FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2110828351> ?p ?o ?g. }

• W2110828351 endingPage "536" @default.
• W2110828351 startingPage "525" @default.
• W2110828351 abstract "Multiple transforming growth factor (TGF)-β–induced fibrogenic signals have been described in vitro. To evaluate mechanisms in vivo, we used an adriamycin nephropathy model in 129x1/Svj mice that display massive proteinuria by days 5 to 7 and pathological findings similar to human focal segmental glomerulosclerosis by day 14. TGF-β mRNA expression increased after day 7 along with nuclear translocation of the TGF-β receptor–specific transcription factor Smad3. Inhibiting TGF-β prevented both pathological changes and type-I collagen and fibronectin mRNA expression, but proteinuria persisted. Renal Akt was phosphorylated in adriamycin-treated mice, suggesting PI3-kinase activation. Expression of mRNA for the p110γ isozyme of PI3-kinase was specifically increased and p110γ colocalized with nephrin by immunohistochemistry early in disease. Nephrin levels subsequently decreased. Inhibition of p110γ by AS605240 preserved nephrin expression and prevented proteinuria. In cultured podocytes, adriamycin stimulated p110γ expression. AS605240, but not a TGF-β receptor kinase inhibitor, prevented adriamycin-induced cytoskeletal disorganization and apoptosis, supporting a role for p110γ in podocyte injury. AS605240, at a dose that decreased proteinuria, prevented renal collagen mRNA expression in vivo but did not affect TGF-β-stimulated collagen induction in vitro. Thus, PI3-kinase p110γ mediates initial podocyte injury and proteinuria, both of which precede TGF-β-mediated glomerular scarring. Multiple transforming growth factor (TGF)-β–induced fibrogenic signals have been described in vitro. To evaluate mechanisms in vivo, we used an adriamycin nephropathy model in 129x1/Svj mice that display massive proteinuria by days 5 to 7 and pathological findings similar to human focal segmental glomerulosclerosis by day 14. TGF-β mRNA expression increased after day 7 along with nuclear translocation of the TGF-β receptor–specific transcription factor Smad3. Inhibiting TGF-β prevented both pathological changes and type-I collagen and fibronectin mRNA expression, but proteinuria persisted. Renal Akt was phosphorylated in adriamycin-treated mice, suggesting PI3-kinase activation. Expression of mRNA for the p110γ isozyme of PI3-kinase was specifically increased and p110γ colocalized with nephrin by immunohistochemistry early in disease. Nephrin levels subsequently decreased. Inhibition of p110γ by AS605240 preserved nephrin expression and prevented proteinuria. In cultured podocytes, adriamycin stimulated p110γ expression. AS605240, but not a TGF-β receptor kinase inhibitor, prevented adriamycin-induced cytoskeletal disorganization and apoptosis, supporting a role for p110γ in podocyte injury. AS605240, at a dose that decreased proteinuria, prevented renal collagen mRNA expression in vivo but did not affect TGF-β-stimulated collagen induction in vitro. Thus, PI3-kinase p110γ mediates initial podocyte injury and proteinuria, both of which precede TGF-β-mediated glomerular scarring. Renal fibrosis is a complex process involving multiple cell types and a broad variety of mediators. Podocyte injury is one of the initial steps in the sequence leading to glomerulosclerosis and subsequent renal scarring.1.Barisoni L. Schnaper H.W. Kopp J.B. A proposed taxonomy for the podocytopathies: a reassessment of the primary nephrotic diseases.Clin J Am Soc Nephrol. 2007; 2: 529-542Crossref PubMed Scopus (201) Google Scholar,2.Mundel P. Reiser J. Proteinuria: an enzymatic disease of the podocyte?.Kidney Int. 2010; 77: 571-580Abstract Full Text Full Text PDF PubMed Scopus (228) Google Scholar Misdirected attempts at tissue repair then involve numerous other cells in scar formation.3.Schnaper H.W. Hubchak S.C. Runyan C.E. et al.A conceptual framework for the molecular pathogenesis of progressive kidney disease.Pediatr Nephrol. 