Abstract: TH-PO944
Cross-Talk of Tet2 and Autophagy Promotes Senescence and Kidney Aging
Session Information
- Geriatric Nephrology: Innovations and Insights
October 24, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Geriatric Nephrology
- 1300 Geriatric Nephrology
Authors
- Mao, Xinyue, Mayo Clinic Department of Internal Medicine, Rochester, Minnesota, United States
- Li, Lu, Mayo Clinic Department of Internal Medicine, Rochester, Minnesota, United States
- Li, Xiaoyan, Mayo Clinic Department of Internal Medicine, Rochester, Minnesota, United States
- Zhou, Xia, Mayo Clinic Department of Internal Medicine, Rochester, Minnesota, United States
- Li, Xiaogang, Mayo Clinic Department of Internal Medicine, Rochester, Minnesota, United States
Background
Kidneys are highly susceptible to the aging process. In renal aging, a complex interplay of genetics, epigenetics, and cellular dysfunction leads to a decline in renal function. Dysregulation of DNA methylation is a prominent feature of aging. However, the role of the ten eleven translocation (Tet) enzymes, which oxidize 5-methylcytosines (5mCs) and promote locus-specific reversal of DNA methylation, in senescence and kidney aging is largely unknown.
Methods
We performed Western blot, qRT-PCR, immunoprecipitation (IP), GST pull-down assay, reduced representation bisulfite sequencing (RRBS) and methylation-specific PCR (MSP) to investigate a crosstalk of Tets and autophagy in renal tubular cells upon induction of senescence and aged kidneys upon treatment with autophagy inhibitor or Tets activator.
Results
The proteins of Tets family members (Tet1, Tet2 and Tet3) were decreased in senescent renal tubular cells and in aged kidneys, but not their mRNAs, compared to the controls. Treatment with the autophagy inhibitor (lys05) but not the proteasome inhibitor (MG132) only blocked the downregulation of Tet2 protein but not Tet1/3 upon induction of senescence. Treatment with lys05 also increased the Tet2 protein levels in aged kidneys. We found that Tet2 interacts with ATG7, but not other autophagy proteins. Knockdown of ATG7 with siRNA also blocked senescence mediated Tet2 downregulation. Tet2 directly binds to ATG7 as examined with purified GST pull-down assay. We defined the domain of Tet2 that interacts with ATG7 with Tet2 truncated constructs. We further found that AMPK mediated Tet2 phosphorylation could decrease the interaction between Tet2 and ATG7, blocking autophagy mediated Tet2 downregulation in senescent renal tubular cells. By performing RRBS, we identified three autophagy-related genes (PIK3C2B, PIK3C3 and PIK3CA), which were hypermethylated in senescent renal tubular cells as examined by MSP. Treatment with Tet2 activator AA increased the expression of PIK3C2B, PIK3C3 and PIK3CA but decreased two senescence markers, p16 and p21, supporting a direct role of Tet2 in the regulation of autophagy and senescence.
Conclusion
Tet2 is recognized as a substrate of autophagy, and is subjected to autophagy protein ATG7 mediated degradation. The downregulation of Tet2 increased the methylation of autophagy-related genes in senescent renal tubular cells and aged kidney.