miR-28-based combination therapy impairs aggressive B cell lymphoma growth by rewiring DNA replication.

Diffuse large B cell lymphoma (DLBCL) is the most common aggressive B cell lymphoma and accounts for nearly 40% of cases of B cell non-Hodgkin lymphoma. DLBCL is generally treated with R-CHOP chemotherapy, but many patients do not respond or relapse after treatment. Here, we analyzed the therapeutic potential of the tumor suppressor microRNA-28 (miR-28) for DLBCL, alone and in combination with the Bruton's tyrosine kinase inhibitor ibrutinib. Combination therapy with miR-28 plus ibrutinib potentiated the anti-tumor effects of monotherapy with either agent by inducing a specific transcriptional cell-cycle arrest program that impairs DNA replication. The molecular actions of miR-28 and ibrutinib synergistically impair DNA replication by simultaneous inhibition of origin activation and fork progression. Moreover, we found that downregulation of the miR-28-plus-ibrutinib gene signature correlates with better survival of ABC-DLBCL patients. These results provide evidence for the effectiveness of a new miRNA-based ibrutinib combination therapy for DLBCL and unveil the miR-28-plus-ibrutinib gene signature as a new predictor of outcome in ABC-DLBCL patients.

Covalently Labeled Fluorescent Exosomes for In Vitro and In Vivo Applications.

The vertiginous increase in the use of extracellular vesicles and especially exosomes for therapeutic applications highlights the necessity of advanced techniques for gaining a deeper knowledge of their pharmacological properties. Herein, we report a novel chemical approach for the robust attachment of commercial fluorescent dyes to the exosome surface with covalent binding. The applicability of the methodology was tested on milk and cancer cell-derived exosomes (from U87 and B16F10 cancer cells). We demonstrated that fluorescent labeling did not modify the original physicochemical properties of exosomes. We tested this nanoprobe in cell cultures and healthy mice to validate its use for in vitro and in vivo applications. We confirmed that these fluorescently labeled exosomes could be successfully visualized with optical imaging.

Interplay between UNG and AID governs intratumoral heterogeneity in mature B cell lymphoma.

Most B cell lymphomas originate from B cells that have germinal center (GC) experience and bear chromosome translocations and numerous point mutations. GC B cells remodel their immunoglobulin (Ig) genes by somatic hypermutation (SHM) and class switch recombination (CSR) in their Ig genes. Activation Induced Deaminase (AID) initiates CSR and SHM by generating U:G mismatches on Ig DNA that can then be processed by Uracyl-N-glycosylase (UNG). AID promotes collateral damage in the form of chromosome translocations and off-target SHM, however, the exact contribution of AID activity to lymphoma generation and progression is not completely understood. Here we show using a conditional knock-in strategy that AID supra-activity alone is not sufficient to generate B cell transformation. In contrast, in the absence of UNG, AID supra-expression increases SHM and promotes lymphoma. Whole exome sequencing revealed that AID heavily contributes to lymphoma SHM, promoting subclonal variability and a wider range of oncogenic variants. Thus, our data provide direct evidence that UNG is a brake to AID-induced intratumoral heterogeneity and evolution of B cell lymphoma.

CD69 Deficiency Enhances the Host Response to Vaccinia Virus Infection through Altered NK Cell Homeostasis.

UNLABELLED: During the host response to viral infection, the transmembrane CD69 protein is highly upregulated in all immune cells. We have studied the role of CD69 in the murine immune response to vaccinia virus (VACV) infection, and we report that the absence of CD69 enhances protection against VACV at both short and long times postinfection in immunocompetent and immunodeficient mice. Natural killer (NK) cells were implicated in the increased infection control, since the differences were greatly diminished when NK cells were depleted. This role of NK cells was not based on an altered NK cell reactivity, since CD69 did not affect the NK cell activation threshold in response to major histocompatibility complex class I NK cell targets or protein kinase C activation. Instead, NK cell numbers were increased in the spleen and peritoneum of CD69-deficient infected mice. That was not just secondary to better infection control in CD69-deficient mice, since NK cell numbers in the spleens and the blood of uninfected CD69(-/-) mice were already augmented. CD69-deficient NK cells from infected mice did not have an altered proliferation capacity. However, a lower spontaneous cell death rate was observed for CD69(-/-) lymphocytes. Thus, our results suggest that CD69 limits the innate immune response to VACV infection at least in part through cell homeostatic survival. IMPORTANCE: We show that increased natural killer (NK) cell numbers augment the host response and survival after infection with vaccinia virus. This phenotype is found in the absence of CD69 in immunocompetent and immunodeficient hosts. As part of the innate immune system, NK lymphocytes are activated and participate in the defense against infection. Several studies have focused on the contribution of NK cells to protection against infection with vaccinia virus. In this study, it was demonstrated that the augmented early NK cell response in the absence of CD69 is responsible for the increased protection seen during infection with vaccinia virus even at late times of infection. This work indicates that the CD69 molecule may be a target of therapy to augment the response to poxvirus infection.

