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Abstract: FR-PO392

Circulating Soluble Nogo-B Ameliorates Diabetic Glomerulopathy Partly by Modulating GSK3β/βcatenin Signaling

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Ricciardi, Carlo alberto, King's College London, London, United Kingdom
  • Hernandez, Ivan, King's College London, London, United Kingdom
  • Fouli, Georgia E., King's College London, London, United Kingdom
  • Hayward, Anthea Elaine, King's College London, London, United Kingdom
  • Long, David A., University College London, London, United Kingdom
  • Gnudi, Luigi, King's College London, London, United Kingdom
Background

Early diabetic glomerulopathy (DG) is characterised by albuminuria, endothelial cell (EC) proliferation, EC glycocalyx disruption and podocyte loss. Nogo-B, expressed in glomerular EC and podocytes, is downregulated in diabetes. A 200-aminoacid N-terminus soluble Nogo-B (sNogo-B) is found in the circulation and (as Nogo-B) binds to its receptor NgBR promoting vascular integrity.
Activation of GSK3β/βcatenin pathway promotes vascular stability; conversely, inactivation of GSK3β with βcatenin cellular accumulation, as seen in diabetes, promotes VEGFR2 signaling and ECs proliferation/vascular permeability.
We investigated whether, in diabetes, sNogo-B overexpression modulates GSK3β/βcatenin and VEGFA signaling towards a stable glomerular capillary.

Methods

Adult DBA2J male mice were made diabetic with streptozotocin; sNogo-B overexpression was initiated after induction of diabetes by adeno-associated vector (AAV)(AAV driving the expression of green fluorescent protein-GFP served as control). Mice with glycemia >22 mM were considered diabetic. Mice were killed after 12-14 weeks of diabetes and kidney tissue collected for electron microscopy and immunofluorescence, respectively for podocyte number and EC proliferation/glycocalyx determination; renal cortex lysate was utilised for VEGFA/VEGFR2 phosphorylation levels (ELISA), and AKT, GSK3β/βcatenin signaling (western immunoblotting). Abuminuria was measured by ELISA.

Results

Diabetes (D) resulted in albuminuria, glomerular EC proliferation, EC glycocalyx disruption and podocyte loss when compared to non-diabetic (ND) mice (ND-GFP vs D-GFP, p<0.01); sNogo-B overexpression ameliorated diabetes-mediated albuminuria and vasculature anatomical alterations and was paralleled by inhibition of diabetes-mediated AKTser473 and GSK3βser9 phosphorylation (D-GFP vs D-sNogo-B, p<0.05). βcatenin was highly expressed in kidney cortex lysate of D-GFP mice (ND-GFP vs D-GFP, p<0.001) and was downregulated in D-sNogo-B mice (D-GFP vs D-sNogo-B, p<0.01), an event paralleled by a normalisation of diabetes-mediated VEGFA/VEGFR2 receptor system activation (D-GFP vs D-sNogo-B, p<0.04).

Conclusion

sNogo-B overexpression in diabetic mice promotes a healthy vasculature via activation of GSK3β/βcatenin pathway; sNogo-B could represent a targetable pathway for the treatment of DG.