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Chronic alcohol consumption causes hepatic injury including fatty liver and fibrosis. Global interests in edible insects as future food source have been increased. We have previously demonstrated a new technology to make hard mature silkworm, Bombyx mori, into edible form, steamed and freeze-dried mature silkworm larval powder (SMSP). Here, we assessed the protective effects of SMSP on ethanol-induced hepatic steatosis and lipid metabolism in rats. SMSP supplementation for 4 weeks significantly attenuated ethanol-induced fat accumulation and LDL/HDL ratio by modulating lipogenesis and fatty acid oxidation-related gene expression such as SIRT1, AMPK, and ACC. SMSP administration also inhibited hepatic fibrosis by decreasing the levels of pro-collagen1 and α-SMA. Moreover, SMSP supplementation effectively restored total antioxidant levels and significantly reduced the levels of hepatic malondialdehyde and TNF-α. Our findings suggest that SMSP supplementation may be the promising strategy for the prevention or treatment of chronic alcoholic fatty liver disease.

Increasing incidence of various cancers has been reported in diabetic patients. O-linked N-acetylglucosamine (O-GlcNAc) modification of proteins at serine/threonine residues (O-GlcNAcylation) is an essential post-translational modification that is upregulated in diabetic patients and has been implicated in tumor growth. However, the mechanisms by which O-GlcNAcylation promotes tumor growth remain unclear. Given that AMP-activated kinase (AMPK) has been thought to play important roles in suppressing tumor growth, we evaluated the involvement of AMPK O-GlcNAcylation on the growth of LoVo cells, a human colon cancer cell line. Results revealed that treatment with Thiamet G (TMG), an inhibitor of O-GlcNAc hydrolase, increased both anchorage-dependent and -independent growth of the cells. O-GlcNAc transferase overexpression also increased the growth. These treatments increased AMPK O-GlcNAcylation in a dose-dependent manner, which led to reduced AMPK phosphorylation and mTOR activation. Chemical inhibition or activation of AMPK led to increased or decreased growth, respectively, which was consistent with the data with genetic inhibition of AMPK. In addition, TMG-mediated acceleration of tumor growth was abolished by both chemical and genetic inhibition of AMPK. To examine the effects of AMPK O-GlcNAcylation in vivo, the LoVo cells were s.c. transplanted onto the backs of BALB/c-nu/nu mice. Injection of TMG promoted the growth and enhanced O-GlcNAcylation of the tumors of the mice. Consistent with in vitro data, AMPK O-GlcNAcylation was increased, which reduced AMPK phosphorylation and resulted in activation of mTOR. Collectively, the higher colon cancer risk of diabetic patients could be due to O-GlcNAcylation-mediated AMPK inactivation and subsequent activation of mTOR.

