-
International Journal of Molecular... Nov 2023The blood-brain barrier (BBB) is a unique and selective feature of the central nervous system's vasculature. BBB dysfunction has been observed as an early sign of... (Review)
Review
The blood-brain barrier (BBB) is a unique and selective feature of the central nervous system's vasculature. BBB dysfunction has been observed as an early sign of Alzheimer's Disease (AD) before the onset of dementia or neurodegeneration. The intricate relationship between the BBB and the pathogenesis of AD, especially in the context of neurovascular coupling and the overlap of pathophysiology in neurodegenerative and cerebrovascular diseases, underscores the urgency to understand the BBB's role more deeply. Preserving or restoring the BBB function emerges as a potentially promising strategy for mitigating the progression and severity of AD. Molecular and genetic changes, such as the isoform ε4 of apolipoprotein E (ApoEε4), a significant genetic risk factor and a promoter of the BBB dysfunction, have been shown to mediate the BBB disruption. Additionally, receptors and transporters like the low-density lipoprotein receptor-related protein 1 (LRP1), P-glycoprotein (P-gp), and the receptor for advanced glycation end products (RAGEs) have been implicated in AD's pathogenesis. In this comprehensive review, we endeavor to shed light on the intricate pathogenic and therapeutic connections between AD and the BBB. We also delve into the latest developments and pioneering strategies targeting the BBB for therapeutic interventions, addressing its potential as a barrier and a carrier. By providing an integrative perspective, we anticipate paving the way for future research and treatments focused on exploiting the BBB's role in AD pathogenesis and therapy.
Topics: Humans; Alzheimer Disease; Blood-Brain Barrier; Amyloid beta-Peptides; Biological Transport; Cerebrovascular Disorders
PubMed: 38003477
DOI: 10.3390/ijms242216288 -
International Journal of Molecular... Sep 2023This review analyzes the causes and consequences of apoptosis resulting from oxidative stress that occurs in mitochondria and cells exposed to the toxic effects of... (Review)
Review
This review analyzes the causes and consequences of apoptosis resulting from oxidative stress that occurs in mitochondria and cells exposed to the toxic effects of different-valence heavy metals (Ag, Tl, Hg, Cd, Pb, Al, Ga, In, As, Sb, Cr, and U). The problems of the relationship between the integration of these toxic metals into molecular mechanisms with the subsequent development of pathophysiological processes and the appearance of diseases caused by the accumulation of these metals in the body are also addressed in this review. Such apoptosis is characterized by a reduction in cell viability, the activation of caspase-3 and caspase-9, the expression of pro-apoptotic genes ( and ), and the activation of protein kinases (ERK, JNK, p53, and p38) by mitogens. Moreover, the oxidative stress manifests as the mitochondrial permeability transition pore (MPTP) opening, mitochondrial swelling, an increase in the production of reactive oxygen species (ROS) and HO, lipid peroxidation, cytochrome c release, a decline in the inner mitochondrial membrane potential (ΔΨ), a decrease in ATP synthesis, and reduced glutathione and oxygen consumption as well as cytoplasm and matrix calcium overload due to Ca release from the endoplasmic reticulum (ER). The apoptosis and respiratory dysfunction induced by these metals are discussed regarding their interaction with cellular and mitochondrial thiol groups and Fe metabolism disturbance. Similarities and differences in the toxic effects of Tl from those of other heavy metals under review are discussed. Similarities may be due to the increase in the cytoplasmic calcium concentration induced by Tl and these metals. One difference discussed is the failure to decrease Tl toxicity through metallothionein-dependent mechanisms. Another difference could be the decrease in reduced glutathione in the matrix due to the reversible oxidation of Tl to Tl near the centers of ROS generation in the respiratory chain. The latter may explain why thallium toxicity to humans turned out to be higher than the toxicity of mercury, lead, cadmium, copper, and zinc.
