AMP Deaminase Research Articles

A mutation in Ampd2 is associated with nephrotic syndrome and hypercholesterolemia in mice.

BackgroundPreviously, we identified three loci affecting HDL-cholesterol levels in a screen for ENU-induced mutations in mice and discovered two mutated genes. We sought to identify the third mutated gene and further characterize the mouse phenotype.MethodsWe engaged, DNA sequencing, gene expression profiling, western blotting, lipoprotein characterization, metabolomics assessment, histology and electron microscopy in mouse tissues.ResultsWe identify the third gene as Ampd2, a liver isoform of AMP Deaminase (Ampd), a central component of energy and purine metabolism pathways. The causative mutation was a guanine-to-thymine transversion resulting in an A341S conversion in Ampd2. Ampd2 homozygous mutant mice exhibit a labile hypercholesterolemia phenotype, peaking around 9 weeks of age (251 mg/dL vs. wildtype control at 138 mg/dL), and was evidenced by marked increases in HDL, VLDL and LDL. In an attempt to determine the molecular connection between Ampd2 dysfunction and hypercholesterolemia, we analyzed hepatic gene expression and found the downregulation of Ldlr, Hmgcs and Insig1 and upregulation of Cyp7A1 genes. Metabolomic analysis confirmed an increase in hepatic AMP levels and a decrease in allantoin levels consistent with Ampd2 deficiency, and increases in campesterol and β-sitosterol. Additionally, nephrotic syndrome was observed in the mutant mice, through proteinuria, kidney histology and effacement and blebbing of podocyte foot processes by electron microscopy.ConclusionIn summary we describe the discovery of a novel genetic mouse model of combined transient nephrotic syndrome and hypercholesterolemia, resembling the human disorder.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-511X-13-167) contains supplementary material, which is available to authorized users.

Inhibition of AMP Deaminase Activity Does Not Improve Glucose Control in Rodent Models of Insulin Resistance or Diabetes

Inhibition of AMP deaminase (AMPD) holds the potential to elevate intracellular adenosine and AMP levels and, therefore, to augment adenosine signaling and activation of AMP-activated protein kinase (AMPK). To test the latter hypothesis, novel AMPD pan inhibitors were synthesized and explored using a panel of in vitro, ex vivo, and in vivo models focusing on confirming AMPD inhibitory potency and the potential of AMPD inhibition to improve glucose control in vivo. Repeated dosing of selected inhibitors did not improve glucose control in insulin-resistant or diabetic rodent disease models. Mice with genetic deletion of the muscle-specific isoform Ampd1 did not showany favorable metabolic phenotype despite being challenged with high-fat diet feeding. Therefore, these results do not support the development of AMPD inhibitors for the treatment of type 2 diabetes.

Effects of Pharmacological AMP Deaminase Inhibition and Ampd1 Deletion on Nucleotide Levels and AMPK Activation in Contracting Skeletal Muscle

AMP-activated protein kinase (AMPK) plays a central role in regulating metabolism and energy homeostasis. It achieves its function by sensing fluctuations in the AMP:ATP ratio. AMP deaminase (AMPD) converts AMP into IMP, and the AMPD1 isoenzyme is expressed in skeletal muscles. Here, effects of pharmacological inhibition and genetic deletion of AMPD were examined in contracting skeletal muscles. Pharmacological AMPD inhibition potentiated rises in AMP, AMP:ATP ratio, AMPK Thr172, and acetyl-CoA carboxylase (ACC) Ser218 phosphorylation induced by electrical stimulation, without affecting glucose transport. In incubated extensor digitorum longus and soleus muscles from Ampd1 knockout mice, increases in AMP levels and AMP:ATP ratio by electrical stimulation were potentiated considerably compared with muscles from wild-type mice, whereas enhanced AMPK activation was moderate and only observed in soleus, suggesting control by factors other than changes in adenine nucleotides. AMPD inhibitors could be useful tools for enhancing AMPK activation in cells and tissues during ATP-depletion.

