Kidney Week

Abstract: SA-OR004

Intravital Imaging Reveals the Important Role of A-Synuclein in Podocytes

Session Information

• A View on the Glomerulus
  November 04, 2017 | Location: Room 294, Morial Convention Center
  Abstract Time: 05:06 PM - 05:18 PM

Category: Glomerular

• 1003 Glomerular: Cell Biology

Authors

• Gyarmati, Georgina, University of Southern California, Los Angeles, CA 90033, California, United States

Georgina Gyarmati, MD, MPH

• Riquier-brison, Anne, University of Southern California, Los Angeles, CA 90033, California, United States

Anne Riquier-brison,

• Peti-Peterdi, Janos, University of Southern California, Los Angeles, CA 90033, California, United States

Janos Peti-Peterdi,

Background

Podocytes are known to functionally express a number of neuron-specific proteins. Recent studies predicted the Parkinson’s and Alzheimer's disease amyloid a-synuclein (SNCA) to be among 136 top podocyte genes (PMID23950145), and top 5 phosphoproteins with increased expression in Fabry disease podocytes (PMID27681560). SNCA was also recently linked to disruption of the autophagy-lysosome pathway and neuropathology in Fabry disease (PMID24529306). The present study aimed to establish the functional importance of SNCA in podocytes.

Methods

Constitutive or tamoxifen-inducible podocyte-specific SNCA knockout mice (i/Pod-SNCA KO) were generated that also expressed the intensely green calcium indicator GCaMP5/Tomato or the green/red mTmG reporter only in podocytes. Serial high resolution intravital multiphoton microscopy (MPM) of the same glomeruli in the same intact living kidney consecutively for three weeks was performed non-invasively via a dorsal abdominal imaging window to directly visualize and track the changes in glomerular and podocyte function including cell [Ca²⁺] after SNCA deletion.

Results

Immunohistochemistry of human and mouse kidney tissue sections confirmed the podocyte-specific expression of SNCA. Intact podocyte and glomerular functions were found at baseline in iPod-SNCA mice. However, within one week of tamoxifen-induced SNCA KO, podocytes developed an enlarged cell body with balled-up appearance, which gradually progressed within two additional weeks to the appearance of focally increased cell [Ca²⁺], podocyte detachment and shedding into the tubular fluid and migration to the parietal Bowman’s capsule, leakage of plasma albumin-Alexa594 into the filtrate and tubular fluid, and glomerular capillary microthrombi blocking blood flow. High magnification MPM found widened podocyte primary and secondary processes and foot process effacement. Histology of constitutive Pod-SNCA kidney sections found numerous tuft adhesions and detached podocytes.

Conclusion

This study visually demonstrated the development and progression of glomerular pathology after SNCA knockout, suggesting the important role of SNCA in maintaining normal podocyte and glomerular functions.

Funding

• NIDDK Support