Topics: Humans; Reactive Oxygen Species; Calcium; Hydrogen Peroxide; Mitochondrial Membrane Transport Proteins; Mitochondria; Apoptosis; Oxidative Stress; Cadmium; Glutathione; Metals, Heavy; Membrane Potential, Mitochondrial
PubMed: 37833908
DOI: 10.3390/ijms241914459 -
Nature Communications Dec 2023The BCL-2 family protein BAX is a major regulator of physiological and pathological cell death. BAX predominantly resides in the cytosol in a quiescent state and upon...
The BCL-2 family protein BAX is a major regulator of physiological and pathological cell death. BAX predominantly resides in the cytosol in a quiescent state and upon stress, it undergoes conformational activation and mitochondrial translocation leading to mitochondrial outer membrane permeabilization, a critical event in apoptosis execution. Previous studies reported two inactive conformations of cytosolic BAX, a monomer and a dimer, however, it remains unclear how they regulate BAX. Here we show that, surprisingly, cancer cell lines express cytosolic inactive BAX dimers and/or monomers. Expression of inactive dimers, results in reduced BAX activation, translocation and apoptosis upon pro-apoptotic drug treatments. Using the inactive BAX dimer structure and a pharmacophore-based drug screen, we identify a small-molecule modulator, BDM19 that binds and activates cytosolic BAX dimers and prompts cells to apoptosis either alone or in combination with BCL-2/BCL-XL inhibitor Navitoclax. Our findings underscore the role of the cytosolic inactive BAX dimer in resistance to apoptosis and demonstrate a strategy to potentiate BAX-mediated apoptosis.
Topics: bcl-2-Associated X Protein; Cytosol; Apoptosis; Biological Transport; Antineoplastic Agents; Proto-Oncogene Proteins c-bcl-2; bcl-X Protein
PubMed: 38104127
DOI: 10.1038/s41467-023-44084-3 -
A signal peptide peptidase is required for ER-symbiosome proximal association and protein secretion.Nature Communications Jul 2023During legume-rhizobia symbiosis, differentiation of the symbiosome (engulfed intracellular rhizobia) is necessary for successful nitrogen fixation. To control...
During legume-rhizobia symbiosis, differentiation of the symbiosome (engulfed intracellular rhizobia) is necessary for successful nitrogen fixation. To control symbiosome differentiation, host cell subcellular components, e.g., ER (endoplasmic reticulum), must adapt robustly to ensure large-scale host protein secretion to the new organelle. However, the key components controlling the adaption of ER in nodule cells remain elusive. We report that Medicago BID1, a nodule-specific signal peptide peptidase (SPP), is central to ER structural dynamics and host protein secretion. In bid1, symbiosome differentiation is blocked. BID1 localizes specifically to the ER membrane and expresses exclusively in nodule cells with symbiosomes. In the wild type ER forms proximal association structures with symbiosomes, but not in bid1. Consequently, in bid1 excessive ER stress responses are induced and ER-to-symbiosome protein secretion is impaired. In summary, a nodule-specific SPP is necessary for ER-symbiosome proximal association, host protein secretion, and symbiosome differentiation.
Topics: Root Nodules, Plant; Protein Transport; Nitrogen Fixation; Symbiosis; Plant Proteins
PubMed: 37468528
DOI: 10.1038/s41467-023-40008-3 -
Journal of Ethnopharmacology Jan 2024Cholestatic Liver Fibrosis (CLF) is a hepatobiliary disease that typically arises as a late-stage complication of cholestasis, which can have multiple underlying causes....
ETHNOPHARMACOLOGICAL RELEVANCE
Cholestatic Liver Fibrosis (CLF) is a hepatobiliary disease that typically arises as a late-stage complication of cholestasis, which can have multiple underlying causes. There are no satisfactory chemical or biological drugs for CLF. Total Astragalus saponins (TAS) are considered to be the main active constituents of the traditional Chinese herb Astragali Radix (AR), which has the obvious improvement effects for treating CLF. However, the mechanism of anti-CLF effects of TAS is still unclear.
