G-quadruplexes mark alternative lengthening of telomeres.

About 10-15% of all human cancer cells employ a telomerase-independent recombination-based telomere maintenance method, known as alternative lengthening of telomere (ALT), of which the full mechanism remains incompletely understood. While implicated in previous studies as the initiating signals for ALT telomere repair, the prevalence of non-canonical nucleic acid structures in ALT cancers remains unclear. Extending earlier reports, we observe higher levels of DNA/RNA hybrids (R-loops) in ALT-positive (ALT+) compared to telomerase-positive (TERT+) cells. Strikingly, we observe even more pronounced differences for an associated four-stranded nucleic acid structure, G-quadruplex (G4). G4 signals are found at the telomere and are broadly associated with telomere length and accompanied by DNA damage markers. We establish an interdependent relationship between ALT-associated G4s and R-loops and confirm that these two structures can be spatially linked into unique structures, G-loops, at the telomere. Additionally, stabilization of G4s and R-loops cooperatively enhances ALT-activity. However, co-stabilization at higher doses resulted in cytotoxicity in a synergistic manner. Nuclear G4 signals are significantly and reproducibly different between ALT+ and TERT+ low-grade glioma tumours. Together, we present G4 as a novel hallmark of ALT cancers with potential future applications as a convenient biomarker for identifying ALT+ tumours and as therapeutic targets.

The Genome of the Steller Sea Lion (Eumetopias jubatus).

The Steller sea lion is the largest member of the Otariidae family and is found in the coastal waters of the northern Pacific Rim. Here, we present the Steller sea lion genome, determined through DNA sequencing approaches that utilized microfluidic partitioning library construction, as well as nanopore technologies. These methods constructed a highly contiguous assembly with a scaffold N50 length of over 14 megabases, a contig N50 length of over 242 kilobases and a total length of 2.404 gigabases. As a measure of completeness, 95.1% of 4104 highly conserved mammalian genes were found to be complete within the assembly. Further annotation identified 19,668 protein coding genes. The assembled genome sequence and underlying sequence data can be found at the National Center for Biotechnology Information (NCBI) under the BioProject accession number PRJNA475770.

An allosteric mechanism for potent inhibition of human ATP-citrate lyase.

ATP-citrate lyase (ACLY) is a central metabolic enzyme and catalyses the ATP-dependent conversion of citrate and coenzyme A (CoA) to oxaloacetate and acetyl-CoA1-5. The acetyl-CoA product is crucial for the metabolism of fatty acids6,7, the biosynthesis of cholesterol8, and the acetylation and prenylation of proteins9,10. There has been considerable interest in ACLY as a target for anti-cancer drugs, because many cancer cells depend on its activity for proliferation2,5,11. ACLY is also a target against dyslipidaemia and hepatic steatosis, with a compound currently in phase 3 clinical trials4,5. Many inhibitors of ACLY have been reported, but most of them have weak activity5. Here we report the development of a series of low nanomolar, small-molecule inhibitors of human ACLY. We have also determined the structure of the full-length human ACLY homo-tetramer in complex with one of these inhibitors (NDI-091143) by cryo-electron microscopy, which reveals an unexpected mechanism of inhibition. The compound is located in an allosteric, mostly hydrophobic cavity next to the citrate-binding site, and requires extensive conformational changes in the enzyme that indirectly disrupt citrate binding. The observed binding mode is supported by and explains the structure-activity relationships of these compounds. This allosteric site greatly enhances the 'druggability' of ACLY and represents an attractive target for the development of new ACLY inhibitors.

Inhibition of Acetyl-CoA Carboxylase by Phosphorylation or the Inhibitor ND-654 Suppresses Lipogenesis and Hepatocellular Carcinoma.

