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Oxidative Medicine and Cellular... 2022Overcoming blood-brain barrier (BBB) to improve brain bioavailability of therapeutic drug remains an ongoing concern. Prodrug is one of the most reliable approaches for... (Review)
Review
Overcoming blood-brain barrier (BBB) to improve brain bioavailability of therapeutic drug remains an ongoing concern. Prodrug is one of the most reliable approaches for delivering agents with low-level BBB permeability into the brain. The well-known antioxidant capacities of cysteine (Cys) and its vital role in glutathione (GSH) synthesis indicate that Cys-based prodrug could potentiate therapeutic drugs against oxidative stress-related neurodegenerative disorders. Moreover, prodrug with Cys moiety could be recognized by the excitatory amino acid transporter 3 (EAAT3) that is highly expressed at the BBB and transports drug into the brain. In this review, we summarized the strategies of crossing BBB, properties of EAAT3 and its natural substrates, Cys and its donors, and Cys donor-based brain-targeting prodrugs by referring to recent investigations. Moreover, the challenges that we are faced with and future research orientations were also addressed and proposed. It is hoped that present review will provide evidence for the pursuit of novel Cys donor-based brain-targeting prodrug.
Topics: Animals; Antioxidants; Biological Transport; Blood-Brain Barrier; Cysteine; Excitatory Amino Acid Transporter 3; Glutathione; Humans; Neurodegenerative Diseases; Oxidative Stress; Permeability; Prodrugs; Signal Transduction
PubMed: 35251474
DOI: 10.1155/2022/4834117 -
Current Opinion in Immunology Aug 2023Viral blockade of the transporter associated with antigen processing (TAP) diminishes surface and endosomal recycling compartment levels of major histocompatibility... (Review)
Review
Viral blockade of the transporter associated with antigen processing (TAP) diminishes surface and endosomal recycling compartment levels of major histocompatibility complex class-I (MHC-I) in dendritic cells (DCs), and compromises both classical MHC-I presentation and canonical cross-presentation during infection to impair CD8 T-cell immunity. Virus-specific CD8 T cells are thought to be cross-primed mostly by uninfected TAP-sufficient DCs through cross-presentation of viral peptides from internalized virus-infected dying cells. The dilemma is that CD8 T cells primed to TAP-dependent viral peptides are mismatched to the TAP-independent epitopes presented on tissues infected with immune-evasive viruses. Noncanonical cross-presentation in DCs overcomes cell-intrinsic TAP blockade to nevertheless prime protective TAP-independent CD8 T cells best-matched against the infection. Exploitation of noncanonical cross-presentation may prevent chronic infections with immune-evasive viruses. It may also control immune-evasive cancers that have downmodulated TAP expression.
Topics: Humans; Cross-Priming; Dendritic Cells; Antigen Presentation; Histocompatibility Antigens Class I; CD8-Positive T-Lymphocytes; Membrane Transport Proteins; Peptides; Viruses
PubMed: 37116384
DOI: 10.1016/j.coi.2023.102327 -
Biochemical Society Transactions Apr 2020Solute carrier (SLC) transporters play important roles in regulating the movement of small molecules and ions across cellular membranes. In mammals, they play an... (Review)
Review
Solute carrier (SLC) transporters play important roles in regulating the movement of small molecules and ions across cellular membranes. In mammals, they play an important role in regulating the uptake of nutrients and vitamins from the diet, and in controlling the distribution of their metabolic intermediates within the cell. Several SLC families also play an important role in drug transport and strategies are being developed to hijack SLC transporters to control and regulate drug transport within the body. Through the addition of amino acid and peptide moieties several novel antiviral and anticancer agents have been developed that hijack the proton-coupled oligopeptide transporters, PepT1 (SCL15A1) and PepT2 (SLC15A2), for improved intestinal absorption and renal retention in the body. A major goal is to understand the rationale behind these successes and expand the library of prodrug molecules that utilise SLC transporters. Recent co-crystal structures of prokaryotic homologues of the human PepT1 and PepT2 transporters have shed important new insights into the mechanism of prodrug recognition. Here, I will review recent developments in our understanding of ligand recognition and binding promiscuity within the SLC15 family, and discuss current models for prodrug recognition.
