Structural insights into IL-6 signaling inhibition by therapeutic antibodies.

Antibody inhibitors of the interleukin-6 (IL-6) signaling pathway, such as tocilizumab and sarilumab, have been used to treat rheumatoid arthritis, chimeric antigen receptor T cell-induced cytokine storm, and severe COVID-19 pneumonia. Here, we solve the cryogenic electron microscopy structures of sarilumab and tocilizumab in complex with IL-6R to resolutions of 3.2 and 3.

Structural basis of vitamin C recognition and transport by mammalian SVCT1 transporter.

Vitamin C (L-ascorbic acid) is an essential nutrient for human health, and its deficiency has long been known to cause scurvy. Sodium-dependent vitamin C transporters (SVCTs) are responsible for vitamin C uptake and tissue distribution in mammals. Here, we present cryogenic electron microscopy structures of mouse SVCT1 in both the apo and substrate-bound states.

Cryo-EM structure of the plant nitrate transporter AtCLCa reveals characteristics of the anion-binding site and the ATP-binding pocket.

Nitrate is one of the major nitrogen sources for most plants. Chloride channel (CLC) proteins mediate the transport and vacuole storage of nitrate in plants, but the structural basis of nitrate transport by plant CLC proteins remains unknown. Here, we solved the cryo-EM structure of ATP-bound Arabidopsis thaliana CLCa (AtCLCa) at 2.

Structure and Function of Plant and Mammalian TPC Channels.

Two-pore channels (TPCs) belong to the family of voltage-gated tetrameric cation channels and are ubiquitously expressed in organelles of animals and plants. These channels are believed to be evolutionary intermediates between homotetrameric voltage-gated potassium/sodium channels and the four-domain, single subunit, voltage-gated sodium/calcium channels. Each TPC subunit contains 12 transmembrane segments that can be divided into two homologous copies of an S1-S6 Shaker-like 6-TM domain.

Structural insights into the Ca-dependent gating of the human mitochondrial calcium uniporter.

Mitochondrial Ca uptake is mediated by an inner mitochondrial membrane protein called the mitochondrial calcium uniporter. In humans, the uniporter functions as a holocomplex consisting of MCU, EMRE, MICU1 and MICU2, among which MCU and EMRE form a subcomplex and function as the conductive channel while MICU1 and MICU2 are EF-hand proteins that regulate the channel activity in a Ca-dependent manner. Here, we present the EM structures of the human mitochondrial calcium uniporter holocomplex (uniplex) in the presence and absence of Ca, revealing distinct Ca dependent assembly of the uniplex.

Structural Mechanism of EMRE-Dependent Gating of the Human Mitochondrial Calcium Uniporter.

Mitochondrial calcium uptake is crucial to the regulation of eukaryotic Ca homeostasis and is mediated by the mitochondrial calcium uniporter (MCU). While MCU alone can transport Ca in primitive eukaryotes, metazoans require an essential single membrane-spanning auxiliary component called EMRE to form functional channels; however, the molecular mechanism of EMRE regulation remains elusive. Here, we present the cryo-EM structure of the human MCU-EMRE complex, which defines the interactions between MCU and EMRE as well as pinpoints the juxtamembrane loop of MCU and extended linker of EMRE as the crucial elements in the EMRE-dependent gating mechanism among metazoan MCUs.

Structural and functional characterization of an otopetrin family proton channel.

The otopetrin (OTOP) proteins were recently characterized as proton channels. Here we present the cryo-EM structure of OTOP3 from (XtOTOP3) along with functional characterization of the channel. XtOTOP3 forms a homodimer with each subunit containing 12 transmembrane helices that can be divided into two structurally homologous halves; each half assembles as an α-helical barrel that could potentially serve as a proton conduction pore.

Structural mechanisms of phospholipid activation of the human TPC2 channel.

Mammalian two-pore channels (TPCs) regulate the physiological functions of the endolysosome. Here we present cryo-EM structures of human TPC2 (HsTPC2), a phosphatidylinositol 3,5-bisphosphate (PI(3,5)P)-activated, Na selective channel, in the ligand-bound and apo states. The apo structure captures the closed conformation, while the ligand-bound form features the channel in both open and closed conformations.

Ruthenium(II) salicylate complexes inducing ROS-mediated apoptosis by targeting thioredoxin reductase.

Thioredoxin reductase (TrxR), a major component of the thioredoxin system, makes a critical role in regulating cellular redox signaling and is found to be overexpressed in many human cancer cells. TrxR has become an attractive target for anticancer agents. In this work, three Ru(II) complexes with salicylate as ligand, [Ru(phen)(SA)] (phen = 1,10-phenanthroline, SA = salicylate, 1), [Ru(dmb)(SA)] (dmb = 4,4'-dimethyl-2,2'-bipyridine, 2) and [Ru(bpy)(SA)] (bpy = 2,2'-bipyridine, 3), were synthesized and characterized.

Structural insights into the voltage and phospholipid activation of the mammalian TPC1 channel.

The organellar two-pore channel (TPC) functions as a homodimer, in which each subunit contains two homologous Shaker-like six-transmembrane (6-TM)-domain repeats. TPCs belong to the voltage-gated ion channel superfamily and are ubiquitously expressed in animals and plants. Mammalian TPC1 and TPC2 are localized at the endolysosomal membrane, and have critical roles in regulating the physiological functions of these acidic organelles.

Cytotoxicity in vitro, cellular uptake, localization and apoptotic mechanism studies induced by ruthenium(II) complex.

