In silico strategy to design an efficient organic photoswitch based on excited-state cation transfer

A new class of photoswitches and the corresponding elementary photoinduced reaction, the so-called Excited-State Cation Transfer (ESCT), are investigated. This reaction relies on an intramolecular photo-release/photo-complexation of cation: after irradiation, the cation is translocated from a complexation site 1 to a site 2 during the excited state lifetime. Our purpose is thus to develop a computational strategy based on Density Functional theory (DFT) and its time-dependent counterpart (TD-DFT) to improve the different properties of the ESCT photoswitches, namely (i) the ground state complexation constant K, (ii) the excited state complexation constant K*, (iii) the photoejection properties and (iv) the population of the triplet states from a singlet state via intersystem crossing to increase the lifetime of the excited state. In this work, we are interested in optimizing the ESCT properties of a betaine pyridinium chromophore substituted by a 15-aza-5-crown, that was previously shown to efficiently photoeject a Ca2+ cation from the site 1 but no photo-recapture was observed in the site 2 [Aloïse et al., Phys. Chem. Chem. Phys., 2016, 22, 15384]. To this purpose, we have investigated the impact of the modification of the site 1 on the ESCT properties by introducing different substituents (EDG groups, halogen atoms) at different positions. So far, promising systems have been identified but a simultaneous improvement of all the ESCT photoswitches properties has yet not been achieved.

Father's perceptions and care involvement for their very preterm infants at French neonatal intensive care units

Objectives

We aimed to evaluate (1) fathers' perceptions and care involvement for their very premature infants and their views of the hospitalization period based on parental reports and (2) their evolution over time.

Methods

We used an online parental survey to assess answers from parents of very preterm infants who were successfully discharged from French neonatal units. We analysed answers from February 2014 to January 2019 to an anonymous internet-based survey from the GREEN committee of the French Neonatal Society. Responses were compared for period 1 (P1, 1998 to 2013) and period 2 (P2, 2014 to 2019).

Results

We analyzed 2,483 surveys, 124 (5%) from fathers and 2,359 (95%) from mothers. At birth, 1,845 (80%) fathers were present in the hospital, but only 879 (38%) were near the mother. The presence of fathers in the NICU increased from P1 to P2 (34.5% vs. 43.1%, p = 0.03). Nearly two thirds of fathers accompanied their infants during transfer to the NICU (1,204 fathers, 60.6%). Fathers and mothers had similar perceptions regarding relationships with caregivers and skin-to-skin contact with their infants. However, more fathers than mothers felt welcome in the NICU and in care involvement regarding requests for their wishes when they met their infant (79% vs. 60%, p = 0.02) and in the presentation of the NICU (91% vs. 76%; p = 0.03). Mothers and fathers significantly differed in the caring procedures they performed (p = 0.01), procedures they did not perform but wanted to perform (p < 0.001), and procedures they did not perform and did not want to perform (p < 0.01).

Conclusion

Most fathers were present at the births of their very preterm infants, but fewer fathers were near the mother at this time. Less than two thirds of fathers accompanied their infants to the NICU. There should be further changes to better meet the specific needs of the fathers of infants requiring care in the NICU. Continuing assessment with an online questionnaire may be useful to monitor changes over time in father's involvement in NICUs.

A Highly Sensitive and Selective Optical Sensor for the On-Line Detection of Cesium in Water

In this study, we have undertaken the development of two fluorescent sensors based on calixarene compounds for the purpose of detecting cesium in water. By introducing the sulfonate functional groups, we have considerably improved the water solubility of sensors, enabling complete dissolution of products in aqueous media and direct analysis of polluted water samples. Through rigorous experiments, we have demonstrated that the complexation of Cs+ ions with sensors 1 and 2 in water leads to a remarkable enhancement of fluorescence. This fluorescence enhancement serves as a reliable indication of cesium presence and allows for sensitive detection. To further advance the practical application of our sensors, we have successfully integrated calixarene sensors 1 and 2 into a microfluidic sensor chip. This integration has enabled real-time, on-line measurements and has resulted in the development of a portable detection device capable of detecting cesium ions in water samples at parts per billion (ppb) levels. This device holds great promise for environmental monitoring and assessment, providing a convenient and efficient solution for cesium detection. Our work represents a significant advancement in the field of cesium detection, displaying the efficacy of calixarene-based fluorescent sensors and their integration into microfluidic systems. The enhanced water solubility, fluorescence response, and portability of our detection device offers tremendous potential for applications in environmental monitoring, water quality assessment, and emergency response scenarios where rapid and accurate cesium detection is crucial.

