Ku70/Ku80 and DNA-dependent protein kinase catalytic subunit modulate RAG-mediated cleavage: implications for the enforcement of the 12/23 rule

The 12/23 rule is a critical step for regulation of V(D)J recombination. To date, only the RAG proteins and high mobility group protein 1 or 2 have been implicated in 12/23 regulation. Through protein fractionation and biochemical experiments, we find that Ku70/Ku80 and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) modulate RAG-mediated cleavage. Modulation of cleavage by Ku70/80 and DNA-PKcs results in preferential inhibition of 12/12 and 23/23 DNA cleavage, thus increasing 12/23 rule specificity. This observation indicates that DNA repair factors, Ku70/80 and DNA-PKcs, might be present upstream of the DNA cleavage events and not recruited downstream as is currently thought, assigning new nonrepair functions to the DNA-dependent protein kinase.     

Where do we stand now? Mouse early embryo patterning meeting in Freiburg, Germany (2005)

Mechanism underlying mammalian preimplantation development has long been a subject of controversy and the central question has been if any "determinants" play a key role in a manner comparable to the non-mammalian "model" system. During the last decade, this issue has been revived (Pearson, 2002; Rossant and Tam, 2004) by claims that the axes of the mouse blastocyst are anticipated at the egg ("prepatterning model"; Gardner, 1997; Gardner, 2001; Piotrowska et al., 2001; Piotrowska and Zernicka-Goetz, 2001; Zernicka-Goetz, 2005), suggesting that a mechanism comparable to that operating in non-mammals may be at work. However, recent studies by other laboratories do not support these claims ("regulative model"; Alarcon and Marikawa, 2003; Chroscicka et al., 2004; Hiiragi and Solter, 2004; Alarcon and Marikawa, 2005; Louvet-Vallee et al., 2005; Motosugi et al., 2005) and the issue is currently under hot debate (Vogel, 2005). Deepening our knowledge of this issue will not only provide an essential basis for understanding mammalian development, but also directly apply to ongoing clinical practices such as intracytoplasmic sperm injection (ICSI) and preimplantation genetic diagnosis (PGD). These practices were originally supported by a classical premise that mammalian preimplantation embryos are highly regulative (Tarkowski, 1959; Tarkowski, 1961; Tarkowski and Wroblewska, 1967; Rossant, 1976), in keeping with the "regulative model". However, if the "prepatterning model" is correct, the latter will require critical reassessment.     

T-cell antigen-receptor stoichiometry: pre-clustering for sensitivity

The T-cell antigen receptor (TCR x CD3) is a multi-subunit complex that is responsible for triggering an adaptive immune response. It shows high specificity and sensitivity, while having a low affinity for the ligand. Furthermore, T cells respond to antigen over a wide concentration range. The stoichiometry and architecture of TCR x CD3 in the membrane have been under intense scrutiny because they might be the key to explaining its paradoxical properties. This review highlights new evidence that TCR x CD3 is found on intact unstimulated T cells in a monovalent form (one ligand-binding site per receptor) as well as in several distinct multivalent forms. This is in contrast to the TCR x CD3 stoichiometries determined by several biochemical means; however, these data can be explained by the effects of different detergents on the integrity of the receptor. Here, we discuss a model in which the multivalent receptors are important for the detection of low concentrations of ligand and therefore confer sensitivity, whereas the co-expressed monovalent TCR x CD3s allow a wide dynamic range.     

Oral health related quality of life of edentulous patients after denture relining with a silicone-based soft liner

doi: 10.1111/j.1741‐2358.2011.00503.x Oral health related quality of life of edentulous patients after denture relining with a silicone‐based soft liner Background: Knowledge of benefits caused by a treatment on quality of life is very relevant. Despite the wide use and acceptance of soft denture liners, it is necessary to evaluate the patient’s response about the use of these materials with regard to improvement in oral health related quality of life (OHRQoL). Objectives: The aim of this study was to evaluate the influence of denture relining in the OHRQoL of edentulous patients. Materials and methods: Thirty‐two complete denture wearers had their lower dentures relined with a silicone‐based material (Mucopren soft, Kettenbach, Germany) according to chairside procedures. OHRQoL was assessed before and after 3 months of relining by means of OHIP‐EDENT, and the median scores were compared by Wilcoxon test (p ≤ 0.05). Results: After 3 months of relining, participants reported significant improvement of their OHRQoL (p ≤ 0.01). Conclusion: Denture relining with a soft liner may have a positive impact on the perceived oral health of edentulous patients.     