2010; 25: 2223-2230Crossref PubMed Scopus (13) Google Scholar Multiple studies have implicated transforming growth factor (TGF)-β as a pivotal cytokine that promotes both physiological healing and pathological scarring, including in the kidney.4.Yamamoto T. Noble N.A. Miller D.E. et al.Sustained expression of TGF-β1 underlies development of progressive kidney fibrosis.Kidney Int. 1994; 45: 916-927Abstract Full Text PDF PubMed Scopus (434) Google Scholar, 5.Tamaki K. Okuda S. Ando T. et al.TGF-β1 in glomerulosclerosis and interstitial fibrosis of adriamycin nephropathy.Kidney Int. 1994; 45: 525-536Abstract Full Text PDF PubMed Scopus (156) Google Scholar, 6.Bottinger E.P. Bitzer M. TGF-β signaling in renal disease.J Am Soc Nephrol. 2002; 13: 2600-2610Crossref PubMed Scopus (662) Google Scholar, 7.Schnaper H.W. Jandeska S. Runyan C.E. et al.TGF-β signal transduction in chronic kidney disease.Front Biosci. 2009; 14: 2448-2465Crossref PubMed Scopus (107) Google Scholar We previously showed that TGF-β activates type-I collagen expression in cultured kidney mesangial and epithelial cells via a complex signaling mechanism in which the classical TGF-β/Smad pathway is regulated by a number of non-canonical pathways involving ERK MAP kinase,8.Hayashida T. Decaestecker M. Schnaper H.W. Cross-talk between ERK MAP kinase and Smad signaling pathways enhances TGF-β-dependent responses in human mesangial cells.FASEB J. 2003; 17: 1576-1578Crossref PubMed Google Scholar phosphatidylinositol-3-kinase (PI3K),9.Runyan C.E. Schnaper H.W. Poncelet A.C. The phosphatidylinositol 3-kinase/Akt pathway enhances Smad3-stimulated mesangial cell collagen I expression in response to transforming growth factor-β1.J Biol Chem. 2004; 279: 2632-2639Crossref PubMed Scopus (200) Google Scholar protein kinase Cδ,10.Runyan C.E. Schnaper H.W. Poncelet A.C. Smad3 and PKCδ mediate TGF-β1-induced collagen I expression in human mesangial cells.Am J Physiol Renal Physiol. 2003; 285: F413-F422Crossref PubMed Scopus (93) Google Scholar and the Rho-family GTPases.11.Hubchak S.C. Runyan C.E. Kreisberg J.I. et al.Cytoskeletal rearrangement and signal transduction in TGF-β1-stimulated mesangial cell collagen accumulation.J Am Soc Nephrol. 2003; 14: 1969-1980Crossref PubMed Scopus (46) Google Scholar,12.Hubchak S.C. Sparks E.E. Hayashida T. et al.Rac1 promotes TGF-β-stimulated mesangial cell type I collagen expression through a PI3K/Akt-dependent mechanism.Am J Physiol Renal Physiol. 2009; 297: F1316-F1323Crossref PubMed Scopus (53) Google Scholar In diabetes, TGF-β has been shown to interact with PI3K to promote mesangial cell dysfunction.13.Kato M. Yuan H. Xu Z.G. et al.Role of the Akt/FoxO3a pathway in TGF-β1-mediated mesangial cell dysfunction: a novel mechanism related to diabetic kidney disease.J Am Soc Nephrol. 2006; 17: 3325-3335Crossref PubMed Scopus (156) Google Scholar,14.Reeves W.B. Andreoli T.E. Transforming growth factor β contributes to progressive diabetic nephropathy.Proc Natl Acad Sci USA. 2000; 97: 7667-7669Crossref PubMed Scopus (204) Google Scholar TGF-β-PI3K cross talk also was demonstrated to be important in renal epithelial-to-mesenchymal transition in vitro and in vivo.15.Kattla J.J. Carew R.M. Heljic M. et al.Protein kinase B/Akt activity is involved in renal TGF-β1-driven epithelial-mesenchymal transition in vitro and in vivo.Am J Physiol Renal Physiol. 2008; 295: F215-F225Crossref PubMed Scopus (112) Google Scholar The present study was aimed at elucidating the involvement of TGF-β and PI3K in an animal model of acquired kidney fibrosis. Adriamycin (ADR)-induced kidney damage is one of the few existing murine models of acquired glomerulonephropathy,16.Fogo A.B. Animal models of FSGS: lessons for pathogenesis and treatment.Semin Nephrol. 2003; 23: 161-171Abstract Full Text Full Text PDF PubMed Scopus (92) Google Scholar in which progressive renal changes lead to terminal renal failure.17.Okuda S. Oh Y. Tsuruda H. et al.Adriamycin-induced nephropathy as a model of chronic progressive glomerular disease.Kidney Int. 1986; 29: 502-510Abstract Full Text PDF PubMed Scopus (206) Google Scholar By a mechanism that is not completely understood, ADR induces pathological glomerular changes that are similar to human focal segmental glomerular sclerosis.18.Yasuda K. Park H.C. Ratliff B. et al.Adriamycin nephropathy: a failure of endothelial progenitor cell-induced repair.Am J Pathol. 