Excess of guide RNA reduces knockin efficiency and drastically increases on-target large deletions

CRISPR-Cas9 cleavage efficacy and accuracy are the main challenges gene editing faces, and they are particularly affected by the optimal formation of the ribonucleoprotein (RNP) complex. We used nano differential scanning fluorimetry, a label and immobilization-free assay, to demonstrate that an equimolar ratio of Cas9 and guide RNA (gRNA) is optimal for RNP complex formation. We almost achieved 50% of green fluorescent protein (GFP) to blue fluorescent protein (BFP) conversion using a biallelic homozygous GFP human induced pluripotent stem cell line, when 0.4 μM of Cas9, equimolar Cas9/gRNA ratio and 2 μM of single-stranded oligonucleotide, were used and showed that increasing Cas9/gRNA ratio did not further improve KI efficiency. Additionally, excess gRNA decreased point mutation KI efficiency in rat embryos and drastically increased the occurrence of on-target large deletions. These findings highlight the importance of CRISPR/Cas9 stoichiometric optimization to ensure efficient and accurate KI generation, which will be applicable to other in vitro as well as in vivo models.

CBP-HSF2 structural and functional interplay in Rubinstein-Taybi neurodevelopmental disorder

Patients carrying autosomal dominant mutations in the histone/lysine acetyl transferases CBP or EP300 develop a neurodevelopmental disorder: Rubinstein-Taybi syndrome (RSTS). The biological pathways underlying these neurodevelopmental defects remain elusive. Here, we unravel the contribution of a stress-responsive pathway to RSTS. We characterize the structural and functional interaction between CBP/EP300 and heat-shock factor 2 (HSF2), a tuner of brain cortical development and major player in prenatal stress responses in the neocortex: CBP/EP300 acetylates HSF2, leading to the stabilization of the HSF2 protein. Consequently, RSTS patient-derived primary cells show decreased levels of HSF2 and HSF2-dependent alteration in their repertoire of molecular chaperones and stress response. Moreover, we unravel a CBP/EP300-HSF2-N-cadherin cascade that is also active in neurodevelopmental contexts, and show that its deregulation disturbs neuroepithelial integrity in 2D and 3D organoid models of cerebral development, generated from RSTS patient-derived iPSC cells, providing a molecular reading key for this complex pathology.

Unravelling the true MOF-5 luminescence

Highly pure millimeter-sized MOF-5 single crystals were synthesized and characterized. Photoluminescence (PL) spectroscopy and time-correlated single photon counting (TCSPC) demonstrate a solvent-guest dependency of MOF-5 emission and its ligand-centred nature. These results allow measuring the true MOF-5 luminescence free of solvent at a wavelength of 355 nm, a significantly lower wavelength than previously published. MOF-5 emission was also evaluated with different solvents and various degrees of water intake, explaining previously published observations. Comparison between lifetimes shows the fluorophore stabilization within the frameworks and demonstrates the progressive influence of the Zn₄O subunits on the fluorescence during hydration. Overall, this work highlights the necessity to obtain phase-pure material, especially when moisture sensitivity can play a role, before ascribing electronic transitions. This study is a rigorous new take on the iconic MOF-5 and on its photoluminescence properties.

This study provides a rigorous analysis of MOF-5 fluorescence, unifying previously dissimilar results. Pure MOF-5 fluorescence was identified as only ligand centered and the rise of other mode of emission were observed when exposed to humidity.

