Kidney Week

Abstract: TH-PO084

Induction of Cell Cycle Inhibitor p16Ink4a and Cellular Senescence in Heme Protein-Mediated AKI

Session Information

• AKI: Mechanisms - I
  November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Singh, Raman Deep, Mayo Clinic Division of Nephrology and Hypertension, Rochester, Minnesota, United States

Raman Deep Singh,

• Croatt, Anthony J., Mayo Clinic Division of Nephrology and Hypertension, Rochester, Minnesota, United States

Anthony J. Croatt,

• Ackerman, Allan W., Mayo Clinic Division of Nephrology and Hypertension, Rochester, Minnesota, United States

Allan W. Ackerman,

• Grande, Joseph P., Mayo Clinic Division of Nephrology and Hypertension, Rochester, Minnesota, United States

Joseph P. Grande,

• Nath, Karl A., Mayo Clinic Division of Nephrology and Hypertension, Rochester, Minnesota, United States

Karl A. Nath,

Background

Senescent cells (SCs) exhibit cellular arrest due to upregulation of cell cycle inhibitors such as p16^Ink4a. In this study, we demonstrate senescence in heme protein-mediated acute kidney injury (HP-AKI) with the upregulation of p16^Ink4a gene along with a senescent phenotype exhibited by murine kidneys.

Methods

p16^Ink4a mRNA expression was assessed by RT-PCR and RNAish in the murine glycerol model of HP-AKI, and in murine kidneys after administration of hemoglobin, myoglobin, and hemin. A senescent phenotype was assessed by β-galactosidase staining and lamin B1 protein expression using immunofluorescence and western blotting.

Results

Renal p16^Ink4a mRNA was significantly increased at 8, 24, and 48 hours in the glycerol model of HP-AKI. Localization of mRNA using RNAish revealed significantly increased p16^Ink4a mRNA expression in the proximal tubules. Similarly, administration of hemoglobin, myoglobin, or hemin to mice with intact kidneys significantly increased p16^Ink4a mRNA expression in the kidney. RNAseq analysis of the HP-AKI model showed telomere erosion as reflected by reduced expression of genes in the 1MB telomeric region in HP-AKI model. A senescent phenotype within HP-AKI kidneys was additionally demonstrated by increased β-galactosidase activity and decreased lamin B1 protein expression.

Conclusion

Glycerol-induced HP-AKI resulted in upregulation of the cell cycle inhibitor, p16^Ink4A, the latter mainly induced in proximal tubules. HP-AKI also resulted in telomere erosion as revealed by reduced expression of genes in the 1MB telomeric region. Confirmation of a senescent phenotype in HP-AKI was provided by increased β-galactosidase activity and decreased lamin B1 protein expression. The kidney subjected to HP-AKI thus exhibits a senescent phenotype which we suggest is driven by upregulation of p16^Ink4a mRNA expression within the injured kidney.

β-Galactosidase staining at 24 hours after HP-AKI in the kidney of A) sham and B) HP-AKI mice

Funding

• NIDDK Support