Introduction: Carfilzomib (Cfz), an irreversible proteasome inhibitor (PI), is an approved agent against relapsed/refractory multiple myeloma (R/R MM). Cfz is associated with high incidence of cardiovascular adverse effects. Hypertension stands as the most frequent cardiovascular complication of Cfz. Even though thrombotic microangiopathy (TMA) is inculpated of Cfz's hypertensive phenotype, its exact pathophysiology is still elusive. In our previous work, we showed that Cfz establishes cardiotoxicity in vivo in a Protein Phosphatase 2A (PP2A)-AMP-activated kinase α (AMPKα)-dependent manner (Efentakis P et al. Blood. 2019;133(7):710-723) but does not lead to a permanent vascular deficit, indicating that hypertension is not vascular derived [Efentakis P et al. IJMS 2020;21(15):E5185]. Taking under consideration that renal homeostasis plays an important role in blood pressure regulation we sought to (i) characterize the dose-dependent manifestation of Cfz-induced hypertension; (ii) investigate the molecular signaling of Cfz in the kidneys by proteomic and immunoblotting analyses and (iii) study the renal ion channels regulation. Methods: Forty C57Bl/6 mice (12-14 weeks of age) were randomly assigned to: (i) Acute Protocol: a. Control [Normal Saline (N/S) 0.9%] and b. Cfz (8mg/kg) for two days and (ii) Sub-acute Protocol: a) Control (N/S 0.9%,) and b) Cfz (8mg/kg) for seven days. Intraperitoneal administration of N/S 0.9% and Cfz was performed at two consecutive and on alternate days for the acute and sub-acute protocols respectively. At baseline and endpoint of the experiments, systolic (SBP) and diastolic blood pressure (DBP) were measured, and subsequently mice were sacrificed for the collection of blood and renal samples. Blood samples were collected in citrate buffer for hematological/coagulation profiling [prothrombin time (PT) and INR estimation] and for cleaved Von Willebrand Factor (cl. VWF) immunoblotting assessment as well as for blood testing of white blood cells (WBCs) and platelets. Renal samples underwent histological proteomic and molecular analyses. Results: SBP and DBP were found to be elevated in Cfz group only in the sub-acute protocol compared to control (SBP: 78.5±2.0 vs 68.2±0.7, p Conclusion: Sub-acute Cfz treatment establishes a renal-derived hypertensive phenotype and a circulating inflammatory phenotype as indicated by the increased neutrophil and WBCs count in the blood. TMA does not seem to be implicated with the observed phenotype in vivo as investigated molecularly and histologically. Cfz-induced dephosphorylation of AMPKα and the subsequent dysregulation of the collecting duct renal ion channel homeostasis is found to be responsible for the observed effect. Therefore, Cfz seems to induce hypertension by a dysregulation of water-ion re-absorbance leading to increased cardiac preload. The latter comes in agreement with clinical data showing that some Cfz-treated patients present with fluid retention, which can be attributed to the aforementioned renal effects of the drug. Disclosures Efentakis: Amgen: Research Funding. Kastritis:Amgen: Consultancy, Honoraria, Research Funding; Genesis Pharma: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria. Dimopoulos:BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Personal fees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Personal fees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Personal fees, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Personal fees, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Personal fees, Research Funding, Speakers Bureau. Andreadou:Amgen: Research Funding. Terpos:Amgen: Honoraria, Research Funding; Genesis pharma SA: Honoraria, Other: travel expenses , Research Funding; Janssen: Honoraria, Research Funding; Takeda: Honoraria, Other: travel expenses , Research Funding; Celgene: Honoraria; Sanofi: Honoraria; BMS: Honoraria.

Aging is associated with vascular endothelial dysfunction, reduced exercise tolerance, and impaired whole‐body glucose metabolism. Interleukin‐37 (IL‐37), an anti‐inflammatory cytokine of the interleukin‐1 family, exerts salutary physiological effects in young mice independent of its inflammation‐suppressing properties. Here, we assess the efficacy of IL‐37 treatment for improving physiological function in older age. Old mice (26–28 months) received daily intraperitoneal injections of recombinant human IL‐37 (recIL‐37; 1 µg/200 ml PBS) or vehicle (200 ml PBS) for 10–14 days. Vascular endothelial function (ex vivo carotid artery dilation to increasing doses of acetylcholine, ACh) was enhanced in recIL‐37 vs. vehicle‐treated mice via increased nitric oxide (NO) bioavailability (all p, Physiological function declines with aging, increasing risk of chronic diseases and disability. We show for the first time that treatment with a novel anti‐inflammatory compound interleukin‐37 (IL‐37) improves multiple physiological functions in old mice, and identify potential roles of reduced superoxide production, improved oxidative metabolism and circulating factors in mediating improvements. Our findings support IL‐37 therapy as a novel strategy for improving diverse physiological functions in old age.

C‑type natriuretic peptide (CNP), from the family of natriuretic peptides (NPs), has been shown to induce antihypertrophic and antifibrotic effects in cardiomyocytes. However, the roles of CNP in the atrial dysregulation of connexin (Cx)40 and Cx43 remain to be elucidated. The present study aimed to investigate the effects of CNP on angiotensin (Ang) II‑induced Cx40 and Cx43 dysregulation in isolated perfused beating rat left atria. A rat isolated perfused beating atrial model was used and the protein levels were determined via western blotting. Ang II significantly upregulated NF‑κB, activator protein‑1, transforming growth factor‑β1 (TGF‑β1), collagen I and matrix metalloproteinase 2, leading to atrial fibrosis, and downregulated expression of Cx40 and Cx43. The changes in Cx40 and Cx43 induced by Ang II were abolished by CNP through upregulation of phosphorylated AMP‑activated kinase a1 (AMPK) and downregulation of TGF‑β1. The effects of CNP on AMPK and TGF‑β1 levels were inhibited by KT5823 and pertussis toxin, inhibitors of protein kinase G (PKG) and NP receptor type C (NPR‑C), respectively. Thus, CNP can prevent Ang II‑induced dysregulation of Cx40 and Cx43 through activation of AMPK via the CNP‑PKG and CNP‑NPR‑C pathways in isolated beating rat atria. The present findings suggested that CNP may be therapeutically useful for clinical conditions involving cardiac dysregulation of Cx expression‑related diseases.

