The outcome of renal ischemia-reperfusion injury is unchanged in AMPK-β1 deficient mice

AIM: Activation 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. METHODS: AMPK 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. RESULTS: Basal 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. CONCLUSION: The 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

How Can We Improve Oncofertility Care for Patients? A Systematic Scoping Review of Current International Practice and Models of Care

© The Author(s) 2018. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. BACKGROUND: Fertility preservation (FP) is an important quality of life issue for cancer survivors of reproductive age. Despite the existence of broad international guidelines, the delivery of oncofertility care, particularly amongst paediatric, adolescent and young adult patients, remains a challenge for healthcare professionals (HCPs). The quality of oncofertility care is variable and the uptake and utilization of FP remains low. Available guidelines fall short in providing adequate detail on how oncofertility models of care (MOC) allow for the real-world application of guidelines by HCPs. OBJECTIVE AND RATIONALE: The aim of this study was to systematically review the literature on the components of oncofertility care as defined by patient and clinician representatives, and identify the barriers, facilitators and challenges, so as to improve the implementation of oncofertility services. SEARCH METHODS: A systematic scoping review was conducted on oncofertility MOC literature published in English between 2007 and 2016, relating to 10 domains of care identified through consumer research: communication, oncofertility decision aids, age-appropriate care, referral pathways, documentation, training, supportive care during treatment, reproductive care after cancer treatment, psychosocial support and ethical practice of oncofertility care. A wide range of electronic databases (CINAHL, Embase, PsycINFO, PubMed, AEIPT, Education Research Complete, ProQuest and VOCED) were searched in order to synthesize the evidence around delivery of oncofertility care. Related citations and reference lists were searched. The review was undertaken following registration (International prospective register of systematic reviews (PROSPERO) registration number CRD42017055837) and guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). OUTCOMES: A total of 846 potentially relevant studies were identified after the removal of duplicates. All titles and abstracts were screened by a single reviewer and the final 147 papers were screened by two reviewers. Ten papers on established MOC were identified amongst the included papers. Data were extracted from each paper and quality scores were then summarized in the oncofertility MOC summary matrix. The results identified a number of themes for improving MOC in each domain, which included: the importance of patients receiving communication that is of a higher quality and in different formats on their fertility risk and FP options; improving provision of oncofertility care in a timely manner; improving access to age-appropriate care; defining the role and scope of practice of all HCPs; and improving communication between different HCPs. Different forms of decision aids were found useful for assisting patients to understand FP options and weigh up choices. WIDER IMPLICATIONS: This analysis identifies core components for delivery of oncofertility MOC. The provision of oncofertility services requires planning to ensure services have safe and reliable referral pathways and that they are age-appropriate and include medical and psychological oncofertility care into the survivorship period. In order for this to happen, collaboration needs to occur between clinicians, allied HCPs and executives within paediatric and adult hospitals, as well as fertility clinics across both public and private services. Training of both cancer and non-cancer HCPs is needed to improve the knowledge of HCPs, the quality of care provided and the confidence of HCPs with these consultations

The role of AMPK in bone and cholesterol metabolism

© 2012 Dr. Shanna Shiu-Nam TamThe central focus of this thesis explores the biology of AMP-activated protein kinase (AMPK), an important whole-body energy regulator, firstly in bone metabolism, and secondly in the regulation of cholesterol metabolism. AMPK is a ubiquitously-expressed αβγ heterotrimeric enzyme. Since AMPK plays important roles in modulating metabolism in response to diet and exercise, both of which influence bone mass, the influence of AMPK on bone mass was investigated in mice. In the first part, I will present data that the non-specific AMPK activator, AICAR, enhanced the formation of osteoclasts (bone-resorbing cells) in vitro and caused bone loss in vivo. However, the in vitro effects were shown to be AMPK-independent. Next, I will present genetic evidence that AMPK is important for the maintenance of normal bone mass, as germline deletion of either AMPK β1 or β2 subunit isoforms resulted in reduced trabecular bone density and mass, but without affecting osteoblast or osteoclast numbers. In Chapter 6, I focussed on one of the substrates of AMPK named 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), which catalyses the rate limiting step in the mevalonate pathway. Mevalonate is essential for the synthesis of important bioactive sterols (e.g. cholesterol) and non-sterol isoprenoids, which are important for processes such as protein prenylation. Phosphorylation of residue S871 of HMGR by AMPK inhibits its activity, presumably to conserve cellular energy by shutting down cholesterol synthesis. To study the physiological importance of this phosphorylation control of HMGR by AMPK, our laboratory generated a knock-in mutation in mice by homologous recombination and Cre-mediated excision to introduce a modified exon 20 to encode Alanine at residue 871. The data suggests that lack of regulation of HMGR by AMPK in mice did not lead to any overt physical phenotypic differences or compensatory up- or down-regulation in the expression of other mevalonate pathway genes. However, these mice displayed slightly altered lipid profiles in the brain, liver and plasma. The lack of a more prominent phenotype may reflect the importance of the mevalonate pathway and its multivalent backup regulation