The incidence of hepatocellular carcinoma (HCC) is rapidly increasing due to the prevalence of obesity and non-alcoholic fatty liver disease, but the molecular triggers that initiate disease development are not fully understood. We demonstrate that mice with targeted loss-of-function point mutations within the AMP-activated protein kinase (AMPK) phosphorylation sites on acetyl-CoA carboxylase 1 (ACC1 Ser79Ala) and ACC2 (ACC2 Ser212Ala) have increased liver de novo lipogenesis (DNL) and liver lesions. The same mutation in ACC1 also increases DNL and proliferation in human liver cancer cells. Consistent with these findings, a novel, liver-specific ACC inhibitor (ND-654) that mimics the effects of ACC phosphorylation inhibits hepatic DNL and the development of HCC, improving survival of tumor-bearing rats when used alone and in combination with the multi-kinase inhibitor sorafenib. These studies highlight the importance of DNL and dysregulation of AMPK-mediated ACC phosphorylation in accelerating HCC and the potential of ACC inhibitors for treatment.

Acetyl-coenzyme A carboxylase inhibition reduces de novo lipogenesis in overweight male subjects: A randomized, double-blind, crossover study.

NDI-010976, an allosteric inhibitor of acetyl-coenzyme A carboxylases (ACC) ACC1 and ACC2, reduces hepatic de novo lipogenesis (DNL) and favorably affects steatosis, inflammation, and fibrosis in animal models of fatty liver disease. This study was a randomized, double-blind, placebo-controlled, crossover trial evaluating the pharmacodynamic effects of a single oral dose of NDI-010976 on hepatic DNL in overweight and/or obese but otherwise healthy adult male subjects. Subjects were randomized to receive either NDI-010976 (20, 50, or 200 mg) or matching placebo in period 1, followed by the alternate treatment in period 2; and hepatic lipogenesis was stimulated with oral fructose administration. Fractional DNL was quantified by infusing a stable isotope tracer, [1-13 C]acetate, and monitoring 13 C incorporation into palmitate of circulating very low-density lipoprotein triglyceride. Single-dose administration of NDI-010976 was well tolerated at doses up to and including 200 mg. Fructose administration over a 10-hour period stimulated hepatic fractional DNL an average of 30.9 ± 6.7% (mean ± standard deviation) above fasting DNL values in placebo-treated subjects. Subjects administered single doses of NDI-010976 at 20, 50, or 200 mg had significant inhibition of DNL compared to placebo (mean inhibition relative to placebo was 70%, 85%, and 104%, respectively). An inverse relationship between fractional DNL and NDI-010976 exposure was observed with >90% inhibition of fractional DNL associated with plasma concentrations of NDI-010976 >4 ng/mL. CONCLUSION: ACC inhibition with a single dose of NDI-010976 is well tolerated and results in a profound dose-dependent inhibition of hepatic DNL in overweight adult male subjects. Therefore, NDI-010976 could contribute considerable value to the treatment algorithm of metabolic disorders characterized by dysregulated fatty acid metabolism, including nonalcoholic steatohepatitis. (Hepatology 2017;66:324-334).

Inhibition of acetyl-CoA carboxylase suppresses fatty acid synthesis and tumor growth of non-small-cell lung cancer in preclinical models.

Continuous de novo fatty acid synthesis is a common feature of cancer that is required to meet the biosynthetic demands of a growing tumor. This process is controlled by the rate-limiting enzyme acetyl-CoA carboxylase (ACC), an attractive but traditionally intractable drug target. Here we provide genetic and pharmacological evidence that in preclinical models ACC is required to maintain the de novo fatty acid synthesis needed for growth and viability of non-small-cell lung cancer (NSCLC) cells. We describe the ability of ND-646-an allosteric inhibitor of the ACC enzymes ACC1 and ACC2 that prevents ACC subunit dimerization-to suppress fatty acid synthesis in vitro and in vivo. Chronic ND-646 treatment of xenograft and genetically engineered mouse models of NSCLC inhibited tumor growth. When administered as a single agent or in combination with the standard-of-care drug carboplatin, ND-646 markedly suppressed lung tumor growth in the Kras;Trp53-/- (also known as KRAS p53) and Kras;Stk11-/- (also known as KRAS Lkb1) mouse models of NSCLC. These findings demonstrate that ACC mediates a metabolic liability of NSCLC and that ACC inhibition by ND-646 is detrimental to NSCLC growth, supporting further examination of the use of ACC inhibitors in oncology.