AIM OF THE STUDY
The present study was undertaken to investigate the therapeutic effects of TAS against bile duct ligation (BDL) and 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) -induced CLF models and to reveal the potential mechanism to support its clinic use with scientific evidence.
MATERIALS AND METHODS
In this study, BDL-induced CLF rats were treated with TAS (20 mg/kg, 40 mg/kg) and DDC-induced CLF mice were treated with 56 mg/kg TAS. The therapeutic effects of TAS on extrahepatic and intrahepatic CLF models were evaluated by serum biochemical analysis, liver histopathology and hydroxyproline (Hyp). Thirty-nine individual bile acids (BAs) in serum and liver were quantified by using UHPLC-Q-Exactive Orbitrap HRMS. qRT-PCR, Western blot and immunohistochemistry analysis were used to measure the expression of liver fibrosis and ductular reaction markers, inflammatory factors and BAs related metabolic transporters, along with nuclear receptor farnesoid X receptor (FXR).
RESULTS
The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBiL), direct bilirubin (DBiL) and contents of liver Hyp were dose-dependently improved after treatment for TAS in BDL and DDC- induced CLF models. And the increased levels of ALT and AST were significantly improved by total extract from Astragali radix (ASE) in BDL model. The liver fibrosis and ductular reaction markers, α-smooth muscle actin (α-SMA) and cytokeratin 19 (CK19), were significantly ameliorated in TAS group. And the liver expression of inflammatory factors: interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were significantly decreased after TAS treatment. In addition, TAS significantly ameliorated taurine-conjugated BAs (tau-BAs) levels, particularly α-TMCA, β-TMCA and TCA contents in serum and liver, which correlated with induced expressions of hepatic FXR and BAs secretion transporters. Furthermore, TAS significantly improved short heterodimer partner (SHP), cholesterol 7α-hydroxylase (Cyp7a1), Na taurocholate cotransport peptide (NTCP) and bile-salt export pump (BSEP) mRNA and protein expression.
CONCLUSIONS
TAS exerted a hepatoprotective effect against CLF by ameliorating liver injury, inflammation and restoring the altered tau-BAs metabolism to produce a positive regulatory effect on FXR-related receptors and transporters.
Topics: Rats; Mice; Animals; Saponins; Liver; Cholestasis, Intrahepatic; Liver Cirrhosis; Cholestasis; Bile Acids and Salts; Membrane Transport Proteins; Bilirubin
PubMed: 37400008
DOI: 10.1016/j.jep.2023.116833 -
Critical Care (London, England) Nov 2023Critically ill patients suffer from acute muscle wasting, which is associated with significant physical functional impairment. We describe data from nested muscle biopsy...
BACKGROUND
Critically ill patients suffer from acute muscle wasting, which is associated with significant physical functional impairment. We describe data from nested muscle biopsy studies from two trials of functional electrical stimulation (FES) that did not shown improvements in physical function.
METHODS
Primary cohort: single-centre randomized controlled trial. Additional healthy volunteer data from patients undergoing elective hip arthroplasty. Validation cohort: Four-centre randomized controlled trial.
INTERVENTION
FES cycling for 60-90min/day.
ANALYSES
Skeletal muscle mRNA expression of 223 genes underwent hierarchal clustering for targeted analysis and validation.
