Tetraspanin CD9 modulates ADAM17-mediated shedding of LR11 in leukocytes

LR11, also known as SorLA or SORL1, is a type-I membrane protein from which a large extracellular part, soluble LR11 (sLR11), is released by proteolytic shedding on cleavage with a disintegrin and metalloproteinase 17 (ADAM17). A shedding mechanism is presumed to have a key role in the functions of LR11, but the evidence for this has not yet been demonstrated. Tetraspanin CD9 has been recently shown to regulate the ADAM17-mediated shedding of tumor necrosis factor-α and intercellular adhesion molecule-1 on the cell surface. Here, we investigated the role of CD9 on the shedding of LR11 in leukocytes. LR11 was not expressed in THP-1 monocytes, but it was expressed and released in phorbol 12-myristate 13-acetate (PMA)-induced THP-1 macrophages (PMA/THP-1). Confocal microscopy showed colocalization of LR11 and CD9 proteins on the cell surface of PMA/THP-1. Ectopic neo-expression of CD9 in CCRF-SB cells, which are LR11-positive and CD9-negative, reduced the amount of sLR11 released from the cells. In contrast, incubation of LR11-transfected THP-1 cells with neutralizing anti-CD9 monoclonal antibodies increased the amount of sLR11 released from the cells. Likewise, the PMA-stimulated release of sLR11 increased in THP-1 cells transfected with CD9-targeted shRNAs, which was negated by treatment with the metalloproteinase inhibitor GM6001. These results suggest that the tetraspanin CD9 modulates the ADAM17-mediated shedding of LR11 in various leukemia cell lines and that the association between LR11 and CD9 on the cell surface has an important role in the ADAM17-mediated shedding mechanism.     

A measure of rotatability for second order response surface designs

The concept of rotatability introduced by Box and Hunter (1957,Ann. Math. Statist.,28, 195–241) is an important design criterion for response surface design. Recently, a few measures of rotatability that enable us to assess the degree of rotatability for a given response surface design have been introduced. In this paper, a new measure of rotatability for second order response surface designs is suggested, and illustrated for 3 ^k factorial design and central composite design. Also a short comparison is made between the proposed measure with the previously suggested measures.     

Hydration-dependent protein dynamics revealed by molecular dynamics simulation of crystalline staphylococcal nuclease

Molecular dynamics simulations of crystalline Staphylococcal nuclease in full and minimal hydration states were performed to study hydration effects on protein dynamics at temperatures ranging from 100 to 300 K. In a full hydration state (hydration ratio in weight, h=0.49), gaps are fully filled with water molecules, whereas only crystal waters are included in a minimal hydration state (h=0.09). The inflection of the atomic mean-square fluctuation of protein as a function of temperature, known as the glass-like transition, is observed at approximately 220 K in both cases, which is more significant in the full hydration state. By examining the temperature dependence of residual fluctuation, we found that the increase of fluctuations in the loop and terminal regions, which are exposed to water, is much greater than that in other regions in the full hydration state, but the mobilities of the corresponding regions are relatively restricted in the minimal hydration state by intermolecular contact. The atomic mean-square fluctuation of water molecules in the full hydration state at 300 K is 1 order of magnitude greater than that in the minimal hydration state. Above the transition temperature, most water molecules in the full hydration state behave like bulk water and act as a lubricant for protein dynamics. In contrast, water molecules in the minimal hydration state tend to form more hydrogen bonds with the protein, restricting the fluctuation of these water molecules to the level of the protein. Thus, intermolecular interaction and solvent mobility are important to understand the glass-like transition in proteins.     

Asymmetric total synthesis of (+)-phoslactomycin B

(+)-Phoslactomycin B was synthesized by a highly enantio- and stereoselective approach involving asymmetric pentenylation, Suzuki-Miyaura coupling, ring-closing metathesis, asymmetric dihydroxylation, and Stille coupling. The synthetic method developed enables us to synthesize three other isomers concerning the C11-OH and Delta12-double bond.     

