Biotransformation of monoterpenoids, (−)- and menthols, terpinolene and carvotanacetone by Aspergillus species

Four monoterpenoids, (−)- and (+)-menthols, terpinolene and carvotanacetone were biotransformed by Aspergillus niger and several related species. Aspergillus niger converted (−)-menthol to 1-, 2-, 6-, 7-, and 9-hydroxymenthols and the mosquito repellent-active 8-hydroxymenthol. On the other hand, (+)-menthol was smoothly biotransformed by A. niger to give 7-hydroxymenthol. Aspergillus cellulosae biotransformed (−)-menthol specifically to 4-hydroxymenthol. Terpinolene and (−)-carvotanacetone were converted by A. niger to two , β-unsaturated ketones, a fenchane-type compound and diastereoisomeric p-menthane-2,9-diols and 8-hydroxycarvomenthol, respectively.     

Synthesis of Nα,Nδ-dicarbobenzoxy-L-ornithyl-β-alanine benzyl ester,a derivative of salty peptide,in 1,1,1-trichloroethane with polyethylene glycol-modified papain

Summary N,N-Dicarbobenzoxy-L-ornithyl--alanine benzyl ester, a derivative of salty peptide, was synthesized from N,N-dicarbobenzoxy-L-ornithine ethyl ester and -alanine benzyl ester in 1,1,1-trichloroethane using papain modified with polyethylene glycol. The peptide bond formation proceeded in a transparent organic solvent at room temperature and the product was obtained as precipitates from the reaction system.     

How is the relationship between TWIST-1 and BCR-ABL1 gene expressions in chronic myeloid leukaemia patients?

Background: The activation and increased expression of BCR-ABL1 lead to malignant chronic myelogenous leukaemia (CML) cells, as well as the resistance to antitumour agents and apoptosis inducers. Moreover, TWIST-1 protein is a prognostic factor of leukemogenesis, and its level is raised in CML patients with cytogenetic resistance to imatinib. So, there is a likely relationship between BCR-ABL1 and TWIST-1 genes.

Objective: The aim of the study was to assess the relationship between TWIST-1 and BCR-ABL1 expressions.

Methods: Peripheral blood samples were obtained from 44 CML patients under treatment and also from ten healthy subjects as normal controls. The expression of TWIST-1 and BCR-ABL1 genes was measured using real-time PCR, and ABL1 was used as the reference gene. The gene expression was evaluated by REST software.

Results: The expression levels of TWIST-1 and BCR-ABL1 genes in CML patients was changed 40.23?±?177.75-fold and 6?±?18-fold, respectively.

Discussion: No significant relationship was observed between the expressions of TWIST-1 and BCR-ABL1 genes. All patients with TWIST-1 expression levels?≥100-fold had failure of response to treatment.

Conclusion: The probability of the relationship between BCR-ABL1 and TWIST-1 is still debatable, and the average of TWIST-1 expression has been higher in patients without response to treatment. Definitive conclusion needs further investigations.     

The phenylic hydroxyl group is essential for the induction of stress response by sodium salicylate

We have shown that sodium salicylate (SA) activates the heat shock promoter and induces the expression of heat shock proteins (Hsps) with a concomitant increase in the thermotolerance of cells. To identify the functional groups of SA necessary for the induction of Hsps, we evaluated the effect of various derivatives of SA using a mammalian cell line containing a reporter gene downstream of an hsp105 promoter. Among the derivatives, the compounds in which the carboxyl group of SA was substituted activated the hsp105 promoter at 37 degrees C as SA did, but the compounds in which the hydroxyl group was substituted did not. Thus, the phenylic hydroxyl group but not the carboxyl group of SA seemed to be necessary for a stress-induced response. In addition, the orientation of two functional groups on the benzene ring of SA derivatives was also important for the induction of a response. Among these compounds, salicylalcohol which strongly induced the expression of Hsps suppressed the protein aggregation and apoptosis caused by an expanded polyglutamine tract in a cellular model of polyglutamine disease. These findings may aid in the development of novel effective Hsp-inducers.     

Physical and functional interaction between DDB and XPA in nucleotide excision repair

Damaged DNA-binding protein (DDB), consisting of DDB1 and DDB2 subunits recognizes a wide spectrum of DNA lesions. DDB is dispensable for in vitro nucleotide excision repair (NER) reaction, but stimulates this reaction especially for cyclobutane pyrimidine dimer (CPD). Here we show that DDB directly interacts with XPA, one of core NER factors, mainly through DDB2 subunit and the amino-acid residues between 185 and 226 in XPA are important for the interaction. Interestingly, the point mutation causing the substitution from Arg-207 to Gly, which was previously identified in a XP-A revertant cell-line XP129, diminished the interaction with DDB in vitro and in vivo. In a defined system containing R207G mutant XPA and other core NER factors, DDB failed to stimulate the excision of CPD, although the mutant XPA was competent for the basal NER reaction. Moreover, in vivo experiments revealed that the mutant XPA is recruited to damaged DNA sites with much less efficiency compared with wild-type XPA and fails to support the enhancement of CPD repair by ectopic expression of DDB2 in SV40-transformed human cells. These results suggest that the physical interaction between DDB and XPA plays an important role in the DDB-mediated NER reaction.     

