Biomedical subjects

Yoshiki Katayama

Publications and source records attributed to Yoshiki Katayama.

At least 19 recordsLinked to original sources

PubMed2026

A transient, B cell-targeted tolerance switch using nanoparticles loaded with metabolizable AhR agonists for antigen-specific immune regulation.

Achieving antigen-specific immune tolerance without systemic immunosuppression remains a major challenge in biomaterial-based immunotherapy. Here, we report a simple nanoparticle (NP)-based platform that enables a transient, B cell-targeted tolerance switch. NPs encapsulating metabolizable aryl hydrocarbon receptor (AhR) agonists-FICZ or ITE-preferentially accumulate in splenic marginal zone B cells and convert them into IL-10-producing regulatory B cells (Bregs). This study provides the first in vivo evidence that Bregs can directly present antigen and induce regulatory T cells (Tregs), establishing a NP-controlled Breg-Treg pathway. These Bregs promote antigen-specific Tregs expansion only when co-exposed to antigen, establishing time-gated, antigen-restricted immune regulation. By exploiting the rapid metabolism of AhR agonists, this system provides precise temporal control of tolerance induction while preserving vaccine responses. In mouse models, co-administration of FICZ-containing NP with antigen suppressed anti-drug antibody formation and ameliorated allergic inflammation. This NP platform demonstrates a strategy for safe, antigen-specific immunomodulation and offers a clinically adaptable framework for allergy and biotherapeutic tolerance.

Animals↗

PubMed2006

Mass-tag technology responding to intracellular signals as a novel assay system for the diagnosis of tumor.

A novel mass spectrometry-based assay system for determining protein kinase activity employing mass-tagged substrate peptide probes was used for the diagnosis of tumors. Two peptide probes (H-type and D-type) were synthesized containing the same substrate peptide sequence for protein kinase C (PKC). The molecular weights of the two probes differ because of the incorporation of deuterium into the acetyl groups of the D-type probe. The lysates of the normal and tumor tissue were prepared and reacted with the H- and D-type peptide probes, respectively. The PKC activities of the normal and tumor tissues can be compared simply and directly by calculating the phosphorylated ratio to each peptide probe, obtained from the peak intensity of the mass spectrum after mixing of the two reaction solutions. The phosphorylation ratio for the reaction of the H-type peptide probe with the tumor tissue lysate (B16 melanoma) was more than three times higher than that of the D type peptide probe with the normal skin tissue lysate. These results show that the novel assay system for detecting protein kinase activity using mass-tag technology can be a simple and useful means to profile protein kinase activity for cell or tissue lysate samples, and can be applied to the diagnosis of tumors.

Animals↗

PubMed2006

Structural advantage of dendritic poly(L-lysine) for gene delivery into cells.

This study aimed to investigate the relationships between structures of gene carrier molecules and their activities for gene delivery into cells. We compared 2 types of poly(L-lysine) as carriers, that is, dendritic poly(L-lysine) (KG6) and linear poly(L-lysine) (PLL). KG6 formed a neutral DNA complex, and its DNA compaction level was weaker than that of PLL. The amount of DNA binding and uptake into cells mediated by PLL was 4-fold higher than that with KG6. However, KG6-mediated gene expression was 100-fold higher than that by PLL. Since pK(a) values of terminal amines of KG6 were lowered even though small amounts of DNA were internalized into cells, sufficient DNA amounts for effective gene expression escaped to the cytosol due to the proton sponge effect in the endosome. In addition, weakly compacted DNA with KG6 was advantageous in accessing RNA polymerase in the cell nucleus. On the other hand, PLL did not show the proton sponge effect in the endosome and resulted in strong compaction of DNA. Even though large DNA amounts were internalized into cells, most of the DNA would not take part in gene expression systems in the nucleus. Amount of induced cytokine production after intravenous injection of DNA complexes with KG6 and PLL was low, and was similar to the case when DNA was injected alone. Therefore, no significant difference in effects on cytokine production was observed between KG6 and PLL.

