Impaired Wound Healing in Hypoxic Renal Tubular Cells: Roles of Hypoxia-Inducible Factor-1 and Glycogen Synthase Kinase 3β/β-Catenin Signaling

Rich amount of phenolic compounds are available in Trianthema portulacastrum L. (TP) leaves and are traditionally utilized as a wound dressing material. Oxidative stress and inflammation affect the Wnt/β-catenin pathway by modulating the glycogen synthase kinase-3β (GSK) activity subjected to delay in wound healing. The objective of the current study was to explore the wound healing effect of ferric oxide nanoparticles biosynthesized with fractionated TP extract (FeTP). The ability of TP active components (polyphenols) to inhibit the GSK was explored by using molecular docking studies. FeTP were synthesized, characterized, utilized to prepare an ointment and its efficacy was investigated against full-thickness dermal wounds. Different wound healing parameters, level of enzymatic antioxidants, hydroxyproline content and tissue cytokines level were analyzed. Histopathology was performed to confirm the healing by newly formed tissue architecture. Rats treated with FeTP showed significantly swift healing with faster wound contraction rate, high tensile strength and hydroxyproline content along with the utilization of less time for epithelialization. Histopathological study also validated the potential wound healing effect of FeTP with complete re-epithelialization. The results of the present study cumulatively revealed that the green synthesized FeTP ointment approach may serve as a potential tool for dermal wound healing.

Download Full-text

HIF-1-mediated production of exosomes during hypoxia is protective in renal tubular cells

AJP Renal Physiology ◽

10.1152/ajprenal.00178.2017 ◽

2017 ◽

Vol 313 (4) ◽

pp. F906-F913 ◽

Cited By ~ 37

Author(s):

Wei Zhang ◽

Xiangjun Zhou ◽

Qisheng Yao ◽

Yutao Liu ◽

Hao Zhang ◽

...

Keyword(s):

Cell Injury ◽

Hypoxia Inducible Factor ◽

Atp Depletion ◽

Tubular Cell ◽

Renal Tubular Cell ◽

Dependent Manner ◽

Protective Effects ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Exosomes are nano-sized vesicles produced and secreted by cells to mediate intercellular communication. The production and function of exosomes in kidney tissues and cells remain largely unclear. Hypoxia is a common pathophysiological condition in kidneys. This study was designed to characterize exosome production during hypoxia of rat renal proximal tubular cells (RPTCs), investigate the regulation by hypoxia-inducible factor-1 (HIF-1), and determine the effect of the exosomes on ATP-depletion-induced tubular cell injury. Hypoxia did not change the average sizes of exosomes secreted by RPTCs, but it significantly increased exosome production in a time-dependent manner. HIF-1 induction with dimethyloxalylglycine also promoted exosome secretion, whereas pharmacological and genetic suppression of HIF-1 abrogated the increase of exosome secretion under hypoxia. The exosomes from hypoxic RPTCs had inhibitory effects on apoptosis of RPTCs following ATP depletion. The protective effects were lost in the exosomes from HIF-1α knockdown cells. It is concluded that hypoxia stimulates exosome production and secretion in renal tubular cells. The exosomes from hypoxic cells are protective against renal tubular cell injury. HIF-1 mediates exosome production during hypoxia and contributes to the cytoprotective effect of the exosomes.

Download Full-text

Hypoxia-inducible factor modulates tubular cell survival in cisplatin nephrotoxicity

AJP Renal Physiology ◽

10.1152/ajprenal.00081.2005 ◽

2005 ◽

Vol 289 (5) ◽

pp. F1123-F1133 ◽

Cited By ~ 70

Author(s):

Tetsuhiro Tanaka ◽

Ichiro Kojima ◽

Takamoto Ohse ◽

Reiko Inagi ◽

Toshio Miyata ◽

...

Keyword(s):