In a state of caloric restriction (CR), improved insulin action was associated with the activation of AMP-activated kinase (AMPK). Here, we verified whether AMPK was involved in impaired β-cell function in islets from rats subjected to CR for 21 days. Eight-week-old male rats were distributed into a control (CTL) group that was fed an isocaloric diet ad libitum or a CR group that received 60% of the food consumed by the CTL group. From days 18-21, CTL and CR rats were treated with sense (CTLS and CRS) or antisense (CTLAS and CRAS) AMPKα2 oligonucleotides. Caloric restriction was associated with decreased body weight, perigonadal fat pads and insulinaemia, while higher glucose tolerance was observed in CRS rats. Antisense treatment normalized insulinaemia and glucose tolerance in CRAS rats and increased cholesterolaemia in CRAS and CTLAS groups. These effects were associated with reduced pAMPK/AMPK protein expression in the liver of rats treated with antisense oligonucleotides. Additionally, CRS islets showed higher pAMPK/AMPK content and lower glucose-induced insulin release. As expected, antisense oligonucleotides against AMPKα2 efficiently reduced pAMPK/AMPK protein in CRAS and CTLAS islets. The lower AMPK content in CRAS islets normalized the insulin secretion in islets exposed to 16.7 mM glucose. In addition, CTLAS islets presented higher insulin secretion at 2.8 and 16.7 mM glucose. These findings support the hypothesis that higher AMPK protein expression is involved in impaired β-cell function in islets from rats subjected to CR for 21 days.

Hypoxia induces pulmonary vasoconstriction and reconstruction in the pulmonary arteries and pulmonary veins (PVs), and elevation of intracellular calcium concentration ([Ca2+]i) is a primary factor of these processes. In the present study, the role of transient receptor potential cation channels (TRPCs) in mediating the hypoxia-induced elevation of [Ca2+]i in rat distal pulmonary venous smooth muscle cells (PVSMCs) was investigated. Rats with chronic hypoxic pulmonary hypertension (CHPH) were used for in vivo experiments, and PVSMCs were isolated for in vitro experiments. [Ca2+]i was measured using fura-2-based fluorescence calcium imaging. Reverse transcription-quantitative polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels of TRPCs. Methyl thiazolyl tetrazolium and Transwell assays were used to investigate the proliferation and migration of PVSMCs, respectively. The results of the present study demonstrated that TRPC6 was increased in the distal PVs of CHPH rats, and in PVSMCs exposed to hypoxic conditions (4% O2, 72 h); however, TRPC1 was not. The 1-oleoyl-2-acetyl-sn-glycerol-induced [Ca2+]i elevation was increased in PVSMCs isolated from CHPH rats and in PVSMCs cultured under hypoxic conditions (4% O2, 72 h). Hypoxia induced PVSMC [Ca2+]i elevation, proliferation and migration. These alterations were inhibited following TRPC6 knockdown. Results from the present study suggest that TRPC6 expression is increased during chronic hypoxia, which contributes to Ca2+ entry into the cell, thus promoting proliferation and migration of PVSMCs.

