Reconstitution of Human Casein Micelle and Its Properties

Human casein micelles were reconstituted from isolated κ- and β-caseins and calcium ions. Micelle formation was recognized in the presence of calcium chloride even at the low concentration of 5mM. At pH levels ranging from 5.5 to 8.0, the re-formed micelles were quite stable so that precipitation of β-casein was not observed. The large micelles were constituted by a higher ratio of β-casein to κ-casein (16:1 by weight) than the small micelles (3: 1). The κ-casein in the small micelles contained carbohydrates to about 43% (w/w) in the molecule, whereas that in the large micelles was only about 25%. When the casein micelles were re-formed from κ-easein and fractionated β-casein components, the extent of phosphorylation of the β-casein component was found to influence the micelle formation; i.e., the β-casein component with no phosphate (the 0-P form) was disadvantageous to form micelles, but the component with 5 phosphates (the 5-P form) formed micelles most easily.     

HTLV-1 bZIP Factor Impairs Anti-viral Immunity by Inducing Co-inhibitory Molecule,T Cell Immunoglobulin and ITIM Domain (TIGIT)

Human T-cell leukemia virus type 1 (HTLV-1) infects CD4⁺ T cells and induces proliferation of infected cells in vivo, which leads to the onset of adult T-cell leukemia (ATL) in some infected individuals. The HTLV-1 bZIP factor (HBZ) gene, which is encoded in the minus strand of HTLV-1, plays critical roles in pathogenesis. In this study, RNA-seq and ChIP-seq analyses using HBZ transduced T cells revealed that HBZ upregulates the expression and promoter acetylation levels of a co-inhibitory molecule, T cell immunoglobulin and ITIM domain (TIGIT), in addition to those of regulatory T cells related genes, Foxp3 and Ccr4. TIGIT was expressed on CD4⁺ T cells from HBZ-transgenic (HBZ-Tg) mice, and on ATL cells and HTLV-1 infected CD4⁺ T cells of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in vivo. Expression of Blimp1 and IL-10 was upregulated in TIGIT⁺CD4⁺ cells of HBZ-Tg mice compared with TIGIT^-CD4⁺ T cells, suggesting the correlation between TIGIT expression and IL-10 production. When CD4⁺ T cells from HBZ-Tg mice were stimulated with TIGIT’s ligand, CD155, their production of the inhibitory cytokine IL-10 was enhanced. Furthermore, dendritic cells from HBZ-Tg mice produced high levels of IL-10 after stimulation. These data suggest that HBZ alters immune system to suppressive state via TIGIT and IL-10. Importantly, TIGIT suppressed T-cell responses to another HTLV-1 virus protein, Tax, in vitro. Blocking of TIGIT and PD-1 slightly increased anti-Tax T-cell activity in some HAM/TSP patients. These results suggest that HBZ-induced TIGIT on HTLV-1 infected cells impairs T-cell responses to viral antigens. This study shows that HBZ-induced TIGIT plays a pivotal role in attenuating host immune responses and shaping a microenvironment favorable to HTLV-1.     

Evolution of chromosome number in grasshoppers (Orthoptera: Caelifera: Acrididae)

Organisms Diversity & Evolution - Orthoptera have some of the largest genomes of all insects. At the same time, the architecture of their genomes remains poorly understood. Comparative...     

Overexpression of an ADP-ribosylation factor-guanine nucleotide exchange factor, BIG2, uncouples brefeldin A-induced adaptor protein-1 coat dissociation and membrane tubulation.

BIG2 is a guanine nucleotide exchange factor (GEF) for the ADP-ribosylation factor (ARF) family of small GTPases, which regulate membrane association of COPI and adaptor protein (AP)-1 coat protein complexes. A fungal metabolite, brefeldin A (BFA), inhibits ARF-GEFs and leads to redistribution of coat proteins from membranes to the cytoplasm and membrane tubulation of the Golgi complex and the trans-Golgi network (TGN). To investigate the function of BIG2, we examined the effects of BIG2-overexpression on the BFA-induced redistribution of ARF, coat proteins, and organelle markers. The BIG2 overexpression blocked BFA-induced redistribution from membranes of ARF1 and the AP-1 complex but not that of the COPI complex. These observations indicate that BIG2 is implicated in membrane association of AP-1, but not that of COPI, through activating ARF. Furthermore, not only BIG2 but also ARF1 and AP-1 were found as queues of spherical swellings along the BFA-induced membrane tubules emanating from the TGN. These observations indicate that BFA-induced AP-1 dissociation from TGN membranes and tubulation of TGN membranes are not coupled events and suggest that a BFA target other than ARF-GEFs exists in the cell.     

