Kidney Week

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

Khadija Banu,

• Basgen, John M., Icahn School of Medicine at Mount Sinai, New York, New York, United States

John M. Basgen,

• Lin, Qisheng, Icahn School of Medicine at Mount Sinai, New York, New York, United States

Qisheng Lin,

• Cumpelik, Arun, Icahn School of Medicine at Mount Sinai, New York, New York, United States

Arun Cumpelik,

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

Lewis Kaufman,

• Planoutene, Marina, Icahn School of Medicine at Mount Sinai, New York, New York, United States

Marina Planoutene,

• Murphy, Barbara T., Icahn School of Medicine at Mount Sinai, New York, New York, United States

Barbara T. Murphy,

• He, John Cijiang, Icahn School of Medicine at Mount Sinai, New York, New York, United States

John Cijiang He,

• Menon, Madhav C., Icahn School of Medicine at Mount Sinai, New York, New York, United States

Madhav C. Menon,

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-V_glom, podocyte & endothelial fraction of V_glom 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 V_glom hypertrophy in remnant kidneys

Results

At day-7, CAGS-TG mice showed restricted V_glom hypertrophy with reduced expansion of PodoV_glom 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-V_glom & V_glom 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 V_glom/Podocyte hypertrophy

Funding

• NIDDK Support