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Kidney Week

Abstract: TH-PO873

Epigenetic Regulation of Gremlin-1, a Key Player in Diabetic Nephropathy Development

Session Information

Category: Diabetic Kidney Disease

  • 601 Diabetic Kidney Disease: Basic

Authors

  • Marchant, Vanessa, Centro de Estudios Científicos, CECs, Valdivia, Chile
  • Mezzano, Sergio A., Universidad Austral de Chile, Valdivia, Chile
  • Ruiz-Ortega, Marta, Universidad Autonoma, Madrid, Spain
  • Kerr, Bredford, Centro de Estudios Científicos, CECs, Valdivia, Chile
Background

Gremlin-1 (Grem1) is a protein highly expressed in the kidney of both diabetic nephropathy (DN) patients and experimental models. However, the molecular mechanism underlying the induction of Grem1 in DN is not fully understood. Emerging evidence supports a role for epigenetic regulation in the pathogenesis of diabetic nephropathy, but the epigenetic regulation of Grem1 has not been explored. This work aimed to study the role of epigenetic mechanisms in the control of renal expression of Grem1 and its association with diabetic nephropathy.

Methods

We first evaluated the renal expression of Grem1 in 4, 8, 12, and 16-week-old mice from a diabetic nephropathy model (BTBR ob/ob) and in 8-week-old mice from an epigenetic disruption model (Mecp2-null) by RT-qPCR. Additionally, we determined renal expression levels of Mecp2 in 16-week-old BTBR ob/ob mice by Western Blot. Next, the DNA sequence of Grem1 was analyzed with bioinformatics tools to identify potential methylable CpG islands (CGI). Chromatin immunoprecipitation using anti-Mecp2 antibody followed by PCR was performed to assess the binding of Mecp2 to the Grem1 CGI previously identified. Methylated DNA enrichment by MBD-capture was performed to evaluate the methylation level of the Grem1 CGI.

Results

We observed that Grem1 renal expression is increasing in BTBR ob/ob mice starting from 8 weeks of age and according to the progression of the phenotype associated with DN. Renal expression of Mecp2 in 16-week-old BTBR ob/ob mice was also increased. Additionally, Grem1 renal expression was increased in Mecp2-null mice compared to wild-type. Next, we identified a ~2 kb CGI in Grem1 sequence, that includes its transcription start site. We found that in the kidney of wild-type mice, there is a ~4% of basal methylation in two zones of Grem1 CGI and Mecp2 binds to several regions of the Grem1 CGI.

Conclusion

Our results strongly suggest that Mecp2 epigenetically represses Grem1 expression by binding to a methylated CpG island in Grem1 promoter and coding gene. These results allow us to propose that an epigenetic mechanism underlies the induction of Grem1 gene expression in diabetic nephropathy development.

Funding acknowledgement: PFB CECs 01/2007, FONDECYT 1160465, FONDECYT 1181574, CONICYT-PFCHA 21160495.

Funding

  • Government Support - Non-U.S.