Role for neuronally derived fractalkine in mediating interactions between neurons and CX3CR1-expressing microglia

A recently identified chemokine, fractalkine, is a member of the chemokine gene family, which consists principally of secreted, proinflammatory molecules. Fractalkine is distinguished structurally by the presence of a CX3C motif as well as transmembrane spanning and mucin-like domains and shows atypical constitutive expression in a number of nonhematopoietic tissues, including brain. We undertook an extensive characterization of this chemokine and its receptor CX3CR1 in the brain to gain insights into use of chemokine-dependent systems in the central nervous system. Expression of fractalkine in rat brain was found to be widespread and localized principally to neurons. Recombinant rat CX3CR1, as expressed in Chinese hamster ovary cells, specifically bound fractalkine and signaled in the presence of either membrane-anchored or soluble forms of fractalkine protein. Fractalkine stimulated chemotaxis and elevated intracellular calcium levels of microglia; these responses were blocked by anti-CX3CR1 antibodies. After facial motor nerve axotomy, dramatic changes in the levels of CX3CR1 and fractalkine in the facial nucleus were evident. These included increases in the number and perineuronal location of CX3CR1-expressing microglia, decreased levels of motor neuron-expressed fractalkine mRNA, and an alteration in the forms of fractalkine protein expressed. These data describe mechanisms of cellular communication between neurons and microglia, involving fractalkine and CX3CR1, which occur in both normal and pathological states of the central nervous system.

Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent

An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

Cloned pigs produced by nuclear transfer from adult somatic cells

Since the first report of live mammals produced by nuclear transfer from a cultured differentiated cell population in 1995 (ref. 1), successful development has been obtained in sheep, cattle, mice and goats using a variety of somatic cell types as nuclear donors. The methodology used for embryo reconstruction in each of these species is essentially similar: diploid donor nuclei have been transplanted into enucleated MII oocytes that are activated on, or after transfer. In sheep and goat pre-activated oocytes have also proved successful as cytoplast recipients. The reconstructed embryos are then cultured and selected embryos transferred to surrogate recipients for development to term. In pigs, nuclear transfer has been significantly less successful; a single piglet was reported after transfer of a blastomere nucleus from a four-cell embryo to an enucleated oocyte; however, no live offspring were obtained in studies using somatic cells such as diploid or mitotic fetal fibroblasts as nuclear donors. The development of embryos reconstructed by nuclear transfer is dependent upon a range of factors. Here we investigate some of these factors and report the successful production of cloned piglets from a cultured adult somatic cell population using a new nuclear transfer procedure.

Long-term prevention of renal insufficiency, excess matrix gene expression, and glomerular mesangial matrix expansion by treatment with monoclonal antitransforming growth factor-beta antibody in db/db diabetic mice

Emerging evidence suggests that transforming growth factor-beta (TGF-beta) is an important mediator of diabetic nephropathy. We showed previously that short-term treatment with a neutralizing monoclonal anti-TGF-beta antibody (alphaT) in streptozotocin-diabetic mice prevents early changes of renal hypertrophy and increased matrix mRNA. To establish that overactivity of the renal TGF-beta system mediates the functional and structural changes of the more advanced stages of nephropathy, we tested whether chronic administration of alphaT prevents renal insufficiency and glomerulosclerosis in the db/db mouse, a model of type 2 diabetes that develops overt nephropathy. Diabetic db/db mice and nondiabetic db/m littermates were treated intraperitoneally with alphaT or control IgG, 300 microgram three times per week for 8 wk. Treatment with alphaT, but not with IgG, significantly decreased the plasma TGF-beta1 concentration without decreasing the plasma glucose concentration. The IgG-treated db/db mice developed albuminuria, renal insufficiency, and glomerular mesangial matrix expansion associated with increased renal mRNAs encoding alpha1(IV) collagen and fibronectin. On the other hand, treatment with alphaT completely prevented the increase in plasma creatinine concentration, the decrease in urinary creatinine clearance, and the expansion of mesangial matrix in db/db mice. The increase in renal matrix mRNAs was substantially attenuated, but the excretion of urinary albumin factored for creatinine clearance was not significantly affected by alphaT treatment. We conclude that chronic inhibition of the biologic actions of TGF-beta with a neutralizing monoclonal antibody in db/db mice prevents the glomerulosclerosis and renal insufficiency resulting from type 2 diabetes.