Ruthenium-based complexes have been regarded as one of the most potential metal-based candidates for anticancer therapy. Herein, two ruthenium (II) methylimidazole complexes [Ru(MeIm)(4npip)] (complex 1) and [Ru(MeIm)(4mopip)] (complex 2) were synthesized and evaluated for their in vitro anticancer activities. The results showed that these ruthenium (II) methylimidazole complexes exhibited moderate antitumor activity comparable with cisplatin against A549, NCI-H460, MCF-7 and HepG2 human cancer cells, but with less toxicity to a human normal cell line HBE.

Structures of the calcium-activated, non-selective cation channel TRPM4.

TRPM4 is a calcium-activated, phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P) -modulated, non-selective cation channel that belongs to the family of melastatin-related transient receptor potential (TRPM) channels. Here we present the electron cryo-microscopy structures of the mouse TRPM4 channel with and without ATP. TRPM4 consists of multiple transmembrane and cytosolic domains, which assemble into a three-tiered architecture.

Structure of mammalian endolysosomal TRPML1 channel in nanodiscs.

Transient receptor potential mucolipin 1 (TRPML1) is a cation channel located within endosomal and lysosomal membranes. Ubiquitously expressed in mammalian cells, its loss-of-function mutations are the direct cause of type IV mucolipidosis, an autosomal recessive lysosomal storage disease. Here we present the single-particle electron cryo-microscopy structure of the mouse TRPML1 channel embedded in nanodiscs.

Synthesis, characterization, cellular uptake and apoptosis-inducing properties of two highly cytotoxic cyclometalated ruthenium(II) β-carboline complexes.

Two new cyclometalated Ru(II) complexes of the general formula [Ru(N-N)(1-Ph-βC)](PF), where N-N = 4,4'-dimethyl-2,2'-bipyridine (dmb, Ru1), 2,2'-bipyridine (bpy, Ru2), and 1-Ph-βC (1-phenyl-9H-pyrido[3,4-b]indole) is a β-carboline alkaloids derivatives, have been synthesized and characterized. The in vitro cytotoxicities, cellular uptake and localization, cell cycle arrest and apoptosis-inducing mechanisms of these complexes have been extensively explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, inductively coupled plasma mass spectrometry (ICP-MS), flow cytometry, comet assay, inverted fluorescence microscope as well as western blotting experimental techniques. Notably, Ru1 and Ru2 exhibit potent antiproliferative activities against selected human cancer cell lines with IC values lower than those of cisplatin and other non-cyclometalated Ru(II) β-carboline complexes.

A Novel Sensor Selection and Power Allocation Algorithm for Multiple-Target Tracking in an LPI Radar Network.

Radar networks are proven to have numerous advantages over traditional monostatic and bistatic radar. With recent developments, radar networks have become an attractive platform due to their low probability of intercept (LPI) performance for target tracking. In this paper, a joint sensor selection and power allocation algorithm for multiple-target tracking in a radar network based on LPI is proposed.

A mammary repopulating cell population characterized in mammary anlagen reveals essential mammary stroma for morphogenesis.

The cells with mammary repopulating capability can achieve mammary gland morphogenesis in a suitable cellular microenvironment. Using cell surface markers of CD24, CD29 and CD49f, mouse mammary repopulating unit (MRU) has been identified in adult mammary epithelium and late embryonic mammary bud epithelium. However, embryonic MRU remains to be fully characterized at earlier mammary anlagen stage.

Structural basis for differential recognition of brassinolide by its receptors.

Brassinosteroids, a group of plant steroid hormones, regulate many aspects of plant growth and development. We and other have previously solved the crystal structures of BRI1(LRR) in complex with brassinolide, the most active brassinosteroid identified thus far. Although these studies provide a structural basis for the recognition of brassinolide by its receptor BRI1, it still remains poorly understood how the hormone differentiates among its conserved receptors.

Chitin-induced dimerization activates a plant immune receptor.

Pattern recognition receptors confer plant resistance to pathogen infection by recognizing the conserved pathogen-associated molecular patterns. The cell surface receptor chitin elicitor receptor kinase 1 of Arabidopsis (AtCERK1) directly binds chitin through its lysine motif (LysM)-containing ectodomain (AtCERK1-ECD) to activate immune responses. The crystal structure that we solved of an AtCERK1-ECD complexed with a chitin pentamer reveals that their interaction is primarily mediated by a LysM and three chitin residues.

Structural insight into brassinosteroid perception by BRI1.

Brassinosteroids are essential phytohormones that have crucial roles in plant growth and development. Perception of brassinosteroids requires an active complex of BRASSINOSTEROID-INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED KINASE 1 (BAK1). Recognized by the extracellular leucine-rich repeat (LRR) domain of BRI1, brassinosteroids induce a phosphorylation-mediated cascade to regulate gene expression.

Silver(I) oxide mediated selective monoprotection of diols in pyranosides.

The reaction of 4, 6-O-benzylidene-d-pyranosides with a stoichiometric amount of TsCl, AcCl, and BzCl in the presence of silver(I) oxide and a catalytic amount of potassium iodide led to monosubstituted derivatives in high regioselectivity and in good yields.

[Inhibitory effect and kinetic analysis of sodium quercetin-7,4'-disulphate on recombinant human protein kinase CK2 holoenzyme].

Aim: To study the direct effect and kinetics of sodium quercetin-7,4'-disulphate (SQDS) on recombinant human protein kinase CK2 holoenzyme.

Methods: The recombinant human CK2 holoenzyme activity was assayed by detecting incorporation of 32P of [gamma-32P] ATP into the substrate in various conditions.

Results: The recombinant human CK2 was a second messenger (Ca2+, cAMP and cGMP) independent protein kinase.