IL-15Rα membrane anchorage in either cis or trans is required for stabilization of IL-15 and optimal signaling

Interleukin (IL)-15 plays an important role in the communication between immune cells. It delivers its signal through different modes involving three receptor chains: IL-15Rα, IL-2Rβ and IL-2Rγc. The combination of the different chains result in the formation of IL-15Rα/IL-2Rβ/γc trimeric or IL-2Rβ/γc dimeric receptors. In this study, we have investigated the role of the IL-15Rα chain in stabilizing the cytokine in the IL-2Rβ/γc dimeric receptor. By analyzing the key amino acid residues of IL-15 facing IL-2Rβ, we provide evidence of differential interfaces in the presence or in the absence of membrane-anchored IL-15Rα. Moreover, we found that the anchorage of IL-15Rα to the cell surface regardless its mode of presentation - i.e. cis or trans - is crucial for complete signaling. These observations show how the cells can finely modulate the intensity of cytokine signaling through the quality and the level of expression of the receptor chains.

Impact of the number of electric pulses on cell electrochemotherapy in vitro: Limits of linearity and saturation

In this study the evolution in the efficiency of electrochemotherapy (reversible electroporation) with pulse number was assessed in vitro. Experiments were performed using 100 μs pulses at different electric field intensities and the chemotherapeutic agent bleomycin. Additionally, electrical impedance spectroscopy measurements were used as a different method to study in real time the changes produced on cells with pulse number during trains of consecutive pulses. Our results show that the relation between pulse number and the observed outcome is complex and difficult to fully characterize. This relation can display a highly linear behaviour up to a certain number of pulses and/or field intensity applied. However, the relation between the number of pulses and the observed outcome always evolves to a saturation or at least a reduction in the electric field effects that is displayed when either electric field intensity or pulse number are increased. An exponential model was found to best describe this relation within the range of experimental conditions considered. Electrical impedance measurements confirmed the results and gave a more precise quantification of this dependence. The study highlights the importance that pulse number has in the electrochemotherapy protocols and establishes some limits in the use of this parameter.

Water-soluble aluminium fluorescent sensor based on aggregation-induced emission enhancement

Development of a portable miniature system for Al(iii) detection in pure aqueous solutions using a novel AIEE compound.

Emergence of NK Cell Hyporesponsiveness after Two IL-15 Stimulation Cycles

IL-15 is a cytokine playing a crucial role in the function of immune cells, including NK and CD8 T cells. In this study, we demonstrated that in vivo, in mice, IL-15-prestimulated NK cells were no longer able to respond to a second cycle of IL-15 stimulation. This was illustrated by defects in cell maturation, proliferation, and activation, seemingly linked to the environment surrounding NK cells but not related to the presence of CD4 regulatory T cells, TGF-β, or IL-10. Moreover, NK cells from immunodeficient mice could respond to two cycles of IL-15 stimulation, whereas an adoptive transfer of CD44⁺CD8⁺ cells impaired their responsiveness to the second cycle. Conversely, in immunocompetent mice, NK cell responsiveness to a second IL-15 stimulation was restored by the depletion of CD8⁺ cells. These biological findings refine our understanding of the complex mode of action of NK cells in vivo, and they should be taken into consideration for IL-15-based therapy.

Synthesis and photophysical properties of extended π conjugated naphthalimides

A series of π conjugated naphthalimide derivatives having an imide group as an acceptor conjugated with a methoxy arylethynyl or a methoxyphenyl triazole as a donor were prepared by Sonogashira coupling or "click" chemistry. Their photophysical properties were investigated by steady state and time resolved fluorescence spectroscopy and modelled by TD-DFT calculations. Compound Naphth-AlkyneOMe has a high fluorescence quantum yield and displays efficient photoinduced charge transfer in solution as well as in the powder state. Compound Naphth-TriazoleOMe exhibits a very high Stokes shift and its fluorescence quantum yield is low, which can be rationalized by theoretical calculations.