Diacylglycerol Kinase �� Augments C-Raf Activity and B-Raf/C-Raf Heterodimerization

The Ras/B-Raf/C-Raf/MEK/ERK signaling cascade is critical for the control of many fundamental cellular processes, including proliferation, survival, and differentiation. This study demonstrated that small interfering RNA-dependent knockdown of diacylglycerol kinase η (DGKη) impaired the Ras/B-Raf/C-Raf/MEK/ERK pathway activated by epidermal growth factor (EGF) in HeLa cells. Conversely, the overexpression of DGKη1 could activate the Ras/B-Raf/C-Raf/MEK/ERK pathway in a DGK activity-independent manner, suggesting that DGKη serves as a scaffold/adaptor protein. By determining the activity of all the components of the pathway in DGKη-silenced HeLa cells, this study revealed that DGKη activated C-Raf but not B-Raf. Moreover, this study demonstrated that DGKη enhanced EGF-induced heterodimerization of C-Raf with B-Raf, which transmits the signal to C-Raf. DGKη physically interacted with B-Raf and C-Raf, regulating EGF-induced recruitment of B-Raf and C-Raf from the cytosol to membranes. The DGKη-dependent activation of C-Raf occurred downstream or independently of the already known C-Raf modifications, such as dephosphorylation at Ser-259, phosphorylation at Ser-338, and interaction with 14-3-3 protein. Taken together, the results obtained strongly support that DGKη acts as a novel critical regulatory component of the Ras/B-Raf/C-Raf/MEK/ERK signaling cascade via a previously unidentified mechanism.The Ras/Raf/MEK³/ERK signaling pathway is critical for the transduction of the extracellular signals to the nucleus, regulating diverse physiological processes such as cell proliferation, differentiation, and survival (1, 2). The binding of extracellular ligands, such as growth factors and cytokines, to cell surface receptors activates Ras. The Raf serine/threonine kinase transmits signals from activated Ras to the downstream protein kinases, MEK1 and MEK2, subsequently leading to activation of ERK1 and ERK2.In mammals, the Raf kinase consists of three isoforms, A-Raf, B-Raf, and C-Raf (Raf-1). It is clinically known that both B-Raf and C-Raf mutations are associated with human cancers (3–5). Knock-out mouse studies demonstrated that each individual Raf isoform has distinct functions, although the three Raf isoforms have high homology in the amino acid sequence (6). The mechanisms underlying C-Raf activation are complicated and thus are not completely understood (3). In response to extracellular signals, C-Raf is initially recruited from cytosol to the plasma membrane and undergo conformational changes by binding directly to the active Ras (7). In addition, other modifications and factors are required for the sufficient activation of C-Raf. For example, dephosphorylation of Ser-259 and phosphorylation of Ser-338, Tyr-341, Thr-491, and Ser-494 are critical for the activation of C-Raf (8–11). Feedback phosphorylation of C-Raf by ERK was also reported to be important for the modulation of C-Raf activity (12, 13). C-Raf activity is regulated by the interaction with 14-3-3 protein (14). Moreover, the heterodimerization of C-Raf with B-Raf, which transmits the signal to C-Raf, has been reported to play an essential role in the activation of the MEK-ERK signaling pathway (15–17). Although B-Raf and C-Raf are the central regulatory components in the Ras/B-Raf/C-Raf/MEK/ERK signaling cascade involved in a variety of pathophysiological events, the activation mechanisms of C-Raf by B-Raf are still unclear.Diacylglycerol kinase (DGK) catalyzes the phosphorylation of diacylglycerol to generate phosphatidic acid. DGK has been recently recognized as an emerging key regulator in a wide range of cell signaling systems (18–20). To date, 10 mammalian DGK isozymes have been identified. They characteristically contain two or three protein kinase C-like C1 domains and a catalytic region and are subdivided into five subtypes according to their structural features (18–20). Their structural variety and distinct expression patterns in tissues allow us to presume that each DGK isozyme has its own biological functions. Indeed, recent studies have revealed that individual DGK isozymes play distinct roles in cell functions through interactions with unique partner proteins such as protein kinase C (21, 22), Ras guanyl nucleotide-releasing protein (23, 24), phosphatidylinositol-4-phosphate 5-kinase (25), chimerins (26, 27), AP-2 (28), and PSD-95 (29).DGKη belongs to the type II DGKs containing a pleckstrin homology domain at the N terminus and the separated catalytic region (19, 30). Two alternative splicing products of DGKη have been identified as DGKη1 and -η2 (31). DGKη2 possesses a sterile α-motif (SAM) domain at the C terminus, whereas DGKη1 does not. This study demonstrated that the expression levels of DGKη1 and -η2 were regulated differently by glucocorticoid, and that they were translocated from the cytoplasm to endosomes in response to stress stimuli as osmotic shock and oxidative stress (31). However, the physiological roles of DGKη remain unknown.This study showed that siRNA-dependent knockdown of DGKη inhibits cell proliferation of the HeLa cells. In addition, DGKη is required for the Ras/B-Raf/C-Raf/MEK/ERK signaling cascade activated by epidermal growth factor (EGF). Intriguingly, DGKη regulates recruitment of B-Raf and C-Raf from cytosol to membranes and their heterodimerization. Moreover, this study demonstrated that DGKη activates C-Raf but not B-Raf in an EGF-dependent manner. The data show DGKη as a novel key regulator of the Ras/B-Raf/C-Raf/MEK/ERK signaling pathway.     

Photo-immobilization of biological components on gold-coated chips for measurements using surface plasmon resonance (SPR) and a quartz crystal microbalance (QCM)

The photo-immobilization technique is useful for immobilization of various biomolecules on assorted material surfaces, independent of the organic functional groups that may be present. Here, we report a convenient new photo-immobilization technique that was developed by combining a nonbiofouling polymer containing polyethylene glycol and a photoreactive crosslinker for surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) measurements. By this method, nonspecific interactions were reduced and various types of molecules, bovine serum albumin, heparin, dsDNA, phosphatidylserine, Tobacco Mosaic Virus, and norfloxacine, were immobilized on an alkane thiol-modified gold surface by a single method. The interactions of photo-immobilized biomolecules and their corresponding antibodies were investigated by SPR and QCM. In addition, SPR imaging was possible using the present method.