Enhanced inhibition of ERK signaling by a novel allosteric MEK inhibitor, CH5126766, that suppresses feedback reactivation of RAF activity.

Tumors with mutant RAS are often dependent on extracellular signal-regulated kinase (ERK) signaling for growth; however, MEK inhibitors have only marginal antitumor activity in these tumors. MEK inhibitors relieve ERK-dependent feedback inhibition of RAF and cause induction of MEK phosphorylation. We have now identified a MEK inhibitor, CH5126766 (RO5126766), that has the unique property of inhibiting RAF kinase as well.

An orally available, small-molecule interferon inhibits viral replication.

Most acute hepatitis C virus (HCV) infections become chronic and some progress to liver cirrhosis or hepatocellular carcinoma. Standard therapy involves an interferon (IFN)-α-based regimen, and efficacy of therapy has been significantly improved by the development of protease inhibitors. However, several issues remain concerning the injectable form and the side effects of IFN.

In vitro activity of isavuconazole against 140 reference fungal strains and 165 clinically isolated yeasts from Japan.

The in vitro susceptibilities of 140 laboratory reference strains of fungi, including type strains, and 165 clinical yeast isolates from Japan towards isavuconazole compared with fluconazole (FLC), itraconazole (ITC), voriconazole and amphotericin B were measured. Broth microdilution methods based on Clinical and Laboratory Standards Institute (CLSI) methods were used for yeasts, and RPMI-MOPS medium semi-solidified with 0.2% low-melting-point agarose based on CLSI guidelines was used for moulds.

Host sphingolipid biosynthesis as a target for hepatitis C virus therapy.

An estimated 170 million individuals worldwide are infected with hepatitis C virus (HCV), a serious cause of chronic liver disease. Current interferon-based therapy for treating HCV infection has an unsatisfactory cure rate, and the development of more efficient drugs is needed. During the early stages of HCV infections, various host genes are differentially regulated, and it is possible that inhibition of host proteins affords a therapeutic strategy for treatment of HCV infection.

Piperazine propanol derivative as a novel antifungal targeting 1,3-beta-D-glucan synthase.

1,3-beta-D-Glucan synthase, which synthesizes a main component of fungal cell wall, is one of the promising targets for antifungal agents. In order to identify novel chemical classes of 1,3-beta-D-glucan synthase inhibitors, we screened a chemical library monitoring inhibition of the Candida albicans 1,3-beta-D-glucan synthase activity. The piperazine propanol derivative GSI578 [(2,6-difluoro-phenyl)-carbamic acid 3-(4-benzothiazol-2-yl-piperazine-1-yl)-propyl ester] was identified as a potent inhibitor against 1,3-beta-D-glucan synthase with an IC50 value of 0.

[Evaluation of targets for antifungal drugs using a system to regulate gene expression].

A system to regulate gene expression is a convenient tool to explore gene function(s) not only in prokaryote but also in eukaryote. Such manipulation tools are scarce in the medical mycology field due to its complexity and diploidity. Although systems to regulate gene expression have been constructed, most of them are restricted in their application to particular culture conditions due to the nature of the promoter used.

Differential sensitivity between Fks1p and Fks2p against a novel beta -1,3-glucan synthase inhibitor, aerothricin3 [corrected].

Fks1p and Fks2p are catalytic subunits of beta-1,3-glucan synthase, which synthesize beta-1,3-glucan, a main component of the cell wall in Saccharomyces cerevisiae. Although Fks1p and Fks2p are highly homologous, sharing 88.1% identity, it has been shown that Fks2p is more sensitive than Fks1p to one of echinocandin derivatives, which inhibits beta-1,3-glucan synthase activity.

Sequence-based approach for identification of cell wall proteins in Saccharomyces cerevisiae.

Open reading frames (ORFs) in the genome of Saccharomyces cerevisiae were screened for cell wall proteins and extracellular proteins, using an in silico sequence analysis combined with biochemical examination. The selection criteria used in the sequence analysis were the presence of a signal sequence for secretion and the absence of any targeting and retention signal to/in intracellular components. By using the PSORT II program, 163 ORFs/proteins were selected as potential extracellular proteins, including cell wall proteins.