Topics: Animals; Biological Transport; Crystallography, X-Ray; Drug Design; Humans; Oligopeptides; Peptide Transporter 1; Prodrugs; Symporters; Valacyclovir; Valganciclovir
PubMed: 32219385
DOI: 10.1042/BST20180302 -
Journal of Pharmacological Sciences Oct 2019Neurons extend axons far from cell bodies, and retrograde communications from distal axons to cell bodies and/or dendrites play critical roles in the development and... (Review)
Review
Neurons extend axons far from cell bodies, and retrograde communications from distal axons to cell bodies and/or dendrites play critical roles in the development and maintenance of neuronal circuits. In neurotrophin signaling, the retrograde axonal transport of endosomes containing active ligand-receptor complexes from distal axons to somatodendrite compartments mediates retrograde signaling. However, the generality and specificity of these endosome-based transportations called "signaling endosomes" remain to be elucidated. Here, I summarize the discovery of semaphorin3A signaling endosomes, the first example other than neurotrophins to regulate dendritic development via AMPA receptor GluA2 localization in dendrites. The molecular components of Sema3A and neurotrophin signaling endosomes are distinct, but partially overlap to regulate specific and common cellular events. Because receptors are transported back to the cell bodies, neurons must replenish receptors on the growth cone surface to ensure continued response to the target-derived ligands. Recent findings have demonstrated that retrograde signaling endosomes also induce anterograde delivery of nascent receptors in neurotrophin signaling. The coupling between anterograde and retrograde axonal transport via signaling endosomes therefore plays a critical role in regulating proper neuronal network formation.
Topics: Animals; Axonal Transport; Axons; Cell Communication; Endosomes; Humans; Nerve Growth Factors; Protein Transport; Receptors, AMPA; Retrograde Degeneration; Semaphorin-3A; Signal Transduction
PubMed: 31679963
DOI: 10.1016/j.jphs.2019.10.001 -
Methods in Molecular Biology (Clifton,... 2022Normal functions of cell-surface proteins are dependent on their proper trafficking from the site of synthesis to the cell surface. Transport proteins mediating solute...
Normal functions of cell-surface proteins are dependent on their proper trafficking from the site of synthesis to the cell surface. Transport proteins mediating solute transfer across the plasma membrane constitute an important group of cell-surface proteins. There are several diseases resulting from mutations in these proteins that interfere with their transport function or trafficking, depending on the impact of the mutations on protein folding and structure. Recent advances in successful treatment of some of these diseases with small molecules which correct the mutations-induced folding and structural changes underline the need for detailed structural and biophysical characterization of membrane proteins. This requires methods to express and purify these proteins using heterologous expression systems. Here, using the solute carrier (SLC) transporter NaCT (Na-coupled citrate transporter) as an example, we describe experimental strategies for this approach. We chose this example because several mutations in NaCT, distributed throughout the protein, cause a severe neurologic disease known as early infantile epileptic encephalopathy-25 (EIEE-25). NaCT was modified with various peptide tags, including a RGS-His, a Twin-Strep, the SUMOstar domain, and an enhanced green fluorescent protein (EGFP), each alone or in various combinations. When transiently expressed in HEK293 cells, recombinant NaCT proteins underwent complex glycosylation, compartmentalized with the plasma membrane, and exhibited citrate transport activity similar to the nontagged protein. Surface NaCT expression was enhanced by the presence of SUMOstar on the N-terminus. The dual-purpose peptide epitopes RGS-His and Twin-Strep facilitated detection of NaCT by immunohistochemistry and western blot and may serve useful tags for affinity purification. This approach sets the stage for future analyses of mutant NaCT proteins that may alter protein folding and trafficking. It also demonstrates the capability of a transient mammalian cell expression system to produce human NaCT of sufficient quality and quantity to augment future biophysical and structural studies and drug discovery efforts.
Topics: Animals; Biological Transport; Cell Membrane; HEK293 Cells; Humans; Mammals; Membrane Proteins; Mutant Proteins; Peptides; Symporters
PubMed: 35773591
DOI: 10.1007/978-1-0716-2368-8_18 -
Chemistry (Weinheim An Der Bergstrasse,... Aug 2023Single molecules that co-transport cations as well as anions across lipid membranes are few despite their high biological utility. The elegant yet simple lipidomimmetic...