Mitochondrial Membrane ◽

Functional Role ◽

Hypoxia Inducible Factor ◽

Tubular Cell ◽

Apoptotic Cells ◽

Outer Medulla ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Hypoxia-inducible factor (HIF)-1 is a transcription factor mediating cellular response to hypoxia. Although it is expressed in tubular cells of the ischemic kidney, its functional role is not fully clarified in the pathological context. In this study, we investigated a role of HIF in tubular cell apoptosis induced by cisplatin. HIF-1α was expressed in tubular cells in the outer medulla 3 days after cisplatin (6 mg/kg) administration. With the in vivo administration of cobalt to activate HIF, the number of apoptotic renal tubular cells became much smaller in the outer medulla, compared with the vehicle group. We also examined the functional role of HIF-1 in vitro using immortalized rat proximal tubular cells (IRPTC). In hypoxia, IRPTC that express dominant-negative (dn) HIF-1α showed impaired survival in cisplatin injury at variable doses (25–100 μM, 24 h), which was not obvious in normoxia. The observed difference in cell viability in hypoxia was associated with the increased number of apoptotic cells in dnHIF-1α clones (Hoechst 33258 staining). Studies on intracellular signaling revealed that the degree of cytochrome c release, dissipation of mitochondrial membrane potentials, and caspase-9 activity were all more prominent in dnHIF-1α clones than in control IRPTC, pointing to the accelerated signaling of mitochondrial pathways. We propose that HIF-1 mediates cytoprotection against cisplatin injury in hypoxic renal tubular cells, by reducing the number of apoptotic cells through stabilization of mitochondrial membrane integrity and suppression of apoptosis signaling. A possibility was suggested that activation of HIF-1 could be a new promising therapeutic target for hypoxic renal diseases.

Download Full-text

mTORC1 Hyperactivity Inhibits Serum Deprivation-Induced Apoptosis via Increased Hexokinase II and GLUT1 Expression, Sustained Mcl-1 Expression, and Glycogen Synthase Kinase 3β Inhibition

Molecular and Cellular Biology ◽

10.1128/mcb.01946-08 ◽

2009 ◽

Vol 29 (18) ◽

pp. 5136-5147 ◽

Cited By ~ 27

Author(s):

Prashanth T. Bhaskar ◽

Veronique Nogueira ◽

Krushna C. Patra ◽

Sang-Min Jeon ◽

Youngkyu Park ◽

...

Keyword(s):

Glycogen Synthase ◽

Hypoxia Inducible Factor ◽

Feedback Mechanism ◽

Serum Deprivation ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3Β ◽

Hexokinase Ii ◽

Negative Feedback Mechanism ◽

Glut1 Expression ◽

Induced Apoptosis

ABSTRACT The current concept is that Tsc-deficient cells are sensitized to apoptosis due to the inhibition of Akt activity by the negative feedback mechanism induced by the hyperactive mTORC1. Unexpectedly, however, we found that Tsc1/2-deficient cells exhibit increased resistance to serum deprivation-induced apoptosis. mTORC1 hyperactivity contributes to the apoptotic resistance of serum-deprived Tsc1/2-deficient cells in part by increasing the growth factor-independent expression of hexokinase II (HKII) and GLUT1. mTORC1-mediated increase in hypoxia-inducible factor 1α (HIF1α) abundance, which occurs in the absence of serum in normoxic Tsc2-deficient cells, contributes to these changes. Increased HIF1α abundance in these cells is attributed to both an increased level and the sustained translation of HIF1α mRNA. Sustained glycogen synthase kinase 3β inhibition and Mcl-1 expression also contribute to the apoptotic resistance of Tsc2-deficient cells to serum deprivation. The inhibition of mTORC1 activity by either rapamycin or Raptor knockdown cannot resensitize these cells to serum deprivation-induced apoptosis because of elevated Akt activity that is an indirect consequence of mTORC1 inhibition. However, the increased HIF1α abundance and the maintenance of Mcl-1 protein expression in serum-deprived Tsc2 −/ − cells are dependent largely on the hyperactive eIF4E in these cells. Consistently, the reduction of eIF4E levels abrogates the resistance of Tsc2 −/ − cells to serum deprivation-induced apoptosis.

Download Full-text

Abstract 132: Hypoxia-inducible Factor Prolyl-hydroxylase-2 Mediates Transforming Growth Factor Beta 1-induced Epithelial-mesenchymal Transition In Renal Tubular Cells

Hypertension ◽

10.1161/hyp.60.suppl_1.a132 ◽

2012 ◽

Vol 60 (suppl_1) ◽

Author(s):

Weiqing Han ◽

Jun-Pin Hu ◽

Pin-Lan Li ◽

Ningjun Li

Keyword(s):

Signaling Pathway ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Epithelial Mesenchymal Transition ◽

Kidney Diseases ◽

Hypoxia Inducible Factor ◽

Mesenchymal Transition ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Renal Tubular

