• The Korean Journal of Physiology
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• v.30 no.2
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• pp.197-208
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• 1996

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

• The Korean Journal of Zoology
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• v.24 no.3
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• pp.145-150
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• 1981

저자들이 1975년부터 1980년까지 동해안에서 採集된 四方海綿類를 同定한 結果, 이들 중 스피로포리다 해면目 유두해면科의 한종이 신종으로 밝혀져, Tetilla koreana로 命名하고 記載 報告한다. 이 종은 특징있는 태생형 (viviparous)의 유성생식을 하며 성체의 체내 (endosome)에 많은 발생배 (embryo or yound sponge)를 품고 있다. 완模式 標本은 梨大 自然史 博物館에 副模式 標本은 梨大 生物學科에 보관하고 있다.

• Molecules and Cells
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• v.19 no.1
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• pp.39-45
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• 2005

RPK118 is a sphingosine kinase-1-binding protein that has been implicated in sphingosine 1 phosphate-mediated signaling. It contains a PX (phox homology) domain and two pseudo-kinase domains, and co-localizes with sphingosine kinase-1 on early endosomes. In this study we identified a novel RPK118-binding protein, PRDX3 (peroxiredoxin-3), by yeast two-hybrid screening. The interaction between these proteins was confirmed by pull-down assays and co-immunoprecipitation experiments. Deletion studies showed that RPK118 interacted with PRDX3 through its pseudokinase domains, and with early endosomes through its PX domain. Double immunofluorescence experiments demonstrated that PRDX3 co-localized with RPK118 on early endosomes in COS7 cells. PRDX3 is a member of the antioxidant family of proteins synthesized in the cytoplasm and functioning in mitochondria. Our findings indicate that RPK118 is a PRDX3-binding protein that may be involved in transporting PRDX3 from the cytoplasm to its mitochondrial site of function or to other membrane structures via endosome trafficking.

• Biomolecules & Therapeutics
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• v.10 no.4
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• pp.293-302
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• 2002

The classical concept for iron uptake into mammalian cells has been the endocytosis of transferrin( $T_{f}$ )-bound F $e^{3+}$ via the $T_{f}$ - $T_{f}$ receptor cycle. In this case, we could not explain the uptake of F $e^{2＋}$ ion and the export of iron from endosome. Studies on iron transport revealed that other transport system exists in epithelial cells of the intestine. One of non- $T_{f}$ -receptor-mediated transport systems is Nramp2/DMT1/DCT1 which transports M $n^{＋＋}$, $Mg^{＋＋}$, Z $n^{＋＋}$, $Co^{＋＋}$, N $i^{＋＋}$ or C $u^{＋＋}$ ion as well as F $e^{+2}$ ion. DMT1 was cloned from intestines of iron-deficient rats and shown to be a hydrogen ion-coupled iron transporter and a protein regulated by absorbed dietary iron. DMT1 is founded in other cells such as cortical and hippocampal glial cells as well as endothelial cells in duodenum. Two F $e^{3+}$ ion bound to transferrin( $T_{f}$ ) are taken up via the $T_{f}$ - $T_{f}$ receptor cycle in the intestinal epithelial cell. F $e^{3+}$ in endosome was converted to F $e^{2＋}$ ion, and then exported to cytosol via DMT1. F $e^{2＋}$ ion is taken up into cytosol via DMT1. Several other transporters such as FET, FRE, CCC2, AFT1, SMF, FTR, ZER, ZIP, ZnT and CTR have been reported recently and dysfunction of the transporters are related with diseases containing Wilson's disease, Menkes disease and hemochromatosis. Evidences from several studies strongly suggest that DMT1 is the major transporter of iron in the intestine and functions critically in transport of other metal ions.

• Nutrition Research and Practice
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• v.17 no.5
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• pp.827-843
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• 2023

BACKGROUND/OBJECTIVES: Mitochondrial DNA leakage leads to inflammatory responses via endosome activation. This study aims to evaluate whether the perennial grass water extract (Pogonatherum panicum) ameliorate mitochondrial DNA (mtDNA) leakage. MATERIALS/METHODS: The major bioactive constituents of P. paniceum (PPW) were investigated by high-performance liquid chromatography, after which their antioxidant activities were assessed. In addition, RAW 264.7 macrophages were stimulated with lipopolysaccharide, resulting in mitochondrial damage. Quantitative polymerase chain reaction and enzyme-linked immunosorbent assay were used to examine the gene expression and cytokines. RESULTS: Our results showed that PPW extract-treated activated cells significantly decrease reactive oxygen species and nitric oxide levels by reducing the p2^phox and iNOS expression and lowering cytokine-encoding genes, including IL-6, TNF-α, IL-1β, PG-E2 and IFN-γ relative to the lipopolysaccharide (LPS)-activated macrophages. Furthermore, we observed that LPS enhanced the mtDNA leaked into the cytoplasm, increasing the transcription of Tlr9 and signaling both MyD88/Irf7-dependent interferon and MyD88/NF-κb p65-dependent inflammatory cytokine mRNA expression but which was alleviated in the presence of PPW extract. CONCLUSIONS: Our data show that PPW extract has antioxidant and anti-inflammatory activities by facilitating mtDNA leakage and lowering the Tlr9 expression and signaling activation.