RESULTS
Positively enriched pathways between healthy volunteers and ICU participants were "stress response", "response to stimuli" and "protein metabolism", in keeping with published data. Positively enriched pathways between admission and day 7 ICU participants were "FOXO-mediated transcription" (admission = 0.48 ± 0.94, day 7 = - 0.47 ± 1.04 mean log fold change; P = 0.042), "Fatty acid metabolism" (admission = 0.50 ± 0.67, day 7 = 0.07 ± 1.65 mean log fold change; P = 0.042) and "Interleukin-1 processing" (admission = 0.88 ± 0.50, day 7 = 0.97 ± 0.76 mean log fold change; P = 0.054). Muscle mRNA expression of UCP3 (P = 0.030) and DGKD (P = 0.040) decreased in both cohorts with no between group differences. Changes in IL-18 were not observed in the validation cohort (P = 0.268). Targeted analyses related to intramuscular mitochondrial substrate oxidation, fatty acid oxidation and intramuscular inflammation showed PPARγ-C1α; (P < 0.001), SLC25A20 (P = 0.017) and UCP3 (P < 0.001) decreased between admission and day 7 in both arms. LPIN-1 (P < 0.001) and SPT1 (P = 0.044) decreased between admission and day 7. IL-18 (P = 0.011) and TNFRSF12A (P = 0.009) increased in both arms between admission and day 7. IL-1β (P = 0.007), its receptor IL-1R1 (P = 0.005) and IL-6R (P = 0.001) decreased in both arms between admission and day 7. No between group differences were seen in any of these (all p > 0.05).
CONCLUSIONS
Intramuscular inflammation and altered substrate utilization are persistent in skeletal muscle during first week of critical illness and are not improved by the application of Functional Electrical Stimulation-assisted exercise. Future trials of exercise to prevent muscle wasting and physical impairment are unlikely to be successful unless these processes are addressed by other means than exercise alone.
Topics: Humans; Critical Illness; Interleukin-18; Intensive Care Units; Muscular Atrophy; Electric Stimulation; Fatty Acids; RNA, Messenger; Membrane Transport Proteins
PubMed: 37932834
DOI: 10.1186/s13054-023-04664-7 -
Journal of the American Chemical Society Aug 2023Membrane proteins are a crucial class of therapeutic targets that remain challenging to modulate using traditional occupancy-driven inhibition strategies or current...
Membrane proteins are a crucial class of therapeutic targets that remain challenging to modulate using traditional occupancy-driven inhibition strategies or current proteolysis-targeting degradation approaches. Here, we report that the inherent endolysosomal sorting machinery can be harnessed for the targeted degradation of membrane proteins. A new degradation technique, termed signal-mediated lysosome-targeting chimeras (SignalTACs), was developed by genetically fusing the signaling motif from the cation-independent mannose-6-phosphate receptor (CI-M6PR) to a membrane protein binder. Antibody-based SignalTACs were constructed with the CI-M6PR signal peptides fused to the C-terminus of both heavy and light chains of IgG. We demonstrated the scope of this platform technology by degrading five pathogenesis-related membrane proteins, including HER2, EGFR, PD-L1, CD20, and CD71. Furthermore, two simplified constructs of SignalTACs, nanobody-based and peptide-based SignalTACs, were created and shown to promote the lysosomal degradation of target membrane proteins. Compared to the parent antibodies, SignalTACs exhibited significantly higher efficiency in inhibiting tumor cell growth both in vitro and in vivo. This work provides a simple, general, and robust strategy for degrading membrane proteins with molecular precision and may represent a powerful platform with broad research and therapeutic applications.
Topics: Membrane Proteins; Receptor, IGF Type 2; Lysosomes; Protein Transport; Cations
PubMed: 37552887
DOI: 10.1021/jacs.3c07687 -
Drug Discovery Today Aug 2023Efficient intracellular delivery is essential for most therapeutic agents; however, existing delivery vectors face a dilemma between efficiency and toxicity, and always... (Review)
Review
Efficient intracellular delivery is essential for most therapeutic agents; however, existing delivery vectors face a dilemma between efficiency and toxicity, and always encounter the challenge of endolysosomal trapping. The cell-penetrating poly(disulfide) (CPD) is an effective tool for intracellular delivery, as it is taken up through thiol-mediated cellular uptake, thus avoiding endolysosomal entrapment and ensuring efficient cytosolic availability. Upon cellular uptake, CPD undergoes reductive depolymerization by glutathione inside cells and has minimal cytotoxicity. This review summarizes CPD's chemical synthesis approaches, cellular uptake mechanism, and recent advances in the intracellular delivery of proteins, antibodies, nucleic acids, and other nanoparticles. Overall, CPD is a promising candidate carrier for efficient intracellular delivery.
