Discovery and Optimization of Potent and Orally Available CTP Synthetase Inhibitors for Use in Treatment of Diseases Driven by Aberrant Immune Cell Proliferation.

Herein, we report the discovery of a first-in-class chemotype 2-(alkylsulfonamido)thiazol-4-yl)acetamides that act as pan-selective inhibitors of cytidine 5'-triphosphate synthetase (CTPS1/2), critical enzymes in the de novo pyrimidine synthesis pathway. Weak inhibitors identified from a high-throughput screening of 240K compounds have been optimized to a potent, orally active agent, compound 27, which has shown significant pharmacological responses at 10 mg/kg dose BID in a well-established animal model of inflammation.

First characterisation of two important postulated intermediates in the formation of a HydT DNA lesion, a thymidine oxidation product.

A number of environmental pollutants and endogenous oxidation agents form 1-(2-deoxy-ß-d-ribofuranosyl)-5-hydroxy-5-methylhydantoin (HydT), an important DNA lesion resulting from thymidine oxidation. In this paper, two intermediates, postulated in the formation of HydT, have been characterised for the first time. The first, N1-formyl-N3-pyruvoylurea intermediate, was produced by the ozonolysis reaction of 2',3',5'-tri-O-acetylribo-, 3',5'-di-O-TBS- and N3,O3',O5-tribenzyl-protected thymidines and was shown to produce, upon decomposition and depending on the protecting group and the conditions, HydT alone, or together with protected-ß-d-ribofuranosyl-N1-formylurea and formamide products. In addition, the second and long sought, open-chain-pyruvoylurea intermediate, was produced through de novo synthesis in protected ß-d-ribofuranosyl-, 2-deoxy-ß-d-ribofuranosyl- and 2-deoxy-ß-d-ribopyranosyl systems. The conditions that induce the cyclization to the hydantoin ring of HydT have been determined. The chemistry utilised in the de novo synthesis is suitable for generating isotopically labelled HydT, as a reference in isotope-dilution-aided quantification of DNA damage.

Divergent C-H Insertion-Cyclization Cascades of N-Allyl Ynamides.

Gold carbene reactivity patterns were accessed by ynamide insertion into a C(sp(3) )H bond. A substantial increase in molecular complexity occurred through the cascade polycyclization of N-allyl ynamides to form fused nitrogen-heterocycle scaffolds. Exquisite selectivity was observed despite several competing pathways in an efficient gold-catalyzed synthesis of densely functionalized C(sp(3) )-rich polycycles and a copper-catalyzed synthesis of fused pyridine derivatives. The respective gold-keteniminium and ketenimine activation pathways have been explored through a structure-reactivity study, and isotopic labeling identified turnover-limiting CH bond-cleavage in both processes.

Highly regioselective synthesis of 2,4,5-(hetero)aryl substituted oxazoles by intermolecular [3+2]-cycloaddition of unsymmetrical internal alkynes.

A robust N-nucleophilic 1,3-N,O-dipole equivalent reacts with unsymmetrical internal alkynes under gold catalysis. Conjugation from a remote nitrogen lone pair enables and controls this convergent and highly regioselective process.

A complex between contactin-1 and the protein tyrosine phosphatase PTPRZ controls the development of oligodendrocyte precursor cells.

The six members of the contactin (CNTN) family of neural cell adhesion molecules are involved in the formation and maintenance of the central nervous system (CNS) and have been linked to mental retardation and neuropsychiatric disorders such as autism. Five of the six CNTNs bind to the homologous receptor protein tyrosine phosphatases gamma (PTPRG) and zeta (PTPRZ), but the biological roles of these interactions remain unclear. We report here the cocrystal structure of the carbonic anhydrase-like domain of PTPRZ bound to tandem Ig repeats of CNTN1 and combine these structural data with binding assays to show that PTPRZ binds specifically to CNTN1 expressed at the surface of oligodendrocyte precursor cells. Furthermore, analyses of glial cell populations in wild-type and PTPRZ-deficient mice show that the binding of PTPRZ to CNTN1 expressed at the surface of oligodendrocyte precursor cells inhibits their proliferation and promotes their development into mature oligodendrocytes. Overall, these results implicate the PTPRZ/CNTN1 complex as a previously unknown modulator of oligodendrogenesis.

Clinical significance of ephrin (eph)-A1, -A2, -a4, -a5 and -a7 receptors in pancreatic ductal adenocarcinoma.