Acetyl-CoA carboxylase inhibition by ND-630 reduces hepatic steatosis, improves insulin sensitivity, and modulates dyslipidemia in rats.

Simultaneous inhibition of the acetyl-CoA carboxylase (ACC) isozymes ACC1 and ACC2 results in concomitant inhibition of fatty acid synthesis and stimulation of fatty acid oxidation and may favorably affect the morbidity and mortality associated with obesity, diabetes, and fatty liver disease. Using structure-based drug design, we have identified a series of potent allosteric protein-protein interaction inhibitors, exemplified by ND-630, that interact within the ACC phosphopeptide acceptor and dimerization site to prevent dimerization and inhibit the enzymatic activity of both ACC isozymes, reduce fatty acid synthesis and stimulate fatty acid oxidation in cultured cells and in animals, and exhibit favorable drug-like properties. When administered chronically to rats with diet-induced obesity, ND-630 reduces hepatic steatosis, improves insulin sensitivity, reduces weight gain without affecting food intake, and favorably affects dyslipidemia. When administered chronically to Zucker diabetic fatty rats, ND-630 reduces hepatic steatosis, improves glucose-stimulated insulin secretion, and reduces hemoglobin A1c (0.9% reduction). Together, these data suggest that ACC inhibition by representatives of this series may be useful in treating a variety of metabolic disorders, including metabolic syndrome, type 2 diabetes mellitus, and fatty liver disease.

Nonhuman primates and other animal models in diabetes research.

Animal models are important for determining the pathogenesis of and potential treatments for obesity and diabetes. Nonhuman primates (NHPs) are particularly useful for studying these disorders. As in humans, type 2 diabetes mellitus is the most common form of diabetes in NHPs and occurs more often in older obese animals, with a metabolic progression from insulin resistance (IR) and impaired glucose tolerance to overt diabetes. Histopathologic changes in pancreatic islets are also similar to those seen in humans with diabetes. Initially, there is islet hyperplasia with abundant insulin production to compensate for IR, followed by insufficient insulin production with replacement of islets with islet-associated amyloid. Diabetic NHPs also have adverse changes in plasma lipid and lipoprotein concentrations, biomarkers of obesity, inflammation, and oxidative stress, and protein glycation that contribute to the numerous complications of the disease. Furthermore, sex hormones, pregnancy, and environmental factors (e.g., diet and stress) affect IR and can also contribute to diabetes progression in NHPs. Additionally, due to their similar clinical and pathologic characteristics, NHPs have been used in many pharmacological studies to assess new therapeutic agents. For these reasons, NHPs are particularly valuable animal models of obesity and diabetes for studying disease pathogenesis, risk factors, comorbidities, and therapeutic interventions.

The adipocyte as an endocrine organ in the regulation of metabolic homeostasis.

Over the past decade and a half it has become increasingly clear that adipose tissue is a much more complex organ than was initially considered and that its metabolic functions extend well beyond the classical actions of thermoregulation and of storage and release of fatty acids. In fact, it is now well established that adipose tissue plays a critical role in maintenance of energy homeostasis through secretion of a large number of adipokines that interact with central as well as peripheral organs such as the brain, liver, pancreas, and skeletal muscle to control diverse processes, such as food intake, energy expenditure, carbohydrate and lipid metabolism, blood pressure, blood coagulation, and inflammation. While many of these adipokines are adipocyte-derived and have a variety of endocrine functions, others are produced by resident macrophages and interact in a paracrine fashion to control adipocyte metabolism. It is also abundantly clear that the dysregulation of adipokine secretion and action that occurs in obesity plays a fundamental role in the development of a variety of cardiometabolic disorders, including the metabolic syndrome, type 2 diabetes, inflammatory disorders, and vascular disorders, that ultimately lead to coronary heart disease. Described herein are the traditional as well as endocrine roles of adipose tissue in controlling energy metabolism and their dysregulation in obesity that leads to development of cardiometabolic disorders, with a focus on what is currently known regarding the characteristics and roles in both health and disease of the adipocyte-derived adipokines, adiponectin, leptin, resistin, and retinol binding protein 4, and the resident macrophage-derived adipokines, tumor necrosis factor-α and interleukin-6. This article is part of a Special Issue entitled 'Central Control of Food Intake'.

