The Outcome of Renal Ischemia-Reperfusion Injury Is Unchanged in AMPK-β1 Deficient Mice

Abstract

AimActivation of the master energy-regulator AMP-activated protein kinase (AMPK) in the heart reduces the severity of ischemia-reperfusion injury (IRI) but the role of AMPK in renal IRI is not known. The aim of this study was to determine whether activation of AMPK by acute renal ischemia influences the severity of renal IRI.MethodsAMPK expression and activation and the severity of renal IRI was studied in mice lacking the AMPK β1 subunit and compared to wild type (WT) mice.ResultsBasal expression of activated AMPK, phosphorylayed at αThr172, was markedly reduced by 96% in AMPK-β1−/− mice. Acute renal ischaemia caused a 3.2-fold increase in α1-AMPK activity and a 2.5-fold increase in α2-AMPK activity (P<0.001) that was associated with an increase in AMPK phosphorylation of the AMPK-α subunit at Thr172 and Ser485, and increased inhibitory phosphorylation of the AMPK substrate acetyl-CoA carboxylase. After acute renal ischemia AMPK activity was reduced by 66% in AMPK-β1−/− mice compared with WT. There was no difference, however, in the severity of renal IRI at 24-hours between AMPK-β1−/− and WT mice, as measured by serum urea and creatinine and histological injury score. In the heart, macrophage migration inhibitory factor (MIF) released during IRI contributes to AMPK activation and protects from injury. In the kidney, however, no difference in AMPK activation by acute ischemia was observed between MIF−/− and WT mice. Compared with the heart, expression of the MIF receptor CD74 was found to be reduced in the kidney.ConclusionThe failure of AMPK activation to influence the outcome of IRI in the kidney contrasts with what is reported in the heart. This difference might be due to a lack of effect of MIF on AMPK activation and lower CD74 expression in the kidney.

Gender difference in the development of cardiac lesions following acute ischemic-reperfusion renal injury in albino rats

“…These results are in line with Mount et al (2012) and Chen et al (2012). Furthermore, Kadkhodaee et al (2009) reported that the rise of renal injury markers was dependent on the renal ischemia time, and Jung et al (2009) found the increase in renal injury markers reached the peak 48 hours after the renal I/R injury.…”

Novel mechanisms of Na+ retention in obesity: phosphorylation of NKCC2 and regulation of SPAK/OSR1 by AMPK

“…Rabbit antibodies directed against pNKCC1 (T212/217)/ pNKCC2 (T96/T101), pNKCC2 (S126), and pNCC (T58) have previously been described (10). Rabbit antibodies against AMPK-␣ and pACC1 (S79) have previously been described (33,50). Mouse antibody against NKCC1/NKCC2 (T4) was obtained from the Developmental Studies Hybridoma Bank (University of Iowa).…”

AMPK couples plasma renin to cellular metabolism by phosphorylation of ACC1

“…Antibodies directed against AMPK-␣1, AMPK-␣2, AMPK phospho-Thr 172 , and ACC1 phospho-Ser 79 have previously been described (20,42,55). Rabbit antibodies against NKCC2, Na ϩ -Cl Ϫ cotransporter (NCC), and the ␤-subunit of ENaC (ENaC-␤) were obtained from StressMarq Biosciences.…”

“…Kidneys were excised rapidly and snap frozen in liquid nitrogen as previously described (42). Lysates were prepared using a glass on glass Dounce homogenizer in lysis buffer [containing 50 mM Tris·HCl (pH 7.5), 1 mM EGTA, 1 mM EDTA, 50 mM sodium fluoride, 5 mM sodium pyrophosphate, 1 mM sodium orthovanadate, 1% (wt/vol) Nonidet P-40, 0.27 M sucrose, and 0.1% (vol/vol) 2-mercaptoethanol].…”

“…In skeletal and cardiac muscle, fatty acid oxidation is regulated by ACC2, which possesses an NH 2 -terminal extension containing a mitochondrial localization domain. The liver expresses both isoforms of ACC (28), whereas the kidney expresses mainly ACC1 (42).…”