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Abstract: SA-PO256

Store-Operated Ca2+ Entry Inhibition Ameliorated High Glucose- and Ang2-Induced Podocyte Apoptosis and Mitochondria Damage

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Tao, Yu, University of North Texas Health Science Center, Department of Physiology and Anatomy, Fort Worth, Texas, United States
  • Yazdizadeh Shotorbani, Parisa, University of North Texas Health Science Center, Department of Physiology and Anatomy, Fort Worth, Texas, United States
  • Chen, Zhenglan, University of North Texas Health Science Center, Department of Physiology and Anatomy, Fort Worth, Texas, United States
  • Inman, Denise M., University of North Texas Health Science Center, North Texas Eye Research Institute, Pharmaceutical Science, Fort Worth, Texas, United States
  • Ma, Rong, University of North Texas Health Science Center, Department of Physiology and Anatomy, Fort Worth, Texas, United States
Background

Diabetic Nephropathy (DN) is the most common cause of end stage renal disease. Podocyte apoptosis is one of early features of the disease and mitochondria impairment is a contributor to podocyte injury in diabetic kidney. Hyperglycemia and increased renal angiotensin II (ANG II) are two pathogenic stimuli for onset and progression of podocyte pathology in DN. However, the mechanism of the podocyte injury induced by the diabetes-related stress is not fully understood. Store-operated Ca2+ entry (SOCE) has multiple functions in both excitable and non-excitable cells. It is known that ANG II activates SOCE by releasing endoplasmic reticulum Ca2+. Our previous study demonstrated that high glucose (HG) treatment enhanced SOCE by increasing Orai1 protein abundance in podocyte. However, the role of SOCE in podocyte apoptosis and mitochondria dysfunction in the setting of diabetes remains unclear. The present study was carried out to test the hypothesis that enhanced SOCE mediated HG- and ANG II-induced podocyte apoptosis and mitochondria damage.

Methods

All experiments were performed using cultured human podocytes. BTP2 (4 µM) was used as the SOCE inhibitor. Podocyte apoptosis was determined by flow cytometry using Annexin V/Propidium iodide (PI) staining. Mitochondria function was evaluated by measuring: 1) the mitochondria membrane potential (MMP) using TMRE fluorescence, 2) generation of mitochondria reactive oxygen species (ROS) using MitoSox Red Mitochondrial Superoxide Indicator, 3) ATP production using ATP assay kit, and 4) mitochondria respiratory function [oxygen consumption rate (OCR)] and mitochondria ATP production by seahorse analysis.

Results

Both HG (25 mM) and ANG II (1 μM) treatments for 24 hours significantly increased podocyte apoptosis. All responses were significantly blunted by BTP2 (4 µM). HG (25 mM) treatment significantly decreased podocyte MMP, ATP production and increased mitochondrial ROS generation, all of which were significantly inhibited by BTP2 treatment. Furthermore, HG (25 mM) and ANG II (1 μM) treatment for 24 hours significantly reduced podocyte OCR and mitochondria ATP production, which were significantly blunted by BTP2.

Conclusion

SOCE contributed to HG- and ANG II-induced podocyte apoptosis and mitochondria damage.

Funding

  • NIDDK Support