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Peptides Nov 2023The field of peptides exploded in the 1970's and has continued to be a major area of discovery. Among the early discoveries was that peptides administered peripherally... (Review)
Review
The field of peptides exploded in the 1970's and has continued to be a major area of discovery. Among the early discoveries was that peptides administered peripherally could affect brain functions. This led Kastin to propose that peptides could cross the blood-brain barrier (BBB). Although initially very controversial, Kastin, I, and others demonstrated not only that peptides can cross the BBB, but elucidated many fundamental characteristics of that passage. That work was in large part the basis of the 2022 Viktor Mutt Lectureship. Here, we review some of the early work with current updates on topics related to the penetration of peptides across the BBB. We briefly review mechanisms by which peripherally administered peptides can affect brain function without crossing the BBB, and then review the major mechanisms by which peptides and their analogs have been show to cross the BBB: transmembrane diffusion, saturable transport, and adsorptive transcytosis. Saturable transport systems are adaptable to physiologic changes and can be altered by disease states. In particular, the transport across the BBB of insulin and of pituitary adenylate cyclase activating polypeptide (PACAP) illustrate many of the concepts regarding peptide transport across the BBB.
Topics: Blood-Brain Barrier; Biological Transport; Pituitary Adenylate Cyclase-Activating Polypeptide; Insulin
PubMed: 37598757
DOI: 10.1016/j.peptides.2023.171079 -
Methods and Applications in Fluorescence Jan 2022Postprandial insulin-stimulated glucose uptake into target tissue is crucial for the maintenance of normal blood glucose homeostasis. This step is rate-limited by the... (Review)
Review
Postprandial insulin-stimulated glucose uptake into target tissue is crucial for the maintenance of normal blood glucose homeostasis. This step is rate-limited by the number of facilitative glucose transporters type 4 (GLUT4) present in the plasma membrane. Since insulin resistance and impaired GLUT4 translocation are associated with the development of metabolic disorders such as type 2 diabetes, this transporter has become an important target of antidiabetic drug research. The application of screening approaches that are based on the analysis of GLUT4 translocation to the plasma membrane to identify substances with insulinomimetic properties has gained global research interest in recent years. Here, we review methods that have been implemented to quantitate the translocation of GLUT4 to the plasma membrane. These methods can be broadly divided into two sections: microscopy-based technologies (e.g., immunoelectron, confocal or total internal reflection fluorescence microscopy) and biochemical and spectrometric approaches (e.g., membrane fractionation, photoaffinity labeling or flow cytometry). In this review, we discuss the most relevant approaches applied to GLUT4 thus far, highlighting the advantages and disadvantages of these approaches, and we provide a critical discussion and outlook into new methodological opportunities.
Topics: Diabetes Mellitus, Type 2; Glucose Transporter Type 4; Humans; Insulin; Microscopy, Fluorescence; Protein Transport
PubMed: 35008072
DOI: 10.1088/2050-6120/ac4998 -
International Journal of Molecular... Jul 2022Ultrashort peptides (USPs), consisting of 2-7 amino-acid residues, are a group of signaling molecules that regulate gene expression and protein synthesis under normal... (Review)
Review
Ultrashort peptides (USPs), consisting of 2-7 amino-acid residues, are a group of signaling molecules that regulate gene expression and protein synthesis under normal conditions in various diseases and ageing. USPs serve as a basis for the development of drugs with a targeted mechanism of action. The purpose of this review is to systematize the available data on USP transport involving POT and LAT transporters in various organs and tissues under normal, pathological and ageing conditions. The carriers of the POT family (PEPT1, PEPT2, PHT1, PHT2) transport predominantly di- and tripeptides into the cell. Methods of molecular modeling and physicochemistry have demonstrated the ability of LAT1 to transfer not only amino acids but also some di- and tripeptides into the cell and out of it. LAT1 and 2 are involved in the regulation of the antioxidant, endocrine, immune and nervous systems' functions. Analysis of the above data allows us to conclude that, depending on their structure, di- and tripeptides can be transported into the cells of various tissues by POT and LAT transporters. This mechanism is likely to underlie the tissue specificity of peptides, their geroprotective action and effectiveness in the case of neuroimmunoendocrine system disorders.
Topics: Amino Acids; Biological Transport; Membrane Transport Proteins; Organ Specificity; Peptides; Symporters
PubMed: 35887081
DOI: 10.3390/ijms23147733 -
Chimia Jun 2021This review on intracellular delivery and oral bioavailability of peptides reflects a number of principal investigations at Novartis. Our studies were aimed at either... (Review)
Review
This review on intracellular delivery and oral bioavailability of peptides reflects a number of principal investigations at Novartis. Our studies were aimed at either understanding features enabling peptides to interfere with intracellular protein-protein interactions, or to achieve a more patient-friendly delivery by the oral route. In the light of these objectives, we have also spent some effort on assay development to come up with alternative methods for monitoring cellular peptide uptake. This summary of our insights is intended to help in the assessment and development of peptide therapeutics requiring membrane transition.
