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Abstract: FR-PO077

Preconditioning Mice with a Pharmacologic Activator of AMPK Ameliorates Ischemic AKI by Activating Akt

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Lieberthal, Wilfred, Stony Brook University Medical Center, Stony Brook, New York, United States
  • Abate, Mersema, Stony Brook University Hospital, Stony Brook, New York, United States
  • Levine, Jerrold S., University of Illinois, Chicago, Illinois, United States
Background

We have reported that preconditioning renal tubular cells (RTCs) with A-769662 (a novel small molecule activator of AMPK), reduces the death of renal tubular cells (RTCs) induced by metabolic stress in vitro and ameliorates the severity of ischemic AKI in mice. (Liebertal, W. et al: American J Phyiol Renal Physiol 311:F731-739, 2016). Our objective in this study was to determine whether Akt plays a role in mediating these effects of A-769662.

Methods

We knocked down expression of the beta-domain of AMPK by > 85% using shRNA (“KD” RTCs). In control RTCs a “scrambled” shRNA was used. Ischemic AKI was induced by subjecting the kidneys to ischemia-reperfusion injury (IRI).

Results

Preconditioning control cells with A-769662 increased the phosphorylation (activity) of AMPK, and reduced the death of these cells induced by exposing them to metabolic stress. However, in KD cells A-769662 had no measurable effects on the activation of AMPK or on their survival after stress. These data show that the activation of AMPK by A-769662 is profoundly impaired in KD RTCs. A-769662 activated Akt in control but not in KD RTCs. These findings demonstrate that the activation of Akt by A-7609662 is AMPK-dependent, and not the result a nonspecific “off target” kinase. It also shows that AMPK acts upstream of Akt. We show, that inhibiting Akt with a specific Akt inhibitor in control cells during the preconditioning period, reduced the pro-survival effect of A-769662 by ~50%. These findings suggest that Akt contributes to the pro-survival effects of A-7698662 in vitro. We next evaluated the role of AMPK and Akt in modulating the severity of ischemic AKI in vivo. We show that preconditioning mice with A-769662 activated AMPK and Akt in the renal cortex, and that inhibiting Akt, while having no effect on the activation of AMPK, reduced the activation of Akt. Finally, we provide novel evidence, that A-769662 ameliorates the severity of ischemic AKI, and that Akt contributes to this effect.

Conclusion

) A-769662 activates AMPK and Akt in control RTCs and in the kidneys of mice; ii) the activation of Akt by A-760662 is mediated by AMPK; iii) The activation of Akt contributes to the pro-survival effects of A-769662 in vitro, and to the beneficial of A-769662 in ischemic AKI in vivo; iv) the mechanisms responsible for the activation of Akt by AMPK remain to be elucidated

Funding

  • Commercial Support