Single molecules that co-transport cations as well as anions across lipid membranes are few despite their high biological utility. The elegant yet simple lipidomimmetic peptide design herein enables efficient HCl transport without the use of any external additives for proton transport. The carboxylic acids in the dipeptide scaffold provide a handle to append two long hydrophobic tails and also provide a polar hydrophilic carboxylate group. The peptide central unit also provides NH sites for anion binding. Protonation of the carboxylate group coupled with the weak halide binding of the terminal NH group results in HCl transport with transport rates of H >Cl . The lipid-like structure also facilitates seamless membrane integration and flipping of the molecule. The biocompatibility, design simplicity, and potential pH regulation of these molecules open up several avenues for their therapeutic use.
Topics: Ion Transport; Anions; Peptides; Lipids; Biological Transport
PubMed: 37218621
DOI: 10.1002/chem.202301020 -
Bioconjugate Chemistry Dec 2023Systemic delivery of therapeutics into the brain is greatly impaired by multiple biological barriers─the blood-brain barrier (BBB) and the extracellular matrix (ECM)...
Systemic delivery of therapeutics into the brain is greatly impaired by multiple biological barriers─the blood-brain barrier (BBB) and the extracellular matrix (ECM) of the extracellular space. To address this problem, we developed a combinatorial approach to identify peptides that can shuttle and transport across both barriers. A cysteine-constrained heptapeptide M13 phage display library was iteratively panned against an established BBB model for three rounds to select for peptides that can transport across the barrier. Using next-generation DNA sequencing and analysis, we identified peptides that were selectively enriched from successive rounds of panning for functional validation in vitro and in vivo. Select peptide-presenting phages exhibited efficient shuttling across the BBB model. Two clones, Pep-3 and Pep-9, exhibited higher specificity and efficiency of transcytosis than controls. We confirmed that peptides Pep-3 and Pep-9 demonstrated better diffusive transport through the extracellular matrix than gold standard nona-arginine and clinically trialed angiopep-2 peptides. In studies, we demonstrated that systemically administered Pep-3 and Pep-9 peptide-presenting phages penetrate the BBB and distribute into the brain parenchyma. In addition, free peptides Pep-3 and Pep-9 achieved higher accumulation in the brain than free angiopep-2 and may exhibit brain targeting. In summary, these and studies highlight that combinatorial phage display with a designed selection strategy can identify peptides as promising carriers, which are able to overcome the multiple biological barriers of the brain and shuttle different-sized molecules from small fluorophores to large macromolecules for improved delivery into the brain.
Topics: Blood-Brain Barrier; Brain; Peptides; Biological Transport; Cell Surface Display Techniques
PubMed: 38085066
DOI: 10.1021/acs.bioconjchem.3c00446 -
Biochimica Et Biophysica Acta. Reviews... Jan 2020RLIP (Ral-interacting protein) is a multifunctional protein that couples ATP hydrolysis with the movement of substances. Its primary function appears to be in the plasma... (Review)
Review
RLIP (Ral-interacting protein) is a multifunctional protein that couples ATP hydrolysis with the movement of substances. Its primary function appears to be in the plasma membrane, where it catalyzes the ATP-dependent efflux of glutathione-conjugates (GS-Es), as well as un-metabolized drugs and toxins. In the plasma membrane, its interaction with the clathrin adaptor protein AP2 localizes it to endocytic vesicle, where its GS-E-stimulated ATPase and transport activity are required for clathrin-dependent endocytosis (CDE). CDE is an essential mechanism for internalizing ligand-receptor complexes that signal proliferation (EGF, insulin, IGF1), apoptosis (TNFα, TRAIL, Fas-L), and differentiation and morphogenesis (TGFβ, WNT, Notch, SHH). Aberrant functioning of these pathways appears crucial for most cancer cells to evade apoptosis, invade surrounding tissues, and metastasize. Internalization of receptor-ligand complexes by CDE begins a sequence of events that can terminate, initiate, or modulate downstream signaling; the consequences of signaling through these downstream pathways may be inherently different in cancer and normal cells, a view supported by numerous basic and clinical observations. In this review, we will discuss the GS-E transport activity of RLIP, which determines the rate of ligand endocytosis, and how the inhibition and/or depletion of RLIP globally disrupts in ligand-receptor signaling.