METABOLISM OF PURINE NUCLEOSIDES AND BASES IN SUSPENSION-CULTURED ARABIDOPSIS THALIANA CELLS

We study the metabolism of purine nucleosides and purine bases in suspension-cultured cells of the model plant Arabidopsis thaliana . [8- 14 C]Adenosine, [8- 14 C]guanosine, [8- 14 C]inosine, [8- 14 C]xanthosine, [8- 14 C]adenine, [8- 14 C]guanine, [8- 14 C]hypoxanthine and [8- 14 C]xanthine were administered to cells in the cell division phase, and the uptake and metabolic fate of these compounds were monitored for 4h. The rates of uptake of most purines were within the range 60-70 nmol/gFW. Xanthine and xanthosine were taken up more slowly. The rate of uptake was ordered as hypoxanthine > adenine > inosine > guanosine > guanine > adenosine > xanthosine> xanthine. A large amount of radioactivity from [8- 14 C]adenosine, [8- 14 C]guanosine, [8- 14 C]adenine and [8- 14 C]guanine, and a limited amount from [8- 14 C]inosine and [8- 14 C]hypoxanthine, was incorporated into nucleotides and RNA. The so-called purine salvage pathways of adenosine, guanosine, adenine, guanine, inosine and hypoxanthine are therefore functional in A. thaliana . These tracer experiments also reveal that significant amounts of these compounds were converted to xanthine, and enter the catabolic pathway via allantoin. Neither xanthosine nor xanthine is used in the synthesis of nucleotides and RNA. These compounds are entirely catabolized via allantoin and allantoic acid. Deamination of adenine and guanine rings takes place at the stage of AMP deaminase and guanosine deaminase, respectively. The pattern of purine metabolism in A. thaliana is similar to that in other plants. Adenine salvage activity estimated from the metabolism of [8- 14 C]adenine, the cellular concentration of ATP, and expression of the APT1 gene encoding adenine phosphoribosyltransferase all increased markedly at the lag phase of cell proliferation . These observations imply that the salvage pathway is important during the early stages of cell culture in A. thaliana .

T.P.29: Role of AMP deaminase and adenylate kinase in production of ammonia in skeletal muscle of patients with McArdle’s disease

McArdle’s disease is characterized by deficiency of enzyme myophosphorylase that disrupts the mechanism of glycogen breakdown in skeletal muscle. In McArdle patients, during physical activities, little or no lactate is released in the skeletal muscle but level of ammonia gets excessively increased. Production of ammonia is catalysed by AMP deaminase (AMPD) and Adenylate kinase (AK). We measured the activities of AMPD and AK in 11 molecular genetically confirmed McArdle patients and compared with the respective activities of 27 healthy controls. AMPD deficiency is commonly found to be associated with a stop mutation p.Q12X in AMPD1 gene. Therefore, all McArdle patients and controls were screened for this mutation. The p.Q12X stop mutation was identified heterozygote in 2 patients and 7 controls. The AMPD activities in patients and controls that did not harbour this mutation were significantly higher than in respective heterozygote patients and controls. However, there was no significant difference in the AMPD activities between patients and controls. The activities of AK were also not significantly different in patients and controls (p = 0.644). Present study shows that the high ammonia production in McArdle patients is not based on enzyme induction of AMPD and AK but derives from other mechanisms (such as increased enzyme catalytic reaction, stimulated by for instance a highly concentrated ADP, or from alternative pathways of the muscle (like the protein metabolism).

Developmental stage dependent metabolic regulation during meiotic differentiation in budding yeast.