Animals↗

PubMed2006

A protein kinase signal-responsive gene carrier modified RGD peptide.

We have previously reported artificial gene-regulation systems responding to cyclic AMP-dependent protein kinase (PKA) using a cationic polymer. However, this polymer alone cannot deliver any gene into living cells. In the present work, we modified the signal-responsive polymer to the RGD peptide for the introduction of a polymer/DNA complex into living cells and succeeded in regulating the gene expression responding to intracellular PKA activation.

Cell Line, Tumor↗

PubMed2006

Phosphorylation of Rho-associated kinase (Rho-kinase/ROCK/ROK) substrates by protein kinases A and C.

Rho-associated kinase (Rho-kinase/ROCK/ROK) is a serine/threonine kinase and plays an important role in various cellular functions. The cAMP-dependent protein kinase (protein kinase A/PKA) and protein kinase C (PKC) are also serine/threonine kinases, and directly and/or indirectly take part in the signal transduction pathways of Rho-kinase. They have similar phosphorylation site motifs, RXXS/T and RXS/T. The purpose of this study was to identify whether sites phosphorylated by Rho-kinase could be targets for PKA and PKC and to find peptide substrates that are specific to Rho-kinase, i.e., with no phosphorylation by PKA and PKC. A total of 18 substrates for Rho-kinase were tested for phosphorylation by PKA and PKC. Twelve of these sites were easily phosphorylated. These results mean that Rho-kinase substrates can be good substrates for PKA and/or PKC. On the other hand, six Rho-kinase substrates showing no or very low phosphorylation efficiency (<20%) for PKA and PKC were identified. Kinetic parameters (K(m) and k(cat)) showed that two of these peptides could be useful as substrates specific to Rho-kinase phosphorylation.

Amino Acid Motifs↗

PubMed2006

PEG-modified gold nanorods with a stealth character for in vivo applications.

Gold nanorods prepared in hexadecyltrimethylammonium bromide (CTAB) solution are expected to provide novel materials for photothermal therapy and photo-controlled drug delivery systems. Since gold nanorods stabilized with CTAB show strong cytotoxicity, we developed a technique to modify these with polyethyleneglycol (PEG) for medical applications. PEG-modification was achieved by adding mPEG-SH in the CTAB solution, then, excess CTAB was removed by dialysis. PEG-modified gold nanoparticles showed a nearly neutral surface, and had little cytotoxicity in vitro. Following intravenous injection into mice, 54% of injected PEG-modified gold nanoparticles were found in blood at 0.5 h after intravenous injection, whereas most of gold was detected in the liver in the case of original gold nanorods stabilized with CTAB.

Animals↗

PubMed2006

Human exposure to bisphenol A.

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl)propane, is made by combining acetone and phenol. It has estrogenic activity and is acutely toxic to aquatic organisms. BPA is used mainly as a material for the production of epoxy resins and polycarbonate plastics. Due to an increase in products based on epoxy resins and polycarbonate plastics, human exposure to BPA has increased. The environment (aquatic environment, air and soil) can be one source of human BPA exposure, but the primary route of human exposure is foods. The daily human intake of BPA is <1 microg/kg body weight/day on the basis of several studies, and whether these doses can have an adverse endocrine disruptive effect on humans, especially fetuses, needs to be studied carefully.

Air Pollutants, Occupational↗

PubMed2006

CyclinB2 and BIRC5 genes as surrogate biomarkers for neurite outgrowth in SH-SY5Y subclonal cells.

