Abstract: FR-PO125
Sham Surgery Suppresses Autophagy in the Kidney and Heart
Session Information
- AKI: Mechanisms - Inflammation/Sepsis/Remote Injury
November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Authors
- Brown, Carolyn Nicole, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Holditch, Sara, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Skrypnyk, Nataliya, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Altmann, Chris, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Klawitter, Jelena, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Faubel, Sarah, UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
- Edelstein, Charles L., UC Denver Anschutz Medical Campus, Aurora, Colorado, United States
Background
Renal ischemia/reperfusion (IR) and compensatory hypertrophy induced by unilateral nephrectomy (UNX) activate mTOR, a suppressor of autophagy. Autophagy maintains proteostasis by sequestering proteins into autophagosomes for delivery to the lysosome where cargo is recycled. The aim of the study was to determine the effect of sham surgery (SHAM), UNX, or IR on mTOR and autophagy in the kidney & heart in wildtype mice.
Methods
IR was induced by bilateral renal pedicle clamp; mice were sacrificed 24 or 72hr later. UNX was performed; mice were sacrificed 2hr later. Normal mice without surgical manipulation (NORM), SHAM, IR, and UNX mice were treated with vehicle or bafilomycin (BAF) 2hr before sacrifice. LC3-II and p62 were measured by immunoblot. Increased LC3-II (autophagosome marker) after BAF or decreased p62 (degraded by autophagy) were used as markers of autophagy.
Results
Autophagy was suppressed in the kidney 2hr after UNX and SHAM compared to NORM kidneys, but only 2hr after UNX in the heart. There was suppressed autophagy in the heart at 24hr of both IR & SHAM that normalized by 72hr. Suppressed autophagy in the kidney & heart in SHAM, UNX, & IR was associated with statistically significant increases in mTOR (pS6, p4E-BP1, pAkt). To determine a possible mechanism of suppressed autophagy, metabolomics analysis was performed on 2hr NORM, SHAM, & UNX kidneys. Of 225 metabolites measured, folate, fructose phosphate, & glycine with known roles in autophagy regulation were significantly decreased (P<0.05) in both SHAM and UNX vs. NORM kidneys.
Conclusion
SHAM suppresses autophagy in the kidney & heart. Increased mTOR and suppressed autophagy in the kidney & heart caused by SHAM have important implications for researchers using models requiring surgery. The connection between suppressed autophagy & folate, fructose phosphate, & glycine merits further study.
| Table 1. UNX | NORM | NORM+BAF | SHAM | SHAM+BAF | NEPH | NEPH+BAF | |||||
| KIDNEY | LC3-II | 0.5 | 0.8* | 1.0* | 1.2 | 1.4* | 1.4 | ||||
| p62 | 0.3 | 0.3 | 1.0* | 1.3 | 1.7* | 1.8 | |||||
| HEART | LC3-II | 0.3 | 1.1* | 1.1* | 2.3# | 1.0 | 1.0 | ||||
| p62 | 0.9 | 1.0 | 1.3 | 1.5 | 0.8# | 0.8 | |||||
| Table 2. IR | NORM | NORM+BAF | 24HR SHAM | 24HR SHAM+BAF | 24HR IR | 24HR IR+BAF | 72HR SHAM | 72HR SHAM+BAF | 72HR IR | 72HR IR+BAF | |
| KIDNEY | LC3-II | 0.2 | 0.7* | 0.6* | 1.0# | 1.5# | 1.8 | 0.9 | 2.1^ | 1.0 | 1.9& |
| p62 | 1.3# | 1.4 | 0.4 | 0.5 | 1.4# | 1.9 | 0.5 | 0.6 | 0.6 | 1.0 | |
| HEART | LC3-II | 1.0 | 1.4* | 1.0 | 0.8 | 1.0 | 1.2 | 0.8 | 1.0 | 0.7 | 1.1& |
| p62 | 0.3 | 1.2* | 1.1* | 1.3 | 1.4* | 1.4 | 0.7 | 0.6 | 0.6 | 0.5 | |
Table 1: *P<0.05 vs NORM #P<0.05 vs SHAM Table 2:*P<0.05 vs NORM, #P<0.05 vs 24HR SHAM, ^P <0.05 vs 72HR SHAM, &P<0.05 vs 72HR IR
Funding
- Veterans Affairs Support