Short-term hyperglycemia increases arterial superoxide production and iron dysregulation in atherosclerotic monkeys.

The incidence and severity of atherosclerotic vascular disease are increased in diabetic patients, in part because of increased production of reactive oxygen species (ROS). Previously, we found both increased atherosclerosis and arterial protein oxidation 6 months after streptozotocin-induced diabetes in monkeys fed an atherogenic diet, the pattern of which was indicative of redox-active transition metal involvement. The goal of this study was to determine if short-term (1 month) hyperglycemia increases oxidative stress and dysregulates iron metabolism before differences in atherosclerosis. Cynomolgus monkeys with preexisting atherosclerosis were stratified by dietary history and plasma lipids and received either streptozotocin (STZ-DM; n = 10) or vehicle (control; n = 10). One month after diabetes induction, blood and artery samples were collected. There were no differences in plasma lipoprotein cholesterol, arterial cholesterol, and atherosclerosis between control and STZ-DM. However, plasma lipid peroxides were elevated 137% (P < .01); arterial superoxide was increased 47% (P < .05); plasma ferritin, an indicator of whole-body iron stores, was 46% higher (P < .05); and iron deposition within aortic atherosclerotic lesions was more prevalent in STZ-DM compared with controls. Arterial levels of the antioxidant enzymes, superoxide dismutase, catalase, and heme oxygenase-1 were not higher in STZ-DM, although superoxide was higher, suggesting impaired antioxidant response. The increase in ROS before differences in atherosclerosis supports ROS as an initiating event in diabetic vascular disease. Further studies are needed to determine if increases in iron stores and arterial iron deposition promote hydroxyl radical formation from superoxide and accelerate diabetic vascular damage.

A selective cannabinoid-1 receptor antagonist, PF-95453, reduces body weight and body fat to a greater extent than pair-fed controls in obese monkeys.

Cannabinoid-1 (CB(1)) receptor antagonists exhibit pharmacological properties favorable to treatment of obesity, caused by both centrally mediated effects on appetite and peripherally mediated effects on energy metabolism. However, the relative contribution of these effects to the weight loss produced by CB(1) receptor antagonists remains unclear. Here, we compare food intake-related and independent effects of the CB(1)-selective antagonist 1-(7-(2-chlorophenyl)-8-(4-chlorophenyl)-2-methylpyrazolo[1,5-a][1,3,5]triazin-4-yl)-3-(methylamino) azetidine-3-carboxamide (PF-95453) in obese cynomolgus monkeys. Monkeys were divided into three study groups (n = 10 each) and treated once daily for 8 weeks with either vehicle or PF-95453 as follows: 1, fed ad libitum and dosed orally with vehicle; 2, fed ad libitum and dosed orally with PF-95453 (0.5 mg/kg weeks 1-3, 1.0 mg/kg weeks 4-8); and 3, fed an amount equal to the amount consumed by the drug-treated group and dosed orally with vehicle (pair-fed). PF-95453 treatment significantly reduced food consumption by 23%, body weight by 10%, body fat by 39%, and leptin by 34% while increasing adiponectin by 78% relative to vehicle-treated controls. Pair-fed animals did not exhibit reductions in body weight or leptin but did show significantly reduced body fat (11%) and increased adiponectin (15%) relative to vehicle-treated controls but markedly less than after PF-95453 treatment. Indeed, significant differences were noted between the drug-treated and pair-fed groups with respect to body weight reduction, body fat reduction, increased adiponectin, and leptin reduction. Similar to humans, monkeys treated with the CB(1) receptor antagonist exhibited decreased body weight and body fat, a substantial portion of which seemed to be independent of the effects on food intake.

