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Abstract: PO1974

Shroom3-FYN Regulates Podometrics via LKB1-AMPK Signaling

Session Information

  • Podocyte Biology
    October 22, 2020 | Location: On-Demand
    Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Banu, Khadija, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Basgen, John M., Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Lin, Qisheng, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Cumpelik, Arun, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Kaufman, Lewis, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Planoutene, Marina, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Murphy, Barbara T., Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • He, John Cijiang, Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Menon, Madhav C., Icahn School of Medicine at Mount Sinai, New York, New York, United States
Background

Previously, we showed Shroom3–FYN interaction regulated podocyte cytoskeleton via FYN activation. Intriguingly, global Shroom3 knockdown mice (CAGS-TG/Shr3 Kd) displayed reduction in glomerular volume-Vglom, podocyte & endothelial fraction of Vglom without podocytopenia [1a]

Methods

To examine mechanism of podometrics regulation by Shr3, we used Shr3 & FYN Kd human podocytes (hPodo) to study cell protein content & growth regulatory pathways; performed unilateral nephrectomy examining Vglom hypertrophy in remnant kidneys

Results

At day-7, CAGS-TG mice showed restricted Vglom hypertrophy with reduced expansion of PodoVglom vs NTGs [1b]. We observed reduced hPodo volume (FSC), Protein:DNA ratios (n=5; P<0.01) & inhibited ribosomal biogenesis (18S RNA) in vitro & in vivo suggesting reduced protein synthesis and FYN to be downstream of Shr3 in regulating hPodo size. Notably, we observed increased AMPK activation, increased p-EF2 & autophagy (high p-ULK1 and LC3II levels) downstream of AMPK in vitro/in vivo by immunoblot (IB) & immunofluorescence (IF)[1c] suggesting negative regulation of protein synthesis. Next, we examined LKB1 localization (AMPK-kinase) by IB after subcellular fractionation & IF in Shr3/FYN Kd hPodo identifying increased LKB1 Cytosolic:Nuclear ratio, explaining AMPK activation due to increased cytosolic pool of active LKB1 [1d]. Finally, we used an AMPK inhibitor, Compound C in CAGS-TG mice and observed reversal of podometric changes-Vglom & Vglom fractions, induction of podocytopenia with AMPK-inhibition [1e]

Conclusion

Here, we show Shroom3-FYN interaction regulating podometrics via AMPK-signaling in podocytes. The protective morphometric effects have implications to disease models with podocyte/nephron loss requiring obligate Vglom/Podocyte hypertrophy

Funding

  • NIDDK Support