Structurally related odorant ligands of the olfactory receptor OR51E2 differentially promote metastasis emergence and tumor growth

Olfactory receptors are G protein-coupled receptors. Some of them are expressed in tumor cells, such as the OR51E2 receptor overexpressed in LNCaP prostate cancer cells. It is considered a prostate tumor marker. We previously demonstrated that this receptor is able to promote LNCaP cell invasiveness in vitro upon stimulation with its odorant agonist β-ionone, leading to increased generation of metastases in vivo. In the present study, we show that even a relatively short exposure to β-ionone is sufficient to promote metastasis emergence. Moreover, α-ionone, considered an OR51E2 antagonist, in fact promotes prostate tumor growth in vivo. The combination of α-ionone with β-ionone triggers a higher increase in the total tumor burden than each molecule alone. To support the in vivo results, we demonstrate in vitro that α-ionone is a real agonist of OR51E2, mainly sustaining LNCaP cell growth, while β-ionone mainly promotes cell invasiveness. So, while structurally close, α-ionone and β-ionone appear to induce different cellular effects, both leading to increased tumor aggressiveness. This behaviour could be explained by a different coupling to downstream effectors, as it has been reported for the so-called biased ligands of other G protein-coupled receptors.

Gallein, a Gβγ subunit signalling inhibitor, inhibits metastatic spread of tumour cells expressing OR51E2 and exposed to its odorant ligand

Objective

We previously reported that the olfactory receptor OR51E2, overexpressed in LNCaP prostate cancer cells, promotes cell invasiveness upon stimulation of its agonist β-ionone, and this phenomenon increases metastatic spread. Furthermore, we showed that the induced cell invasiveness involves a PI3 kinase dependent signalling pathway. We report here the results of a new investigation to address whether gallein, a small inhibitor of G protein βγ subunit interaction with PI3 kinase, can inhibit β-ionone effects both in vitro and in vivo.

Results

We demonstrate that gallein can inhibit the β-ionone-induced cell invasiveness in vitro, as well as the spread of metastases in vivo. LNCaP cell invasiveness, assessed using spheroid cultures in collagen gels in vitro, was increased by β-ionone and the effect was reversed by co-administration of gallein. LNCaP tumour cells, subcutaneously inoculated to immunodeficient mice, generated more metastases in vivo when β-ionone was applied through the skin. Furthermore, the intraperitoneal injection of gallein inhibited this increased metastasis spread. Our results thus support the role of OR51E2 in the β-ionone observed effects, and suggest that gallein could be a potential new agent in personalized medicine of the tumours expressing OR51E2.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2879-z) contains supplementary material, which is available to authorized users.

Pyroelectricity as a possible mechanism for cell membrane permeabilization

The effects of pyroelectricity on cell membrane permeability had never been explored. Pyroelectricity consists in the generation of an electric field in the surface of some materials when a change in temperature is produced. In the present study, tourmaline microparticles, which are known to display pyroelectrical properties, were subjected to different changes in temperature upon exposure to cells in order to induce an electric field at their surface. Then, the changes in the permeability of the cell membrane to a cytotoxic agent (bleomycin) were assessed by a cloning efficacy test. An increase in the permeability of the cell membrane was only detected when tourmaline was subjected to a change in temperature. This suggests that the apparition of an induced pyroelectrical electric field on the material could actually be involved in the observed enhancement of the cell membrane permeability as a result of cell electropermeabilization.

Cutting Edge: Differential Fine-Tuning of IL-2- and IL-15-Dependent Functions by Targeting Their Common IL-2/15Rβ/γc Receptor

Interleukin 2 and IL-15 are two closely related cytokines, displaying important functions in the immune system. They share the heterodimeric CD122/CD132 receptor to deliver their signals within target cells. Their specificity of action is conferred by their α receptor chains, IL-2Rα and IL-15Rα. By combining an increased affinity for CD122 and an impaired recruitment of CD132, we have generated an original molecule named IL-2Rβ/γ (CD122/CD132) inhibitor (BiG), targeting the CD122/CD132 receptor. BiG efficiently inhibited IL-15- and IL-2-dependent functions of primary cells, including CD8 T and NK cells, in vitro and in vivo. We also report a differential dynamic of action of these cytokines by highlighting a major role played by the IL-2Rα receptor. Interestingly, due to the presence of IL-2Rα, BiG had no impact on IL-2-dependent regulatory T cell proliferation. Thus, by acting as a fine switch in the immune system, BiG emphasizes the differential roles of these two cytokines.