2010; 176: 1685-1695Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar TGF-β involvement in the ADR model has been suggested in earlier studies.5.Tamaki K. Okuda S. Ando T. et al.TGF-β1 in glomerulosclerosis and interstitial fibrosis of adriamycin nephropathy.Kidney Int. 1994; 45: 525-536Abstract Full Text PDF PubMed Scopus (156) Google Scholar,19.Li J. Campanale N.V. Liang R.J. et al.Inhibition of p38 mitogen-activated protein kinase and transforming growth factor-β1/Smad signaling pathways modulates the development of fibrosis in adriamycin-induced nephropathy.Am J Pathol. 2006; 169: 1527-1540Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar Some of the model's limitations include severity of the kidney injury and strain specificity—mostly restricted to Balb/c mice.20.Lui S.L. Tsang R. Chan K.W. et al.Rapamycin attenuates the severity of murine adriamycin nephropathy.Am J Nephrol. 2009; 29: 342-352Crossref PubMed Scopus (16) Google Scholar A genome-wide search linked strain susceptibility to anthracyclines to a specific genetic locus, which is shared between Balb/c and 129/SvJ, but not with C57BL6 mice.21.Zheng Z. Schmidt-Ott K.M. Chua S. et al.A Mendelian locus on chromosome 16 determines susceptibility to doxorubicin nephropathy in the mouse.Proc Natl Acad Sci USA. 2005; 102: 2502-2507Crossref PubMed Scopus (85) Google Scholar,22.Papeta N. Zheng Z. Schon E.A. et al.Prkdc participates in mitochondrial genome maintenance and prevents adriamycin-induced nephropathy in mice.J Clin Invest. 2010; 120: 4055-4064Crossref PubMed Scopus (83) Google Scholar Accordingly, we extended the ADR model to the 129x1/SvJ strain and observed that ADR indeed induces similar, but milder, pathological changes than were seen in Balb/C strain of mice. We implicate TGF-β and the p110γ isoform of PI3K in the pathogenesis of this nephropathy model. Our data suggest that PI3K p110γ promotes podocyte injury resulting in proteinuria, via cell signaling that is not directly dependent on TGF-β/Smad3 pathway activation. Conversely, TGF-β/Smad3 signaling is not involved in proteinuria, but instead has a significant part in consequent fibrogenesis. Our results define mechanisms underlying proteinuria and fibrogenesis in chronic kidney disease and indicate that these mechanisms are likely to be distinct. Three to five days following tail-vein administration of one dose of ADR (15mg/kg body weight) to 129x1/Svj mice, albuminuria developed and progressed to massive proteinuria and hypoalbuminemia during the second and third weeks of disease (Figure 1a and b). In addition, ADR-treated mice manifested hypercholesterolemia (Figure 1b and Table 1). Renal function was mild initially, primarily with blood urea nitrogen elevation, but progressed to advanced kidney dysfunction with doubling of baseline serum creatinine about 4 weeks after ADR (Figure 1b). By light microscopy, kidneys of ADR-treated mice showed glomerular mesangial hypercellularity and extracellular matrix expansion accompanied by partially collapsed glomerular capillary loops. Two weeks following ADR administration, some of the glomeruli had segmental sclerosis/hyalinosis, whereas others showed proliferation of parietal epithelial cells reminiscent of cellular crescents. Global glomerular sclerosis with hyalinization of the entire glomerular tuft was observed as well. Influx of inflammatory cells into the interstitium, accompanied by interstitial edema, was also seen. Tubular atrophy followed, beginning at week 2 (Figure 1c) and progressing thereafter (not shown). At 2 weeks, mRNA expression of fibronectin and type-I collagen in kidneys of ADR-treated mice increased up to 15-fold (Figure 2a). At the same time, an increased amount of connective tissue in the glomerular and tubular compartments was observed, as assessed by trichrome staining (Figure 2b, top panels). This was associated with increased type-I collagen expression, as demonstrated by immunohistochemistry (Figure 2b, bottom panels).Table 1Nephrotic indices and kidney function of 129/SvJ mice 2 weeks after ADR administrationAlbumin (g/dl)Cholesterol (mg/dl)BUN (mg/dl)Creatinine (mg/dl)Control (N)2.8±0.77 (31)153±26 (26)37.9±14.3 (31)0.25±0.07 (31)ADR (N)2.17±0.83 (29)410±228 (28)51.5±30.7 (29)0.27±0.11 (25)P value0.004<0.0010.0360.499Abbreviations: ADR, adriamycin; BUN, blood urea nitrogen. Open table in a new tab Figure 2Extracellular matrix accumulation in mouse adriamycin (ADR) nephropathy. (a) mRNA analysis by quantitative PCR shows increased fibronectin and type-I collagen by 14 days (N=2–4 at each time point. Statistical analyses for