Neurite outgrowth plays a key role in neuronal development and regeneration, and is the hallmark assay for the effects of neurotrophic factors such as nerve growth factor (NGF). However, measuring neurite outgrowth is a slow and resource-intensive process. We therefore wanted to identify surrogate biomarkers for neurite outgrowth activity by gene expression analysis in SH-O10 cells, a subclone of the human SH-SY5Y neuroblastoma cell line but with much higher NGF-induced neurite outgrowth activity. Microarray analysis identified seven genes where mRNA levels were changed. NGF-induced decreases in levels of two genes, CyclinB2 and BIRC5, were confirmed by quantitative real-time RT-PCR. Levels of NGF-induced decreases in CyclinB2 and BIRC5 mRNA in several SH-SY5Y subclones with different neurite outgrowth responses correlated with their neurite outgrowth activities. Decreases in CyclinB2 and BIRC5 mRNA induced by FK506 or retinoic acid, both of which exert potentiation of NGF-induced neurite outgrowth effects but with different mechanisms, also correlated with their neurite outgrowth activities. In conclusion, decreasing levels of CyclinB2 and BIRC5 mRNA strongly correlate with neurite outgrowth activities in terms of NGF-related effect in SH-SY5Y subclonal cells, and have potential to become quantitative surrogate biomarkers for measuring NGF-related neurite outgrowth.

Antineoplastic Agents↗

PubMed2006

Stabilizing of plasmid DNA in vivo by PEG-modified cationic gold nanoparticles and the gene expression assisted with electrical pulses.

This study aimed to investigate the benefits of combining the use of PEG-modified cationic gold nanoparticles with electroporation for in vivo gene delivery. PEG-modified cationic gold nanoparticles were prepared by NaBH(4) reduction of HAuCl(4) in the presence of 2-aminoethanethiol and mPEG-SH. Zeta-potential of the particles was nearly neutral (+0.1 mV). After forming complexes with plasmid DNA at a w/w ratio of 8.4, nanoparticle complexes were 90 nm for at least 60 min and showed a negative zeta-potential. After intravenous injection of DNA-nanoparticle complexes, 20% of gold were detected in blood at 120 min after injection and 5% of DNA were observed in blood after 5 min, suggesting that PEG-modified nanoparticles were stably circulating in the blood flow, but some of the DNA bound to particles degraded during circulation. When electroporation was applied to a lobe of the liver following injection of DNA-nanoparticle complexes, significant gene expression was specifically observed in the pulsed lobe. We concluded that PEG-modified nanoparticles maintained DNA more stably in the blood flow than in the case of naked DNA and electroporation assisted in restricted gene expression of circulating DNA in limited areas of the liver.

Animals↗

PubMed2006

Diclofenac, a non-steroidal anti-inflammatory drug, suppresses apoptosis induced by endoplasmic reticulum stresses by inhibiting caspase signaling.

Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used in the treatment of inflammation and pain. In many reports, NSAIDs have induced apoptosis in a variety of cell lines such as colon cancer cells. On the other hand, more recently a few reports have found that NSAIDs protect against apoptosis. Here we investigate endoplasmic reticulum (ER)-stress-induced apoptosis of neuronal cells. The aim of this study is to examine the involvement of NSAIDs, in particular diclofenac, on ER-stress-induced apoptosis of human neuroblastoma SH-SY5Y cells. Diclofenac significantly suppressed SH-SY5Y cell death induced by two types of ER-stress-inducing agents: thapsigargin, an inhibitor of Ca2+-ATPase on the endoplasmic reticulum membrane, and tunicamycin, a glycosylation blocker. Other NSAIDs, such as indomethacin, ibuprofen, aspirin, and ketoprofen, also suppressed ER-stress-induced SH-SY5Y cell death. The dose-dependent anti-apoptotic effect of diclofenac did not correlate with the reduction of prostaglandin release. Administration of prostaglandin E2, which was a primary product of arachidonic metabolism, showed no effects against anti-apoptotic effects produced by diclofenac. Thapsigargin and tunicamycin each significantly activated caspase-3, -9, and -2 in the intrinsic apoptotic pathway in SH-SY5Y cells. Diclofenac suppressed the activation of caspases induced by both ER stresses. Thapsigargin and tunicamycin decreased the mitochondrial membrane potential in SH-SY5Y cells. Diclofenac suppressed the mitochondrial depolarization induced by both ER stresses. Diclofenac inhibited ER-stress-induced apoptosis of SH-SY5Y cells by suppressing the activation of caspases in the intrinsic apoptotic pathway. This is the first report to find that diclofenac has protective effects against ER-stress-induced apoptosis.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2006

Peptide vector for gene delivery with high affinity for phosphatidylserine.

