glomerular diseases and in other human pathologies with nephrotic syndromes such as HIV and Hantavirus infection, diabetes and cardiovascular disorders. Here, we show that suPAR induces nephrin down-modulation in human podocytes. This phenomenon is mediated only by full-length suPAR, is time-and dose-dependent and is associated with the suppression of Wilms' tumor 1 (WT-1) transcription factor expression. Moreover, an antagonist of alpha v beta 3 integrin RGDfv blocked suPAR-induced suppression of nephrin. These in vitro data were confirmed in an in vivo uPAR knock out Plaur(-/-) mice model by demonstrating that the infusion of suPAR inhibits expression of nephrin and WT-1 in podocytes and induces proteinuria. This study unveiled that interaction of full-length suPAR with alpha v beta 3 integrin expressed on podocytes results in down-modulation of nephrin that may affect kidney functionality in different human pathologies characterized by increased concentration of suPAR

Full-length soluble urokinase plasminogen activator receptor down-modulates nephrin expression in podocytes

Increased plasma level of soluble urokinase-type plasminogen activator receptor (suPAR) was associated recently with focal segmental glomerulosclerosis (FSGS). In addition, different clinical studies observed increased concentration of suPAR in various glomerular diseases and in other human pathologies with nephrotic syndromes such as HIV and Hantavirus infection, diabetes and cardiovascular disorders. Here, we show that suPAR induces nephrin down-modulation in human podocytes. This phenomenon is mediated only by full-length suPAR, is time-and dose-dependent and is associated with the suppression of Wilms' tumor 1 (WT-1) transcription factor expression. Moreover, an antagonist of alpha v beta 3 integrin RGDfv blocked suPAR-induced suppression of nephrin. These in vitro data were confirmed in an in vivo uPAR knock out Plaur(-/-) mice model by demonstrating that the infusion of suPAR inhibits expression of nephrin and WT-1 in podocytes and induces proteinuria. This study unveiled that interaction of full-length suPAR with alpha v beta 3 integrin expressed on podocytes results in down-modulation of nephrin that may affect kidney functionality in different human pathologies characterized by increased concentration of suPAR

Disruption of APOL1-miR193a Axis Induces Disorganization of Podocyte Actin Cytoskeleton

Abstract APOL1-miR193a axis participates in the preservation of molecular phenotype of differentiated podocytes (DPDs). We examined the hypothesis that APOL1 (G0) preserves, but APOL1 risk alleles (G1 and G2) disrupt APOL1-miR193a axis in DPDs. DPDG0s displayed down-regulation of miR193a, but upregulation of nephrin expression. DPDG1s/G2s exhibited an increase in miR193a and down-regulation of the expression of adherens complex’s constituents (CD2AP, nephrin, and dendrin). DPDG0s showed decreased Cathepsin L, enhanced dynamin expressions, and the intact actin cytoskeleton. On the contrary, DPDG1s/G2s displayed an increase in Cathepsin L, but down-regulation of dynamin expressions and disorganization of the actin cytoskeleton. APOL1 silencing enhanced miR193a and Cathepsin L, but down-regulated dynamin expressions. DPDG1s/G2s displayed nuclear import of dendrin, indicating an occurrence of destabilization of adherens complexes in APOL1 risk milieu. These findings suggest that DPDG1s and DPDG2s developed disorganized actin cytoskeleton as a consequence of disrupted APOL1-miR193a axis. Interestingly, docking and co-labeling studies suggested an interaction between APOL1 and CD2AP. APOL1 G1/G1 and APOL1 G1/G2 transgenic mice displayed nuclear import of dendrin indicating destabilization of adherens complexes in podocytes; moreover, these mice showed a four-fold increase in urinary albumin to creatinine ratio and development of focal segmental glomerular lesions

Modulation of APOL1-miR193a Axis Prevents Podocyte Dediffrentiation in High Glucose Milieu

The loss of podocyte (PD) molecular phenotype is an important feature of diabetic podocytopathy. We hypothesized that high glucose (HG) induces dedifferentiation in differentiated podocytes (DPDs) through alterations in the apolipoprotein (APO) L1-microRNA (miR) 193a axis. HG-induced DPD dedifferentiation manifested in the form of downregulation of Wilms’ tumor 1 (WT1) and upregulation of paired box 2 (PAX2) expression. WT1-silenced DPDs displayed enhanced expression of PAX2. Immunoprecipitation of DPD cellular lysates with anti-WT1 antibody revealed formation of WT1 repressor complexes containing Polycomb group proteins, enhancer of zeste homolog 2, menin, and DNA methyltransferase (DNMT1), whereas silencing of either WT1 or DNMT1 disrupted this complex with enhanced expression of PAX2. HG-induced DPD dedifferentiation was associated with a higher expression of miR193a, whereas inhibition of miR193a prevented DPD dedifferentiation in HG milieu. HG downregulated DPD expression of APOL1. miR193a-overexpressing DPDs displayed downregulation of APOL1 and enhanced expression of dedifferentiating markers; conversely, silencing of miR193a enhanced the expression of APOL1 and preserved DPD phenotype. Moreover, stably APOL1G0-overexpressing DPDs displayed the enhanced expression of WT1 but attenuated expression of miR193a; nonetheless, silencing of APOL1 reversed these effects. Since silencing of APOL1 enhanced miR193a expression as well as dedifferentiation in DPDs, it appears that downregulation of APOL1 contributed to dedifferentiation of DPDs through enhanced miR193a expression in HG milieu. Vitamin D receptor agonist downregulated miR193a, upregulated APOL1 expression, and prevented dedifferentiation of DPDs in HG milieu. These findings suggest that modulation of the APOL1-miR193a axis carries a potential to preserve DPD molecular phenotype in HG milieu.</jats:p

HIV-1 Promotes Renal Tubular Epithelial Cell Protein Synthesis: Role of mTOR Pathway

Tubular cell HIV-infection has been reported to manifest in the form of cellular hypertrophy and apoptosis. In the present study, we evaluated the role of mammalian target of rapamycin (mTOR) pathway in the HIV induction of tubular cell protein synthesis. Mouse proximal tubular epithelial cells (MPTECs) were transduced with either gag/pol-deleted NL4-3 (HIV/MPTEC) or empty vector (Vector/MPTEC). HIV/MPTEC showed enhanced DNA synthesis when compared with Vector/MPTECs by BRDU labeling studies. HIV/MPTECs also showed enhanced production of β-laminin and fibronection in addition to increased protein content per cell. In in vivo studies, renal cortical sections from HIV transgenic mice and HIVAN patients showed enhanced tubular cell phosphorylation of mTOR. Analysis of mTOR revealed increased expression of phospho (p)-mTOR in HIV/MPTECs when compared to vector/MPTECs. Further downstream analysis of mTOR pathway revealed enhanced phosphorylation of p70S6 kinase and associated diminished phosphorylation of eEF2 (eukaryotic translation elongation factor 2) in HIV/MPTECs; moreover, HIV/MPTECs displayed enhanced phosphorylation of eIF4B (eukaryotic translation initiation factor 4B) and 4EBP-1 (eukaryotic 4E binding protein). To confirm our hypothesis, we evaluated the effect of rapamycin on HIV-induced tubular cell downstream signaling. Rapamycin not only attenuated phosphorylation of p70S6 kinase and associated down stream signaling in HIV/MPTECs but also inhibited HIV-1 induced tubular cell protein synthesis. These findings suggest that mTOR pathway is activated in HIV-induced enhanced tubular cell protein synthesis and contributes to tubular cell hypertrophy