Topics: Administration, Oral; Biological Availability; Biological Transport; Humans; Peptides; Permeability
PubMed: 34233817
DOI: 10.2533/chimia.2021.522 -
Frontiers in Cellular and Infection... 2023Copper, a vital element in various physiological processes, is transported from the gastrointestinal tract to tissues and cells through diverse copper transporters.... (Review)
Review
Copper, a vital element in various physiological processes, is transported from the gastrointestinal tract to tissues and cells through diverse copper transporters. Among these transporters, ATP7A and ATP7B play significant roles in regulating systemic copper metabolism and exhibit precise regulation in their intracellular trafficking. These transporters undergo dynamic shuttling between the trans-Golgi network (TGN) and the plasma membrane via the endocytic recycling mechanism, which involves the retromer and other associated factors. Interestingly, the antimicrobial attribute of copper implies a potential connection between microbial infection and copper metabolism. Several microbes, including , , Influenza A virus (IAV) and Zika virus (ZIKV) have been observed to impact the regulatory mechanisms of ATP7A/B, either directly or indirectly, as a means of survival. This review summarizes the key features and trafficking mechanisms of the copper transporters ATP7A/B, and examines the intricate interplay between microbes and copper metabolism. Ultimately, it highlights how microbes can perturb copper homeostasis through interactions with host factors, offering valuable insights into the mechanistic aspects of host-microbe interactions.
Topics: Humans; Copper; Adenosine Triphosphatases; Zika Virus Infection; Cation Transport Proteins; Zika Virus; Copper Transport Proteins; Copper-Transporting ATPases; Peptide Fragments
PubMed: 38106478
DOI: 10.3389/fcimb.2023.1267931 -
Current Opinion in Plant Biology Oct 2023Proteinogenic dipeptides, with few known exceptions, are products of protein degradation. Dipeptide levels respond to the changes in the environment, often in a... (Review)
Review
Proteinogenic dipeptides, with few known exceptions, are products of protein degradation. Dipeptide levels respond to the changes in the environment, often in a dipeptide-specific manner. What drives this specificity is currently unknown; what likely contributes is the activity of the different peptidases that cleave off the terminal dipeptide from the longer peptides. Dipeptidases that degrade dipeptides to amino acids, and the turnover rates of the "substrate" proteins/peptides. Plants can both uptake dipeptides from the soil, but dipeptides are also found in root exudates. Dipeptide transporters, members of the proton-coupled peptide transporters NTR1/PTR family, contribute to nitrogen reallocation between the sink and source tissues. Besides their role in nitrogen distribution, it becomes increasingly clear that dipeptides may also serve regulatory, dipeptide-specific functions. Dipeptides are found in protein complexes affecting the activity of their protein partners. Moreover, dipeptide supplementation leads to cellular phenotypes reflected in changes in plant growth and stress tolerance. Herein we will review the current understanding of dipeptides' metabolism, transport, and functions and discuss significant challenges and future directions for the comprehensive characterization of this fascinating but underrated group of small-molecule compounds.
Topics: Dipeptides; Biological Transport; Amino Acids; Nitrogen
PubMed: 37311365
DOI: 10.1016/j.pbi.2023.102395 -
Biomaterials Science Nov 2022Intracellular delivery of macromolecules is a critical procedure for biological research and drug discovery, including proteins, peptides, vaccines, antibodies and... (Review)
Review
Intracellular delivery of macromolecules is a critical procedure for biological research and drug discovery, including proteins, peptides, vaccines, antibodies and genes. The penetration of macromolecule therapeutics through the cell membrane to intracellular targets is a prerequisite for their biological activity, but most delivery systems rely on the endocytic pathway to enter the cell and confront an inability to escape from the lysosome. A profound understanding of the cellular internalization of transporting carriers can (i) optimize the design of drug delivery systems, (ii) maintain the biological activity of biomolecular drugs, (iii) improve the efficiency of intracellular macromolecule transport and release, (iv) bring new opportunities for the discovery of macromolecule therapeutics and treatment of refractory disease. This article summarizes the uptake pathway of intracellular delivery vehicles for macromolecule drugs, hoping to provide ideas and references for macromolecule therapeutics delivery systems.
Topics: Drug Delivery Systems; Macromolecular Substances; Peptides; Biological Transport; Proteins
PubMed: 36214257
DOI: 10.1039/d2bm01348g -
EMBO Reports Oct 2023Monoamine transporters retrieve serotonin (SERT), dopamine (DAT), and norepinephrine (NET) from the synaptic cleft. Transporter internalization contributes to the...