data at 2 weeks are shown in Figures 4b and 7a). (b) Trichrome staining (upper panels) shows increased glomerular and tubulointerstitial accumulation of extracellular matrix. Specific staining using anti-collagen I antibody shows that type-I collagen accumulates in the glomerulus and the tubulointerstitium (bottom panels). Mice were killed at day 14 after ADR administration. Bars=100μm ( × 10 objective) and 25μm ( × 40 oil objective). Cont, control.View Large Image Figure ViewerDownload (PPT) Abbreviations: ADR, adriamycin; BUN, blood urea nitrogen. By using cell culture systems, we and others previously showed that TGF-β is an important mediator of renal fibrosis. Here, we examined TGF-β involvement in our model of acquired kidney fibrosis. Consistent with previous reports,5.Tamaki K. Okuda S. Ando T. et al.TGF-β1 in glomerulosclerosis and interstitial fibrosis of adriamycin nephropathy.Kidney Int. 1994; 45: 525-536Abstract Full Text PDF PubMed Scopus (156) Google Scholar,19.Li J. Campanale N.V. Liang R.J. et al.Inhibition of p38 mitogen-activated protein kinase and transforming growth factor-β1/Smad signaling pathways modulates the development of fibrosis in adriamycin-induced nephropathy.Am J Pathol. 2006; 169: 1527-1540Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar TGF-β1 mRNA levels were increased in ADR kidneys, peaking around the third week after the injurious stimulus and subsiding gradually thereafter (Figure 3a). The downstream mediator of TGF-β, Smad3, was phosphorylated and accumulated in nuclei of kidney tubular and glomerular cells in ADR-treated mice (Figure 3b), indicating that Smad3 is activated. To test whether TGF-β mediates fibrosis in this model, a soluble TGF-β type-II receptor-Fc (sTβRII-Fc) was used. This chimeric protein has previously been shown to inhibit renal fibrosis in mouse diabetes.23.Russo L.M. del Re E. Brown D. et al.Evidence for a role of transforming growth factor-β1 in the induction of postglomerular albuminuria in diabetic nephropathy: amelioration by soluble TGF-beta type II receptor.Diabetes. 2007; 56: 380-388Crossref PubMed Scopus (108) Google Scholar sTβRII-Fc decreased glomerulomegaly, glomerulosclerosis, and crescent formation in ADR-treated mouse kidneys (Figure 4a and Table 2). Induction of type-I collagen, fibronectin, and TGF-β1 mRNA after ADR administration was also attenuated by sTβRII-Fc (Figure 4b). Interestingly, albuminuria persisted, despite the improved glomerular fibrotic changes, with the sTβRII-Fc treatment (Figure 5a). Further, loss of podocyte markers caused by ADR, as determined by podocalyxin mRNA expression (Figure 5b) and by nephrin staining (Figure 5c), was not prevented by sTβRII-Fc. These results suggest that TGF-β mediates glomerular fibrosis but not podocyte injury and subsequent proteinuria in our model. Successful inhibition of the TGF-β/Smad pathway by the sTβRII-Fc was confirmed by reduction of Smad3 phosphorylation in the treated mouse kidneys (Figure 5d). Efficacy of the sTβRII-Fc was also confirmed in cultured human kidney epithelial cells (HKC) by inhibition of TGF-β-induced COL1A1 mRNA (data not shown).Figure 4Soluble type-II transforming growth factor (TGF)-β receptor (sTβRII-Fc) ameliorates fibrotic changes in adriamycin (ADR) nephropathy. ADR nephropathy was induced as described for Figure 1, and the treatment group additionally received sTβRII-Fc, 4mg/kg via tail vein the day before ADR injection and twice a week intraperitoneally (2mg/kg) until the end of the experiment at day 14. (a) Representative sections stained with periodic acid–Schiff. Inhibition of TGF-β signaling improved the histological outcome of the disease. Bars=25μm ( × 40 oil objective) and 100μm ( × 10 objective). (b) sTβRII-Fc ameliorated type-I collagen (COL1A1), fibronectin, and TGF-β1 mRNA expression induced by ADR (N shown in parentheses under each condition. COL1A1: P=0.019 by one-way analysis of variance (ANOVA), *P=0.005 compared with control, †P=0.0085 compared with ADR; Fibronectin: P<0.001 by one-way ANOVA, *P<0.001 compared with control, †P=0.0046 compared with ADR; TGF-β1: P<0.001 by one-way ANOVA, *P=0.003 compared with control, †P=0.029 compared with ADR. ‘ × ’ represents outliers.View Large Image Figure ViewerDownload (PPT)Table 2Semiquantitative scale of histological changes in 129/SvJ model of acquired