Cyclooxygenase-2, prostaglandin E2, and prostanoid receptor EP2 in fluid flow shear stress-mediated injury in the solitary kidney

Hyperfiltration subjects podocytes to increased tensile stress and fluid flow shear stress (FFSS). We showed a 1.5- to 2.0-fold increase in FFSS in uninephrectomized animals and altered podocyte actin cytoskeleton and increased synthesis of prostaglandin E2 (PGE2) following in vitro application of FFSS. We hypothesized that increased FFSS mediates cellular changes through specific receptors of PGE2. Presently, we studied the effect of FFSS on cultured podocytes and decapsulated isolated glomeruli in vitro, and on solitary kidney in uninephrectomized sv129 mice. In cultured podocytes, FFSS resulted in increased gene and protein expression of cyclooxygenase (COX)-2 but not COX-1, prostanoid receptor EP2 but not EP4, and increased synthesis and secretion of PGE2, which were effectively blocked by indomethacin. Next, we developed a special flow chamber for applying FFSS to isolated glomeruli to determine its effect on an intact glomerular filtration barrier by measuring change in albumin permeability ( Palb) in vitro. FFSS caused an increase in Palb that was blocked by indomethacin ( P < 0.001). Finally, we show that unilateral nephrectomy in sv129 mice resulted in glomerular hypertrophy ( P = 0.006), increased glomerular expression of COX-2 ( P < 0.001) and EP2 ( P = 0.039), and increased urinary albumin excretion ( P = 0.001). Activation of the COX-2-PGE2-EP2 axis appears to be a specific response to FFSS in podocytes and provides a mechanistic basis for alteration in podocyte structure and the glomerular filtration barrier, leading to albuminuria in hyperfiltration-mediated kidney injury. The COX-2-PGE2-EP2 axis is a potential target for developing specific interventions to ameliorate the effects of hyperfiltration-mediated kidney injury in the progression of chronic kidney disease.

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Fluid flow shear stress over podocytes is increased in the solitary kidney

Nephrology Dialysis Transplantation ◽

10.1093/ndt/gft387 ◽

2013 ◽

Vol 29 (1) ◽

pp. 65-72 ◽

Cited By ~ 23

Author(s):

Tarak Srivastava ◽

Gianni E. Celsi ◽

Mukut Sharma ◽

Hongying Dai ◽

Ellen T. McCarthy ◽

...

Keyword(s):

Shear Stress ◽

Fluid Flow ◽

Solitary Kidney ◽

Flow Shear ◽

Flow Shear Stress ◽

Fluid Flow Shear Stress

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Transcription Factor β-Catenin Plays a Key Role in Fluid Flow Shear Stress-Mediated Glomerular Injury in Solitary Kidney

Cells ◽

10.3390/cells10051253 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1253

Author(s):

Tarak Srivastava ◽

Daniel P. Heruth ◽

R. Scott Duncan ◽

Mohammad H. Rezaiekhaligh ◽

Robert E. Garola ◽

...

Keyword(s):

Shear Stress ◽

Transcription Factor ◽

Fluid Flow ◽

Immunofluorescence Microscopy ◽

Solitary Kidney ◽

Glomerular Injury ◽

Flow Shear ◽

Flow Shear Stress ◽

Fluid Flow Shear Stress

Increased fluid flow shear stress (FFSS) in solitary kidney alters podocyte function in vivo. FFSS-treated cultured podocytes show upregulated AKT-GSK3β-β-catenin signaling. The present study was undertaken to confirm (i) the activation of β-catenin signaling in podocytes in vivo using unilaterally nephrectomized (UNX) TOPGAL mice with the β-galactosidase reporter gene for β-catenin activation, (ii) β-catenin translocation in FFSS-treated mouse podocytes, and (iii) β-catenin signaling using publicly available data from UNX mice. The UNX of TOPGAL mice resulted in glomerular hypertrophy and increased the mesangial matrix consistent with hemodynamic adaptation. Uninephrectomized TOPGAL mice showed an increased β-galactosidase expression at 4 weeks but not at 12 weeks, as assessed using immunofluorescence microscopy (p < 0.001 at 4 weeks; p = 0.16 at 12 weeks) and X-gal staining (p = 0.008 at 4 weeks; p = 0.65 at 12 weeks). Immunofluorescence microscopy showed a significant increase in phospho-β-catenin (Ser552, p = 0.005) at 4 weeks but not at 12 weeks (p = 0.935) following UNX, and the levels of phospho-β-catenin (Ser675) did not change. In vitro FFSS caused a sustained increase in the nuclear translocation of phospho-β-catenin (Ser552) but not phospho-β-catenin (Ser675) in podocytes. The bioinformatic analysis of the GEO dataset, #GSE53996, also identified β-catenin as a key upstream regulator. We conclude that transcription factor β-catenin mediates FFSS-induced podocyte (glomerular) injury in solitary kidney.

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The Effect of Fluid Flow Shear Stress and Substrate Stiffness on Yes-Associated Protein (YAP) Activity and Osteogenesis in Murine Osteosarcoma Cells

Cancers ◽

10.3390/cancers13133128 ◽

2021 ◽

Vol 13 (13) ◽

pp. 3128

Author(s):

Thomas R. Coughlin ◽

Ali Sana ◽

Kevin Voss ◽

Abhilash Gadi ◽

Upal Basu-Roy ◽

...

Keyword(s):

Shear Stress ◽

Fluid Flow ◽

Bone Cells ◽

Bone Cancer ◽

Substrate Stiffness ◽

Flow Shear ◽

Fluid Movement ◽

Flow Shear Stress ◽

Fluid Flow Shear Stress ◽

New Treatments

Osteosarcoma (OS) is an aggressive bone cancer originating in the mesenchymal lineage. Prognosis for metastatic disease is poor, with a mortality rate of approximately 40%; OS is an aggressive disease for which new treatments are needed. All bone cells are sensitive to their mechanical/physical surroundings and changes in these surroundings can affect their behavior. However, it is not well understood how OS cells specifically respond to fluid movement, or substrate stiffness—two stimuli of relevance in the tumor microenvironment. We used cells from spontaneous OS tumors in a mouse engineered to have a bone-specific knockout of pRb-1 and p53 in the osteoblast lineage. We silenced Sox2 (which regulates YAP) and tested the effect of fluid flow shear stress (FFSS) and substrate stiffness on YAP expression/activity—which was significantly reduced by loss of Sox2, but that effect was reversed by FFSS but not by substrate stiffness. Osteogenic gene expression was also reduced in the absence of Sox2 but again this was reversed by FFSS and remained largely unaffected by substrate stiffness. Thus we described the effect of two distinct stimuli on the mechanosensory and osteogenic profiles of OS cells. Taken together, these data suggest that modulation of fluid movement through, or stiffness levels within, OS tumors could represent a novel consideration in the development of new treatments to prevent their progression.

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