An Optochemical Oxygen Scavenger Enabling Spatiotemporal Control of Hypoxia.

We present an optochemical O2 scavenging system that enables precise spatiotemporal control of the level of hypoxia in living cells simply by adjusting the light intensity in the illuminated region. The system employs rhodamine containing a selenium or tellurium atom as an optochemical oxygen scavenger that rapidly consumes O2 by photochemical reaction with glutathione as a coreductant upon visible light irradiation (560-590 nm) and has a rapid response time, within a few minutes. The glutathione-consuming quantum yields of the system were calculated as about 5 %. The spatiotemporal O2 consuming in cultured cells was visualized with a hypoxia-responsive fluorescence probe, MAR. Phosphorescence lifetime imaging was applied to confirmed that different light intensities could generate different levels of hypoxia. To illustrate the potential utility of this system for hypoxia research, we show that it can spatiotemporally control calcium ion (Ca2+ ) influx into HEK293T cells expressing the hypoxia-responsive Ca2+ channel TRPA1.

Detachment of Chain-Forming Neuroblasts by Fyn-Mediated Control of cell-cell Adhesion in the Postnatal Brain.

In the rodent olfactory system, neuroblasts produced in the ventricular-subventricular zone of the postnatal brain migrate tangentially in chain-like cell aggregates toward the olfactory bulb (OB) through the rostral migratory stream (RMS). After reaching the OB, the chains are dissociated and the neuroblasts migrate individually and radially toward their final destination. The cellular and molecular mechanisms controlling cell-cell adhesion during this detachment remain unclear. Here we report that Fyn, a nonreceptor tyrosine kinase, regulates the detachment of neuroblasts from chains in the male and female mouse OB. By performing chemical screening and in vivo loss-of-function and gain-of-function experiments, we found that Fyn promotes somal disengagement from the chains and is involved in neuronal migration from the RMS into the granule cell layer of the OB. Fyn knockdown or Dab1 (disabled-1) deficiency caused p120-catenin to accumulate and adherens junction-like structures to be sustained at the contact sites between neuroblasts. Moreover, a Fyn and N-cadherin double-knockdown experiment indicated that Fyn regulates the N-cadherin-mediated cell adhesion between neuroblasts. These results suggest that the Fyn-mediated control of cell-cell adhesion is critical for the detachment of chain-forming neuroblasts in the postnatal OB.SIGNIFICANCE STATEMENT In the postnatal brain, newly born neurons (neuroblasts) migrate in chain-like cell aggregates toward their destination, where they are dissociated into individual cells and mature. The cellular and molecular mechanisms controlling the detachment of neuroblasts from chains are not understood. Here we show that Fyn, a nonreceptor tyrosine kinase, promotes the somal detachment of neuroblasts from chains, and that this regulation is critical for the efficient migration of neuroblasts to their destination. We further show that Fyn and Dab1 (disabled-1) decrease the cell-cell adhesion between chain-forming neuroblasts, which involves adherens junction-like structures. Our results suggest that Fyn-mediated regulation of the cell-cell adhesion of neuroblasts is critical for their detachment from chains in the postnatal brain.

Enhancement of neuroblast migration into the injured cerebral cortex using laminin-containing porous sponge.

After brain injury, neuroblasts generated from endogenous neural stem cells migrate toward the injured site using blood vessels as a scaffold, raising the possibility of reconstructing blood vessel network scaffolds as a strategy for promoting endogenous neuronal regeneration. In this study, we designed biomaterials based on the components and morphology of blood vessel scaffolds, and examined their ability to guide the migration of neuroblasts into a brain lesion site in mice. Transplanted porous sponge containing components of the basement membrane (BM) matrix enhanced neuroblast migration into the lesion, and detailed morphological examination suggested that the infiltrating cells used the BM sponge as a migration scaffold. Laminin (LN)-rich porous sponge also enhanced the migration of neuroblasts into the lesion, whereas BM gel and gelatin porous sponge did not. We conclude that the transplantation of LN-rich porous sponge promotes neuroblast migration into cortical lesions. This study highlights the possibility of using artificial blood vessel scaffolds to promote the regeneration of injured cerebral cortex.

Novel derivatives of aclacinomycin A block cancer cell migration through inhibition of farnesyl transferase.

