Abstract: SA-PO138

Reduction of H3K27Me3 and Metabolic Memory Associated Inflammation in Podocytes

Session Information

Category: Diabetes

  • 503 Diabetes Mellitus and Obesity: Translational

Authors

  • Dieter, Brad, Providence Sacred Heart , Spokane, Washington, United States
  • Meek, Rick L., Providence Sacred Heart , Spokane, Washington, United States
  • Anderberg, Robert J., Providence Sacred Heart , Spokane, Washington, United States
  • Cooney, Sheryl K., Providence Sacred Heart , Spokane, Washington, United States
  • Tuttle, Katherine R., Providence Sacred Heart , Spokane, Washington, United States
Background

Poor glycemic control, even with subsequent periods of well-controlled glycemia, increases risk for diabetic complications. This phenomenon, known as metabolic memory, may cause epigenetic changes such as reduction of histone 3 lysine 27 trimethylation (H3K27Me3), which increases expression of inflammatory mediators including serum amyloid A (SAA) in the diabetic kidney. The aim of this study was to determine if a sustained inflammatory response to metabolic memory may be mediated by increased SAA expression due to H3K27Me3 demethylation near the SAA promoter in podocytes, a cell centrally involved in diabetic kidney disease.

Methods

SAA knockout podocytes were generated using CRISPR-Cas9. In experiments to model metabolic memory, wild type and SAA knockout mouse podocytes were differentiated for 8-10 days, then exposed to advanced glycation end products (AGE, 300 μg/ml) for 7 days, followed by AGE removal and ongoing culture in control conditions for 7 more days. Chromatin immunoprecipitation measured H3K27Me3 near the SAA promoter. qRT-PCR was used to measure mRNA expression of inflammatory mediators: SAA, CXCL5, CCL2, and CCL5. Podocytes were exposed to AGE (300 μg/ml) for 1 day while H3K27Me3 demethylation was prevented by inhibiting the H3K27me3 specific demethylase, jmjd3, with GSK-J1 (20 μM).

Results

In metabolic memory experiments conducted in podocytes (n=6), histone H3K27Me3 near the SAA promoter was markedly reduced (95%) at day 14, while SAA mRNA increased (17±6-fold, p=0.025), as were SAA-dependent inflammatory mediators: CXCL5 (18.5±12-fold, p=0.004), CCL2 (2.0±0.7-fold, p=0.001), and CCL5 (1.6±0.6-fold, p=0.026). SAA knockout in podocytes reduced expression of CXCL5, CCL2, and CCL5 by >60% (p<0.05 for all) in metabolic memory experiments. jmjd3 inhibition reduced AGE-induced expression of SAA and each of the SAA-dependent inflammatory mediators by >60% (p<0.05 for all) in podocytes.

Conclusion

Short term exposure of podocytes to hyperglycemia-related perturbations causes sustained H3K27Me3 demethylation and increased SAA expression, leading to a sustained SAA-dependent inflammatory response.

Funding

  • Private Foundation Support