nephropathyGlomeruliControlADRADR+sTβRIIMesangial hypercelluarity030Mesangial matrix expansion020Parietal cell hyperplasia031Focal sclerosis0Yes0Global sclerosis0Yes0TubulesIntraluminal casts032Tubular atrophy01–21InterstitiumInflammatory infiltrate031Abbreviation: ADR, adriamycin. Open table in a new tab Figure 5Podocyte damage and proteinuria are not mediated by transforming growth factor (TGF)-β. (a) Soluble TGF-β type-II receptor-Fc (sTβRII-Fc) did not decrease proteinuria (day 14; N shown in parentheses for each condition, P=0.0016 by one-way analysis of variance (ANOVA), *P=0.0026, †P=0.004 compared with control). (b) sTβRII-Fc did not prevent an adriamycin (ADR)-stimulated decrease in podocalyxin mRNA expression (day 14; N shown in parentheses for each condition, P=0.0016 by one-way ANOVA, *P=0.0026, †P=0.004 compared with control). (c) Nephrin staining was decreased at day 14 of the ADR administration even with the sTβRII-Fc treatment. 40 × 1.4 (oil) objective. Bar=20μm. (d) Smad3 phosphorylation, determined by densitometrical analyses of immunoblotting, was decreased by sTβRII-Fc, confirming the efficacy of the inhibitory treatment in vivo (day 14; N shown in parentheses for each condition, P=0.0032 by one-way ANOVA, *P=0.0024 compared with control, †P=0.027 compared with ADR). ‘ × ’ represents outliers.View Large Image Figure ViewerDownload (PPT) Abbreviation: ADR, adriamycin. Previous work in our laboratory showed that PI3K activity is required for TGF-β-stimulated type-I collagen production in mesangial cells in culture.9.Runyan C.E. Schnaper H.W. Poncelet A.C. The phosphatidylinositol 3-kinase/Akt pathway enhances Smad3-stimulated mesangial cell collagen I expression in response to transforming growth factor-β1.J Biol Chem. 2004; 279: 2632-2639Crossref PubMed Scopus (200) Google Scholar We therefore examined the role of PI3K in our mouse model of acquired nephropathy. PI3K activity, as determined by staining for phosphorylation of the downstream target protein Akt, was detectable in the ADR-treated mouse kidneys, in glomeruli and to a lesser extent in tubules (Figure 6a). Levels of mRNA were comparable for the most commonly described PI3K catalytic subunits, the ubiquitous isoforms α and β, as well as for their regulatory subunits. In contrast, the p110γ catalytic subunit isoform was specifically upregulated in the ADR kidney (Figure 6b). This finding was at first surprising to us, as the p110γ isoform is particularly highly expressed in lymphoid cells, with low to modest expression in other organs.24.Ohashi P.S. Woodgett J.R. Modulating autoimmunity: pick your PI3 kinase.Nat Med. 2005; 11: 924-925Crossref PubMed Scopus (11) Google Scholar To test whether the upregulation of p110γ mRNA in the ADR kidney reflects its expression by kidney cells, rather than by infiltrating inflammatory cells, kidney sections were stained for p110γ, along with nephrin as a podocyte marker. p110γ staining was weakly positive in glomeruli of control mouse kidney, and became more obvious at days 3 and 6 after ADR administration (Figure 6c). The p110γ staining colocalized with nephrin, suggesting p110γ expression in podocytes. It is noteworthy that disruption of nephrin staining starts as early as day 3 after the ADR administration. The timing of podocyte marker loss and p110γ expression coincides with the onset of albuminuria, but precedes overt fibrotic changes. To further assess a potential role for PI3Kγ in ADR nephropathy, we administered a specific inhibitor of p110γ, AS605240,25.Camps M. Ruckle T. Ji H. et al.Blockade of PI3Kγ suppresses joint inflammation and damage in mouse models of rheumatoid arthritis.Nat Med. 2005; 11: 936-943Crossref PubMed Scopus (676) Google Scholar 30mg/kg body weight intraperitoneally 1 day before ADR administration, followed by injection every other day. No significant animal, tissue, or cell toxicity related to the use of AS605240 was observed during the 2-week period of the experiments. PI3K p110γ inhibition attenuated proteinuria that was induced by ADR (Figure 7a). AS605240 also decreased mRNA expression of type-I collagen and fibronectin (Figure 7b), as well as fibrotic histological changes and collagen deposition (Figure 7c). Nephrin (protein) and podocalyxin (mRNA) expression were preserved in animals treated with AS605240 (Figure 7d and e), suggesting