We have used protein engineering to expand the palette of genetically encoded calcium ion (Ca(2+)) indicators to include orange and improved red fluorescent variants, and validated the latter for combined use with optogenetic activation by channelrhodopsin-2 (ChR2). These indicators feature intensiometric signal changes that are 1.7- to 9.7-fold improved relatively to the progenitor Ca(2+) indicator, R-GECO1. In the course of this work, we discovered a photoactivation phenomenon in red fluorescent Ca(2+) indicators that, if not appreciated and accounted for, can cause false-positive artifacts in Ca(2+) imaging traces during optogenetic activation with ChR2. We demonstrate, in both a beta cell line and slice culture of developing mouse neocortex, that these artifacts can be avoided by using an appropriately low intensity of blue light for ChR2 activation.

Neural progenitors exhibit cell cycle-dependent interkinetic nuclear migration (INM) along the apicobasal axis. Despite recent advances in understanding its underlying molecular mechanisms, the processes to which INM contributes mechanically and the regulation of INM by the apicobasally elongated morphology of progenitors remain unclear. We found that knockdown of the cell-surface molecule TAG-1 resulted in retraction of neocortical progenitors' basal processes. Highly shortened stem-like progenitors failed to undergo basalward INM and became overcrowded in the periventricular (subapical) space. Surprisingly, the overcrowded progenitors left the apical surface and migrated into basal neuronal territories. These observations, together with the results of in toto imaging and physical tests, suggest that progenitors may sense and respond to excessive mechanical stress. Although, unexpectedly, the heterotopic progenitors remained stem-like and continued to sequentially produce neurons until the late embryonic period, histogenesis was severely disrupted. Thus, INM is essential for preventing overcrowding of nuclei and their somata, thereby ensuring normal brain histogenesis.

To achieve highly sensitive and comprehensive assessment of the morphology and dynamics of cells committed to the neuronal lineage in mammalian brain primordia, we generated two transgenic mouse lines expressing a destabilized (d4) Venus controlled by regulatory elements of the Neurogenin2 (Neurog2) or Gadd45g gene. In mid-embryonic neocortical walls, expression of Neurog2-d4Venus mostly overlapped with that of Neurog2 protein, with a slightly (1 h) delayed onset. Although Neurog2-d4Venus and Gadd45g-d4Venus mice exhibited very similar labeling patterns in the ventricular zone (VZ), in Gadd45g-d4Venus mice cells could be visualized in more basal areas containing fully differentiated neurons, where Neurog2-d4Venus fluorescence was absent. Time-lapse monitoring revealed that most d4Venus+ cells in the VZ had processes extending to the apical surface; many of these cells eventually retracted their apical process and migrated basally to the subventricular zone, where neurons, as well as the intermediate neurogenic progenitors that undergo terminal neuron-producing division, could be live-monitored by d4Venus fluorescence. Some d4Venus+ VZ cells instead underwent nuclear migration to the apical surface, where they divided to generate two d4Venus+ daughter cells, suggesting that the symmetric terminal division that gives rise to neuron pairs at the apical surface can be reliably live-monitored. Similar lineage-committed cells were observed in other developing neural regions including retina, spinal cord, and cerebellum, as well as in regions of the peripheral nervous system such as dorsal root ganglia. These mouse lines will be useful for elucidating the cellular and molecular mechanisms underlying development of the mammalian nervous system.

Nutritional status is an important component of cancer care, and malnutrition itself can cause death in 10% to 20% of cancer patients. A nutritional risk index (NRI) is a useful tool for nutritional assessment of cancer patients. This study aimed to evaluate the impact of pretransplant NRI values on outcomes of allogeneic hematopoietic cell transplantation (allo-HSCT). One hundred sixty patients who underwent allo-HSCT between January 2008 and July 2017 at Konan Kosei Hospital were included in this single-center, retrospective analysis. NRI was calculated at the beginning of the conditioning regimen. The patients were divided into high NRI (NRI 97.5) and low NRI (NRI < 97.5) groups, and overall survival (OS), nonrelapse mortality (NRM), and cumulative incidences of acute and chronic graft-versus-host disease (GVHD) were evaluated. Two-year OS rates were 76% (95% confidence interval [CI], 63% to 83%) and 50.4% (95% CI, 38% to 62%) in the high NRI and low NRI groups, respectively (P < .001). One-year cumulative incidences of NRM were 7.9% (95% CI, 3.5% to 15%) and 23% (95% CI, 14% to 33%; P = .014) and 2-year cumulative relapse rates were 17% (95% CI, 10% to 26%) and 32% (95% CI, 21% to 43%; P = .10) in the high NRI and low NRI groups, respectively. The multivariate analysis indicated low NRI was a significant risk factor for OS and NRM. Conversely, high NRI was associated with increased incidences of grades II to IV acute GVHD and chronic GVHD. Additionally, the subgroup analysis according to stem cell source revealed a significant benefit of higher NRI on survival only in umbilical cord blood recipients. Overall, these results suggest that pretransplant NRI might predict OS and NRM after allo-HSCT.

Background Viruses must adapt to the environment of their host cells to establish infection and persist. Diverse mammalian cells, including virus-infected cells, release extracellular vesicles such as exosomes containing proteins and miRNAs, and use these vesicles to mediate intercellular communication. However, the roles of exosomes in viral infection remain unclear. Results We screened viral proteins to identify those responsible for the exosome-mediated enhancement of Epstein–Barr virus (EBV) infection. We identified BGLF2 protein encapsulated in exosomes, which were released by EBV-infected cells. BGLF2 protein is a tegument protein that exists in the space between the envelope and nucleocapsid, and it is released into the cytoplasm shortly after infection. BGLF2 protein-containing exosomes enhanced viral gene expression and repressed innate immunity, thereby supporting the EBV infection. Conclusions The EBV tegument protein BGLF2 is encapsulated in exosomes and released by infected cells to facilitate the establishment of EBV infection. These findings suggest that tegument proteins support viral infection not only between the envelope and nucleocapsid, as well as in extraviral particles such as exosomes. Graphical abstract