Kidney Week

Abstract: SA-OR56

Rapid Podocyte Loss Triggers Formation of Intercellular Bridges

Session Information

• Glomerular Diseases: All about Podocytes
  October 26, 2024 | Location: Room 1, Convention Center
  Abstract Time: 04:40 PM - 04:50 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Cintron Pregosin, Nina, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Nina Cintron Pregosin

• Dang, Emily T., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Emily T. Dang

• Guo, Yiqing, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Yiqing Guo, PhD

• Bronstein, Robert, Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Robert Bronstein, PhD

• Estrada, Chelsea C., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Chelsea C. Estrada, DO

• Gujarati, Nehaben A., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Nehaben A. Gujarati, PhD

• D'Agati, Vivette D., Columbia University Irving Medical Center, New York, New York, United States

Vivette D. D'Agati, MD

• Kaufman, Lewis, Icahn School of Medicine at Mount Sinai, New York, New York, United States

Lewis Kaufman, MD

• Mallipattu, Sandeep K., Stony Brook University Renaissance School of Medicine, Stony Brook, New York, United States

Sandeep K. Mallipattu, MD, FASN

Background

Podocytes are highly specialized terminally differentiated cells that are critical for maintenance of the glomerular filtration barrier. Podocyte loss triggers the activation and proliferation of PECs, leading to crescent formation and glomerular injury. We recently identified intercellular bridges between podocytes and PECs in murine models of proliferative glomerulopathy. However, the role of these bridges between podocytes and PECs is unclear. The goal of this study is to investigate the functional role of podocyte-PEC intercellular bridges in kidney diseases.

Methods

The following models of podocyte injury were used: podocyte-specific loss of Klf4 (Klf4^ΔPod), nephrotoxic serum (NTS) treatment, diabetic kidney disease (db/db), HIV-1 transgenic mice (Tg26), lipopolysaccharide-induced podocyte injury (LPS), and human FSGS. Single-nucleus (sn)RNA-seq, immunohistochemistry, confocal, transmission and scanning electron microscopy (TEM, SEM) were performed. Bridges were studied in vitro using a coculture of immortalized mouse podocytes and PECs.

Results

Intercellular bridges formed in response to rapid podocyte loss (Klf4^ΔPod, Tg26, NTS, FSGS). In NTS-treated mice bridges formed after proteinuria occurred – suggesting bridges play a physiological, rather than pathological role. In contrast, limited bridges formed in models with slow podocyte loss (db/db) or no podocyte loss (LPS). SEM and TEM revealed multiple double-membraned cytoplasmic extensions on the podocyte cell body that resembled slender filopodia, with projections making bridges with neighboring cell bodies. Numerous projections extended from podocytes to the surface of cells lining the bowman’s capsule.

To identify a mechanism for bridge formation, snRNA-seq showed enrichment of several genes encoding trafficking proteins (BIRC3, RAB8A, RAB11A, DYNC1H1). Immunofluorescence staining of a coculture of mouse podocytes and PECs validated the presence of these proteins and mitochondria within intercellular bridges. Live imaging of DiD-labeled cells showed the transport of cellular vesicles via intercellular bridges.

Conclusion

Intercellular bridges form in response to rapid podocyte injury and may serve as a direct, physical mechanism for cellular trafficking between injured podocytes and PECs.

Funding

• NIDDK Support