that in vivo inhibition of p110γ protects against ADR-induced podocyte injury. To determine how p110γ affects podocyte function, we examined its role in podocyte injury in culture. p110γ protein expression was detected by immunoblotting, and AS605240 (1μmol/l) reduced basal Akt activity in cultured podocytes, suggesting that the p110γ isoform is indeed expressed and contributes to downstream Akt activity in podocytes (Figure 8a). In comparison, TGF-β-stimulated Smad activity was not affected by the p110γ inhibitor (not shown). ADR treatment (20μg/ml, 16h) significantly increased p110γ mRNA expression in cultured podocytes (Figure 8b). ADR treatment induced podocyte apoptosis, as detected by expression of cleaved caspase 3 product (Figure 8c) and staining with an early apoptosis marker, cytoDEATH (Figure 8d, upper panels), and disorganization of the cytoskeletal stress fiber pattern (Figure 8e) that is seen normally in differentiated podocytes.26.Mundel P. Reiser J. Kriz W. Induction of differentiation in cultured rat and human podocytes.J Am Soc Nephrol. 1997; 8: 697-705PubMed Google Scholar These podocyte changes were prevented by pretreatment with AS605240, supporting a role for PI3K p110γ in podocyte injury. In contrast, a TGF-β receptor kinase inhibitor, SB431542, did not affect podocyte apoptosis nor cytoskeletal disorganization by ADR. Further, ADR induced cleaved caspase 3 products even in a Smad3-/- podocyte (Figure 8c, bottom panels). Together, these data indicate that ADR-stimulated podocyte damage is mediated by PI3K p110γ, but independent of TGF-β in the time frame that we studied. We next addressed a possible hierarchy between p110γ and TGF-β signaling in our model. The increased pAkt activity that we observed in ADR-treated mouse glomeruli (Figure 6) was not affected by sTβRII-Fc (Figure 9a). Conversely, ADR-stimulated TGF-β1 mRNA expression in mouse kidneys was prevented by treatment with the p110γ inhibitor (Figure 9b). These results suggest that p110γ activation and podocyte injury precede the induction of TGF-β expression. In culture, podocytes express little type-I collagen mRNA both basally and in response to TGF-β1 (data not shown), and TGF-β1 treatment did not change p110γ protein expression (Figure 9c). In the HKC line, the p110γ-specific PI3K inhibitor did not affect TGF-β induction of collagen mRNA expression (Figure 9d), whereas a general PI3K inhibitor that blocks all classes of PI3K including the ubiquitously expressed α and β isoforms, LY294002, abrogated the collagen response, as we have reported previously.9.Runyan C.E. Schnaper H.W. Poncelet A.C. The phosphatidylinositol 3-kinase/Akt pathway enhances Smad3-stimulated mesangial cell collagen I expression in response to transforming growth factor-β1.J Biol Chem. 2004; 279: 2632-2639Crossref PubMed Scopus (200) Google Scholar Therefore, the PI3Kγ inhibitor did not ameliorate fibrosis by directly inhibiting glomerular collagen expression, but rather by preventing glomerular injury and suppressing subsequent production of a fibrogenic cytokine TGF-β. In progressive renal failure, a final common pathway culminates in glomerulosclerosis and tubulointerstitial fibrosis, irrespective of the nature of the original disease. Understanding the molecular mechanisms that are involved is important for developing specific, effective treatments. Animal models of glomerulopathies have been used widely to study signaling pathways involved in the pathogenesis of renal fibrosis. Previous studies suggested that injury to podocytes, essential elements in maintaining glomerular filtration barrier integrity, is the initiating cause of many genetic27.Benoit G. Machuca E. Heidet L. et al.Hereditary kidney diseases: highlighting the importance of classical Mendelian phenotypes.Ann NY Acad Sci. 2010; 1214: 83-98Crossref PubMed Scopus (25) Google Scholar and acquired—both primary and secondary3.Schnaper H.W. Hubchak S.C. Runyan C.E. et al.A conceptual framework for the molecular pathogenesis of progressive kidney disease.Pediatr Nephrol. 