Human MRCKα is regulated by cellular iron levels and interferes with transferrin iron uptake

Myotonic dystrophy kinase-related Cdc42-binding kinase α (MRCKα, formally known as CDC42BPA) is a serine/threonine kinase that can regulate actin/myosin assembly and activity. Recently, it has been shown that it possesses a functional iron responsive element (IRE) in the 3′-untranslated region (UTR) of its mRNA, suggesting that it may be involved in iron metabolism. Here we report that MRCKα protein expression is also regulated by iron levels; MRCKα colocalizes with transferrin (Tf)-loaded transferrin receptors (TfR), and attenuation of MRCKα expression by a short hairpin RNA silencing construct leads to a significant decrease in Tf-mediated iron uptake. Our results thus indicate that MRCKα takes part in Tf-iron uptake, probably via regulation of Tf-TfR endocytosis/endosome trafficking that is dependent on the cellular cytoskeleton. Regulation of the MRCKα activity by intracellular iron levels could thus represent another molecular feedback mechanism cells could use to finely tune iron uptake to actual needs.     

Regulation of serotonin receptor function in the nervous system by lipid rafts and adaptor proteins

5-HT is a phylogenetically conserved monoaminergic neurotransmitter which is crucial for a number of physiological processes and is dysregulated in several disease states including depression, anxiety and schizophrenia. 5-HT neurons in the central nervous system are localized in the raphe nuclei and project to a wide range of target areas. 5-HT exerts its functions through 14 subtypes of 5-HT receptors. The tertiary structures of seven transmembrane 5-HT receptors contain several important features, including cholesterol consensus motifs, prominent intracellular loops and free C-termini. Alterations of cholesterol levels affect binding of ligands to 5-HT receptors and cholesterol-enriched microdomains in the cell membrane, termed lipid rafts, regulate 5-HT receptor internalization and signaling. The intracellular loops and the C-termini of 5-HT receptors provide binding sites for interacting adaptor proteins. Adaptor proteins affect internalization, desensitization as well as G-protein dependent and independent signaling via 5-HT receptors. We will here briefly review recent progress on the role of lipid rafts and adaptor proteins in the regulation of localization, trafficking, signaling and ligand bias of 5-HT receptors.     

Law and Society in Seattle: Law-Related Education as Culturally Responsive Teaching

In this article, I provide a portrait (Sara Lawrence-Lightfoot and Jessica Hoffman Davis 1997) of a renowned law-related education (LRE) program, its teacher, and four of its student-participants. Following the portrait, I discuss theoretical explanations for the success of ethnic-minority students in this and other LRE programs. These explanations include the nature of law as a difficult subject, the many convergences between culturally responsive teaching and LRE, and the relation of the content and methods of LRE to the cultural capital, interests, backgrounds, and ethnic identities of the students. I conclude with a discussion of the reciprocal nature of these processes, research on white teachers who are successful in multicultural contexts, the importance of challenging, accelerated classes, and an argument for expanding research on culturally responsive teaching and the achievement of students of color to include attention to the methods and materials of LRE.     

Macrolide- and tetracycline-adjustable siRNA-mediated gene silencing in mammalian cells using polymerase II-dependent promoter derivatives

RNA interference has emerged as a powerful technology for downregulation of specific genes in cells and animals. We have pioneered macrolide- and tetracycline-adjustable short interfering RNA (siRNA) expression for conditional target gene translation fine-tuning in mammalian/human cell lines based on modified RNA polymerase II promoters. Established macrolide- and tetracycline-dependent transactivators/trans-silencers bound and activated modified target promoters tailored for optimal siRNA expression in response to clinical antibiotics' dosing regimes and modulated desired target genes in Chinese hamster ovary (CHO-K1) and human fibrosarcoma (HT-1080) cells with high precision. Further optimization of adjustable RNA polymerase II-based siRNA-specific promoters as well as their combination with various transmodulators enabled near-perfect regulation configurations in specific cell types. Devoid of major genetic constraints compared to basic RNA polymerase III-based siRNA-specific promoters, we expect RNA polymerase II counterparts to significantly advance siRNA-based molecular interventions in biopharmaceutical manufacturing and gene-function analysis as well as gene therapy and tissue engineering.     

NAD-sensitive hydrogel for the release of macromolecules

A hydrogel membrane containing immobilized ligands and receptors was synthesized and investigated for the controlled diffusion of test proteins (cytochrome C and hemoglobin). Both Cibacron blue (ligand) and lysozyme (receptor) were covalently linked to dextran molecules that were subsequently crosslinked to form a gel. The resulting stable hydrogels contained both covalent and affinity crosslinks such that their intrinsic porosities were sensitive to competitive displacers of the affinity interaction between lysozyme and Cibacron blue. Transport experiments in a twin chamber diffusion cell showed that as NAD was added to the donor side, the dissociation of the binding sites between the Cibacron blue and the lysozyme led to an increase in protein diffusion through the hydrogel. The results showed that addition of NAD caused a saturable concentration-dependent increase in the transport of both cytochrome C and hemoglobin. This effect was shown to be both specific and reversible.     

外场作用下吸引子神经网中神经元活性的直接观察

本文对强稀疏联结吸引子神经网在持续外场作用下神经元的局域活性进行了考察.对恒稳定性的情形给出了其概率分布分式.数值计算对不同情形下其固定分布行为提供了直观而又生动的观察.将分布图与吸引子结构进行了有比较的分析.我们的结果表明:强外场将导致分布图上阻碍神经元正确驰豫过程的不利屏障峰的出现.利于理想检索的有效分布仅能由适度的外场来取得.而且适度的外场对分布或检索的改善又会因网络过载而受到限制.     

Visualizing stimulus-responsive dual-ligand fluorescent probes for hypochlorite: A novel strategy for real application in tap water

As an effective ingredient of disinfectants, ClO⁻ inevitably remains in water, which induces potential health hazards such as lung damage and kidney disease. In this study, we synthesized stimulus-responsive dual-ligand luminol-Tb-GMP coordination polymer nanoparticles (luminol-Tb-GMP CPNPs) as highly selective fluorescent probes for the real-time and visual detection of ClO⁻. CPNPs consist of Tb³⁺, a nuclear metal, that coordinates with GMP and luminol, an auxiliary ligand. GMP can be oxidized by ClO⁻ and damage its structure, resulting in fluorescence quenching of CPNPs. The two-ligand CPNPs sensor has a rapid fluorescent response, significant fluorescent color change, and high sensitivity, with a linear range of 2–18 μM and a detection limit of 0.14 μM. It has been successfully used to detect ClO⁻ in tap water, fountain water, and drinking water. Simultaneously, the portable filter paper strip was prepared to expand the range of applications outside the laboratory, which will provide a promising application for the real-time and semiquantitative analysis of ClO⁻.