Creatine (Cr), phosphocreatine (PCr), and creatine kinases (CK) comprise an energy shuttle linking ATP production in mitochondria with cellular consumption sites. Myocytes cannot synthesize Cr: these cells depend on uptake across the cell membrane by a specialized creatine transporter (CrT) to maintain intracellular Cr levels. Hypoxia interferes with energy metabolism, including the activity of the creatine energy shuttle, and therefore affects intracellular ATP and PCr levels. Here, we report that exposing cultured cardiomyocytes to low oxygen levels rapidly diminishes Cr transport by decreasing V max and K m . Pharmacological activation of AMP‐activated kinase (AMPK) abrogated the reduction in Cr transport caused by hypoxia. Cr supplementation increases ATP and PCr content in cardiomyocytes subjected to hypoxia, while also significantly augmenting the cellular adaptive response to hypoxia mediated by HIF‐1 activation. Our results indicate that: (1) hypoxia reduces Cr transport in cardiomyocytes in culture, (2) the cytoprotective effects of Cr supplementation are related to enhanced adaptive physiological responses to hypoxia mediated by HIF‐1, and (3) Cr supplementation increases the cellular ATP and PCr content in RNCMs exposed to hypoxia.

Background: Caloric restriction is associated with broad therapeutic potential in various diseases and an increase in health and life span. In this study, we assessed the impact of caloric restriction on acute and inflammatory nociception in mice, which were either fed ad libitum or subjected to caloric restriction with 80% of the daily average for two weeks. Results: The behavioral tests revealed that inflammatory nociception in the formalin test and in zymosan-induced mechanical hypersensitivity were significantly decreased when mice underwent caloric restriction. As potential mediators of the diet-induced antinociception, we assessed genes typically induced by inflammatory stimuli, AMP-activated kinase, and the endocannabinoid system which have all already been associated with nociceptive responses. Zymosan-induced inflammatory markers such as COX-2, TNFα, IL-1β, and c-fos in the spinal cord were not altered by caloric restriction. In contrast, AMPKα2 knock-out mice showed significant differences in comparison to C57BL/6 mice and their respective wild type littermates by missing the antinociceptive effects after caloric restriction. Endocannabinoid levels of anandamide and 2-arachidonyl glyceroldetermined in serum by LC-MS/MS were not affected by either caloric restriction alone or in combination with zymosan treatment. However, cannabinoid receptor type 1 expression in the spinal cord, which was not altered by caloric restriction in control mice, was significantly increased after caloric restriction in zymosan-induced paw inflammation. Since increased cannabinoid receptor type 1 signaling might influence AMP-activated kinase activity, we analyzed effects of anandamide on AMP-activated kinase in cell culture and observed a significant activation of AMP-activated kinase. Thus, endocannabionoid-induced AMP-activated kinase activation might be involved in antinociceptive effects after caloric restriction. Conclusion: Our data suggest that caloric restriction has an impact on inflammatory nociception which might involve AMP-activated kinase activation and an increased activity of the endogenous endocannabinoid system by caloric restriction-induced cannabinoid receptor type 1 upregulation.

AMP-activated protein kinase (AMPK) is activated under conditions that deplete cellular ATP levels and elevate AMP levels. We have recently shown that AMPK can represent a valid target for improving the medical treatment of growth hormone (GH)-secreting pituitary adenomas and the effects of its activation or inhibition in pituitary tumour cells are worthy of further characterisation. We aimed to determine whether AMPK may have a role in combined antiproliferative therapies based on multiple drugs targeting cell anabolic functions at different levels in pituitary tumour cells to overcome the risk of cell growth escape phenomena. Accordingly, we tried to determine whether a rationale exists in combining compounds activating AMPK with compounds targeting the phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR/p70S6K signalling pathway. AMPK down-regulation by specific small-interfering RNAs confirmed that activated AMPK had a role in restraining growth of GH3 cells. Hence, we compared the effects of compounds directly targeting the mTOR-p70S6K axis, namely the mTOR inhibitor rapamycin and the p70S6K inhibitor PF-4708671, with the effects of the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on cell signalling and cell growth, in rat pituitary GH3 cells. AICAR was able to reduce growth factor-induced p70S6K activity, as shown by the decrease of phospho-p70S6K levels. However, it was far less effective than rapamycin and PF-4708671. We observed significant differences between the growth inhibitory effects of the three compounds in GH3 and GH1 cells. Interestingly, PF-4708671 was devoid of any effect. AICAR was at least as effective as rapamycin and the co-treatment was more effective than single treatments. AICAR induced apoptosis of GH3 cells, whereas rapamycin caused preferentially a decrease of cell proliferation. Finally, AICAR and rapamycin differed in their actions on growth factor-induced extracellular signal regulated kinase 1/2 phosphorylation. In conclusion, the results of the present study suggest the increased efficacy of combined antiproliferative therapies, including rapamycin analogues and AMPK activators in GH-secreting pituitary tumours, as a result of complementary and only partially overlapping mechanisms of action.