2010; 25: 2223-2230Crossref PubMed Scopus (13) Google Scholar, 28.Kumar P.A. Brosius III.., F.C. Menon R.K. The glomerular podocyte as a target of growth hormone action: implications for the pathogenesis of diabetic nephropathy.Curr Diabetes Rev. 2011; 7: 50-55Crossref PubMed Scopus (34) Google Scholar, 29.Leeuwis J.W. Nguyen T.Q. Dendooven A. et al.Targeting podocyte-associated diseases.Adv Drug Deliv Rev. 2010; 62: 1325-1336Crossref PubMed Scopus (75) Google Scholar—renal diseases. In the present paper, we describe a modified version of a previously established rodent model of ADR nephropathy17.Okuda S. Oh Y. Tsuruda H. et al.Adriamycin-induced nephropathy as a model of chronic progressive glomerular disease.Kidney Int. 1986; 29: 502-510Abstract Full Text PDF PubMed Scopus (206) Google Scholar,30.Wang Y. Wang Y.P. Tay Y.C. et al.Progressive adriamycin nephropathy in mice: sequence of histologic and immunohistochemical events.Kidney Int. 2000; 58: 1797-1804Abstract Full Text Full Text PDF PubMed Scopus (254) Google Scholar and use it to dissect renal fibrotic mechanisms. In 129x1/SvJ mice, proteinuria, chemical indices of nephrotic syndrome, and glomerular and tubulointerstitial accumulation of type-I collagen and fibronectin occur sequentially after ADR administration. These changes are similar in nature and order to those of human focal segmental glomerular sclerosis. In contrast, preliminary experiments with Balb/c mice (not shown) yielded a more diffuse and aggressive pattern of injury. We therefore propose that the present model offers a pattern of injury and response more representative of human, progressive glomerulosclerosis. In evaluating non-canonical TGF-β signaling that we previously described in vitro, we found increased Akt activity in both Balb/c and 129x1/SvJ kidneys after ADR treatment. We were surprised that only the γ isoform of PI3K showed increased expression. PI3K p110γ is highly enriched in leukocytes but also is expressed in cardiomyocytes, endothelial cells, pancreatic islets, and smooth muscle cells.24.Ohashi P.S. Woodgett J.R. Modulating autoimmunity: pick your PI3 kinase.Nat Med. 2005; 11: 924-925Crossref PubMed Scopus (11) Google Scholar, 31.Hirsch E. Lembo G. Montrucchio G. et al.Signaling through PI3Kγ: a common platform for leukocyte, platelet and cardiovascular stress sensing.Thromb Haemost. 2006; 95: 29-35PubMed Google Scholar, 32.Vanhaesebroeck B. Ali K. Bilancio A. et al.Signalling by PI3K isoforms: insights from gene-targeted mice.Trends Biochem Sci. 2005; 30: 194-204Abstract Full Text Full Text PDF PubMed Scopus (388) Google Scholar, 33.Kok K. Geering B. Vanhaesebroeck B. Regulation of phosphoinositide 3-kinase expression in health and disease.Trends Biochem Sci. 2009; 34: 115-127Abstract Full Text Full Text PDF PubMed Scopus (184) Google Scholar The likely source of this isoform in our model is the podocyte, as p110γ colocalizes with nephrin in mouse glomeruli, and cultured podocytes express this isoform. Intact actin cytoskeletal structure is essential for the maintenance of effective foot-processes morphology and normal podocyte function,2.Mundel P. Reiser J. Proteinuria: an enzymatic disease of the podocyte?.Kidney Int. 2010; 77: 571-580Abstract Full Text Full Text PDF PubMed Scopus (228) Google Scholar and PI3K-dependent Akt activity has been shown to regulate this structure.34.Zhu J. Sun N. Aoudjit L. et al.Nephrin mediates actin reorganization via phosphoinositide 3-kinase in podocytes.Kidney Int. 2008; 73: 556-566Abstract Full Text Full Text PDF PubMed Scopus (150) Google Scholar As we previously showed that a pan-PI3K inhibitor, LY294002, blocked TGF-β1 induction of type-I collagen expression in cultured renal cells,9.Runyan C.E. Schnaper H.W. Poncelet A.C. The phosphatidylinositol 3-kinase/Akt pathway enhances Smad3-stimulated mesangial cell collagen I expression in response to transforming grow" @default.
• W2110828351 created "2016-06-24" @default.
• W2110828351 creator A5013753143 @default.
• W2110828351 creator A5018858685 @default.
• W2110828351 creator A5020441553 @default.
• W2110828351 creator A5024912124 @default.
• W2110828351 creator A5054211573 @default.
• W2110828351 creator A5056475996 @default.
• W2110828351 date "2012-09-01" @default.
• W2110828351 modified "2023-09-29" @default.
• W2110828351 title "Divergent roles of Smad3 and PI3-kinase in murine adriamycin nephropathy indicate distinct mechanisms of proteinuria and fibrogenesis" @default.
• W2110828351 cites W1707044792 @default.
• W2110828351 cites W1967471692 @default.
• W2110828351 cites W1972774425 @default.
• W2110828351 cites W1977070803 @default.
