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Kidney Week

Abstract: TH-PO113

Renal Mitochondria Exhibit Cell Type-Specific Heterogeneity and Are Functionally Dynamic

Session Information

  • AKI: Mechanisms - I
    November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Feola, Kyle C., The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Venable, Andrea Henning, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Lee, Lauren Elizabeth, The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Huen, Sarah C., The University of Texas Southwestern Medical Center, Dallas, Texas, United States
Background

Mitochondrial dysfunction is a key component of both acute and chronic kidney disease. Across tissues, mitochondria differ in composition and substrate utilization. As the kidney contains many different cell types, we hypothesize that there is intra-renal mitochondrial heterogeneity contributing to cell-specific mitochondrial function. To interrogate this, we utilized a novel mitochondrial tagging technique to isolate mitochondria in a cell-type specific manner. Here, we investigate the proteomes, metabolomes, and mitochondrial functional capacities of the early and late proximal tubule (PT) and distal convoluted tubule (DCT).

Methods

We generated three lines of mutant mice: early PT (Slc34a1-CreERT2;MITO-Tag); late PT (Ggt1-Cre;MITO-Tag); and DCT (PvAlb-Cre;MITO-Tag), capable of cell-specific isolation of hemagglutinin (HA)-tagged mitochondria. Mice were either fed ad libitum or fasted for 24 hours before kidneys were harvested. Cell-specific mitochondria were isolated using anti-HA magnetic beads and processed for proteomics, metabolomics, or functional analyses. Mitochondrial fatty acid oxidation (FAO) functional capacity was assessed using palmitoyl-CoA/carnitine (CPT1-dependent) or palmitoylcarnitine (CPT1-independent) as substrates and measured by Seahorse (Agilent).

Results

Using these MITO-Tag models, we demonstrated the ability to isolate renal mitochondria in a cell-specific manner. We observed differential mitochondrial protein and metabolite profiles of these cell types at both baseline and in fasting conditions. Pathway analysis revealed FAO as a key differentially regulated process, including CPT1A and CPT1B. CPT1A expression significantly increased with fasting in the late PT, and CPT1B expression was significantly higher in the DCT as compared to the PT cell types. Compared to the fed state, CPT1-dependent mitochondrial FAO capacity significantly increased in both the late PT and DCT in the fasted state. Surprisingly, when mitochondrial FAO capacity was assayed independent of CPT1, DCT mitochondria had significantly lower FAO capacity compared to late PT mitochondria in both baseline and fasting conditions.

Conclusion

We demonstrated the successful use of a system to study cell type-specific mitochondria in the mouse kidney. Our data suggest that FAO is differentially regulated in the renal PT and DCT.

Funding

  • Other NIH Support