A selective peroxisome proliferator-activated receptor alpha agonist, CP-900691, improves plasma lipids, lipoproteins, and glycemic control in diabetic monkeys.

Peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of lipid and glucose metabolism. PPARgamma agonists improve insulin sensitivity and hyperglycemia and are effective in treating type 2 diabetes mellitus (T2DM), whereas PPARalpha agonists are used to treat dyslipidemia and atherosclerosis. The goal here was to examine the efficacy of a selective PPARalpha agonist {(S)-3-[3-(1-carboxy-1-methyl-ethoxy)-phenyl]-piperidine-1-carboxylic acid 4-trifluoromethyl-benzyl ester; CP-900691} on lipid, glycemic, and inflammation indices in 14 cynomolgus monkeys with spontaneous T2DM maintained on daily insulin therapy. Monkeys were dosed orally with either vehicle (n = 7) or CP-900691 (3 mg/kg, n = 7) daily for 6 weeks. CP-900691 treatment increased plasma high-density lipoprotein cholesterol (HDLC) (33 +/- 3 to 60 +/- 4 mg/dL, p < 0.001) and apolipoprotein A1 (96 +/- 5 to 157 +/- 5 mg/dL, p < 0.001), reduced plasma triglycerides (547 +/- 102 to 356 +/- 90 mg/dL, p < 0.01), and apolipoprotein B (62 +/- 3 to 45 +/- 3 mg/dL, p < 0.01), improved the lipoprotein index (HDL to non-HDLC ratio; 0.28 +/- 0.06 to 0.79 +/- 0.16, p < 0.001), decreased body weight (p < 0.01) and C-reactive protein (CRP) (1700 +/- 382 to 304 +/- 102 ng/ml, p < 0.01), and increased adiponectin (1697 +/- 542 to 4242 +/- 1070 ng/ml, p < 0.001) compared with baseline. CP-900691 treatment reduced exogenous insulin requirements by approximately 25% (p < 0.04) while lowering plasma fructosamine from 2.87 +/- 0.09 to 2.22 +/- 0.17 mM (p < 0.05), indicative of improved glycemic control. There were no changes in any of the aforementioned parameters in the vehicle group. Because low HDLC and high triglycerides are well established risk factors for cardiovascular disease, the marked improvements in these parameters, and in glycemic control, body weight, and CRP, suggest that CP-900691 may be of benefit in diabetic and obese or hyperlipidemic populations.

Discovery of small molecule isozyme non-specific inhibitors of mammalian acetyl-CoA carboxylase 1 and 2.

Screening Pfizer's compound library resulted in the identification of weak acetyl-CoA carboxylase inhibitors, from which were obtained rACC1 CT-domain co-crystal structures. Utilizing HTS hits and structure-based drug discovery, a more rigid inhibitor was designed and led to the discovery of sub-micromolar, spirochromanone non-specific ACC inhibitors. Low nanomolar, non-specific ACC-isozyme inhibitors that exhibited good rat pharmacokinetics were obtained from this chemotype.

A class of selective antibacterials derived from a protein kinase inhibitor pharmacophore.

As the need for novel antibiotic classes to combat bacterial drug resistance increases, the paucity of leads resulting from target-based antibacterial screening of pharmaceutical compound libraries is of major concern. One explanation for this lack of success is that antibacterial screening efforts have not leveraged the eukaryotic bias resulting from more extensive chemistry efforts targeting eukaryotic gene families such as G protein-coupled receptors and protein kinases. Consistent with a focus on antibacterial target space resembling these eukaryotic targets, we used whole-cell screening to identify a series of antibacterial pyridopyrimidines derived from a protein kinase inhibitor pharmacophore. In bacteria, the pyridopyrimidines target the ATP-binding site of biotin carboxylase (BC), which catalyzes the first enzymatic step of fatty acid biosynthesis. These inhibitors are effective in vitro and in vivo against fastidious gram-negative pathogens including Haemophilus influenzae. Although the BC active site has architectural similarity to those of eukaryotic protein kinases, inhibitor binding to the BC ATP-binding site is distinct from the protein kinase-binding mode, such that the inhibitors are selective for bacterial BC. In summary, we have discovered a promising class of potent antibacterials with a previously undescribed mechanism of action. In consideration of the eukaryotic bias of pharmaceutical libraries, our findings also suggest that pursuit of a novel inhibitor leads for antibacterial targets with active-site structural similarity to known human targets will likely be more fruitful than the traditional focus on unique bacterial target space, particularly when structure-based and computational methodologies are applied to ensure bacterial selectivity.