C(2) symmetric chiral NHC ligand for asymmetric quaternary carbon constructing copper-catalyzed conjugate addition of grignard reagents to 3-substituted cyclohexenones

The asymmetric construction of quaternary carbon centers by conjugate addition of Grignard reagents to 3-methyl- and 3-ethylcyclohexenones was realized in a maximum enantioselectivity of 80% by using a C 2 symmetric chiral N-heterocyclic carbene (NHC)-copper catalyst, generated from (4 S,5 S)-1,3-bis(2-methoxyphenyl)-4,5-diphenyl-4,5-dihydro-1 H-imidazol-3-ium tetrafluoroborate and copper(II) triflate. The stereostructures of the NHC-Au complexes were analyzed by X-ray crystallography, which rationalized the good stereocontrolling ability of N-aryl NHCs.     

Potentiometry of effective concentration of polyacrylate as scale inhibitor

The concentration of polyacrylate (PA) used as a scale inhibitor was potentiometrically determined with a solid state copper ion-selective electrode after addition of Cu²⁺ as a probe. While the conventional methods monitor only the total concentration of PA, the proposed method measures the free, “effective” concentration of PA in equilibrium with species like Ca²⁺ and CaCO₃. The slope of a potential response to PA was −40 mV decade⁻¹ and the limit of detection was 10^−6.3 M (= mol dm⁻³) at a probe concentration of 10⁻⁶ M. The system could be used to control the PA concentration just enough to prevent the scale formation in various circulating water systems.     

Asymmetric aziridination of cyclic enones using chiral diamine catalysts and its application to the total synthesis of (-)-agelastatin A

The asymmetric aziridination of cyclic enones with N-tosyloxycarbamates, using N-neopentyl 1,2-diphenylethylenediamine as a catalyst, and its application to the formal total synthesis of (-)-agelastatin A, using a one-pot silylation-selenylation procedure and the regioselective aziridine-opening by an azide anion as key steps, are described.     

Multicolor saccharide-sensing chips based on boronic acid-containing thin films showing stepwise release and binding of dyes

A novel saccharide sensor that shows a distinct color change resembling a "traffic signal" was developed. By copolymerizing a boronic acid monomer and an amine monomer on a glass plate, a boronic acid-containing thin film was obtained. After adsorbing anionic blue and yellow dyes, the thin film was immersed in aqueous saccharide solutions containing a cationic red dye. As saccharide concentration increased, the thin film changed its color from green to red via yellow. Origin of the distinct color change was attributed to a stepwise release and binding of dyes.     

Asymmetric palladium-catalyzed hydroarylation of styrenes and dienes

Alkenes are desirable and highly versatile starting materials for organic transformations, and well-known substrates for palladium catalysis. Typically, these reactions result in the formation of a new alkene product via β-hydride elimination. In contrast to this scenario, our laboratory has been involved in the development of alkene hydro- and difunctionalization reactions, where β-hydride elimination can be controlled. We report herein the development of an asymmetric palladium-catalyzed hydroarylation, which yields diarylmethine products in up to 75% ee. Interestingly, a linear free energy relationship is observed between the steric bulk of the ligand within a certain range and the ee of the reaction.     

Evaluation of molecular spin-orbit integrals by a gaussian expansion method

A method is presented for the evaluation of molecular multi-centre spin-orbit integrals of Coulomb, hybrid and exchange types using cartesian gaussian functions. It is shown that if gaussian bases are employed the spin-same-orbit integrals reduce to one-electron field integrals and the spin-other-orbit integrals to two-electron field integrals. The final formulae for these integrals are found to be convenient for computer programming. Some relationships among the nuclear attraction, the field and the field-gradient integrals as well as among the electronic repulsion, the two-electron field, and the zero-field splitting integrals are discussed in connection with the spin-orbit integrals. Some calculations are carried out for the radicals CH₂ and NH.