Gold nanoelectrodes of varied size: transition to molecule-like charging

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase responses consistent with double-layer charging of metal-electrolyte interfaces, whereas smaller core nanoparticles exhibit redox chemical character, including a large central gap. The change in behavior is consistent with new near-infrared spectroscopic data showing an emerging gap between the highest occupied and lowest unoccupied orbitals of 0.4 to 0.9 electron volt.

Nod1, an Apaf-1-like activator of caspase-9 and nuclear factor-kappaB

Ced-4 and Apaf-1 belong to a major class of apoptosis regulators that contain caspase-recruitment (CARD) and nucleotide-binding oligomerization domains. Nod1, a protein with an NH2-terminal CARD-linked to a nucleotide-binding domain and a COOH-terminal segment with multiple leucine-rich repeats, was identified. Nod-1 was found to bind to multiple caspases with long prodomains, but specifically activated caspase-9 and promoted caspase-9-induced apoptosis. As reported for Apaf-1, Nod1 required both the CARD and P-loop for function. Unlike Apaf-1, Nod1 induced activation of nuclear factor-kappa-B (NF-kappaB) and bound RICK, a CARD-containing kinase that also induces NF-kappaB activation. Nod1 mutants inhibited NF-kappaB activity induced by RICK, but not that resulting from tumor necrosis factor-alpha stimulation. Thus, Nod1 is a leucine-rich repeat-containing Apaf-1-like molecule that can regulate both apoptosis and NF-kappaB activation pathways.

Apolipoprotein B-48 is the product of a messenger RNA with an organ-specific in-frame stop codon

The primary structure of human apolipoprotein (apo) B-48 has been deduced and shown by a combination of DNA excess hybridization, sequencing of tryptic peptides, cloned complementary DNAs, and intestinal messenger RNAs (mRNAs) to be the product of an intestinal mRNA with an in-frame UAA stop codon resulting from a C to U change in the codon CAA encoding Gln2153 in apoB-100 mRNA. The carboxyl-terminal Ile2152 of apoB-48 purified from chylous ascites fluid has apparently been cleaved from the initial translation product, leaving Met2151 as the new carboxyl-terminus. These data indicate that approximately 85% of the intestinal mRNAs terminate within approximately 0.1 to 1.0 kilobase downstream from the stop codon. The other approximately 15% have lengths similar to hepatic apoB-100 mRNA even though they have the same in-frame stop codon. The organ-specific introduction of a stop codon to a mRNA appears unprecedented and might have implications for cryptic polyadenylation signal recognition and RNA processing.

Crx, a novel Otx-like paired-homeodomain protein, binds to and transactivates photoreceptor cell-specific genes

The otd/Otx gene family encodes paired-like homeodomain proteins that are involved in the regulation of anterior head structure and sensory organ development. Using the yeast one-hybrid screen with a bait containing the Ret 4 site from the bovine rhodopsin promoter, we have cloned a new member of the family, Crx (Cone rod homeobox). Crx encodes a 299 amino acid residue protein with a paired-like homeodomain near its N terminus. In the adult, it is expressed predominantly in photoreceptors and pinealocytes. In the developing mouse retina, it is expressed by embryonic day 12.5 (E12.5). Recombinant Crx binds in vitro not only to the Ret 4 site but also to the Ret 1 and BAT-1 sites. In transient transfection studies, Crx transactivates rhodopsin promoter-reporter constructs. Its activity is synergistic with that of Nrl. Crx also binds to and transactivates the genes for several other photoreceptor cell-specific proteins (interphotoreceptor retinoid-binding protein, beta-phosphodiesterase, and arrestin). Human Crx maps to chromosome 19q13.3, the site of a cone rod dystrophy (CORDII). These studies implicate Crx as a potentially important regulator of photoreceptor cell development and gene expression and also identify it as a candidate gene for CORDII and other retinal diseases.

Potent and selective inhibitors of the proteasome: dipeptidyl boronic acids

Potent and selective dipeptidyl boronic acid proteasome inhibitors are described. As compared to peptidyl aldehyde compounds, boronic acids in this series display dramatically enhanced potency. Compounds such as 15 are promising new therapeutics for treatment of cancer and inflammatory diseases.