End-binding protein 1 controls signal propagation from the T cell receptor

The role of microtubules (MTs) in the control and dynamics of the immune synapse (IS) remains unresolved. Here, we show that T cell activation requires the growth of MTs mediated by the plus-end specific protein end-binding 1 (EB1). A direct interaction of the T cell receptor (TCR) complex with EB1 provides the molecular basis for EB1 activity promoting TCR encounter with signalling vesicles at the IS. EB1 knockdown alters TCR dynamics at the IS and prevents propagation of the TCR activation signal to LAT, thus inhibiting activation of PLCγ1 and its localization to the IS. These results identify a role for EB1 interaction with the TCR in controlling TCR sorting and its connection with the LAT/PLCγ1 signalosome.     

Genome sequences of the ethanol-tolerant Lactobacillus vini strains LMG 23202T and JP7.8.9

We report on the genome sequences of Lactobacillus vini type strain LMG 23202(T) (DSM 20605) (isolated from fermenting grape musts in Spain) and the industrial strain L. vini JP7.8.9 (isolated from a bioethanol plant in northeast Brazil). All contigs were assembled using gsAssembler, and genes were predicted and annotated using Rapid Annotation using Subsystem Technology (RAST). The identified genome sequence of LMG 23202(T) had 2.201.333 bp, 37.6% G+C, and 1,833 genes, whereas the identified genome sequence of JP7.8.9 had 2.301.037 bp, 37.8% G+C, and 1,739 genes. The gene repertoire of the species L. vini offers promising opportunities for biotechnological applications.     

Potentiation of BCNU cytotoxicity by molecules targeting abasic lesions in DNA.

We describe the synthesis, DNA binding measurements and pharmacological properties of a series of new heterodimeric molecules, in which a 2,6-diaminopurine is linked to a 9-aminoacridine chromophore. The linking chain contains a central N,N'-disubstituted guanidine, connected to the two chromophores by polymethylenic units of variable length.     

Abnormal T cells from MRL/Mp-lpr/lpr mice do not respond to anti-T-cell-receptor antibody or tumor promoter and calcium ionophore A23187 despite the presence of the T-cell-receptor complex and protein kinase c

Abnormal T cells from autoimmune MRL/Mp-lpr/lpr mice express T-cell-receptor complexes on their surfaces. These receptors are nonfunctional, since monoclonal anti-T-cell-receptor antibody-conjugated beads, which normally activate receptor-bearing T cells, were unable to activate these abnormal T cells. In addition, these abnormal T cells are unresponsive to the synergistic effect of phorbolmyristate acetate (PMA) and calcium ionophore A23187, as quantitated by proliferation, interleukin-2(IL-2) production, and the expression of IL-2 receptors. The failure of abnormal T cells to respond to PMA is not due to the absence of PMA receptors since Scatchard plot analysis reveals that there are 1-1.5 X 10(5) PMA-binding sites/cell with a Kd of 6-10 nM on these abnormal T cells. Similar to normal T lymphocytes, protein kinase c activity can be readily detected in the cytosolic fraction of these abnormal T cells. More importantly, in vitro culture of the abnormal T cells with PMA results in translocation of protein kinase c activity from the cytosolic fraction to the membrane fraction. From these experiments we concluded that the defect in the signal-transducing machinery in MRL/Mp-lpr/lpr T cells is not due to the lack of PMA receptors or the absence of protein kinase c activity, but may result from events which occur after the activation and translocation of protein kinase c. However, whether defects in response to a physiological stimulus (i.e., anti-receptor antibody) could occur in a step prior to protein kinase c activation remains to be determined.