Diabetes mellitus (DM) is characterized by dysregulated energy metabolism. Resveratrol (RSV) has been shown to ameliorate hyperglycemia and hyperlipidemia in diabetic animals. However, its overall in vivo effects on energy metabolism and the underlying mechanism require further investigation. In the present study, electrospray ionization-tandem mass spectrometry was employed to characterize the urine and plasma metabolomes of control, streptozotocin-induced DM and RSV-treated DM rats. Using principal component analysis (PCA) and heat map analysis, we discovered significant differences among control and experimental groups. RSV treatment significantly reduced the metabolic abnormalities in DM rats. Compared with the age-matched control rats, the level of carnitine was lower, and the levels of acetylcarnitine and butyrylcarnitine were higher in the urine and plasma of DM rats. RSV treatment ameliorated the deranged carnitine metabolism in DM rats. In addition, RSV treatment attenuated the diabetic ketoacidosis and muscle protein degradation, as evidenced from the attenuation of elevated urinary methyl-histidine and plasma branched-chain amino acids levels in DM rats. The beneficial effects of RSV in DM rats were correlated with activation of hepatic AMP-activated protein kinase and SIRT1 expression, increase of hepatic and muscular mitochondrial biogenesis and inhibition of muscle NF-κB activities. We concluded that RSV possesses multiple beneficial metabolic effects in insulin-deficient DM rats, particularly in improving energy metabolism and reducing protein wasting.

Oxidative stress results in apoptosis of neuronal cells, leading to neurodegenerative disorders. However, the underlying molecular mechanism remains to be elucidated. Here, we show that hydrogen peroxide (H(2)O(2)), a major oxidant generated when oxidative stress occurs, induced apoptosis of neuronal cells (PC12 cells and primary murine neurons), by inhibiting the mammalian target of rapamycin (mTOR)-mediated phosphorylation of ribosomal p70 S6 kinase (S6K1) and eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). N-acetyl-L-cysteine (NAC), a scavenger of reactive oxygen species (ROS), blocked H(2)O(2) inhibition of mTOR signaling. Ectopic expression of wild-type (wt) mTOR, constitutively active S6K1 or downregulation of 4E-BP1 partially prevented H(2)O(2) induction of apoptosis. Furthermore, we identified that H(2)O(2) induction of ROS inhibited the upstream kinases, Akt and phosphoinositide-dependent kinase 1 (PDK1), but not the type I insulin-like growth factor receptor (IGFR), and activated the negative regulator, AMP-activated protein kinase alpha (AMPKalpha), but not the phosphatase and tensin homolog (PTEN) in the cells. Expression of a dominant negative AMPKalpha or downregulation of AMPKalpha1 conferred partial resistance to H(2)O(2) inhibition of phosphorylation of S6K1 and 4E-BP1, as well as cell viability, indicating that H(2)O(2) inhibition of mTOR signaling is at least in part through activation of AMPK. Our findings suggest that AMPK inhibitors may be exploited for prevention of H(2)O(2)-induced neurodegenerative diseases.

Protein phosphorylation is an important post-translational modification of proteins. Postmortem tissues are widely being utilized in the biomedical studies, but the effects of postmortem on protein phosphorylation have not been received enough attention. In the present study, we found here that most proteins in mouse brain, heart, liver, and kidney were rapidly dephosphorylated to various degrees during 20 sec to 10 min postmortem. Phosphorylation of tau at Thr212 and glycogen synthase kinase 3β (GSK-3β) at Ser9 was reduced by 50% in the brain with 40 sec postmortem, a regular time for tissue processing. During postmortem, phosphorylation of cAMP-dependent protein kinase (PKA) and AMP activated kinase (AMPK) was increased in the brain, but not in other organs. Perfusion of the brain with cold or room temperature phosphate-buffered saline (PBS) also caused significant alteration of protein phosphorylation. Cooling down and maintaining mouse brains in the ice-cold buffer prevented the alteration effectively. This study suggests that phosphorylation of proteins is rapidly changed during postmortem. Thus, immediate processing of tissues followed by cooling down in ice-cold buffer is vitally important and perfusion has to be avoided when protein phosphorylation is to be studied.