Targeted disruption of the three Rb-related genes leads to loss of G(1) control and immortalization

The retinoblastoma protein, pRB, and the closely related proteins p107 and p130 are important regulators of the mammalian cell cycle. Biochemical and genetic studies have demonstrated overlapping as well as distinct functions for the three proteins in cell cycle control and mouse development. However, the role of the pRB family as a whole in the regulation of cell proliferation, cell death, or cell differentiation is not known. We generated embryonic stem (ES) cells and other cell types mutant for all three genes. Triple knock-out mouse embryonic fibroblasts (TKO MEFs) had a shorter cell cycle than wild-type, single, or double knock-out control cells. TKO cells were resistant to G(1) arrest following DNA damage, despite retaining functional p53 activity. They were also insensitive to G(1) arrest signals following contact inhibition or serum starvation. Finally, TKO MEFs did not undergo senescence in culture and do possess some characteristics of transformed cells. Our results confirm the essential role of the Rb family in the control of the G(1)/S transition, place the three Rb family members downstream of multiple cell cycle control pathways, and further the link between loss of cell cycle control and tumorigenesis.

Rare-earth-doped biological composites as in vivo shortwave infrared reporters

The extension of in vivo optical imaging for disease screening and image-guided surgical interventions requires brightly-emitting, tissue-specific materials that optically transmit through living tissue and can be imaged with portable systems that display data in real-time. Recent work suggests that a new window across the short wavelength infrared region can improve in vivo imaging sensitivity over near infrared light. Here we report on the first evidence of multispectral, real-time short wavelength infrared imaging offering anatomical resolution using brightly-emitting rare-earth nanomaterials and demonstrate their applicability toward disease-targeted imaging. Inorganic-protein nanocomposites of rare-earth nanomaterials with human serum albumin facilitated systemic biodistribution of the rare-earth nanomaterials resulting in the increased accumulation and retention in tumor tissue that was visualized by the localized enhancement of infrared signal intensity. Our findings lay the groundwork for a new generation of versatile, biomedical nanomaterials that can advance disease monitoring based on a pioneering infrared imaging technique.

Proteasomal proteomics: identification of nucleotide-sensitive proteasome-interacting proteins by mass spectrometric analysis of affinity-purified proteasomes

Ubiquitin-dependent proteolysis is catalyzed by the 26S proteasome, a dynamic complex of 32 different proteins whose mode of assembly and mechanism of action are poorly understood, in part due to the difficulties encountered in purifying the intact complex. Here we describe a one-step affinity method for purifying intact 26S proteasomes, 19S regulatory caps, and 20S core particles from budding yeast cells. Affinity-purified 26S proteasomes hydrolyze both model peptides and the ubiquitinated Cdk inhibitor Sic1. Affinity purifications performed in the absence of ATP or presence of the poorly hydrolyzable analog ATP-gamma-S unexpectedly revealed that a large number of proteins, including subunits of the skp1-cullin-F-box protein ligase (SCF) and anaphase-promoting complex (APC) ubiquitin ligases, copurify with the 19S cap. To identify these proteasome-interacting proteins, we used a recently developed method that enables the direct analysis of the composition of large protein complexes (DALPC) by mass spectrometry. Using DALPC, we identified more than 24 putative proteasome-interacting proteins, including Ylr421c (Daq1), which we demonstrate to be a new subunit of the budding yeast 19S cap, and Ygr232w (Nas6), which is homologous to a subunit of the mammalian 19S cap (PA700 complex). Additional PIPs include the heat shock proteins Hsp70 and Hsp82, the deubiquitinating enzyme Ubp6, and proteins involved in transcriptional control, mitosis, tubulin assembly, RNA metabolism, and signal transduction. Our data demonstrate that nucleotide hydrolysis modulates the association of many proteins with the 26S proteasome, and validate DALPC as a powerful tool for rapidly identifying stoichiometric and substoichiometric components of large protein assemblies.