• Archives of Pharmacal Research
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• v.28 no.1
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• pp.93-99
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• 2005

Intracellular trafficking of transferrin-conjugated dimethyldioctadecyl-ammonium bromide liposome $(T_f-liposome)/DNA$ complexes in HeLa cells was studied using the double-labeled fluorescence technique and confocal microscopy. The size of the $T_f-liposome/DNA$ complex was about 367 nm in diameter and the zeta-potential of it at a 5:1 (w/w) ratio was almost neutral. The intracellular pathway of the $T_f-liposome/DNA$ complex, noted as green (FITC), red (rhodamine) or yellow (FITC + rhodamine) fluorescence, was elucidated from the plasma membrane to the endosome (or lysosome), and finally to the nucleus. The results of this study indicate that plasmid DNA enters into the nucleus not only as a free form but as an associated form complexed with $T_f-liposome$. More interestingly, the $T_f-liposome$ undergoes a nuclear location in the form of ordered structures. This could be a very useful piece of information in designing a safe and advanced gene delivery system.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.277.1-277.1
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• 2002

The purpose of this study was to develop PEl-based gene carriers with optimal serum stability and reduced cytotoxicity. PEl is an efficient gene transfer agent with the ability of DNA condensation and endosome escape: however; use of the polymer in vivo is hampered by signigicant reduction in transfection activity by the presence of serum. Chitosan is a non-toxic. biodegradable and biocompatible polymer with hydrophilic functional groups so it may provide a physical stability against challenge by serum proteins. (omitted)

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.21-26
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• 2002

Effects of cadmium (Cd) intoxication on renal endosomal accumulation of organic cations $(OC^+)$ were studied in rats using $^{14}C-tetraethylammnium$ (TEA) as a substrate. Cd intoxication was induced by s.c. injections of 2 mg Cd/kg/day for $2{\sim}3$ weeks. Renal cortical endosomes were isolated and the endosomal acidification (acridine orange fluorescence change) and TEA uptake (Millipore filtration technique) were assessed. The TEA uptake was an uphill transport mediated by $H^+/OC^+$ antiporter driven by the pH gradient established by $H^+-ATPase.$ In endosomes of Cd-intoxicated rats, the ATP-dependent TEA uptake was markedly attenuated due to inhibition of endosomal acidification as well as $H^+/TEA$ antiport. In kinetic analysis of $H^+/TEA$ antiport, Vmax was reduced and Km was increased in the Cd group. Inhibition of $H^+/TEA$ antiport was also observed in normal endosomes directly exposed to free Cd (but not Cd-metallothionein complex, CdMt) in vitro. These data suggest that during chronic Cd exposure, free Cd ions liberated by lysosomal degradation of CdMt in proximal tubule cells may impair the endosomal accumulation of $OC^+$ by directly inhibiting the $H^+/OC^+$ antiporter activity and indirectly by reducing the intravesicular acidification, the driving force for $H^+/OC^+$ exchange.

• BMB Reports
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• v.47 no.5
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• pp.241-248
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• 2014

CD1 molecules belong to non-polymorphic MHC class I-like proteins and present lipid antigens to T cells. Five different CD1 genes (CD1a-e) have been identified and classified into two groups. Group 1 include CD1a-c and present pathogenic lipid antigens to ${\alpha}{\beta}$ T cells reminiscence of peptide antigen presentation by MHC-I molecules. CD1d is the only member of Group 2 and presents foreign and self lipid antigens to a specialized subset of ${\alpha}{\beta}$ T cells, NKT cells. NKT cells are involved in diverse immune responses through prompt and massive production of cytokines. CD1d-dependent NKT cells are categorized upon the usage of their T cell receptors. A major subtype of NKT cells (type I) is invariant NKT cells which utilize invariant $V{\alpha}14-J{\alpha}18$ TCR alpha chain in mouse. The remaining NKT cells (type II) utilize diverse TCR alpha chains. Engineered CD1d molecules with modified intracellular trafficking produce either type I or type II NKT cell-defects suggesting the lipid antigens for each subtypes of NKT cells are processed/generated in different intracellular compartments. Since the usage of TCR by a T cell is the result of antigen-driven selection, the intracellular metabolic pathways of lipid antigen are a key in forming the functional NKT cell repertoire.

• Korean Journal of Poultry Science
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• v.45 no.3
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• pp.209-217
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• 2018

The innate immune recognition is based on the detection of microbial products. Toll-like receptors (TLRs) located on the cell surface and the endosome senses microbial components and nucleic acids, respectively. Chicken TLRs mediate immune responses by sensing ligands from pathogens, have been studied as immune adjuvants to increase the efficacy of vaccines. Single nucleotide polymorphisms (SNPs) of TLR3 and TLR4 genes in chicken were associated with resistance and susceptibility to viral infection. In this study, SNPs of chTLR3 and chTLR4 genes were retrieved from public database and annotated with chicken reference genome. Three-dimensional models of the chTLR3 and chTLR4 proteins were built using a Swiss modeler. We identified 35 and 13 nsSNPs in chTLR3 and chTLR4 genes respectively. Sorting Intolerant from Tolerant (SIFT) and Polymorphism Phenotyping v2 (Polyphen-2) analyses, suggested that, out of 35 and 13 nsSNPs, 4 and 2 SNPs were identified to be deleterious in chTLR3 and chTLR4 gene respectively. In chTLR3, 1 deleterious SNP was located in ectodomain and 3 were located in the Toll / IL-1 receptor (TIR) domain. Further structural model of chTLR3-TIR domain suggested that 1 deleterious SNP be present in the B-B loop region, which is important for TIR-TIR domain interactions in the downstream signaling. In chTLR4, the deleterious SNPs were located both in the ectodomain and TIR domain. SNPs predicted for chTLR3 and chTLR4 in this study, might be related to resistance or susceptible to viral infection in chickens. Results from this study will be useful to develop the effective measures in chicken against infectious diseases.