Casein kinase 1alpha interacts with retinoid X receptor and interferes with agonist-induced apoptosis

Agonists of retinoid X receptors (RXRs), which include the natural 9-cis-retinoic acid and synthetic analogs, are potent inducers of growth arrest and apoptosis in some cancer cells. As such, they are being used in clinical trials for the treatment and prevention of solid tumors and are used to treat cutaneous T cell lymphoma. However, the molecular mechanisms that underlie the anti-cancer effects of RXR agonists remain unclear. Here, we show that a novel pro-apoptotic pathway that is induced by RXR agonist is negatively regulated by casein kinase 1alpha (CK1alpha). CK1alpha associates with RXR in an agonist-dependent manner and phosphorylates RXR. The ability of an RXR agonist to recruit CK1alpha to a complex with RXR in cells correlates inversely with its ability to inhibit growth. Remarkably, depletion of CK1alpha in resistant cells renders them susceptible to RXR agonist-induced growth inhibition and apoptosis. Our study shows that CK1alpha can promote cell survival by interfering with RXR agonist-induced apoptosis. Inhibition of CK1alpha may enhance the anti-cancer effects of RXR agonists.     

Neuronal roles of the integrin-associated protein (IAP/CD47) in developing cortical neurons

Little is known about the role of the integrin-associated protein (IAP, or CD47) in neuronal development and its function in the central nervous system. We investigated neuronal responses in IAP-overexpressing cortical neurons using a virus-gene transfer system. We found that dendritic outgrowth was significantly enhanced in IAP (form 4)-transfected neurons. Furthermore, synaptic proteins including synaptotagmin, syntaxin, synapsin I, and SNAP25 (25-kDa synaptosomal associated protein) were up-regulated. In accordance with this finding, the release of the excitatory transmitter glutamate and the frequencies of Ca2+ oscillations (glutamate-mediated synaptic transmission) were increased. Interestingly, the overexpression of IAP activated mitogen-activated protein kinase (MAPK), and this activation was required for the IAP-dependent biological effects. After down-regulation of the endogenous IAP by small interfering RNA, MAPK activity, synaptic protein levels, and glutamate release decreased. These observations suggest that the IAP plays important roles in dendritic outgrowth and synaptic transmission in developing cortical neurons through the activation of MAPK.     

Structural analysis of human hair single fibres by scanning microbeam SAXS

The origin of the curliness of human hair was revealed by scanning microbeam small angle X-ray scattering (SAXS), based on the nanostructure of keratin fibre arrangement. Scanning microbeam SAXS patterns of single hair fibres have been measured across the fibres and the differences in the patterns between the inner and the outer sides of the curvature were successfully detected. The analysis of the equatorial and azimuthal scattering intensity profiles showed that the arrangement of the intermediate filaments was different between the inner and the outer sides of the curvature. From the analogy with Merino and Romny wool, it is suggested that different types of cortices exist in human hair. It is concluded that, regardless of the ethnic origins (African, Caucasian, and Asian), the macroscopic curl shape of the hair fibre originate from the inhomogeneity of the internal nanostructure, arising from inhomogeneous distribution of two types of cortices.     

Enhanced activation of T lymphocytes by urease-deficient recombinant bacillus Calmette-Guérin producing heat shock protein 70-major membrane protein-II fusion protein

To activate naive T cells convincingly using Mycobacterium bovis bacillus Calmette-Guérin (BCG), recombinant BCG (BCG-D70M) that was deficient in urease, expressed with gene encoding the fusion of BCG-derived heat shock protein (HSP) 70 and Mycobacterium leprae-derived major membrane protein (MMP)-II, one of the immunodominant Ags of M. leprae, was newly constructed. BCG-D70M was more potent in activation of both CD4(+) and CD8(+) subsets of naive T cells than recombinant BCGs including urease-deficient BCG and BCG-70M secreting HSP70-MMP-II fusion protein. BCG-D70M efficiently activated dendritic cells (DCs) to induce cytokine production and phenotypic changes and activated CD4(+) T cells even when macrophages were used as APCs. The activation of both subsets of T cells was MHC and CD86 dependent. Pretreatment of DCs with chloroquine inhibited both surface expression of MMP-II on DCs and the activation of T cells by BCG-D70M-infected APCs. The naive CD8(+) T cell activation was inhibited by treatment of DCs with brefeldin A and lactacystin so that the T cell was activated by TAP- and proteosome-dependent cytosolic cross-priming pathway. From naive CD8(+) T cells, effector T cells producing perforin and memory T cells having migration markers were produced by BCG-D70M stimulation. BCG-D70M primary infection in C57BL/6 mice produced T cells responsive to in vitro secondary stimulation with MMP-II and HSP70 and more efficiently inhibited the multiplication of subsequently challenged M. leprae than vector control BCG. These results indicate that the triple combination of HSP70, MMP-II, and urease depletion may provide a useful tool for inducing better activation of naive T cells.     

Identification of a Novel Selenium-containing Compound,Selenoneine, as the Predominant Chemical Form of Organic Selenium in the Blood of Bluefin Tuna

A novel selenium-containing compound having a selenium atom in the imidazole ring, 2-selenyl-N_α,N_α,N_α-trimethyl-l-histidine, 3-(2-hydroseleno-1H-imidazol-5-yl)-2-(trimethylammonio)propanoate, was identified from the blood and other tissues of the bluefin tuna, Thunnus orientalis. The selenium-containing compound was purified from the tuna blood in several chromatographic steps. High resolution mass spectrometry and nuclear magnetic resonance spectroscopy showed that the exact mass of the [M+H]⁺ ion of the compound was 533.0562 and the molecular formula was C₁₈H₂₉N₆O₄Se₂. Its gross structure was assigned as the oxidized dimeric form of an ergothioneine selenium analog in which the sulfur of ergothioneine is replaced by selenium. Therefore, we named this novel selenium-containing compound “selenoneine.” By speciation analysis of organic selenium compounds using liquid chromatography inductively coupled plasma mass spectrometry, selenoneine was found widely distributed in various tissues of the tuna, with the highest concentration in blood; mackerel blood contained similar levels. Selenoneine was measurable at 2–4 orders of magnitude lower concentration in a limited set of tissues from squid, tilapia, pig, and chicken. Quantitatively, selenoneine is the predominant form of organic selenium in tuna tissues.     

Production of a polymer-forming fusion protein in Escerichia coli strain BL21

In the course of studying [PSI(+)], a yeast prion, we found inadvertently that Escherichia coli strain BL21 overproducing a fusion protein, in which the prion-domain of Sup35 was connected to the C terminus of glutathione S-transferase, grew normally to the stationary phase and rapidly decreased in colony-forming ability thereafter. Evidence indicated that protein polymers consisting mainly of the fusion protein GST-Sup35NM (about 70% of the mass) and its N-terminal fragments were formed in extract prepared from the cells producing GST-Sup35NM. It was further found that cells of strain BL21 accumulated the protein polymers during prolonged cultivation. Based on these results, we contend that the initially observed defect in colony forming ability is the direct or indirect consequence of intracellular formation and accumulation of the protein polymers.