Pharmacologic inhibition of site 1 protease activity inhibits sterol regulatory element-binding protein processing and reduces lipogenic enzyme gene expression and lipid synthesis in cultured cells and experimental animals.

Sterol regulatory element-binding proteins (SREBPs) are major transcriptional regulators of cholesterol, fatty acid, and glucose metabolism. Genetic disruption of SREBP activity reduces plasma and liver levels of cholesterol and triglycerides and insulin-stimulated lipogenesis, suggesting that SREBP is a viable target for pharmacological intervention. The proprotein convertase SREBP site 1 protease (S1P) is an important posttranscriptional regulator of SREBP activation. This report demonstrates that 10 microM PF-429242 (Bioorg Med Chem Lett 17:4411-4414, 2007), a recently described reversible, competitive aminopyrrolidineamide inhibitor of S1P, inhibits endogenous SREBP processing in Chinese hamster ovary cells. The same compound also down-regulates the signal from an SRE-luciferase reporter gene in human embryonic kidney 293 cells and the expression of endogenous SREBP target genes in cultured HepG2 cells. In HepG2 cells, PF-429242 inhibited cholesterol synthesis, with an IC(50) of 0.5 microM. In mice treated with PF-429242 for 24 h, the expression of hepatic SREBP target genes was suppressed, and the hepatic rates of cholesterol and fatty acid synthesis were reduced. Taken together, these data establish that small-molecule S1P inhibitors are capable of reducing cholesterol and fatty acid synthesis in vivo and, therefore, represent a potential new class of therapeutic agents for dyslipidemia and for a variety of cardiometabolic risk factors associated with diabetes, obesity, and the metabolic syndrome.

Partial blockage of sterol biosynthesis with a squalene synthase inhibitor in early postnatal Niemann-Pick type C npcnih null mice brains reduces neuronal cholesterol accumulation, abrogates astrogliosis, but may inhibit myelin maturation.

Niemann-Pick C disease (NPC) is a fatal, neurovisceral genetic disorder. Cell culture studies showed that NPC1 or NPC2 mutations cause malfunctions in cellular cholesterol trafficking and lead to accumulation of cholesterol and other lipids in the late endo/lysosomes. Previous work showed that neuronal cholesterol accumulation occurs in the brains of young postnatal NPC1-/- mice. Here, to evaluate the potential of partial blockage of cholesterol biosynthesis as a therapy for the NPC disease, we first developed a simple method to monitor the relative rates of lipid biosynthesis in mice brains. We next administered squalene synthase inhibitor (SSI) CP-340868 to young mice. The results show that treating 8-day-old NPC1-/- mice with CP-340868 for 6 days significantly inhibits cholesterol biosynthesis in the mice brains. It reduces neuronal cholesterol accumulation, reduces GM3 ganglioside accumulation, and diminishes astrogliosis in the brain. These results suggest that neuronal cholesterol accumulation contributes to early pathogenesis in the NPC1-/- mice brains. The SSI treatment also reduced brain galactolipid content, suggesting that blocking endogenous cholesterol synthesis in the young mice brains may disrupt the normal myelin maturation processes. The methods described in the current work have general applicability for lipid metabolism studies in mice brains in various pathophysiological conditions.

Aminopyrrolidineamide inhibitors of site-1 protease.

The discovery and efficacy of a series of potent aminopyrrolidineamide-based inhibitors of sterol regulatory element binding protein site-1 protease is described.