• W2110828351 cites W1979813835 @default.
• W2110828351 cites W1987218173 @default.
• W2110828351 cites W2011610612 @default.
• W2110828351 cites W2012008369 @default.
• W2110828351 cites W2014012091 @default.
• W2110828351 cites W2014699428 @default.
• W2110828351 cites W2018453308 @default.
• W2110828351 cites W2019153641 @default.
• W2110828351 cites W2024607547 @default.
• W2110828351 cites W2034691869 @default.
• W2110828351 cites W2045832382 @default.
• W2110828351 cites W2057321164 @default.
• W2110828351 cites W2062754674 @default.
• W2110828351 cites W2070953859 @default.
• W2110828351 cites W2072361327 @default.
• W2110828351 cites W2078369355 @default.
• W2110828351 cites W2086100077 @default.
• W2110828351 cites W2086590742 @default.
• W2110828351 cites W2092288827 @default.
• W2110828351 cites W2100519746 @default.
• W2110828351 cites W2102115518 @default.
• W2110828351 cites W2102633875 @default.
• W2110828351 cites W2102715455 @default.
• W2110828351 cites W2104828404 @default.
• W2110828351 cites W2105824620 @default.
• W2110828351 cites W2110010480 @default.
• W2110828351 cites W2119655207 @default.
• W2110828351 cites W2130769950 @default.
• W2110828351 cites W2132130814 @default.
• W2110828351 cites W2132631212 @default.
• W2110828351 cites W2132803823 @default.
• W2110828351 cites W2142364904 @default.
• W2110828351 cites W2156436523 @default.
• W2110828351 cites W2166678824 @default.
• W2110828351 cites W2170723783 @default.
• W2110828351 cites W4328000949 @default.
• W2110828351 doi "https://doi.org/10.1038/ki.2012.139" @default.
• W2110828351 hasPubMedCentralId "https://www.ncbi.nlm.nih.gov/pmc/articles/3425729" @default.
• W2110828351 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/22534961" @default.
• W2110828351 hasPublicationYear "2012" @default.
• W2110828351 type Work @default.
• W2110828351 sameAs 2110828351 @default.
• W2110828351 citedByCount "22" @default.
• W2110828351 countsByYear W21108283512012 @default.
• W2110828351 countsByYear W21108283512013 @default.
• W2110828351 countsByYear W21108283512014 @default.
• W2110828351 countsByYear W21108283512015 @default.
• W2110828351 countsByYear W21108283512016 @default.
• W2110828351 countsByYear W21108283512017 @default.
• W2110828351 countsByYear W21108283512019 @default.
• W2110828351 countsByYear W21108283512022 @default.
• W2110828351 crossrefType "journal-article" @default.
• W2110828351 hasAuthorship W2110828351A5013753143 @default.
• W2110828351 hasAuthorship W2110828351A5018858685 @default.
• W2110828351 hasAuthorship W2110828351A5020441553 @default.
• W2110828351 hasAuthorship W2110828351A5024912124 @default.
• W2110828351 hasAuthorship W2110828351A5054211573 @default.
• W2110828351 hasAuthorship W2110828351A5056475996 @default.
• W2110828351 hasBestOaLocation W21108283511 @default.
• W2110828351 hasConcept C126322002 @default.
• W2110828351 hasConcept C134018914 @default.
• W2110828351 hasConcept C2779561371 @default.
• W2110828351 hasConcept C2780091579 @default.
• W2110828351 hasConcept C2781184683 @default.
• W2110828351 hasConcept C502942594 @default.
• W2110828351 hasConcept C555293320 @default.
• W2110828351 hasConcept C71924100 @default.
• W2110828351 hasConceptScore W2110828351C126322002 @default.
• W2110828351 hasConceptScore W2110828351C134018914 @default.
• W2110828351 hasConceptScore W2110828351C2779561371 @default.
• W2110828351 hasConceptScore W2110828351C2780091579 @default.
• W2110828351 hasConceptScore W2110828351C2781184683 @default.
• W2110828351 hasConceptScore W2110828351C502942594 @default.
• W2110828351 hasConceptScore W2110828351C555293320 @default.
• W2110828351 hasConceptScore W2110828351C71924100 @default.
• W2110828351 hasIssue "5" @default.
• W2110828351 hasLocation W21108283511 @default.
• W2110828351 hasLocation W21108283512 @default.
• W2110828351 hasLocation W21108283513 @default.
• W2110828351 hasLocation W21108283514 @default.
• W2110828351 hasLocation W21108283515 @default.
• W2110828351 hasOpenAccess W2110828351 @default.
• W2110828351 hasPrimaryLocation W21108283511 @default.

• next