Abstract: FR-PO237

Modulation of Epigenetics Preserves Podocyte Phenotype in HIV Milieu

Session Information

Category: Cell Biology

  • 202 Apoptosis, Proliferation, Autophagy, Cell Senescence, Cell Transformation

Authors

  • Kumar, Vinod, Fienstine Institute for Medical Research, New York, New York, United States
  • Ayasolla, Kamesh R., Feinstein Institute for Medical Research, Great Neck, New York, United States
  • Lan, Xiqian, Feinstein Institute for Medical Research, Great Neck, New York, United States
  • Marashi Shoshtari, Seyedeh Shadafarin, The Feinstein Institute for Medical Research, Manhasset, New York, United States
  • Malhotra, Ashwani, Feinstein Inst.Med research and NSLIJ, Manhasset, New York, United States
  • Singhal, Pravin C., North Shore LIJ Health System, Great Neck, New York, United States
Background

Epgenetics have been reported to play an important role in the development of HIV-Associated Nephropathy (HIVAN). Recent report demonstrated that epigenetic alterations upregulated podocyte expression of SNAIL in HIVAN. We hypothesize that HIV-induced podocyte SNAIL expression compromises podocyte integrity (loss of podocyte markers such as nephrin and p-cadherin), however, vitamin D receptor agonist (VDA) has the potential to reverse this effect of SNAIL in HIV milieu. In this scenario, VDA would not only down regulate podocyte expression of SNAIL but would also preserve podocyte phenotype in HIV milieu.

Methods

Renal tissues of 6- week old control, HIVAN (Tg26), and VDR agonist (VDA)- treated Tg26 (2 weeks) mice (4 mice in each group) and vector/human podocytes (V/HP) or HIV (NL4-3)-transduced human podocytes (HIV/HPs) (n=4) were evaluated for expression SNAIL, VDR, nephrin, and p-cadherin. ChIP assays was carried to confirm binding of SNAIL to nephrin promoter. Immunoprecipitation (IP) studies were carried out to analyze composition of SNAIL repressor complexes. Genomic DNA was isolated and CpG island methylation was measured in V/HPs and HIV/HPs

Results

Protein blots of renal tissues from HIVAN mice and HIV/HPs displayed enhanced expression of SNAIL but down regulation of nephrin, p-cadherin, and VDR. VDA partially preserved expression of nephrin in renal tissues of Tg26 mice as well as in HIV/HPs. Genomic DNA methylation studies confirmed hypermethylated CpG islands at Nephrin promoter in HIV/HPs.ChIP assay suggested that enhanced SNAIL expression by HIV/HPs was the consequence of histone 3 methylation at lysine (K) 4 residues (H3K4me3) on SNAIL promoter, whereas, down regulation of nephrin could be due to consequence of histone 3 methylation at lysine 27 residues (H3K27me3). Co-immunoprecipitation studies in lysates of HIV/HPs revealed the association of histone deacetylase (HDAC) 4, DNMT3b and DNMT1, mSin3A and EZH2 with SNAIL; conversely, VDA treatment of HIV/HPs decreased the expression of HDAC4, DNMT3B, DNMT1, mSin3A, and EZH2 (disruption of SNAIL complex).

Conclusion

VDA preserves podocyte nephrin expression through down regulation of SNAIL transcription, disruption of SNAIL repressor complex, and attenuation of methylation at H3K27 residues at nephrin promoter.

Funding

  • NIDDK Support