Topics: Disulfides; Proteins; Nanoparticles; Antibodies; Biological Transport; Cell-Penetrating Peptides
PubMed: 37321318
DOI: 10.1016/j.drudis.2023.103668 -
Nature Structural & Molecular Biology Dec 2023Over half of mitochondrial proteins are imported from the cytosol via the pre-sequence pathway, controlled by the TOM complex in the outer membrane and the TIM23 complex...
Over half of mitochondrial proteins are imported from the cytosol via the pre-sequence pathway, controlled by the TOM complex in the outer membrane and the TIM23 complex in the inner membrane. The mechanisms through which proteins are translocated via the TOM and TIM23 complexes remain unclear. Here we report the assembly of the active TOM-TIM23 supercomplex of Saccharomyces cerevisiae with translocating polypeptide substrates. Electron cryo-microscopy analyses reveal that the polypeptide substrates pass the TOM complex through the center of a Tom40 subunit, interacting with a glutamine-rich region. Structural and biochemical analyses show that the TIM23 complex contains a heterotrimer of the subunits Tim23, Tim17 and Mgr2. The polypeptide substrates are shielded from lipids by Mgr2 and Tim17, which creates a translocation pathway characterized by a negatively charged entrance and a central hydrophobic region. These findings reveal an unexpected pre-sequence pathway through the TOM-TIM23 supercomplex spanning the double membranes of mitochondria.
Topics: Membrane Transport Proteins; Mitochondrial Precursor Protein Import Complex Proteins; Carrier Proteins; Mitochondrial Membrane Transport Proteins; Saccharomyces cerevisiae Proteins; Protein Transport; Mitochondria; Saccharomyces cerevisiae; Mitochondrial Proteins; Peptides; Membrane Proteins
PubMed: 37696957
DOI: 10.1038/s41594-023-01103-7 -
Structure (London, England : 1993) Aug 2023The HNRNPH2 proline-tyrosine nuclear localization signal (PY-NLS) is mutated in HNRNPH2-related X-linked neurodevelopmental disorder, causing the normally nuclear...
The HNRNPH2 proline-tyrosine nuclear localization signal (PY-NLS) is mutated in HNRNPH2-related X-linked neurodevelopmental disorder, causing the normally nuclear HNRNPH2 to accumulate in the cytoplasm. We solved the cryoelectron microscopy (cryo-EM) structure of Karyopherin-β2/Transportin-1 bound to the HNRNPH2 PY-NLS to understand importin-NLS recognition and disruption in disease. HNRNPH2 RPGPY is a typical R-X-P-Y motif comprising PY-NLS epitopes 2 and 3, followed by an additional Karyopherin-β2-binding epitope, we term epitope 4, at residues DRP; no density is present for PY-NLS epitope 1. Disease variant mutations at epitopes 2-4 impair Karyopherin-β2 binding and cause aberrant cytoplasmic accumulation in cells, emphasizing the role of nuclear import defect in disease. Sequence/structure analysis suggests that strong PY-NLS epitopes 4 are rare and thus far limited to close paralogs of HNRNPH2, HNRNPH1, and HNRNPF. Epitope 4-binidng hotspot Karyopherin-β2 W373 corresponds to close paralog Karyopherin-β2b/Transportin-2 W370, a pathological variant site in neurodevelopmental abnormalities, suggesting that Karyopherin-β2b/Transportin-2-HNRNPH2/H1/F interactions may be compromised in the abnormalities.
Topics: Karyopherins; Nuclear Localization Signals; Epitopes; Tyrosine; Proline; Cryoelectron Microscopy; Active Transport, Cell Nucleus; beta Karyopherins; Cell Nucleus
PubMed: 37279758
DOI: 10.1016/j.str.2023.05.010