Reduced virulence of Candida albicans mutants lacking the GNA1 gene encoding glucosamine-6-phosphate acetyltransferase.

The yeast GNA1 gene encodes glucosamine-6-phosphate acetyltransferase which catalyses the reaction of glucosamine 6-phosphate with acetyl-CoA to form N-acetylglucosamine 6-phosphate, a fundamental precursor in UDP-N-acetylglucosamine biosynthesis. Candida albicans mutants lacking GNA1 were viable in the presence of N-acetylglucosamine. To confirm the physiological importance of C.

The yeast Chs4 protein stimulates the trypsin-sensitive activity of chitin synthase 3 through an apparent protein-protein interaction.

Inducible overexpression of the CHS4 gene under the control of the GAL1 promoter increased Chs3p (chitin synthase 3) activity in Saccharomyces cerevisiae several fold. Approximately half of the Chs3p activity in the membranes of cells overexpressing Chs4p was extracted using CHAPS and cholesteryl hemisuccinate. The detergent-extractable Chs3p activity appeared to be non-zymogenic because incubation with trypsin decreased enzyme activity in both the presence and absence of the substrate, UDP-N-acetylglucosamine.

The Candida albicans gene for mRNA 5-cap methyltransferase: identification of additional residues essential for catalysis.

The 5'-cap structure of eukaryotic mRNA is methylated at the terminal guanosine by RNA (guanine-N7-)-methyltransferase (cap MTase). Saccharomyces cerevisiae ABD1 (ScABD1) and human hMet (also called CMT1) genes are responsible for this enzyme. The ABD1 homologue was cloned from the pathogenic fungus Candida albicans and named C.

The Candida albicans CHS4 gene complements a Saccharomyces cerevisiae skt5/chs4 mutation and is involved in chitin biosynthesis.

The Candida albicans CHS4 gene encoding chitin synthase 4 has been isolated using the Saccharomyces cerevisiae CHS4/SKT5 gene as a probe. The gene contains a 2061 bp open reading frame capable of encoding a protein of 687 amino acids (76053 Da). No intron was observed in the gene.

A controllable gene-expression system for the pathogenic fungus Candida glabrata.

A system for controlling gene expression was established in the pathogenic fungus Candida glabrata to elucidate the physiological functions of genes. To control the expression of the gene of interest, the C. glabrata cells were first transformed with the plasmid carrying the tetracycline repressor-transactivator fusion tetR::GAL4, then with the DNA fragment containing the controllable cassette, the tetracycline operator chimeric promoter (tetO::ScHOP1).

Isolation of CaSLN1 and CaNIK1, the genes for osmosensing histidine kinase homologues, from the pathogenic fungus Candida albicans.

Recent studies have revealed that fungi possess a mechanism similar to bacterial two-component systems to respond to extracellular changes in osmolarity. In Saccharomyces cerevisiae, Sln1p contains both histidine kinase and receiver (response regulator) domains and acts as an osmosensor protein that regulates the downstream HOG1 MAP kinase cascade. SLN1 of Candida albicans was functionally cloned using an S.

Biochemical and genetic characterization of Rbf1p, a putative transcription factor of Candida albicans.

A Candida albicans gene encoding a novel DNA-binding protein that bound to the RPG box of Saccharomyces cerevisiae and the telomeric repeat sequence of C. albicans was previously cloned and designated RBF1 (RPG-box-binding factor). In this report, determination of the functional domains of the protein is described.

A DNA-binding protein from Candida albicans that binds to the RPG box of Saccharomyces cerevisiae and the telomeric repeat sequence of C. albicans.

Electromobility shift assays with a DNA probe containing the Saccharomyces cerevisiae ENO1 RPG box identified a specific DNA-binding protein in total protein extracts of Candida albicans. The protein, named Rbf1p (RPG-box-binding protein 1), bound to other S. cerevisiae RPG boxes, although the nucleotide recognition profile was not completely the same as that of S.