Abstract: TH-PO256

HIF-1-Mediated Production of Exosomes during Hypoxia Is Protective in Renal Tubular Cells

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Zhang, Wei, Augusta University, Augusta, Georgia, United States
  • Zhou, Xiangjun, Taihe Hospital, Hubei University of Medicine, ----Shiyan, China
  • Zhang, Hao, The Third Xiangya Hospital of Central South University, Changsha, HuNan, China
  • Wen, Jin, Sichuan University, Augusta, Georgia, United States
  • Dong, Zheng, Georgia Regents University, Augusta, Georgia, United States
Background

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 patho-physiological condition in kidneys. This study was designed to characterize exosome production during hypoxia of rat renal proximal tubular cells (RPTC), investigate the regulation by hypoxia-inducible factor-1 (HIF-1), and determine the effect of the exosomes on ATP-depletion induced tubular cell injury.

Methods

RPTCs were treated with or without hypoxia. Exosomes were isolated by ultracentrifugation. Transmission electron microscopy and Nanoparticle Tracking Analyzer (NTA) Zeta View as well as Immunoblot analysis were used to qualify and quantify exosomes. HIF-1α inducer DMOG and its inhibitor YC-1 were used for HIF-1α induction or inhibition. A stable HIF-1α knockout MEF cell line and HIF-1α siRNA induced kknockdownRPTC cells were used to verify the role of HIF-1α in exosomes production. Conditioned exosomes were administrated as a pretreatment before Azide induced ATP-depletion injury in RPTC cells. Hoechst staining, morphology images and caspase-3 expression by immunoblot were conducted to evaluate the death and survival rate of the cells.

Results

The average size of exosome secreted in hypoxia condition was comparable to the normal condition by the NTA measurement. Hypoxia significantly increased exosome production in a time-dependent manner. HIF-1α induction by DMOG also slightly promoted exosomes secretion. Pharmacal or genomic inhibition of HIF-1α abrogated exosome increase under hypoxia condition; Pretreatment with hypoxic exosomes from tubular cells attenuated the apoptosis of RPTCs after Azide induced ATP-depletion. Exosomes form HIF-1α knock down cells failed to decrease cell apoptosis rate and caspase-3 expression.

Conclusion

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.

Funding

  • NIDDK Support