TIA-1 is a translational silencer that selectively regulates the expression of TNF-alpha

TIA-1 and TIAR are related proteins that bind to an AU-rich element (ARE) in the 3' untranslated region of tumor necrosis factor alpha (TNF-alpha) transcripts. To determine the functional significance of this interaction, we used homologous recombination to produce mutant mice lacking TIA-1. Although lipopolysaccharide (LPS)-stimulated macrophages derived from wild-type and TIA-1(-/-) mice express similar amounts of TNF-alpha transcripts, macrophages lacking TIA-1 produce significantly more TNF-alpha protein than wild-type controls. The half-life of TNF-alpha transcripts is similar in wild-type and TIA-1(-/-) macrophages, indicating that TIA-1 does not regulate transcript stability. Rather, the absence of TIA-1 significantly increases the proportion of TNF-alpha transcripts that associate with polysomes, suggesting that TIA-1 normally functions as a translational silencer. TIA-1 does not appear to regulate the production of interleukin 1 beta, granulocyte-macrophage colony-stimulating factor or interferon gamma, indicating that its effects are, at least partially, transcript specific. Mice lacking TIA-1 are hypersensitive to the toxic effects of LPS, indicating that this translational control pathway may regulate the organismal response to microbial stress.

A neural circuit for circadian regulation of arousal

An unknown aspect of behavioral state regulation is how the circadian oscillator of the suprachiasmatic nucleus (SCN) regulates sleep and waking. In this report, we describe the necessary elements for a circuit that provides circadian regulation of arousal. Trans-synaptic retrograde tracing revealed a prominent indirect projection from the SCN to the noradrenergic nucleus locus coeruleus (LC), a brain arousal system. Double-labeling experiments revealed several possible links between the SCN and the LC, including the dorsomedial (DMH) and paraventricular hypothalamic nuclei (PVN), as well as medial and ventrolateral pre-optic areas. Lesion studies confirmed that the DMH is a substantial relay in this circuit. Next, neurophysiology experiments revealed circadian variations in LC impulse activity. Lesions of the DMH eliminated these circadian changes in LC activity, confirming the functionality of the SCN-DMH-LC circuit. These results reveal mechanisms for regulation of circadian and sleep-waking functions.

Preimplantation genetic testing for aneuploidy versus morphology as selection criteria for single frozen-thawed embryo transfer in good-prognosis patients: a multicenter randomized clinical trial

OBJECTIVE

To evaluate the benefit of next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) for embryo selection in frozen-thawed embryo transfer.

DESIGN

Randomized controlled trial.

SETTING

Not applicable.

PATIENT(S)

Women aged 25-40 years undergoing IVF with at least two blastocysts that could be biopsied.

INTERVENTION(S)

Randomization for single frozen-thawed embryo transfer with embryo selection based on PGT-A euploid status versus morphology.

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate (OPR) at 20 weeks' gestation per embryo transfer.

RESULT(S)

A total of 661 women (average age 33.7 ± 3.6 years) were randomized to PGT-A (n = 330) or morphology alone (n = 331). The OPR was equivalent between the two arms, with no significant difference per embryo transfer (50% [137/274] vs. 46% [143/313]) or per intention to treat (ITT) at randomization (41.8% [138/330] vs. 43.5% [144/331]). Post hoc analysis of women aged 35-40 years showed a significant increase in OPR per embryo transfer (51% [62/122] vs. 37% [54/145]) but not per ITT.

CONCLUSION(S)

PGT-A did not improve overall pregnancy outcomes in all women, as analyzed per embryo transfer or per ITT. There was a significant increase in OPR per embryo transfer with the use of PGT-A in the subgroup of women aged 35-40 years who had two or more embryos that could be biopsied, but this was not significant when analyzed by ITT.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02268786.

Sequence, structure, receptor-binding domains and internal repeats of human apolipoprotein B-100