An immunohistochemical study on cathepsin D in human hippocampus

Cathepsin D is a lysosomal enzyme involved in neuronal degeneration. In this study, the immunohistochemistry of cathepsin D was studied in hippocampal CA1 neurons that are vulnerable to ischemia, and parahippocampal glial cells. CA1 neurons from the majority of cases showed cathepsin D immunoreactivity in the cytoplasm, whereas shrunk neurons were unstained in only one case. There was no statistically significant correlation between the postmortem interval between death and autopsy, and cathepsin D immunoreactivity in CA1 neurons. These observations indicate that cathepsin D immunoreactivity is not a sensitive marker for neuronal degeneration or postmortem changes. On the other hand, there was a statistically significant correlation between age and cathepsin D immunoreactivity in the cytoplasm of parahippocampal glial cells. This shows that senescence is correlated with cathepsin D expression in humans as has been reported previously in an animal study.     

B7-H3 contributes to the development of pathogenic Th2 cells in a murine model of asthma

B7-H3 is a new member of the B7 family. The receptor for B7-H3 has not been identified, but it seems to be expressed on activated T cells. Initial studies have shown that B7-H3 provides a stimulatory signal to T cells. However, recent studies suggest a negative regulatory role for B7-H3 in T cell responses. Thus, the immunological function of B7-H3 is controversial and unclear. In this study, we investigated the effects of neutralizing anti-B7-H3 mAb in a mouse model of allergic asthma to determine whether B7-H3 contributes to the development of pathogenic Th2 cells and pulmonary inflammation. Administration of anti-B7-H3 mAb significantly reduced airway hyperreactivity with a concomitant decrease in eosinophils in the lung as compared with control IgG-treated mice. Treatment with anti-B7-H3 mAb also resulted in decreased production of Th2 cytokines (IL-4, IL-5, and IL-13) in the draining lymph node cells. Although blockade of B7-H3 during the induction phase abrogated the development of asthmatic responses, B7-H3 blockade during the effector phase did not inhibit asthmatic responses. These results indicated an important role for B7-H3 in the development of pathogenic Th2 cells during the induction phase in a murine model of asthma.     

Vinyldiaminotriazine-acridine conjugate as G-quadruplex alkylating agent

Higher-order structures of nucleic acids have become widely noted for their biological consequences and the discovery of an alkylating small molecule for these structures has been of interest due to its therapeutic potential. We previously developed the vinyldiaminotriazine (VDAT)-acridine conjugate as a T-T mismatch alkylating agent. In this report, we focused on the finding of the alkylation to the G-quadruplex (G4) DNA with VDAT-acridine conjugates. The VDAT-acridine conjugates exhibited a considerable alkylation ability to G4 under mild conditions. Moreover, the investigation of properties with the alkylated G4 revealed that alkylation by this conjugate significantly increased the stability of the G4 structure. This study provides a starting point in the further development of selective G4 alkylating small molecules.     

Learning to simulate others' decisions

A fundamental challenge in social cognition is how humans learn another person's values to predict their decision-making behavior. This form of learning is often assumed to require simulation of the other by direct recruitment of one's own valuation process to model the other's process. However, the cognitive and neural mechanism of simulation learning is not known. Using behavior, modeling, and fMRI, we show that simulation involves two learning signals in a hierarchical arrangement. A simulated-other's reward prediction error processed in ventromedial prefrontal cortex mediated simulation by direct recruitment, being identical for valuation of the self and simulated-other. However, direct recruitment was insufficient for learning, and also required observation of the other's choices to generate?a simulated-other's action prediction error encoded in dorsomedial/dorsolateral prefrontal cortex. These findings show that simulation uses a core prefrontal circuit for modeling the other's valuation to generate prediction and an adjunct circuit for tracking behavioral variation to refine prediction.     

Protein kinase Cdelta plays a non-redundant role in insulin secretion in pancreatic beta cells

Protein kinase C (PKC) is considered to modulate glucose-stimulated insulin secretion. Pancreatic beta cells express multiple isoforms of PKCs; however, the role of each isoform in glucose-stimulated insulin secretion remains controversial. In this study we investigated the role of PKCdelta, a major isoform expressed in pancreatic beta cells on beta cell function. Here, we showed that PKCdelta null mice manifested glucose intolerance with impaired insulin secretion. Insulin tolerance test showed no decrease in insulin sensitivity in PKCdelta null mice. Studies using islets isolated from these mice demonstrated decreased glucose- and KCl-stimulated insulin secretion. Perifusion studies indicated that mainly the second phase of insulin secretion was decreased. On the other hand, glucose-induced influx of Ca2+ into beta cells was not altered. Immunohistochemistry using total internal reflection fluorescence microscopy and electron microscopic analysis showed an increased number of insulin granules close to the plasma membrane in beta cells of PKCdelta null mice. Although PKC is thought to phosphorylate Munc18-1 and facilitate soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors complex formation, the phosphorylation of Munc18-1 by glucose stimulation was decreased in islets of PKCdelta null mice. We conclude that PKCdelta plays a non-redundant role in glucose-stimulated insulin secretion. The impaired insulin secretion in PKCdelta null mice is associated with reduced phosphorylation of Munc18-1.