BackgroundThe meiotic developmental pathway in yeast enables both differentiation of vegetative cells into haploid spores that ensure long-term survival, and recombination of the parental DNA to create genetic diversity. Despite the importance of proper metabolic regulation for the supply of building blocks and energy, little is known about the reprogramming of central metabolic pathways in meiotically differentiating cells during passage through successive developmental stages.ResultsMetabolic regulation during meiotic differentiation in budding yeast was analyzed by integrating information on genome-wide transcriptional activity, 26 enzymatic activities in the central metabolism, the dynamics of 67 metabolites, and a metabolic flux analysis at mid-stage meiosis. Analyses of mutants arresting sporulation at defined stages demonstrated that metabolic reprogramming is tightly controlled by the progression through the developmental pathway. The correlation between transcript levels and enzymatic activities in the central metabolism varies significantly in a developmental stage-dependent manner. The complete loss of phosphofructokinase activity at mid-stage meiosis enables a unique setup of the glycolytic pathway which facilitates carbon flux repartitioning into synthesis of spore wall precursors during the co-assimilation of glycogen and acetate. The need for correct homeostasis of purine nucleotides during the meiotic differentiation was demonstrated by the sporulation defect of the AMP deaminase mutant amd1, which exhibited hyper-accumulation of ATP accompanied by depletion of guanosine nucleotides.ConclusionsOur systems-level analysis shows that reprogramming of the central metabolism during the meiotic differentiation is controlled at different hierarchical levels to meet the metabolic and energetic needs at successive developmental stages.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-014-0060-x) contains supplementary material, which is available to authorized users.

Differential up-regulation of ammonia detoxifying enzymes in cerebral cortex, cerebellum, hippocampus, striatum and liver in hyperammonemia.

In order to gain insight into the ammonia-detoxification mechanisms in the brain and liver tissues, we have investigated the effects of hyperammonemia in rats, in vivo, on the activity levels of a number of ammonia- and glutamate-metabolizing enzymes in mitochondria and the cytosolic fractions of the cerebral cortex, cerebellum, hippocampus, striatum and liver. In general, the ammonia metabolizing enzymes - glutaminase, glutamine synthetase, glutamate dehydrogenase, AMP deaminase, adenosine deaminase, as well as aspartate aminotransferase and alanine aminotransferase - are differentially upregulated in various brain and liver regions of the hyperammonemic rats, indicating that divergent ammonia-detoxification mechanisms are involved in the various brain regions and liver in acute hyperammonemia.

P01 : Blockade of AMP degradation pathways enhances hypoactivity response

A variety of mammals, including several species of ground squirrels, prairie dogs, hamsters, and marsupials, innately enter into hypometabolic states, such as hibernation and daily torpor, to reduce energy expenditure during unfavorable environmental conditions such as cold winter. The mechanism of metabolic suppression in these instances is still largely unknown. Our lab has developed a method for inducing a torpor-like state in non-hibernating mammals termed Adenosine monophosphate (AMP)-Induced Deep Hypometabolism (AIDH). Using this method, we have previously shown that CD73 deficient mice (CD73KO) have a more dramatic response to AIDH when compared to WT mice. CD73 is an ecto-nucleotidase responsible for dephosphorylating AMP to Adenosine. Based on initial evidence showing AMP entering the re d blood cell (RBC), we proceeded to knock-out the main AMP degradation enzyme inside the RBCs, AMP deaminase 3 (AMPD3) in mice. In the AMPD3KO mice, we also observed an enhanced response to AIDH. To further categorize the importance of both of these enzymes, a double knock-out mouse line (DKO) deficient in both AMPD3 and CD73 were created. Here we report the initial findings of a further enhanced response to AIDH.

A04 Session 1: Translational Hibernation : Whole body cooling via 5′-AMP mediated hypometabolism

A transient hypometabolic state can be induced in mammals by 5′-AMP administration. During the hypometabolic state, core body temperature (Tb) of the animal can be readily reduced from euthermia. For example, at ambient temperature (Ta) of 15 °C, the Tb of mice can be reduced to 1–2 °C above Ta for 6–9 h until they spontaneously returned to euthermia. We have observed that several species of non-hibernating mammals, from mice to dogs, are responsive to 5′-AMP induced hypometabolism suggesting that the underlying biochemical and physiological mechanism is highly conserved among mammals. The mechanism for this induced hypometabolic state remains to be fully elucidated. We have shown that mice deficient in A1, A2A, A2B or A3 adenosine receptors does not response differently to 5’-AMP induced hypometabolism from wild type. Upon 5′-AMP administration, the A1 adenosine receptor deficient mice enter into the hypometabolic state similar to wild type mice without displaying bradycardia. This observation rules out a severe heart rate reduction by adenosine as an underlying cause for the observed hypometabolism. In addition, mice deficient in extracellular 5′-Ecto-nucleotidase (CD73) have an enhanced hypometabolic response to 5′-AMP. These observations show that dephosphorylation of 5′-AMP into adenosine reduced the efficacy of 5′-AMP to induce hypometabolism. Our studies further show that radiolabeled 5′-AMP is taken up by the erythrocytes and administrations of 5′-AMP enhanced the level of deoxyhemoglobin. We proposed that this hypometabolism is caused by a reduced erythrocyte oxygen transport due to the altered cellular adenylate equilibrium upon 5′-AMP uptake by erythrocytes. To further test the role of erythrocytes in mediating this behavior, we created a genetically modified mouse model deficient in adenosine monophosphate deaminase 3 (AMPD3), the key 5′-AMP catabolic enzyme in erythrocytes. We have observed that the loss of AMPD3 significantly enhanced the efficacy of 5′-AMP to induce hypometabolic response in mice.

