Gadolinium oxysulfide nanoparticles as multimodal imaging agents for T2-weighted MR, X-ray tomography and photoluminescence

We have synthesized gadolinium oxysulfide nanoparticles (NPs) doped with other lanthanides (Eu(3+), Er(3+), Yb(3+)) via a hydroxycarbonate precursor precipitation route followed by a sulfuration process under a H2S-Ar atmosphere at 750 °C in order to propose new multimodal nanoplatforms for Magnetic Resonance (MR), X-ray and photoluminescence imaging. Gd2O2S:Eu(3+) NPs strongly absorb near UV (≈ 300-400 nm) and re-emit strong red light (624 nm). They can be easily internalized by cancer cells, and imaged by epifluorescence microscopy under excitation in the NUV (365 nm). They are not cytotoxic for living cells up to 100 μg mL(-1). Consequently, they are well adapted for in vitro imaging on cell cultures. Gd2O2S:Eu(3+) NPs also show strong transverse relaxivity and strong X-ray absorption allowing their use as contrast agents for T2-weighted MRI and X-ray tomography. Our study shows that Gd2O2S:Eu(3+) NPs are considerably better than commercial Ferumoxtran-10 NPs as negative contrast agents for MRI. Upconversion emission of Gd2O2S:Er; Yb (1; 8%) NPs under infrared excitation (λ(ex) = 980 nm) shows mainly red emission (≈ 650-680 nm). Consequently, they are more specifically designed for in vivo deep fluorescence imaging, because both excitation and emission are located inside the "transparency window" of biological tissues (650-1200 nm). Magnetic relaxivity and X-ray absorption behaviors of Gd2O2S:Er; Yb NPs are almost similar to Gd2O2S:Eu(3+) NPs.

DNA polymerase theta up-regulation is associated with poor survival in breast cancer, perturbs DNA replication, and promotes genetic instability

"Replicative stress" is one of the main factors underlying neoplasia from its early stages. Genes involved in DNA synthesis may therefore represent an underexplored source of potential prognostic markers for cancer. To this aim, we generated gene expression profiles from two independent cohorts (France, n=206; United Kingdom, n=117) of patients with previously untreated primary breast cancers. We report here that among the 13 human nuclear DNA polymerase genes, DNA Polymerase (POLQ) is the only one significantly up-regulated in breast cancer compared with normal breast tissues. Importantly, POLQ up-regulation significantly correlates with poor clinical outcome (4.3-fold increased risk of death in patients with high POLQ expression), and this correlation is independent of Cyclin E expression or the number of positive nodes, which are currently considered as markers for poor outcome. POLQ expression provides thus an additional indicator for the survival outcome of patients with high Cyclin E tumor expression or high number of positive lymph nodes. Furthermore, to decipher the molecular consequences of POLQ up-regulation in breast cancer, we generated human MRC5-SV cell lines that stably overexpress POLQ. Strong POLQ expression was directly associated with defective DNA replication fork progression and chromosomal damage. Therefore, POLQ overexpression may be a promising genetic instability and prognostic marker for breast cancer.

Ligand binding but undetected functional response of FcR after their capture by T cells via trogocytosis

Intercellular transfer of cell surface proteins by trogocytosis is common and could affect T cell responses. Yet, the role of trogocytosis in T cell function is still elusive, and it is unknown whether a molecule, once captured by T cells, harbors the same biological properties as in donor APC. In this study, we showed that FcgammaR as well as the associated FcRgamma subunit could be detected at high levels on murine and human T cells after their intercellular transfer from FcgammaR-expressing APC. Capture of FcgammaR occurred during coculture of T cells with FcgammaR-expressing APC upon Ab- or Ag-mediated T cell stimulation. Once captured by T cells, FcgammaR were expressed in a conformation compatible with physiological function and conferred upon T cells the ability to bind immune complexes and to provision B cells with this source of Ag. However, we were unable to detect downstream signal or signaling-dependent function following the stimulation of FcgammaR captured by T cells, and biochemical studies suggested the improper integration of FcgammaR in the recipient T cell membrane. Thus, our study demonstrates that T cells capture FcgammaR that can efficiently exert ligand-binding activity, which, per se, could have functional consequences in T cell-B cell cooperation.

Design of an improved set of oligonucleotide primers for genotyping MeCP2tm1.1Bird KO mice by PCR

BACKGROUND

The strain of MeCP2tm1.1Bird mice is a broadly used model for Rett syndrome. Because males carrying the invalidated MeCP2 locus are sterile, this strain has to be maintained in a heterozygous state. All animals therefore have to be genotyped at every generation to discriminate those carrying the invalidated allele (+/- females and y/- males) from those that do not. This is conveniently carried out by PCR on tail genomic DNA but because the primer pairs described initially for this purpose yield very similar size DNA bands on the WT and the KO alleles, this requires to carry out two independent PCR reactions on tail DNA preparations from all animals.

RESULTS

After cloning and sequencing the PCR fragment amplified on the KO allele, we tested several sets of primers that were designed to yield PCR fragments of different sizes on the KO and WT alleles.

CONCLUSION

We have thus identified a set of three primers that allows for efficient genotyping of the animals by a single PCR reaction. Furthermore, using of this set of primers also resolves a recurrent problem related to the tendency of one of the initial primers to give rise to a non specific band because of its capacity to anneal at both ends of a repeated genomic element which we have identified as MurvyLTR.