Monoamine transporters retrieve serotonin (SERT), dopamine (DAT), and norepinephrine (NET) from the synaptic cleft. Transporter internalization contributes to the regulation of their surface expression. Clathrin-mediated endocytosis of plasma membrane proteins requires adaptor protein-2 (AP2), which recruits cargo to the nascent clathrin cage. However, the intracellular portions of monoamine transporters are devoid of a conventional AP2-binding site. Here, we identify a MAD2 (mitotic arrest deficient-2) interaction motif in the C-terminus of SERT, which binds the closed conformation of MAD2 and allows for the recruitment of two additional mitotic spindle assembly checkpoint (SAC) proteins, BubR1 and p31 , and of AP2. We visualize MAD2, BubR1, and p31 in dorsal raphe neurons, and depletion of MAD2 in primary serotonergic rat neurons decreases SERT endocytosis in the soma. Our findings do not only provide mechanistic insights into transporter internalization but also allow for rationalizing why SAC proteins are present in post-mitotic neurons.
Topics: Rats; Animals; Serotonin Plasma Membrane Transport Proteins; Mad2 Proteins; Nuclear Proteins; Cell Cycle Proteins; Adaptor Proteins, Signal Transducing; Endocytosis; Spindle Apparatus; Clathrin
PubMed: 37530743
DOI: 10.15252/embr.202153408 -
Biochimica Et Biophysica Acta.... Jun 2020In the mitochondria of healthy cells, Apoptosis-Inducing factor (AIF) is required for the optimal functioning of the respiratory chain machinery, mitochondrial... (Review)
Review
In the mitochondria of healthy cells, Apoptosis-Inducing factor (AIF) is required for the optimal functioning of the respiratory chain machinery, mitochondrial integrity, cell survival, and proliferation. In all analysed species, it was revealed that the downregulation or depletion of AIF provokes mainly the post-transcriptional loss of respiratory chain Complex I protein subunits. Recent progress in the field has revealed that AIF fulfils its mitochondrial pro-survival function by interacting physically and functionally with CHCHD4, the evolutionarily-conserved human homolog of yeast Mia40. The redox-regulated CHCHD4/Mia40-dependent import machinery operates in the intermembrane space of the mitochondrion and controls the import of a set of nuclear-encoded cysteine-motif carrying protein substrates. In addition to their participation in the biogenesis of specific respiratory chain protein subunits, CHCHD4/Mia40 substrates are also implicated in the control of redox regulation, antioxidant response, translation, lipid homeostasis and mitochondrial ultrastructure and dynamics. Here, we discuss recent insights on the AIF/CHCHD4-dependent protein import pathway and review current data concerning the CHCHD4/Mia40 protein substrates in metazoan. Recent findings and the identification of disease-associated mutations in AIF or in specific CHCHD4/Mia40 substrates have highlighted these proteins as potential therapeutic targets in a variety of human disorders.
Topics: Apoptosis Inducing Factor; Cysteine; Disulfides; Electron Transport Complex I; Gene Expression Regulation; Humans; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Precursor Protein Import Complex Proteins; Mitochondrial Proteins; Mutation; Protein Transport; Saccharomyces cerevisiae
PubMed: 32105825
DOI: 10.1016/j.bbadis.2020.165746 -
Amino Acids Aug 2022L-Carnosine (β-alanyl-L-histidine) is a well-known antioxidant and neuroprotector in various models on animals and cell cultures. However, while there is a plethora of...
L-Carnosine (β-alanyl-L-histidine) is a well-known antioxidant and neuroprotector in various models on animals and cell cultures. However, while there is a plethora of data demonstrating its efficiency as a neuroprotector, there is a distinct lack of data regarding the mechanism of its take up by neurons. According to literature, cultures of rat astrocytes, SKPT cells and rat choroid plexus epithelial cells take up carnosine via the H-coupled PEPT2 membrane transporter. We've assessed the effectiveness and mechanism of carnosine transport, and its stability in primary rat cortical culture neurons. We demonstrated that neurons take up carnosine via active transport with Km = 119 μM and a maximum velocity of 0.289 nmol/mg (prot)/min. Passive transport speed constituted 0.21∙10 nmol/mg (prot)/min (with 119 μM concentration in the medium)-significantly less than active transport speed. However, carnosine concentrations over 12.5 mM led to passive transport speed becoming greater than active transport speed. Using PEPT2 inhibitor zofenopril, we demonstrated that PEPT2-dependent transport is one of the main modes of carnosine take up by neurons. Our experiments demonstrated that incubation with carnosine does not affect PEPT2 amount present in culture. At the same time, after removing carnosine from the medium, its elimination speed by culture cells reached 0.035 nmol/mg (prot)/min, which led to a decrease in carnosine quantity to control levels in culture within 1 h. Thus, carnosine is taken up by neurons with an effectiveness comparable to that of other PEPT2 substrates, but its elimination rate suggests that for effective use as a neuroprotector it's necessary to either maintain a high concentration in brain tissue, or increase the effectiveness of glial cell synthesis of endogenous carnosine and its shuttling into neurons, or use more stable chemical modifications of carnosine.
Topics: Animals; Biological Transport, Active; Carnosine; Choroid Plexus; Membrane Transport Proteins; Rats; Symporters
PubMed: 34694500
DOI: 10.1007/s00726-021-03094-5