New sensitive and selective calixarene-based fluorescent sensors for the detection of Cs+ in an organoaqueous medium

A calixarene-based fluorescent sensor has been designed for the detection of Cs⁺ in the micromolar range.

A Highly Selective Potassium Sensor for the Detection of Potassium in Living Tissues

The development of highly selective sensors for potassium is of great interest in biology. Two new hydrosoluble potassium sensors (Calix-COU-Alkyne and Calix-COU-Am) based on a calix[4]arene bis(crown-6) and an extended coumarin were synthesized and characterized. The photophysical properties and complexation studies of these compounds have been investigated and show high molar extinction coefficients and high fluorescence quantum yields. Upon complexation with potassium in the millimolar concentration range, an increase of one- and two-photon fluorescence emission is detected. A twofold fluorescence enhancement is observed upon excitation at λ=405 nm. The ligands present excellent selectivity for potassium in the presence of various competitive cations in water and in a physiological medium. The photophysical properties are not affected by the presence of a large amount of competing cations (Na⁺ , Ca²⁺ , Mg²⁺ , etc.). Ex vivo measurements on mouse hippocampal slices show that Calix-COU-Alkyne accumulates extracellularly and does not alter the neuronal activity. Furthermore, the sensor can be utilized to monitor slow extracellular K⁺ increase induced by inhibition of K⁺ entry into the cells.

Can betaine pyridinium derivatives be used to control the photoejection of cation?

Using a combination of advanced DFT/TDDFT calculations together with ultrafast and stationary spectroscopies we have investigated the photochemistry and cationic complexation ability of 1-pyridinio-benzimidazolate (PyB) and analogs substituted by 15-aza-5-crown (PyB-Aza) or dimethyl-amino groups (PyB-DiMe). Focusing on PyB-Aza, the first aim was to assess the competitive complexation of the imidazole bridge vs. the macrocycle. In acetonitrile, it was found by absorption and emission that the imidazole moiety binds efficiently through lateral electrostatic interaction of high charge density cations and especially Ca(2+) to form a 1 : 1, metal : ligand (M : L) complex. Modulation of the complexation toward para substitution of the phenyl ring with a donor group is reported with values ranging from log K = 3.4 to 6.8. Complexation values are properly predicted by DFT calculations. From a photochemical point of view, for the same series, the trend is parallel to the rate of the photo-release process, found to be less than 200 femtosecond (fs), the fastest photorelease characteristic time reported so far. Unlike photoinduced charge transfer molecules linked with an aza-crown group, the mechanism appears simpler with no participation of loose complexes due to the macrocavity effect. Relaxation mechanisms after cation ejection are discussed as well. Finally, even if any photoinduced translocation of cation is reported for the PyB-Aza molecule between two complexation sites, a discussion about the use of betaine pyridinium as a molecular tool for the smart manipulation of cation systems is initiated.

Cell membrane permeabilization by 12-ns electric pulses: Not a purely dielectric, but a charge-dependent phenomenon

Electric pulses of a few nanoseconds in duration can induce reversible permeabilization of cell membrane and cell death. Whether these effects are caused by ionic or purely dielectric phenomena is still discussed. We address this question by studying the impact of conductivity of the pulsing buffer on the effect of pulses of 12 ns and 3.2 MV/m on the DC-3F mammalian cell line. When pulses were applied in a high-conductivity medium (1.5 S/m), cells experienced both reversible electropermeabilization and cell death. On the contrary, no effect was observed in the low-conductivity medium (0.1 S/m). Possible artifacts due to differences in viscosity, temperature increase or electrochemical reactions were excluded. The influence of conductivity reported here suggests that charges still play a role, even for 12-ns pulses. All theoretical models agree with this experimental observation, since all suggest that only high-conductivity medium can induce a transmembrane voltage high enough to induce pore creation, in turn. However, most models fail to describe why pulse accumulation is experimentally required to observe biological effects. They mostly show no increase of permeabilization with accumulation of pulses. Currently, only one model properly describes pulse accumulation by modeling diffusion of the altered membrane regions.

