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Abstract: FR-PO342

Podocyte-Specific Clusterin Triggers the Activation of Proximal Tubule-Specific CAMK1D Signaling to Attenuate Kidney Injury in Diabetic Kidney Disease

Session Information

Category: Diabetic Kidney Disease

  • 701 Diabetic Kidney Disease: Basic

Authors

  • Gujarati, Nehaben A., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States
  • Owusu Frimpong, Bismark, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States
  • Zaidi, Malaika, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States
  • Mallipattu, Sandeep K., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States
Background

The role of podocyte-proximal tubule (PT) crosstalk in the progression of Diabetic Kidney Disease (DKD) remains understudied. Podocyte-specific overexpression of Krüppel-like factor 6 (KLF6), a zinc finger transcription factor, attenuated proximal tubule (PT) injury in murine DKD model. Initial snRNA-seq studies demonstrated a potential interaction between podocyte Clusterin (CLU), a secretory ligand, and proximal tubule CAMK1D. The aim of this study is to investigate the mechanism by which the podocyte primes the PT to attenuate kidney injury in DKD.

Methods

Conditioned media (CM) was collected from GFP-labeled podocytes obtained from podocyte-specific induction of KLF6 (KLF6PODTA) and control mice to carry out proteomic analysis and in vitro assays in primary (1°) PT. 1° PT cells were treated with control CM as well as CM blocked with CLU antibody. CAMK1D signaling was pharmacologically inhibited using STO-609, an inhibitor of the upstream kinase CAMKK. Oxygen consumption rate (OCR) was measured with seahorse analyzer. Immunofluorescence staining, western blot analysis, and pulldown assay for calmodulin were performed. Single nuclei ATAC (SnATAC) and snRNA sequencing were conducted on the kidney cortex of all mice.

Results

Immunostaining of experimental mice as well as proteomic analysis of the podocyte CM and urine, led to identification of CLU as a potential ligand for PT signaling. KLF6PODTA CM-treated 1° PT cells demonstrated an increase in calmodulin binding affinity as well as an increase in OCR compared to control CM-treated cells in high glucose (HG) conditions, and this OCR change was abated by the addition of CLU blocking antibody. CAMK1D expression was unique to the first segment of PT in mouse as well as human tissue. 1° PT cells treated with STO-609 had a decrease in cell viability and OCR in HG conditions, a decrease in p-DRP1, and an increase in fragmented mitochondria. SnATACseq in combination with snRNAseq also validated pathways related to calcium signaling and podocyte-PT communication.

Conclusion

These data suggest that CLU secreted from podocytes attenuates mitochondrial fission in the PT by inducing CAMK1D signaling, thereby priming the PT against injury under diabetic conditions.

Funding

  • NIDDK Support