In the course of screening for an inhibitor of farnesyl transferase (FTase), we identified two compounds, N-benzyl-aclacinomycin A (ACM) and N-allyl-ACM, which are new derivatives of ACM. N-benzyl-ACM and N-allyl-ACM inhibited FTase activity with IC50 values of 0.86 and 2.93 µM, respectively. Not only ACM but also C-10 epimers of each ACM derivative failed to inhibit FTase. The inhibition of FTase by N-benzyl-ACM and N-allyl-ACM seems to be specific, because these two compounds did not inhibit geranylgeranyltransferase or geranylgeranyl pyrophosphate (GGPP) synthase up to 100 µM. In cultured A431 cells, N-benzyl-ACM and N-allyl-ACM also blocked both the membrane localization of H-Ras and activation of the H-Ras-dependent PI3K/Akt pathway. In addition, they inhibited epidermal growth factor (EGF)-induced migration of A431 cells. Thus, N-benzyl-ACM and N-allyl-ACM inhibited EGF-induced migration of A431 cells by inhibiting the farnesylation of H-Ras and subsequent H-Ras-dependent activation of the PI3K/Akt pathway.

Involvement of 14-3-3 proteins in the second epidermal growth factor-induced wave of Rac1 activation in the process of cell migration.

Immense previous efforts have elucidated the core machinery in cell migration, actin remodeling regulated by Rho family small GTPases including RhoA, Cdc42, and Rac1; however, the spatiotemporal regulation of these molecules remains largely unknown. Here, we report that EGF induces biphasic Rac1 activation in the process of cell migration, and UTKO1, a cell migration inhibitor, inhibits the second EGF-induced wave of Rac1 activation but not the first wave. To address the regulation mechanism and role of the second wave of Rac1 activation, we identified 14-3-3ζ as a target protein of UTKO1 and also showed that UTKO1 abrogated the binding of 14-3-3ζ to Tiam1 that was responsible for the second wave of Rac1 activation, suggesting that the interaction of 14-3-3ζ with Tiam1 is involved in this event. To our knowledge, this is the first report to use a chemical genetic approach to demonstrate the mechanism of temporal activation of Rac1.

Synthesis and anti-migrative evaluation of moverastin derivatives.

Cell migration of tumor cells is essential for invasion of the extracellular matrix and for cell dissemination. Inhibition of the cell migration involved in the invasion process represents a potential therapeutic approach to the treatment of tumor metastasis; therefore, a novel series of derivatives of moverastins (moverastins A and B), an inhibitor of tumor cell migration, was designed and chemically synthesized. Among these moverastin derivatives, several compounds showed stronger cell migration inhibitory activity than parental moverastins, and UTKO1 was found to have the most potent inhibitory activity against the migration of human esophageal tumor EC17 cells in a chemotaxis cell chamber assay. Interestingly, although moverastins are considered to inhibit tumor cell migration by inhibiting farnesyltransferase (FTase), UTKO1 did not inhibit FTase, indicating that UTKO1 inhibited tumor cell migration by a mechanism other than the inhibition of FTase.

[A study of measurements of and factors influencing threshold levels of taste perception].

The threshold levels of taste perception on the right and left side of the tip, root of tongue and soft palate in 60 healthy volunteers were measured by means of an electrogustometry test and a filter-paper disk taste test to confirm the following hypotheses: (1) the threshold on the tip of the tongue was lower than those of the root of the tongue and soft palate, (2) there was a different threshold level between sweet, salty, sour and bitter tastes on the tip of the tongue, (3) some personal properties influenced the person's threshold. Measured threshold levels were compared between these six locations with multiple comparisons. Factors influencing the threshold level on the tip of the tongue, thereafter, were investigated using multivariate logistic regression models. Those factors included sex, age, serological, psychological and behavioral factors. As a result, the thresholds levels on the tip of the tongue were significantly lower than the root of the tongue and soft palate. The thresholds for sweet and bitter taste on the tip of the tongue were also lower than those for salty and sour taste. Increase of age, male, serological increase of zinc and usual alcohol drinking were identified as factors of increase for several thresholds, and increase of anxiety was identified as a factor of decrease for two thresholds of four tastes (sweet, salty, sour and bitter) on the tip of the tongue in the logistic regression models. Increase of depression, mouth breathing, habitual tonus of the tongue and smoking did not appear to be influential factors.