AMP-activated kinase (AMPK), a protein that regulates energy balance and metabolism, has recently been identified in boar spermatozoa where regulates key functional sperm processes essential for fertilization. This work's aims are AMPK identification, intracellular localization, and their role in human spermatozoa function. Semen was obtained from healthy human donors. Sperm AMPK and phospho-Thr172-AMPK were analyzed by Western blotting and indirect immunofluorescence. High- and low-quality sperm populations were separated by a 40%–80% density gradient. Human spermatozoa motility was evaluated by an Integrated Semen Analysis System (ISAS) in the presence or absence of the AMPK inhibitor compound C (CC). AMPK is localized along the human spermatozoa, at the entire acrosome, midpiece and tail with variable intensity, whereas its active form, phospho-Thr172-AMPK, shows a prominent staining at the acrosome and sperm tail with a weaker staining in the midpiece and the postacrosomal region. Interestingly, spermatozoa bearing an excess residual cytoplasm show strong AMPK staining in this subcellular compartment. Both AMPK and phospho-Thr172-AMPK human spermatozoa contents exhibit important individual variations. Moreover, active AMPK is predominant in the high motility sperm population, where shows a stronger intensity compared with the low motility sperm population. Inhibition of AMPK activity in human spermatozoa by CC treatment leads to a significant reduction in any sperm motility parameter analyzed: percent of motile sperm, sperm velocities, progressivity, and other motility coefficients. This work identifies and points out AMPK as a new molecular mechanism involved in human spermatozoa motility. Further AMPK implications in the clinical efficiency of assisted reproduction and in other reproductive areas need to be studied.

Autophagy is an important cell-biological process responsible for the disposal of long-lived proteins, protein aggregates, defective organelles and intracellular pathogens. It is activated in response to cellular stress and plays a role in development, cell differentiation, and ageing. Moreover, it has been shown to be involved in different pathologies, including cancer and neurodegenerative diseases. It is a long standing issue whether and how the Ca2+ ion is involved in its regulation. The role of the inositol 1,4,5-trisphosphate receptor, the main intracellular Ca2+-release channel, in apoptosis is well recognized, but its role in autophagy only recently emerged and is therefore much less well understood. Positive as well as negative effects on autophagy have been reported for both the inositol 1,4,5-trisphosphate receptor and Ca2+. This review will critically present the evidence for a role of the inositol 1,4,5-trisphosphate receptor/Ca2+-release channel in autophagy and will demonstrate that depending on the cellular conditions it can either suppress or promote autophagy. Suppression occurs through Ca2+ signals directed to the mitochondria, fueling ATP production and decreasing AMP-activated kinase activity. In contrast, Ca2+-induced autophagy can be mediated by several pathways including calmodulin-dependent kinase kinase beta, calmodulin-dependent kinase I, protein kinase C theta, and/or extracellular signalregulated kinase. ispartof: Cell Communication and Signaling vol:10 issue:1 pages:17- ispartof: location:England status: published

Plasma urate level is primarily regulated by urinary excretion, and ~70% of urate excretion is due to tubular secretion. Birds, which only secrete urate, and humans, which secrete and reabsorb, mai...

Nucleoside diphosphate kinase (NDPK) has many roles and is present in different locations in the cell. Membrane-bound NDPK is present in epithelial fractions enriched for the apical membrane. Here, we show in human, mouse and sheep airway membranes, that the phosphorylation state of membrane-bound NDPK on histidine and serine residues differs dependent on many regulatory factors. GTP (but not ATP) promotes serine phosphorylation (pSer) of NDPK. Further we find that rising [AMP] promotes pSer (only with GTP) but inhibits histidine phosphorylation (pHis) of NDPK from both donors. We find that NDPK co-immunoprecipitates reciprocally with AMP-activated kinase and that these two proteins can co-localise in human airways. AMP concentrations rise rapidly when ATP is depleted or during hypoxia. We find that, in human airway cells exposed to hypoxia (3% oxygen), membrane-bound NDPK is inhibited. Although histidine phosphorylation should in principle be independent of the nucleotide triphosphates used, we speculate that this membrane pool of NDPK may be able to switch function dependent on nucleotide species.