Since phosphatidylserine (PS) is known to translocate to the external face of the plasma membrane when the cell membrane becomes disordered, we decided to focus our attention on PS as a target molecule for gene delivery. In this paper, the novel peptide Td3701 was designed, synthesized, and characterized for its physico-chemico-biological properties. Td3701 simultaneously exhibited both characters as a DNA carrier and a sensor probe for active targeting, which seemed to be triggered by structural changes in the presence of PS. This is a very unique character among nonviral vectors, and it is believed that Td3701 could be used for selective gene delivery.

Amino Acid Sequence↗

PubMed2006

Intracellular signal-responsive artificial gene regulation.

In gene therapy, in order to avoid serious side effects due to the unexpected expression of the transgene in non-target cells, transgenes have to be delivered only to the target cells. In response to this issue, many researchers have aimed at developing target cell-selective gene carriers using active targeting strategies. However, such methodology does not always work, because an ideal molecular marker, which is specific to the target disease cells, is not always available. In this study, we introduce a new concept regarding target disease cell-selective gene therapy (D-RECS). Here, we use intracellular signals, which are activated to an extraordinary degree only in the target disease cells, as a trigger for transgene expression using polymer-peptide conjugates. This strategy could actually activate gene expression in the target signal-activated cells only. Hyper-activation of certain intracellular signals has been reported in many diseases. Thus, this new strategy is expected to provide a powerful methodology for future gene therapy. In this review, the basic concept, some examples, and the molecular design of D-RECS carriers are introduced.

Animals↗

PubMed2006

The features and shortcomings for gene delivery of current non-viral carriers.

Since the viral vector for gene therapy has serious problems, including oncogenesity and other adverse effects, non-viral carriers have attracted a great deal of attention. Non-viral carriers are expected to achieve gene therapy without serious side effects. However, the most critical issue of gene delivery by non-viral carriers is the low-expression efficiencies of the desired gene. In order to apply non-viral carriers for gene therapy in practical clinical usage, further understanding of the cellular barriers against gene delivery is a prerequisite. Moreover, additional intelligent concepts for gene delivery are also needed. We will summarize the features and shortcomings of currently developed non-viral delivery systems. Especially, we will address the current progress of cationic lipids (lipoplex) and cationic polymers (polyplex) in terms of transfection efficiency. Furthermore, our group has developed a system that responds to the particular intracellular signals of target disease cells. We have named this gene delivery system a drug delivery system based on responses cellular signal (D-RECS). We will introduce this new concept of intelligent non-viral delivery system that our group recently developed.

Animals↗

PubMed2006

[Gene delivery system responding to the intracellular signal].

We designed a peptide-polymer conjugate as a novel gene carrier, which could control gene-expression responding to intracellular cAMP-dependent protein kinase (PKA) or caspase-3 signal. Each polymer containing a substrate peptide (ALRRASLG for PKA or GGGDEVD GGRKKRRQRRRPPQ for caspase-3) could form a tight complex with plasmid DNA via electrostatic interaction, and in this state, the gene expression was totally suppressed. Once the grafted peptides become phosphorylated or hydrolyzed by the appropriate enzyme, the net charge of the peptide changes from cationic to neutral or anionic, respectively, and the polymer then releases the DNA, such that expression of the foreign gene should become activated. We expect that these systems can be applied to the novel highly cell specific gene delivery strategy.

Caspase 3↗

PubMed2005

An intracellular kinase signal-responsive gene carrier for disordered cell-specific gene therapy.