Three-dimensional quantitative structure-activity relationship analysis of human CYP51 inhibitors.

CYP51 fulfills an essential requirement for all cells, by catalyzing three sequential mono-oxidations within the cholesterol biosynthesis cascade. Inhibition of fungal CYP51 is used as a therapy for treating fungal infections, whereas inhibition of human CYP51 has been considered as a pharmacological approach to treat dyslipidemia and some forms of cancer. To predict the interaction of inhibitors with the active site of human CYP51, a three-dimensional quantitative structure-activity relationship model was constructed. This pharmacophore model of the common structural features of CYP51 inhibitors was built using the program Catalyst from multiple inhibitors (n = 26) of recombinant human CYP51-mediated lanosterol 14alpha-demethylation. The pharmacophore, which consisted of one hydrophobe, one hydrogen bond acceptor, and two ring aromatic features, demonstrated a high correlation between observed and predicted IC(50) values (r = 0.92). Validation of this pharmacophore was performed by predicting the IC(50) of a test set of commercially available (n = 19) and CP-320626-related (n = 48) CYP51 inhibitors. Using predictions below 10 microM as a cutoff indicative of active inhibitors, 16 of 19 commercially available inhibitors (84%) and 38 of 48 CP-320626-related inhibitors (79.2%) were predicted correctly. To better understand how inhibitors fit into the enzyme, potent CYP51 inhibitors were used to build a Cerius(2) receptor surface model representing the volume of the active site. This study has demonstrated the potential for ligand-based computational pharmacophore modeling of human CYP51 and enables a high-throughput screening system for drug discovery and data base mining.

Acetyl-coenzyme A carboxylases: versatile targets for drug discovery.

Acetyl-coenzyme A carboxylases (ACCs) have crucial roles in fatty acid metabolism in humans and most other living organisms. They are attractive targets for drug discovery against a variety of human diseases, including diabetes, obesity, cancer, and microbial infections. In addition, ACCs from grasses are the targets of herbicides that have been in commercial use for more than 20 years. Significant progresses in both basic research and in drug discovery have been made over the past few years in the studies on these enzymes. At the basic research level, the crystal structures of the biotin carboxylase (BC) and the carboxyltransferase (CT) components of ACC have been determined, and the molecular basis for ACC inhibition by small molecules are beginning to be understood. At the drug discovery level, a large number of nanomolar inhibitors of mammalian ACCs have been reported and the extent of their therapeutic potential is being aggressively explored. This review summarizes these new progresses and also offers some prospects in terms of the future directions for the studies on these important enzymes.

Old world nonhuman primate models of type 2 diabetes mellitus.

Type 2 diabetes mellitus is a major health problem of increasing incidence. To better study the pathogenesis and potential therapeutic agents for this disease, appropriate animal models are needed. Old World nonhuman primates (NHPs) are a useful animal model of type 2 diabetes; like humans, the disease is most common in older, obese animals. Before developing overt diabetes, NHPs have a period of obesity-associated insulin resistance that is initially met with compensatory insulin secretion. When either a relative or absolute deficiency in pancreatic insulin production occurs, fasting glucose concentrations begin to increase and diabetic signs become apparent. Pathological changes in pancreatic islets are also similar to those seen in human diabetics. Initially there is hyperplasia of the islets with abundant insulin production typically followed by replacement of islets with islet-associated amyloid. Diabetic NHPs have detrimental changes in plasma lipid and lipoprotein concentrations, lipoprotein composition, and glycation, which may contribute to progression of atherosclerosis. As both the prediabetic condition (similar to metabolic syndrome in humans) and overt diabetes become better defined in monkeys, their use in pharmacological studies is increasing. Likely due to their genetic similarity to humans and the similar characteristics of the disease in NHPs, NHPs have been used to study recently developed agonists of the peroxisome proliferators-activated receptors. Importantly, agonists of the different receptor subclasses elicit similar responses in both humans and NHPs. Thus, Old World NHPs are a valuable animal model of type 2 diabetes to study disease progression, associated risk factors, and potential new treatments.