Ephrin (Eph) receptors have been reported to be frequently overexpressed in a wide variety of cancer types, being associated with tumor growth, invasion, metastasis and angiogenesis. The aim of the present study was to evaluate the clinical significance of Eph-A1, -A2, -A4, -A5 and -A7 expression in pancreatic ductal adenocarcinoma. Eph-A1, -A2, -A4, -A5 and -A7 expression and staining intensity were assessed immunohistochemically in tumoral samples of 67 pancreatic adenocarcinoma patients and were statistically analyzed in relation to clinicopathological characteristics, tumor proliferative capacity and patients' survival. Eph receptors were abundantly expressed in pancreatic ductal adenocarcinoma cases examined. Eph-A1 staining intensity was significantly associated with tumor size (pT, p = 0.008) and tumor histopathological stage (pStage, p = 0.012). Eph-A2 expression was significantly associated with patients' age (p = 0.007), while Eph-A4 and Eph-A5 with tumor proliferative capacity (p = 0.019 and p = 0.011, respectively). Pancreatic adenocarcinoma patients with moderate/intense Eph-A5 or Eph-A7 staining presented significantly shorter survival times compared to those with negative/mild one (log-rank test, p = 0.024 and p = 0.009, respectively). Multivariate analysis identified Eph-A5 and Eph-A7 staining intensity as independent prognostic factors (p = 0.048 and p = 0.004, respectively). In conclusion, the present study revealed that Eph receptors were associated with pancreatic cancer characteristics, supporting evidence for their potential clinical application in management and prognosis of pancreatic adenocarcinoma patients.

Structural requirement of TAG-1 for retinal ganglion cell axons and myelin in the mouse optic nerve.

White matter axons organize into fascicles that grow over long distances and traverse very diverse environments. The molecular mechanisms preserving this structure of white matter axonal tracts are not well known. Here, we used the optic nerve as a model and investigated the role of TAG-1, a cell adhesion molecule expressed by retinal axons. TAG-1 was first expressed in the embryonic retinal ganglion cells (RGCs) and later in the postnatal myelin-forming cells in the optic nerve. We describe the consequences of genetic loss of Tag-1 on the developing and adult retinogeniculate tract. Tag-1-null embryos display anomalies in the caliber of RGC axons, associated with an abnormal organization of the astroglial network in the optic nerve. The contralateral projections in the lateral geniculate nucleus are expanded postnatally. In the adult, Tag-1-null mice show a loss of RGC axons, with persistent abnormalities of axonal caliber and additional cytoskeleton and myelination defects. Therefore, TAG-1 is an essential regulator of the structure of RGC axons and their surrounding glial cells in the optic nerve.

VEGF-C is a trophic factor for neural progenitors in the vertebrate embryonic brain.

Vascular endothelial growth factor C (VEGF-C) was first identified as a regulator of the vascular system, where it is required for the development of lymphatic vessels. Here we report actions of VEGF-C in the central nervous system. We detected the expression of the VEGF-C receptor VEGFR-3 in neural progenitor cells in Xenopus laevis and mouse embryos. In Xenopus tadpole VEGF-C knockdowns and in mice lacking Vegfc, the proliferation of neural progenitors expressing VEGFR-3 was severely reduced, in the absence of intracerebral blood vessel defects. In addition, Vegfc-deficient mouse embryos showed a selective loss of oligodendrocyte precursor cells (OPCs) in the embryonic optic nerve. In vitro, VEGF-C stimulated the proliferation of OPCs expressing VEGFR-3 and nestin-positive ventricular neural cells. VEGF-C thus has a new, evolutionary conserved function as a growth factor selectively required by neural progenitor cells expressing its receptor VEGFR-3.

Oligodendrocyte development in the embryonic brain: the contribution of the plp lineage.

Oligodendrocytes are the myelin forming cells of the central nervous system. Over the last decade, their development in the embryonic brain and spinal cord has been documented following the discovery of early oligodendroglial markers. This review highlights the fundamental results obtained on the specification and migration of oligodendroglial cells and illustrates our advances in the knowledge of the cell lineage expressing plp (proteolipid protein), one of the early oligodendroglial genes.

Control of axonophilic migration of oligodendrocyte precursor cells by Eph-ephrin interaction.

The migration of oligodendrocyte precursor cells (OPCs) is modulated by secreted molecules in their environment and by cell-cell and matrix-cell interactions. Here, we ask whether membrane-anchored guidance cues, such as the ephrin ligands and their Eph receptors, participate in the control of OPC migration in the optic nerve. We postulate that EphA and EphB receptors, which are expressed on axons of retinal ganglion cells, interact with ephrins on the surface of OPCs. We show the expression of ephrinA5, ephrinB2 and ephrinB3 in the migrating OPCs of the optic nerve as well as in the diencephalic sites from where they originate. In addition, we demonstrate that coated EphB2-Fc receptors, which are specific for ephrinB2/B3 ligands, induce dramatic changes in the contact and migratory properties of OPCs, indicating that axonal EphB receptors activate ephrinB signaling in OPCs.Based on these findings, we propose that OPCs are characterized by an ephrin code, and that Eph-ephrin interactions between axons and OPCs control the distribution of OPCs in the optic axonal tracts, and the progress and arrest of their migration.