We have previously reported artificial gene-regulation systems responding to cyclic AMP-dependent protein kinase (PKA) using cationic polymer. This cationic polymer (PAK) was a graft-type polymer with an oligopeptide that is a substrate for PKA and could regulate gene-expression in a cell-free system. In the present study, we carried out a detailed characterization of the PAK-DNA complex (AFM observation and DLS measurement) and tried to apply this polymer to living cells. In the unstimulated NIH 3T3 cells, transfection of the PAK-DNA complex showed no expression of the delivered gene. This means that PAK formed a stable complex with DNA in the normal cells to totally suppress gene expression. In contrast, significant expression was seen when the PAK-DNA complex was delivered to forskolin-treated cells. Thus, activated PKA disintegrates the complexes even in living cells, resulting in gene expression. Our results indicate that this type of intracellular signal-responsive polymer will be useful for the cell-specific release of genes.

3T3 Cells↗

PubMed2005

Biodegradation or metabolism of bisphenol A: from microorganisms to mammals.

Bisphenol A (BPA; 2,2-bis(4-hydroxyphenyl)propane; CAS Registry No. 80-05-7) is one of endocrine disruptors and is made by combining acetone and phenol. BPA can be metabolized by extensive organisms. In this review these BPA biodegradations or metabolisms by many organisms from microorganisms to mammals were referred. Though the metabolites of BPA can enhance estrogenicity or toxicity, generally, BPA metabolism by organisms leads to detoxication of BPA.

Animals↗

PubMed2005

A novel transfection method for mammalian cells using gas plasma.

Introduction of foreign genes into target cells is a crucial step for achievement of gene therapy. We have recently developed a novel transfection system for eukaryotic cells, namely the electric pulse-activated gas plasma generator. To measure the transfection efficiency and mortality by flow-cytometry, we employed enhanced green fluorescent protein and propidium iodide staining, respectively. One day after the 1-3s plasma exposures with DNA concentration at 0.5 microg/microl, favorable transfection efficiencies (17.8-21.6%) and mortalities (0.65-2.86%) were obtained for HeLa-S3, HT-1080 and MCF-7 cells. The recipient cells became transiently permeable for plasmid DNA during the plasma exposure, suggesting that plasma-mediated transfection may involve similar mechanisms that accounts for electroporation. The relatively low mortality rates are encouraging in our attempt to apply this system to the various cell lines including the primary cell cultures.

Cell Line, Tumor↗

PubMed2005

Double-modification of lectin using two distinct chemistries for fluorescent ratiometric sensing and imaging saccharides in test tube or in cell.

The site-selective incorporation of two different fluorophores into a naturally occurring protein (lectin, a sugar-binding protein) has been successfully carried out using two distinct orthogonal chemical methods. By post-photoaffinity labeling modification, Con A, a glucose- and mannose-selective lectin, was modified with fluorescein in the proximity of the sugar binding site (Tyr100 site), and the controlled acylation reaction provided the site-selective attachment of coumarin at Lys114. In this doubly modified Con A, the fluorescein emission changed upon the binding to the corresponding sugars, such as the glucose or mannose derivatives, whereas the coumarin emission was constant. Thus, the doubly modified Con A fluorescently sensed the glucose- and mannose-rich saccharides in a ratiometric manner while retaining the natural binding selectivity and affinity, regardless of the double modification. On the benefit of the ratiometric fluorescent analysis using two distinct probes, the sugar trimming process of a glycoprotein can be precisely monitored by the engineered Con A. Furthermore, the doubly modified Con A can be used not only for the convenient fluorescent imaging of saccharides localized on a cell surface, such as the MCF-7, a breast cancer cell having rich high-mannose branch, but also for the ratiometric fluorescent sensing of the glucose concentration inside HepG2 cells. These results demonstrated that the semisynthetic lectin modified doubly by two distinct chemistries is superior to the singly modified one in function, and thus, it may be potentially useful in cell, as well as in test tube.

Biosensing Techniques↗