Ultra-sensitive and selective Hg2+ chemosensors derived from substituted 8-hydroxyquinoline analogues

A mercury concentration of 15 ppt can be selectively detected, in aqueous medium, thanks to a thiophosphinatylated 8-hydroxyquinoline sensor.

Aggregation-induced emission enhancement upon Al3+ complexation with a tetrasulfonated calix[4]bisazacrown fluorescent molecular sensor

A new water-soluble ligand bearing a tetrasulfonated calix[4]arene was constructed for ratiometric detection of Al³⁺ based on an aggregation-induced fluorescence enhancement mechanism.

Synthesis, photophysical, and two-photon absorption properties of elongated phosphane oxide and sulfide derivatives

A series of rod-shaped and related three-branched push-pull derivatives containing phosphane oxide or phosphane sulfide (PO or PS)-as an electron-withdrawing group conjugated to electron-donating groups, such as amino or ether groups, with a conjugated rod consisting of arylene-vinylene or arylene-ethynylene building blocks-were prepared. These compounds were efficiently synthesized by a Grignard reaction followed by Sonogashira coupling. Their photophysical properties including absorption, emission, time-resolved fluorescence, and two-photon absorption (TPA) were investigated with special attention to structure-property relationships. These fluorophores show high fluorescence quantum yields and solvent-dependent experiments reveal that efficient intramolecular charge transfer occurs upon excitation, thereby leading to highly polar excited states, the polarity of which can be significantly enhanced by playing on the end groups and conjugated linker. Rod-shaped and related three-branched systems show similar fluorescence properties in agreement with excitation localization on one of the push-pull branches. By using stronger electron donors or replacing the arylene-ethynylene linkers with an arylene-vinylene one induces significant redshifts of both the low-energy one-photon absorption and TPA bands. Interestingly, a major enhancement in TPA responses is observed, whereas OPA intensities are only weakly affected. Similarly, phosphane oxide derivatives show similar OPA responses than the corresponding sulfides but their TPA responses are significantly larger. Finally, the electronic coupling between dipolar branches promoted by common PO or PS acceptor moieties induces either slight enhancement of the TPA responses or broadening of the TPA band in the near infrared (NIR) region. Such behavior markedly contrasts with triphenylamine-core-mediated coupling, which gives evidence for the different types of interactions between branches.

ATM-dependent expression of IEX-1 controls nuclear accumulation of Mcl-1 and the DNA damage response

The early-response gene product IEX-1 (also known as IER3) was recently found to interact with the anti-apoptotic Bcl-2 family member, myeloid cell leukemia-1 (Mcl-1). In this study we show that this interaction specifically and timely controls the accumulation of Mcl-1 in the nucleus in response to DNA damage. The IEX-1 protein is rapidly induced by γ-irradiation, genotoxic agents or replication inhibitors, in a way dependent on ataxia telangiectasia mutated (ATM) activity and is necessary for Mcl-1 nuclear translocation. Conversely, IEX-1 protein proteasomal degradation triggers the return of Mcl-1 to the cytosol. IEX-1 and Mcl-1 are integral components of the DNA damage response. Loss of IEX-1 or Mcl-1 leads to genomic instability and increased sensitivity to genotoxic and replicative stresses. The two proteins cooperate to maintain Chk1 activation and G2 checkpoint arrest. Mcl-1 nuclear translocation may foster checkpoint and improve the tumor resistance to DNA damage-based cancer therapies. Deciphering the pathways involved in IEX-1 degradation should lead to the discovery of new therapeutic targets to increase sensitivity of tumor cells to chemotherapy.