Metformin in vitro and in vivo increases adenosine signaling in rabbit corpora cavernosa.

In subjects with erectile dysfunction responding poorly to sildenafil, metformin was reported to improve erections. The aim of this study is to investigate metformin's mechanism of action on erectile function, particularly focusing on adenosine (ADO) and nitric oxide (NO) signaling in an animal model of high-fat diet (HFD)-induced metabolic syndrome. In vitro contractility studies of penile strips. Penile expression of genes related to ADO or NO signaling was also evaluated. In vitro contractility studies were used to investigate the effect of in vivo and ex vivo metformin administration on ADO- or acetylcholine (Ach)-induced relaxation of penile strips from HFD as compared with animals fed a regular diet (RD). Expression of ADO receptor type 3 (A3 R), ADO deaminase (ADA), AMP deaminase type 1 (AMPD1), and 2 (AMPD2) was decreased in HFD as compared with RD. Accordingly, in HFD the ADO relaxant effect was potentiated as compared with RD (P < 0.02). In vivo metformin treatment in both RD and HFD significantly increased the ADO relaxing effect (P < 0.0001 and P < 0.01, respectively, vs. relative untreated groups) although to a different extent. In fact, the half-maximal inhibitory concentration (IC50 )/IC50 ratio in RD increased fourfold vs. HFD (RD IC50 ratio = 13.75 ± 2.96; HFD IC50 ratio = 2.85 ± 0.52). In corpora cavernosa (CC) from HFD, in vivo metformin (i) normalized A3 R, ADA, and AMPD1; (ii) further decreased AMPD2; (iii) increased dimethylarginine dimethylamino-hydrolase; and (iv) partially restored impaired Ach-induced relaxation. Ex vivo metformin time and dose dependently increased the relaxant effect of ADO in RD. The potentiating effect of metformin on ADO-induced relaxation was significantly reduced by preincubation with NO synthase inhibitor N(ω) -Nitro-L-arginine methyl ester hydrochloride (L-NAME). Interestingly, in vivo testosterone supplementation in HFD rabbits (i) increased penile expression of endothelial NO synthase and AMPD2 and (ii) restored metformin's potentiating effect on ADO-induced relaxation up to RD level. Metformin in vivo and ex vivo increases ADO signaling in CC, most probably interfering with NO formation and ADO breakdown.

The Role of Histidine-Proline-Rich Glycoprotein as Zinc Chaperone for Skeletal Muscle AMP Deaminase

Metallochaperones function as intracellular shuttles for metal ions. At present, no evidence for the existence of any eukaryotic zinc-chaperone has been provided although metallochaperones could be critical for the physiological functions of Zn2+ metalloenzymes. We propose that the complex formed in skeletal muscle by the Zn2+ metalloenzyme AMP deaminase (AMPD) and the metal binding protein histidine-proline-rich glycoprotein (HPRG) acts in this manner. HPRG is a major plasma protein. Recent investigations have reported that skeletal muscle cells do not synthesize HPRG but instead actively internalize plasma HPRG. X-ray absorption spectroscopy (XAS) performed on fresh preparations of rabbit skeletal muscle AMPD provided evidence for a dinuclear zinc site in the enzyme compatible with a (μ-aqua)(μ-carboxylato)dizinc(II) core with two histidine residues at each metal site. XAS on HPRG isolated from the AMPD complex showed that zinc is bound to the protein in a dinuclear cluster where each Zn2+ ion is coordinated by three histidine and one heavier ligand, likely sulfur from cysteine. We describe the existence in mammalian HPRG of a specific zinc binding site distinct from the His-Pro-rich region. The participation of HPRG in the assembly and maintenance of skeletal muscle AMPD by acting as a zinc chaperone is also demonstrated.