Transforming growth factor beta 1 (TGFβ1)-induced epithelial-mesenchymal transition (EMT) in kidney epithelial cells plays a key role in renal tubulointerstitial fibrosis in chronic kidney diseases. As hypoxia-inducible factor (HIF)-1α is found to mediate TGFβ1 signaling pathway, we tested the hypothesis that HIF-1α and its upstream regulator prolyl hydroxylase domain-containing proteins (PHDs) are involved in TGFβ1-induced EMT in renal tubular cells. Our results showed that TGFβ1 treatment for 48 h stimulated EMT in cultured renal tubular cells as indicated by the decrease in epithelial marker P-cadherin from 1.0 ± 0.02 to 0.40 ± 0.05 ( P < 0.05), and the increase in mesenchymal markers α-smooth muscle actin (2.14 ± 0.32 fold, P < 0.05) and fibroblast-specific protein (2.0 ± 0.17 fold, P < 0.05) as shown in Western blot assay. Meanwhile, TGFβ1 time-dependently increased HIF-1α, which reached its maximum value (2.36 ± 0.2 fold, P < 0.05) at 24 h, and that HIF-1α siRNA significantly inhibited TGFβ1-induced EMT, suggesting that HIF-1α mediated TGFβ1 induced-EMT. Real-time PCR showed that PHD1 and PHD2, rather than PHD3, could be detected, with PHD2 as the predominant form of PHDs (PHD1 : PHD2 = 0.21:1.0). Importantly, TGFβ1 time-dependently decreased PHD2 mRNA and protein level, which reached their maximum value from 1.0 ± 0.15 to 0.45 ± 0.08 ( P < 0.05) for mRNA at 16 h and from 1.0 ± 0.08 to 0.26 ± 0.08 ( P < 0.05) for protein at 24 h, respectively. In contrast, TGFβ1 had no effect on PHD1 mRNA and protein levels. Furthermore, over-expression of PHD2 transgene almost fully prevented TGFβ1-induced HIF-1α accumulation and EMT marker changes, indicating that PHD2 is involved in TGFβ1-induced EMT. Finally, Smad2 inhibitor SB431542 prevented TGFβ1-induced PHD2 decrease, suggesting that Smad2 may mediate TGFβ1-induced EMT through PHD2/HIF-1α. It is concluded that TGFβ1 decreased PHD2 expression via a Smad2-dependent signaling pathway, thereby leading to HIF-1α accumulation and EMT in renal tubular cells. The present study suggests that PHD2/HIF-1α is a novel signaling pathway mediating the fibrogenic effect of TGFβ1 and that manipulating PHD2/HIF-1α pathway may be used as a therapeutic strategy in chronic kidney diseases. (support: NIH grant HL89563 and HL106042)

Download Full-text

Hypoxia inducible factor-1α mediates the profibrotic effect of albumin in renal tubular cells

Scientific Reports ◽

10.1038/s41598-017-15972-8 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 9

Author(s):

Junping Hu ◽

Weili Wang ◽

Fan Zhang ◽

Pin-Lan Li ◽

Krishna M. Boini ◽

...

Keyword(s):

Hypoxia Inducible Factor ◽

Tubular Cells ◽

Hypoxia Inducible Factor 1Α ◽

Renal Tubular Cells ◽

Renal Tubular

Download Full-text

Exosome production and its regulation of EGFR during wound healing in renal tubular cells

AJP Renal Physiology ◽

10.1152/ajprenal.00078.2017 ◽

2017 ◽

Vol 312 (6) ◽

pp. F963-F970 ◽

Cited By ~ 28

Author(s):

Xiangjun Zhou ◽

Wei Zhang ◽

Qisheng Yao ◽

Hao Zhang ◽

Guie Dong ◽

...

Keyword(s):

Wound Healing ◽

Wound Repair ◽

Renal Tubules ◽

Egfr Signaling ◽

Tubular Cells ◽

Renal Tubular Cells ◽

Egfr Activation ◽

Renal Tubular ◽

The Relationship

Kidney repair following injury involves the reconstitution of a structurally and functionally intact tubular epithelium. Growth factors and their receptors, such as EGFR, are important in the repair of renal tubules. Exosomes are cell-produced small (~100 nm in diameter) vesicles that contain and transfer proteins, lipids, RNAs, and DNAs between cells. In this study, we examined the relationship between exosome production and EGFR activation and the potential role of exosome in wound healing. EGFR activation occurred shortly after scratch wounding in renal tubular cells. Wound repair after scratching was significantly promoted by EGF and suppressed by EGFR inhibitor gefitinib. Interestingly, scratch wounding induced a significant increase of exosome production. The exosome production was decreased by EGF and increased by gefitinib, suggesting a suppressive role of EGFR signaling in exosome production. Conversely, inhibition of exosome release by GW4869 and manumycin A markedly increased EGFR activation and promoted wound healing. Moreover, exosomes derived from scratch-wounding cells could inhibit wound healing. Collectively, the results indicate that wound healing in renal tubular cells is associated with EGFR activation and exosome production. Although EGFR activation promotes wound healing, released exosomes may antagonize EGFR activation and wound healing.

Download Full-text