Apolipoprotein (apo) B-100, the major protein component in low density lipoprotein (LDL), is the ligand that binds to the LDL receptor. It is important in the metabolism of LDL and elevated plasma levels of LDL-apo B are strongly associated with increased risk of coronary artery disease. Although apo B-100 is of great clinical and biological importance its primary structure has defied chemical elucidation, mainly because of its enormous size, insolubility, and tendency to aggregate. Less than 5% of the apo B-100 sequence has been reported, despite the efforts of many laboratories over the past twenty years. Here we report the complete amino acid sequence of human apo B-100 as deducted by sequence analysis of complementary DNA clones; 2,366 of the 4,536 residues were also confirmed by direct sequencing of apo B-100 tryptic peptides. The distribution of trypsin-accessible and -inaccessible peptides of the protein on LDL is non-random and they can be grouped into 5 hypothetical domains. Of 20 potential N-glycosylation sites identified in the sequence, 13 were found by direct peptide sequencing to be glycosylated, and 4 unglycosylated. Examination of the primary structure of apo B-100 reveals that it contains a large number of long (greater than 70 residues) internal repeats and an even larger number of shorter ones, suggesting that the apo B-100 sequence was derived largely from internal duplications. Finally, using synthetic peptides of a specific region of apo B-100, we have identified a potential LDL receptor-binding domain (residues 3,345-3,381) which can bind to the LDL receptor and suppress 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase activities in cultured human fibroblasts.

Gene therapy for brain tumors: regression of experimental gliomas by adenovirus-mediated gene transfer in vivo

The therapeutic efficacy of adenovirus-mediated herpes simplex virus thymidine kinase (HSV-tk) gene transduction of rat C6 glioma cells followed by ganciclovir (GCV) administration was studied in tumors generated in the brains of nude mice. C6 glioma cells were efficiently transduced in vitro by a replicative-defective recombinant adenovirus carrying the HSV-tk gene (ADV/RSV-tk) that rendered them sensitive to GCV in a dose-dependent manner. Tumors were generated by stereotaxic intracerebral injection of 1 x 10(4) C6 cells in nude mice. After 8 days of tumor growth, 3 x 10(8) ADV/RSV-tk viral particles were injected into the tumors and the mice subsequently were treated with GCV for 6 days. Tumor size in untreated and treated animals was compared 20 days after tumor implantation. The mean cross-sectional area of the tumors in the treated animals was 23-fold smaller than in control animals and the tumor volume was reduced by > 500-fold. These results demonstrate that the recombinant adenoviral vector can function as an efficient gene delivery vehicle for the treatment of gliomas by in vivo gene therapy.

Tissue invasion and metastasis: Molecular, biological and clinical perspectives

Cancer is a key health issue across the world, causing substantial patient morbidity and mortality. Patient prognosis is tightly linked with metastatic dissemination of the disease to distant sites, with metastatic diseases accounting for a vast percentage of cancer patient mortality. While advances in this area have been made, the process of cancer metastasis and the factors governing cancer spread and establishment at secondary locations is still poorly understood. The current article summarizes recent progress in this area of research, both in the understanding of the underlying biological processes and in the therapeutic strategies for the management of metastasis. This review lists the disruption of E-cadherin and tight junctions, key signaling pathways, including urokinase type plasminogen activator (uPA), phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene (PI3K/AKT), focal adhesion kinase (FAK), β-catenin/zinc finger E-box binding homeobox 1 (ZEB-1) and transforming growth factor beta (TGF-β), together with inactivation of activator protein-1 (AP-1) and suppression of matrix metalloproteinase-9 (MMP-9) activity as key targets and the use of phytochemicals, or natural products, such as those from Agaricus blazei, Albatrellus confluens, Cordyceps militaris, Ganoderma lucidum, Poria cocos and Silybum marianum, together with diet derived fatty acids gamma linolenic acid (GLA) and eicosapentanoic acid (EPA) and inhibitory compounds as useful approaches to target tissue invasion and metastasis as well as other hallmark areas of cancer. Together, these strategies could represent new, inexpensive, low toxicity strategies to aid in the management of cancer metastasis as well as having holistic effects against other cancer hallmarks.

Mechanism of GroEL action: productive release of polypeptide from a sequestered position under GroES

The chaperonin GroEL is a large, double-ring structure that, together with ATP and the cochaperonin GroES, assists protein folding in vivo. GroES forms an asymmetric complex with GroEL in which a single GroES ring binds one end of the GroEL cylinder. Cross-linking studies reveal that polypeptide binding occurs exclusively to the GroEL ring not occupied by GroES (trans). During the folding reaction, however, released GroES can rebind to the GroEL ring containing polypeptide (cis). The polypeptide is held tightly in a proteolytically protected environment in cis complexes, in the presence of ADP. Single turnover experiments with ornithine transcarbamylase reveal that polypeptide is productively released from the cis but not the trans complex. These observations suggest a two-step mechanism for GroEL-mediated folding. First, GroES displaces the polypeptide from its initial binding sites, sequestering it in the GroEL central cavity. Second, ATP hydrolysis induces release of GroES and productive release of polypeptide.