Uric acid-dependent inhibition of AMP kinase induces hepatic glucose production in diabetes and starvation: evolutionary implications of the uricase loss in hominids.

Reduced AMP kinase (AMPK) activity has been shown to play a key deleterious role in increased hepatic gluconeogenesis in diabetes, but the mechanism whereby this occurs remains unclear. In this article, we document that another AMP-dependent enzyme, AMP deaminase (AMPD) is activated in the liver of diabetic mice, which parallels with a significant reduction in AMPK activity and a significant increase in intracellular glucose accumulation in human HepG2 cells. AMPD activation is induced by a reduction in intracellular phosphate levels, which is characteristic of insulin resistance and diabetic states. Increased gluconeogenesis is mediated by reduced TORC2 phosphorylation at Ser171 by AMPK in these cells, as well as by the up-regulation of the rate-limiting enzymes PEPCK and G6Pc. The mechanism whereby AMPD controls AMPK activation depends on the production of a specific AMP downstream metabolite through AMPD, uric acid. In this regard, humans have higher uric acid levels than most mammals due to a mutation in uricase, the enzyme involved in uric acid degradation in most mammals, that developed during a period of famine in Europe 1.5 × 10(7) yr ago. Here, working with resurrected ancestral uricases obtained from early hominids, we show that their expression on HepG2 cells is enough to blunt gluconeogenesis in parallel with an up-regulation of AMPK activity. These studies identify a key role AMPD and uric acid in mediating hepatic gluconeogenesis in the diabetic state, via a mechanism involving AMPK down-regulation and overexpression of PEPCK and G6Pc. The uricase mutation in the Miocene likely provided a survival advantage to help maintain glucose levels under conditions of near starvation, but today likely has a role in the pathogenesis of diabetes.

The purine nucleotide cycle: a cardioprotective pathway induced by HIF‐1α (887.4)

Overexpression of hypoxia inducible factor 1α (HIF‐1α) confers robust ischemic cardioprotection. Previously we showed that HIF‐1α induces the ability to use fumarate as a terminal electron acceptor to sustain mitochondrial anaerobic electron transport chain (ETC) activity. The source of fumarate for ETC activity was established to be the purine nucleotide cycle (PNC). Here, we report that mRNA, protein, and activity of the rate‐limiting enzyme in the PNC, AMP deaminase, is induced by HIF‐1α. Thus, in addition to providing fumarate for anaerobic ETC activity, we hypothesized that induction of the PNC might serve as a mechanism that conserves the nucleotide pool during ischemia. The AMP that accumulates during ischemia can be metabolized by AMP deaminase to IMP, a membrane impermeable metabolite. Alternatively, AMP can be degraded to adenosine, which can diffuse into the interstitial space leading to a reduction of the cardiomyocyte's nucleotide pool. Consistent with our hypothesis, we show that HIF‐1α‐expressing hearts accumulate significantly less adenosine than wildtype hearts during ischemia. Collectively, our findings indicate that the PNC is a novel cardioprotective mechanism induced by HIF‐1α that preserves ETC activity while conserving the nucleotide pool.Grant Funding Source: Supported by NIH grant R01HL084302

Correction: AMP Deaminase 3 Deficiency Enhanced 5′-AMP Induction of Hypometabolism

Correction: AMP Deaminase 3 Deficiency Enhanced 5′-AMP Induction of Hypometabolism

AMP Deaminase 1 Gene Polymorphism and Heart Disease—A Genetic Association That Highlights New Treatment