AMPK is a direct adenylate charge-regulated protein kinase

The adenosine monophosphate ( AMP )–activated protein kinase ( AMPK ) regulates whole-body and cellular energy balance in response to energy demand and supply. AMPK is an αβγ heterotrimer activated by decreasing concentrations of adenosine triphosphate ( ATP ) and increasing AMP concentrations. AMPK activation depends on phosphorylation of the α catalytic subunit on threonine-172 ( Thr172 ) by kinases LKB1 or CaMKKβ, and this is promoted by AMP binding to the γ subunit. AMP sustains activity by inhibiting dephosphorylation of α-Thr172, whereas ATP promotes dephosphorylation. Adenosine diphosphate ( ADP ), like AMP, bound to γ sites 1 and 3 and stimulated α-Thr172 phosphorylation. However, in contrast to AMP, ADP did not directly activate phosphorylated AMPK. In this way, both ADP/ATP and AMP/ATP ratios contribute to AMPK regulation

Severity of renal ischemia-reperfusion injury in wild type and AMPK-β1^−/− mice assessed by serum urea and creatinine at 24 hours post IR.

<p>Serum urea (A) and creatinine (B) were measured 24 hours post renal IR for 18 or 20 minutes in WT and AMPK-β1^−/− mice (n = 6–13 per group). Results are shown as mean ± SD. * P<0.001, ** P<0.01. No significant differences between WT and AMPK-β1^−/− mice were observed.</p

Histological injury 24 hours after renal ischemia-reperfusion injury in wild type and AMPK-β1^−/− mice.

<p>IRI was performed for 20 minutes and the severity of injury was assessed by histology. A. Histological appearance at 24 hours following 20 mins IRI in WT and β1^−/− mice. Images shown are from the region of the corticomedullary junction (CMJ). 200× magnification. The severity of histological injury at 24-hours was quantified in cortex (B), CMJ (C) and medulla (D) as described in methods. No differences were seen between WT and β1^−/− mice. n = 7 for WT and 6 for β1^−/−.</p

AMPK activation and phosphorylation after acute renal ischemia in MIF^−/− mice.

<p>Lysates (1 mg protein) from control (□ no ischemia) and ischemic (▪ 10 min ischemia) kidneys of WT (C57Bl/6) and MIF^−/− mice were immunoprecipitated with antibodies specific for the α1 (A) and α2 (B) AMPK catalytic subunits (n = 10–12 per group for α1 and n = 6 for α2). AMPK activity was measured by ADR-1 peptide activity assay. Results are shown as mean ± SD. α1-AMPK and α2-AMPK activity were increased several fold after 10 minutes ischemia in WT and MIF^−/− mice (* P<0.001). There were no differences in α1-AMPK or α2-AMPK activity between WT and MIF^−/− under either control or ischemic conditions. C. Lysates (1 mg protein) from control (C) and ischemic (Isc) kidneys of WT and MIF^−/− mice were immunoprecipitated with antibodies specific for the α1 AMPK catalytic subunit and analyzed by Western blotting using antibodies against pAMPKαThr¹⁷², pAMPKαSer⁴⁸⁵ and α1AMPK (blot shown representative of 4 experiments). D. In addition, whole kidney lysates (50 µg) from the same experiment were separated by SDS-PAGE and analyzed by Western blot for AMPK phosphorylation at αThr¹⁷² and αSer⁴⁸⁵, with blotting for β-actin as a loading control (blot shown representative of 4 experiments). E. Kidney lysates from this experiment were blotted for inhibitory phosphorylation of ACC at Ser⁷⁹ and expression of total ACC1 (blot shown representative of 4 experiments). F. Heart and kidney lysate was blotted for expression of the MIF receptor CD74.</p

AMPK activation by acute renal ischemia in wild type, AMPK-α1^−/− and AMPK-β1^−/− mice.

<p>Lysates (1 mg protein) from control (□ no ischemia) and ischemic (▪ 10 min ischemia) kidneys of WT (C57Bl/6), AMPK-α1^−/− and AMPK-β1^−/− mice were immunoprecipitated with antibodies specific for the α1 and α2 AMPK catalytic subunits (n = 6–8 per group). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0029887#s3" target="_blank">Results</a> are shown as mean ± SD. In WT mice AMPK activity was increased by acute renal ischaemia (P<0.001). In AMPK-β1^−/− mice, AMPK activity after acute renal ischaemia was reduced compared to WT for both AMPK-α1 (P<0.001) and AMPK-α2 (P<0.001) isoforms. In AMPK-α1^−/− mice there was no activation of AMPK-α1 by acute renal ischemia, whereas AMPK-α2 was activated by acute renal ischemia (P<0.01) by an amount not different to WT. * P<0.001, ** P<0.01.</p

Renal expression of activated AMPK is markedly reduced in AMPK-β1^−/− mice.

<p>A and B. Lysate from WT and AMPK-β1^−/− kidneys were analyzed by Western blot for the activated form of AMPK, phosphorylated at Thr¹⁷² of the catalytic (α) subunit. The membrane was stripped and reblotted to determine expression of the catalytic (α1 and α2) (A) and scaffolding (β1 and β2) (B) subunits of AMPK. Expression of β-actin was determined to confirm even sample loading. C. Expression of activated (phospho-αThr¹⁷²) in kidneys from WT and AMPK-β1^−/− mice was quantified by densitometry using arbitrary units (n = 6 per group). Densitometry for phospho-αThr¹⁷² was corrected for β-actin. * P<0.001 by unpaired t test.</p