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Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport

Nag, Subhra Sankar
http://orcid.org/0000-0002-6872-9178
http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351

Abstract Details

2018, Doctor of Philosophy in Regulatory Biology, Cleveland State University, College of Sciences and Health Professions.
Kidney cyst expansion, stagnant fluid accumulation, and insufficient vascular supply can result in localized chronic ischemia-hypoxia in kidney cysts, as well as in normal renal epithelia adjacent to a cyst. We hypothesize that in normal epithelia near a cyst, the stabilization of Hypoxia Inducible Factor 1a (HIF1a), a major regulator of cellular response to hypoxia, can cause altered paracellular and transcellular transport, transforming a normal absorptive phenotype to a secretory and paracellularly leaky phenotype, leading to cyst expansion. Using 100 µmol/L cobalt chloride (CoCl2), HIF1a was stabilized in cellular nucleus of a mouse cortical collecting duct cell line (mCCD 1296 (d)), which resulted in an increased level of erythropoietin, an effector and reporter molecule of HIF1a. The mCCD monolayers have a high transepithelial resistance (TER) value (¿ 3000 O-cm2) and around 95% amiloride-sensitive voltage value. Equivalent current was calculated to compare active ion transport. Our results showed that TER values decreased significantly after 48 and 72 hours of HIF-stabilization. The decrease of TER value was consistent with the increase in the permeability of 70 kDa FITC-dextran molecules, supporting the hypothesis that HIF-stabilization altered paracellular transport. Stabilization of HIF caused a significant decrease in the protein level of zonula occludin 1 (ZO1), which controls paracellular transport through tight junctions. Decrease in the ZO1 protein level was consistent with the decreased TER value and the increased paracellular permeability. Similarly, HIF-stabilization was found to increase paracellular permeability in Mardin-Darby Canine Kidney (MDCK) epithelial monolayers. In mCCD monolayers, HIF-stabilization for 48 hours caused loss of active sodium ion (Na+) transport, and very interestingly, 72 hours of HIF-stabilization caused a switch in the direction of net active ion transport. HIF-stabilization caused a significant decrease of protein level of sodium-potassium-ATPase (Na+/ K+-ATPase) a1 subunit, the catalytic subunit of the enzyme responsible for active Na+ transport, consistent with the loss of active transport of Na+. Our results indicate that HIF-stabilization can transform a normal absorptive epithelium to a paracellularly leaky and cyst-like secretory epithelium by reversing net Na+ transport and increasing monolayer permeability due to alterations of tight junctions, and thereby HIF-stabilization may contribute to cyst expansion.
Andrew Renick, PhD (Committee Chair)
Roman Kondratov, PhD (Committee Member)
Crystal Weyman, PhD (Committee Member)
Aoron Severson, PhD (Committee Member)
Thomas McIntyre, PhD (Committee Member)
Joseph LaManna, PhD (Committee Member)
204 p.
Biology; Biomedical Research; Biophysics; Cellular Biology
Kidney Cyst; PKD; Renal Transepithelial Transport; Active Na Transport; Passive Transport; Electrophysiology; TER; Equivalent Current; CoCl2; Hypoxia; HIF; Epithelial Tight Junction; FITC-dextran Permeability; ZO1; Na-K-ATPase; ENaC

Recommended Citations

Citations

  • Nag, S. S. (2018). Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport [Doctoral dissertation, Cleveland State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351

    APA Style (7th edition)

  • Nag, Subhra. Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport. 2018. Cleveland State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351.

    MLA Style (8th edition)

  • Nag, Subhra. "Stabilization of Hypoxia Inducible Factor by Cobalt Chloride Can Alter Renal Transepithelial Transport." Doctoral dissertation, Cleveland State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1536931227678351

    Chicago Manual of Style (17th edition)

csu1536931227678351
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© 2018, all rights reserved.
This open access ETD is published by Cleveland State University and OhioLINK.