Hsp26: a temperature-regulated chaperone

Small heat shock proteins (sHsps) are a conserved protein family, with members found in all organisms analysed so far. Several sHsps have been shown to exhibit chaperone activity and protect proteins from irreversible aggregation in vitro. Here we show that Hsp26, an sHsp from Saccharomyces cerevisiae, is a temperature-regulated molecular chaperone. Like other sHsps, Hsp26 forms large oligomeric complexes. At heat shock temperatures, however, the 24mer chaperone complex dissociates. Interestingly, chaperone assays performed at different temperatures show that the dissociation of the Hsp26 complex at heat shock temperatures is a prerequisite for efficient chaperone activity. Binding of non-native proteins to dissociated Hsp26 produces large globular assemblies with a structure that appears to be completely reorganized relative to the original Hsp26 oligomers. In this complex one monomer of substrate is bound per Hsp26 dimer. The temperature-dependent dissociation of the large storage form of Hsp26 into a smaller, active species and the subsequent re-association to a defined large chaperone-substrate complex represents a novel mechanism for the functional activation of a molecular chaperone.

Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand. Australasian Cryptococcal Study Group

A prospective population-based study was conducted in Australia and New Zealand during 1994-1997 to elucidate the epidemiology of cryptococcosis due to Cryptococcus neoformans var. neoformans (CNVN) and C. neoformans var. gattii (CNVG) and to relate clinical manifestations to host immune status and cryptococcal variety. The mean annual incidence per 10(6) population was 6.6 in Australia and 2.2 in New Zealand. Of 312 episodes, CNVN caused 265 (85%; 98% of the episodes in immunocompromised hosts) and CNVG caused 47 (15%; 44% of the episodes in immunocompetent hosts). The incidence of AIDS-associated cases in Australia declined annually (P<.001). Aborigines in rural or semirural locations (P<.001) and immunocompetent males (P<.001) were at increased risk of CNVG infection. Cryptococcomas in lung or brain were more common in immunocompetent hosts (P< or =.03) in whom there was an association only between lung cryptococcomas and CNVG. An AIDS-associated genetic profile of CNVN serotype A was confirmed by random amplification of polymorphic DNA analysis. Resistance to antifungal drugs was uncommon. The epidemiology of CNVN infection has changed substantially. Clinical manifestations of disease are influenced more strongly by host immune status than by cryptococcal variety.

Methionine aminopeptidase (type 2) is the common target for angiogenesis inhibitors AGM-1470 and ovalicin

BACKGROUND

Angiogenesis, the formation of new blood vessels, is essential for tumor growth. The inhibition of angiogenesis is therefore emerging as a promising therapy for cancer. Two natural products, fumagillin and ovalicin, were discovered to be potent inhibitors of angiogenesis due to their inhibition of endothelial cell proliferation. An analog of fumagillin, AGM-1470, is currently undergoing clinical trials for the treatment of a variety of cancers. The underlying molecular mechanism of the inhibition of angiogenesis by these natural drugs has remained unknown.

RESULTS

Both AGM-1470 and ovalicin bind to a common bifunctional protein, identified by mass spectrometry as the type 2 methionine aminopeptidase (MetAP2). This protein also acts as an inhibitor of eukaryotic initiation factor 2alpha (elF-2alpha) phosphorylation. Both drugs potently inhibit the methionine aminopeptidase activity of MetAP2 without affecting its ability to block elF-2alpha phosphorylation. There are two types of methionine aminopeptidase found in eukaryotes, but only the type 2 enzyme is inhibited by the drugs. A series of analogs of fumagillin and ovalicin were synthesized and their potency for inhibition of endothelial cell proliferation and inhibition of methionine aminopeptidase activity was determined. A significant correlation was found between the two activities.

CONCLUSIONS

The protein MetAP2 is a common molecular target for both AGM-1470 and ovalicin. This finding suggests that MetAP2 may play a critical role in the proliferation of endothelial cells and may serve as a promising target for the development of new anti-angiogenic drugs.