Topics: ATP-Binding Cassette Transporters; Cell Membrane; Clathrin; Endocytosis; GTPase-Activating Proteins; Humans; Ligands; Membrane Proteins; Protein Binding; Protein Transport; Signal Transduction
PubMed: 31904398
DOI: 10.1016/j.bbcan.2020.188337 -
Biochemical Society Transactions Oct 2020The conformation with which natural agonistic peptides interact with G protein-coupled receptor(s) (GPCR(s)) partly results from intramolecular interactions such as... (Review)
Review
The conformation with which natural agonistic peptides interact with G protein-coupled receptor(s) (GPCR(s)) partly results from intramolecular interactions such as hydrogen bridges or is induced by ligand-receptor interactions. The conformational freedom of a peptide can be constrained by intramolecular cross-links. Conformational constraints enhance the receptor specificity, may lead to biased activity and confer proteolytic resistance to peptidic GPCR agonists. Chemical synthesis allows to introduce a variety of cross-links into a peptide and is suitable for bulk production of relatively simple lead peptides. Lanthionines are thioether bridged alanines of which the two alanines can be introduced at different distances in chosen positions in a peptide. Thioether bridges are much more stable than disulfide bridges. Biosynthesis of lanthionine-constrained peptides exploiting engineered Gram-positive or Gram-negative bacteria that contain lanthionine-introducing enzymes constitutes a convenient method for discovery of lanthionine-stabilized GPCR agonists. The presence of an N-terminal leader peptide enables dehydratases to dehydrate serines and threonines in the peptide of interest after which a cyclase can couple the formed dehydroamino acids to cysteines forming (methyl)lanthionines. The leader peptide also guides the export of the formed lanthionine-containing precursor peptide out of Gram-positive bacteria via a lanthipeptide transporter. An engineered cleavage site in the C-terminus of the leader peptide allows to cleave off the leader peptide yielding the modified peptide of interest. Lanthipeptide GPCR agonists are an emerging class of therapeutics of which a few examples have demonstrated high efficacy in animal models of a variety of diseases. One lanthipeptide GPCR agonist has successfully passed clinical Phase Ia.
Topics: Alanine; Animals; Anti-Bacterial Agents; Bacterial Proteins; Disulfides; Drug Discovery; GTP-Binding Proteins; Gram-Negative Bacteria; Gram-Positive Bacteria; Humans; Lanthanoid Series Elements; Membrane Transport Proteins; Mice; Peptide Hydrolases; Peptides; Protein Domains; Protein Processing, Post-Translational; Protein Sorting Signals; Rats; Receptors, G-Protein-Coupled; Substrate Specificity; Sulfides
PubMed: 33125486
DOI: 10.1042/BST20200427 -
Trends in Immunology May 2022The essentially monomorphic human antigen presentation molecule HLA-E is an interesting candidate target to enable vaccination irrespective of genetic diversity.... (Review)
Review
The essentially monomorphic human antigen presentation molecule HLA-E is an interesting candidate target to enable vaccination irrespective of genetic diversity. Predictive HLA-E peptide-binding motifs have been refined to facilitate HLA-E peptide discovery. HLA-E can accommodate structurally divergent peptides of both self and microbial origin. Intracellular processing and presentation pathways for peptides by HLA-E for T cell receptor (TCR) recognition remain to be elucidated. Recent studies show that, unlike canonical peptides, inhibition of the transporter associated with antigen presentation (TAP) is essential to allow HLA-E antigen presentation in cytomegalovirus (CMV) infection and possibly also of other non-canonical peptides. We propose three alternative and TAP-independent MHC-E antigen-presentation pathways, including for Mycobacterium tuberculosis infections. These insights may help in designing potential HLA-E targeting vaccines against tumors and pathogens.
Topics: Antigen Presentation; Histocompatibility Antigens Class I; Humans; Membrane Transport Proteins; Peptides; Tuberculosis; Vaccination
PubMed: 35370095
DOI: 10.1016/j.it.2022.03.002