Nucleotide metabolism and signalling is directly linked to myocardial function. Therefore analysis how diversity of genes coding nucleotide metabolism related proteins affects clinical progress of heart disease could provide valuable information for development of new treatments. Several studies identified that polymorphism of AMP deaminase 1 gene (AMPD1), in particular the common C34T variant of this gene was found to benefit patients with heart failure and ischemic heart disease. However, these findings were inconsistent in subsequent studies. This prompted our detailed analysis of heart transplant recipients that revealed diverse effect: improved early postoperative cardiac function associated with C34T mutation in donors, but worse 1-year survival. Our other studies on the metabolic impact of AMPD1 C34T mutation revealed decrease in AMPD activity, increased production of adenosine and de-inhibition of AMP regulated protein kinase. Thus, genetic, clinical and biochemical studies revealed that while long term attenuation of AMPD activity could be deleterious, transient inhibition of AMPD activity before acute cardiac injury is protective. We suggest therefore that pharmacological inhibition of AMP deaminase before transient ischemic event such as during ischemic heart disease or cardiac surgery could provide therapeutic benefit.

Effect of isolated AMP deaminase deficiency on skeletal muscle function

Mutation of the AMP deaminase 1 (AMPD1) gene, the predominate AMPD gene expressed in skeletal muscle, is one of the most common inherited defects in the Caucasian population; 2–3% of individuals in this ethnic group are homozygous for defects in the AMPD1 gene. Several studies of human subjects have reported variable results with some studies suggesting this gene defect may cause symptoms of a metabolic myopathy and/or easy fatigability while others indicate individuals with this inherited defect are completely asymptomatic. Because of confounding problems in assessing muscle symptoms and performance in human subjects with different genetic backgrounds and different environmental experiences such as prior exercise conditioning and diet, a strain of inbred mice with selective disruption of the AMPD1 was developed to study the consequences of muscle AMPD deficiency in isolation. Studies reported here demonstrate that these animals are a good metabolic phenocopy of human AMPD1 deficiency but they exhibit no abnormalities in muscle performance in three different exercise protocols.

AMPD1 rs17602729 is associated with physical performance of sprint and power in elite Lithuanian athletes.

BackgroundThe C34T genetic polymorphism (rs17602729) in the AMPD1 gene, encoding the skeletal muscle-specific isoform of adenosine monophosphate deaminase (AMPD1), is a common polymorphism among Caucasians that can impair exercise capacity. The aim of the present study was twofold: (1) to determine the C34T AMPD1 allele/genotype frequency distributions in Lithuanian athletes (n = 204, stratified into three groups: endurance, sprint/power and mixed) and compare them with the allele/genotype frequency distributions in randomly selected healthy Lithuanian non-athletes (n = 260) and (2) to compare common anthropometric measurements and physical performance phenotypes between the three groups of athletes depending on their AMPD1 genotype.ResultsThe results of our study indicate that the frequency of the AMPD1 TT genotype was 2.4% in the control group, while it was absent in the athlete group. There were significantly more sprint/power-orientated athletes with the CC genotype (86.3%) compared with the endurance-orientated athletes (72.9%), mixed athletes (67.1%), and controls (74.2%). We determined that the AMPD1 C34T polymorphism is not associated with aerobic muscle performance phenotype (VO2max). For CC genotype the short-term explosive muscle power value (based on Vertical Jump test) of athletes from the sprint/power group was significantly higher than that of the endurance group athletes (P < 0.05). The AMPD1 CC genotype is associated with anaerobic performance (Vertical Jump).ConclusionsThe AMPD1 C allele may help athletes to attain elite status in sprint/power-oriented sports, and the T allele is a factor unfavourable for athletics in sprint/power-oriented sports categories. Hence, the AMPD1 C allele can be regarded as a marker associated with the physical performance of sprint and power. Replications studies are required to confirm this association.

