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Abstract: FR-PO914

ApoL1-DNA Cross-Talk with Cytosolic DNA Sensing Pathways in Podocytes

Session Information

Category: Glomerular Diseases

  • 1204 Podocyte Biology

Authors

  • Jha, Alok, Feinstein Institute for Medical Research, Manhasset, New York, United States
  • Kumar, Vinod, Feinstein Institute for Medical Research, Manhasset, New York, United States
  • Ayasolla, Kamesh R., Feinstein Institute for Medical Research, Manhasset, New York, United States
  • Vashistha, Himanshu, Ochsner Health System, New Orleans, Louisiana, United States
  • Lan, Xiqian, Feinstein Institute for Medical Research, Manhasset, New York, United States
  • Malhotra, Ashwani, Feinstein Institute Medical Research and NSLIJ, Manhasset, New York, United States
  • Skorecki, Karl, Rambam Health Care Campus, Haifa, Israel
  • Singhal, Pravin C., North Shore LIJ Health System, Great Neck, New York, United States
Background

Viruses such as HIV are known to release double stranded DNA in cytosol and also known to induce activation of inflammasome Nod-like receptor (NLR) protein (P) 3 in podocytes. APOL1 renal risk variants have also been shown to activate NLRP3 pathway. The NLR family protein NLRC3 is a negative regulator of cytosolic DNA sensing pathway mediated innate immune response. We hypothesize that sensors of the NLR family, including NLRP3 inflammasomes, detect a variety of cytosolic nucleotides and trigger signaling that leads to pyroptosis and the maturation of interleukins.

Methods

Human podocyte stably expressing vector, APOL1G0/G1/G2 were activated with HIV (NL4-3) and evaluated for protein and mRNA expression of NLRP3, IL-1β, and Caspase-1. DNA binding site on ApoL1 variants was identified using DNABIND tool and by analyzing different DNA binding motifs on ApoL1 protein. Helix-turn-Helix motif and Leucine Zipper motif were analyzed using Prabi, iDNA-Prot, GYM2.0, 2Zip tools, and DNABINDPROT for the identification of DNA binding residues on ApoL1 variants protein. Models of ApoL1G0 and its variants ApoL1G1, ApoL1G2, NLRC3, and STING were generated using ITasser and protein-DNA and protein-protein complexes (docking approach); additionally, protein-protein interaction (PPI) interfaces and the thermodynamic properties of the protein-protein complexes were analyzed.

Results

HIV accelerated NLRP3 inflammasomes activation in APOL1RRVs milieu. ApoL1 variants displayed DNA binding sites, and the DNA binding residues provide ensemble for DNA-protein interactions. The ApoL1 and its variants showed potential to form protein-protein interaction (PPI) complexes individually with NLRC3 and STING, and also with the NLRC3-STING complex. Additionally, ApoL1G1 and ApoL1G2 could form thermodynamically favorable complexes with NLRC3 and stable complexes with STING individually. Since the interaction of ApoL1 and its variants seem to be weaker and transient with the NLRC3-STING complex, it indicates that ApoL1 variants and double-stranded cytosolic DNA could sequester NLRC3 and diminish NLRC3 interaction with STING and prevent inhibitory interaction of NLRC3 with STING.

Conclusion

ApoL1 variants provide a feed-forward response to STING pathway mediated inflammasome activation through cross-talk with cytosolic DNA sensing pathway.

Funding

  • NIDDK Support