Establishment of a Zebrafish Infection Model for the Study of Wild-Type and Recombinant European Sheatfish Virus.

Amphibian-like ranaviruses include pathogens of fish, amphibians, and reptiles that have recently evolved from a fish-infecting ancestor. The molecular determinants of host range and virulence in this group are largely unknown, and currently fish infection models are lacking. We show that European sheatfish virus (ESV) can productively infect zebrafish, causing a lethal pathology, and describe a method for the generation of recombinant ESV, establishing a useful model for the study of fish ranavirus infections.

Targeted disruption of the SUCNR1 metabolic receptor leads to dichotomous effects on obesity.

A number of metabolites have signaling properties by acting through G-protein-coupled receptors. Succinate, a Krebs cycle intermediate, increases after dysregulated energy metabolism and can bind to its cognate receptor succinate receptor 1 (Sucnr1, or GPR91) to activate downstream signaling pathways. We show that Sucnr1 is highly expressed in the white adipose tissue (WAT) compartment of mice and regulates adipose mass and glucose homeostasis. Sucnr1(-/-) mice were generated, and weight gain was monitored under basal and nutritional stress (high-fat diet [HFD]) conditions. On chow diet, Sucnr1(-/-) mice had increased energy expenditure, were lean with a smaller WAT compartment, and had improved glucose buffering. Lipolysis measurements revealed that Sucnr1(-/-) mice were released from succinate-induced inhibition of lipolysis, demonstrating a function of Sucnr1 in adipose tissue. Sucnr1 deletion also protected mice from obesity on HFD, but only during the initial period; at later stages, body weight of HFD-fed Sucnr1(-/-) mice was almost comparable with wild-type (WT) mice, but WAT content was greater. Also, these mice became progressively hyperglycemic and failed to secrete insulin, although pancreas architecture was similar to WT mice. These findings suggest that Sucnr1 is a sensor for dietary energy and raise the interesting possibility that protocols to modulate Sucnr1 might have therapeutic utility in the setting of obesity.

Bmi1 is critical to prevent Ikaros-mediated lymphoid priming in hematopoietic stem cells.

Preservation of hematopoietic hierarchy requires a constant and reciprocal interplay between chromatin-specific epigenetic regulators and lineage-modifying transcription factors. The polycomb member Bmi1 is a key factor in hematopoietic stem cell (HSC) maintenance, but its specific physiological role in subsequent hematopoietic lineage-specific commitments is unclear. Here, we generated conditional Bmi1 knockout (Bmi1-KO) mice. Selective ablation of Bmi1 in the hematopoietic system induced extensive upregulation of Ikaros and concomitant Ikaros-dependent lymphoid-lineage transcriptional priming, which is marked by their loss of H2A ubiquitination and increased H3K4 trimethylation in Bmi1-KO long-term HSCs (LT-HSCs). Removal of Ikaros in Bmi1-null LT-HSCs significantly diminished the hematopoietic defects seen in conditional Bmi1-KO mice. These alterations resulted in recovering the Bmi1-KO exhausted quiescent stem-cell pool, whereas the block in Bmi1-KO lymphoid-progenitor differentiation was rescued, allowing the development of mature lymphoid cells. Together, our results indicate that Ikaros is a critical Bmi1 target in vivo that prevents premature lineage specification of HSCs.

[Brain and consciousness]. / El cerebro y la conciencia.

The philosophical and biological concepts of consciousness are briefly reviewed, from Aristoteles to Descartes to the modern neurobiologist of the last 15 years. The CRICK's corticothalamic integration view, the Edelman's primary and higher order consciousness concept as well as the Edelman and Tononi's dynamic core concept were discussed. Then the corticothalamic resonance theory by Llinás was reported. Central to Llinás's theory is the existence of electrical intrinsic properties of neurones in the central nervous system that allows them to oscillate at different frequencies and if the membrane properties are suitable also to resonate at specific frequencies. From this oscillation and the neuronal connectivity result the corticothalamic dynamic loops specific and non specific. The dynamic corticothalamic loop of the specific thalamic nuclei connect directly as well as through the inhibitory interneurones in layer 4, with the pyramids in layer 5 and 6. The pyramids's rhythmic discharge excite the thalamic specific neurones and indirectly through the reticular neurones a rebound burst is also generated in the specific relay neurones. The oscillatory properties of cortical inhibitory interneurones initiates the action of the recurrent circuit whose function is to inform the cerebral cortex of the content of the sensory pathways. On the other side, the thalamocortical resonant loops of the non especific nuclei, particularly the intralaminar, connect with theapical dendrites of layer 1 pyramids whose discharge go to the thalamic relay neurones directly and through the reticular nucleus. The clinical and MEG data are consistent with the suggestion that the intralaminar nucleus works as providing the binding signal to the sensory specif le information conveyed by the specific pathways. In this way the non specific corticothalamic loop would act as the conjunction mechanism along the dendritic apical shaft with the specific sensory information. The specific loop will give the content and the non specific loop the context. Conciousness would be the final result of the summation of specific and non specific 40 Hz activity conveyed by the resonant corticothalamic loops.