Effects of sulfasalazine and tofacitinib on the protein profile of articular chondrocytes

Objective. Sulfasalazine (SSZ) and tofacitinib are effective for treating rheumatoid arthritis, however, their effects on chondrocytes have not been fully understood. We here tried to elucidate their effects on chondrocyte proteins.Methods. We treated chondrocytes from five osteoarthritis patients with IL-1β, IL-1β+ SSZ, IL-1β+ tofacitinib, SSZ alone, and tofacitinib alone. Then, we compared protein profiles of the chondrocytes using two-dimensional differential gel electrophoresis. Further, we identified altered proteins by mass spectrometry.Results. Out of 892 detected protein spots, the IL-1β stimulation changed intensity of 43 spots more than 1.3-fold or less than 1/1.3-fold significantly. SSZ suppressed the IL-1β-induced intensity alteration in 16 (37%) out of the 43 protein spots. Tofacitinib suppressed the IL-1β-induced alteration in 4 (9.3%) out of the 43 spots. The production of AMP deaminase 2 and procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 were increased by IL-1β and the increase was suppressed by SSZ and by tofacitinib. SSZ alone altered intensity of 273 (31%) out of the 852 spots significantly, whereas tofacitinib alone altered intensity of only 24 (2.7%) out of them.Conclusion. SSZ and, to lesser extent, tofacitinib suppress the effects of IL-1β on the protein profiles of chondrocytes. Our data would promote understanding of effects of the drugs on chondrocytes.

Unclassified cardiomyopathies in neuromuscular disorders

Unclassified cardiomyopathies (CMPs) include left ventricular hypertrabeculation or noncompaction (LVHT) and Takotsubo syndrome (TTS). Unclassified CMPs are frequently associated with noncardiac disease, including neuromuscular disorders (NMDs). This review aims at summarizing and discussing recent findings concerning the association of NMDs with unclassified CMPs. Literature search using the database PubMed from 1966 to June 2013 was performed. LVHT has been described in association with dystrophinopathies, myotonic dystrophies, zaspopathies, laminopathies, dystrobrevinopathies, oculopharyngeal muscular dystrophy, tropomyosin-1 mutations, multiminicore disease, Danon disease, mitochondrial disorders, myoadenylate deaminase deficiency, Pompe's disease, glycogen storage disease-IV, fatty acid oxidation disorder, Barth syndrome, ryanodine receptor mutation, inclusion body myopathy, dystrophic epidermolysis bullosa, Charcot-Marie-Tooth neuropathy, hereditary cobolamine deficiency, beta-thalassemia, poliomyelitis, and Friedreich ataxia. Takotsubo syndrome has been described in association with myasthenia gravis, amyotrophic lateral sclerosis, Guillain-Barre syndrome, rhabdomyolysis, mitochondrial disorder, hypokalemia-related myopathy, syndrome malin, hereditary sensorimotor neuropathy, Beals syndrome, polymyalgia rheumatica, and unclassified myopathy. It is important for treating physicians to know about these associations because treatment and outcome of LVHT, including artificial ventilation, are determined by the presence or absence of an NMD. There are also indications that LVHT in NMDs favors the development of TTS. LVHT and TTS may be associated with NMDs. The pathogenetic link between unclassified CMPs and NMDs remains elusive. Outcome of LVHT and treatment of TTS are additionally determined by the presence or absence of an NMD.

AMP Deaminase 3 Deficiency Enhanced 5′-AMP Induction of Hypometabolism

A hypometabolic state can be induced in mice by 5′-AMP administration. Previously we proposed that an underlying mechanism for this hypometabolism is linked to reduced erythrocyte oxygen transport function due to 5′-AMP uptake altering the cellular adenylate equilibrium. To test this hypothesis, we generated mice deficient in adenosine monophosphate deaminase 3 (AMPD3), the key catabolic enzyme for 5′-AMP in erythrocytes. Mice deficient in AMPD3 maintained AMPD activities in all tissues except erythrocytes. Developmentally and morphologically, the Ampd3−/− mice were indistinguishable from their wild type siblings. The levels of ATP, ADP but not 5′-AMP in erythrocytes of Ampd3−/− mice were significantly elevated. Fasting blood glucose levels of the Ampd3−/− mice were comparable to wild type siblings. In comparison to wild type mice, the Ampd3−/− mice displayed a deeper hypometabolism with a significantly delayed average arousal time in response to 5′-AMP administration. Together, these findings demonstrate a central role of AMPD3 in the regulation of 5′-AMP mediated hypometabolism and further implicate erythrocytes in this behavioral response.