Fluorimetric lead detection in a microfluidic device

A microfabricated device has been developed for the selective detection of lead in water. It is based on the use of a selective and sensitive fluorescent molecular sensor for lead (Calix-DANS4) which contains a calix[4]arene bearing four dansyl groups. The microchip-based lead sensor contains a Y-shape microchannel equipped with a passive mixer and moulded on a glass substrate. An optimization of the microcircuit length has been performed in order to have a full complexation of the Calix-DANS4. The detection is performed by using a configuration in which the sensing molecules are excited by two optical fibres, each one connected to a 365 nm UV LED, and the light collection is made by another optical fibre with a photomultiplier. By using this configuration we have shown the possibility to detect lead with a detection limit of 5 ppb. The effect of interfering cations such as calcium has been evaluated. The obtained measurements have been validated by an alternative method (ASV).

Microparticle-induced release of B-lymphocyte regulators by rheumatoid synoviocytes

Introduction

In the present study, we investigated the ability of microparticles isolated from synovial fluids from patients with rheumatoid arthritis or osteoarthritis to induce the synthesis and release of key cytokines of B-lymphocyte modulation such as B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor by rheumatoid fibroblast-like synoviocytes.

Methods

Microparticles were analyzed in synovial fluids from patients with rheumatoid arthritis, osteoarthritis, microcristalline arthritis, and reactive arthritis. In addition, microparticle release after activation from various cell lines (CEM lymphocyte and THP-1 cells) was assessed. Microparticles were isolated by differential centrifugation, and quantitative determinations were carried out by prothrombinase assay after capture on immobilized annexin V. B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor release was evaluated by enzyme-linked immunosorbent assay.

Results

Microparticles isolated from synovial fluids obtained from rheumatoid arthritis and osteoarthritis patients or microparticles derived from activated THP-1 cells were able to induce B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor release by rheumatoid arthritis fibroblast-like synoviocytes. Conversely, CEM-lymphocytes-derived microparticles generated by treatment with a combination of PHA, PMA and Adt-D did not promote the release of B cell-activating factor but favored the secretion of thymic stroma lymphopoietin and secretory leukocyte protease inhibitor by rheumatoid arthritis fibrobast-like synoviocytes. However, microparticles isolated from actinomycin D-treated CEM lymphocytes were not able to induce B cell-activating factor, thymic stroma lymphopoietin, or secretory leukocyte protease inhibitor release, indicating that microparticles derived from apoptotic T cells do not function as effectors in B-cell activation.

Conclusions

These results demonstrate that microparticles are signalling structures that may act as specific conveyors in the triggered induction and amplification of autoimmunity. This study also indicates that microparticles have differential effects in the crosstalk between B lymphocytes and target cells of autoimmunity regarding the parental cells from which they derive.

A novel, generic and effective method for the rapid purification of G protein-coupled receptors

G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are of major therapeutic importance. Structure determination of G protein-coupled receptors and other applications require milligram quantities of purified receptor proteins on a regular basis. Recombinant GPCRs fused to a heterologous biotinylation domain were produced in the yeast Pichia pastoris. We describe an efficient method for their rapid purification that relies on the capture of these receptors with streptavidin immobilized on agarose beads, and their subsequent release by enzymatic digestion with TEV protease. This method has been applied to several GPCRs belonging to the class A rhodopsin subfamily, leading to high yields of purified proteins; it represents a method of choice for biochemical and biophysical studies when large quantities of purified GPCRs are needed.

Rhod-5N as a fluorescent molecular sensor of cadmium(II) ion

The photophysical and complexing properties of Rhod-5N (commercially available) in MOPS buffer are reported. This fluorescent molecular sensor consists of a BAPTA chelating moiety bound to a rhodamine fluorophore. Its fluorescence quantum yield is low and a drastic enhancement of fluorescence intensity upon cation binding was observed. Special attention was paid to the complexation with Cd2+, a well known toxic metal ion. Possible interference with other metal ions (Na+, K+, Mg2+, Ca2+, Zn2+, Pb2+) was examined. Rhod-5N was found to be highly selective of Cd2+ over those interfering cations except Pb2+. The limit of detection is 3.1 microg l(-1).