Publications by authors named "Nahoko Bailey Kobayashi"

3 Publications

  • Page 1 of 1

Secretion of signal peptides via extracellular vesicles.

Biochem Biophys Res Commun 2021 06 5;560:21-26. Epub 2021 May 5.

Department of Brain Function, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi, 464-8601, Japan; Department of Molecular Pharmacokinetics, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 464-8601, Japan.

Signal peptides (SPs) consist of short peptide sequences present at the N-terminal of newly synthesizing proteins and act as a zip code for the translocation of the proteins to the endoplasmic reticulum (ER). It was thought that the SPs are intracellularly degraded after translocation to the ER; however, recent studies showed cleaved SPs have diverse roles for controlling cell functions in auto- and/or intercellular manners. In addition, it still remains obscure how SP fragments translocate away from the site where they are produced. Extracellular vesicles (EV) are important for intercellular communication and can transport functional molecules to specific cells. In this study, we show that SPs are involved in EV from T-REx AspALP cells that were transfected with a human APP SP-inducible expression vector. There was no difference in the average particle size or particle concentration of EV collected from T-REx AspALP cells and T-REx Mock cells. When the SP content in the EV was examined by mass spectrometry, the C-terminal fragment of APP SP was identified in the exosomes (SEV) of T-REx AspALP cells. In our preparation of SEV fractions, no ER-specific proteins were detected; therefore, SPs may be included in SEV but not in the debris of degraded ER. This is the first indication that SPs are secreted from cells via EV.
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http://dx.doi.org/10.1016/j.bbrc.2021.04.073DOI Listing
June 2021

Environmental pH stress influences cellular secretion and uptake of extracellular vesicles.

FEBS Open Bio 2021 03 18;11(3):753-767. Epub 2021 Feb 18.

Keio University School of Medicine, Tsukuba, Japan.

Exosomes (extracellular vesicles/EVs) participate in cell-cell communication and contain bioactive molecules, such as microRNAs. However, the detailed characteristics of secreted EVs produced by cells grown under low pH conditions are still unknown. Here, we report that low pH in the cell culture medium significantly affected the secretion of EVs with increased protein content and zeta potential. The intracellular expression level and location of stably expressed GFP-fused CD63 (an EV tetraspanin) in HeLa cells were also significantly affected by environmental pH. In addition, increased cellular uptake of EVs was observed. Moreover, the uptake rate was influenced by the presence of serum in the cell culture medium. Our findings contribute to our understanding of the effect of environmental conditions on EV-based cell-cell communication.
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http://dx.doi.org/10.1002/2211-5463.13107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931216PMC
March 2021

Active macropinocytosis induction by stimulation of epidermal growth factor receptor and oncogenic Ras expression potentiates cellular uptake efficacy of exosomes.

Sci Rep 2015 Jun 3;5:10300. Epub 2015 Jun 3.

1] Keio Advanced Research Centers (KARC), Keio University, Tsukuba, Ibaraki 300-2611, Japan [2] Institute for Advanced Sciences, Toagosei Co., Ltd., Tsukuba, Ibaraki 300-2611, Japan.

Exosomes are approximately 100-nm vesicles that consist of a lipid bilayer of cellular membranes secreted in large quantities from various types of normal and disease-related cells. Endocytosis has been reported as a major pathway for the cellular uptake of exosomes; however, the detailed mechanisms of their cellular uptake are still unknown. Here, we demonstrate the active induction of macropinocytosis (accompanied by actin reorganisation, ruffling of plasma membrane, and engulfment of large volumes of extracellular fluid) by stimulation of cancer-related receptors and show that the epidermal growth factor (EGF) receptor significantly enhances the cellular uptake of exosomes. We also demonstrate that oncogenic K-Ras-expressing MIA PaCa-2 cells exhibit intensive macropinocytosis that actively transports extracellular exosomes into the cells compared with wild-type K-Ras-expressing BxPC-3 cells. Furthermore, encapsulation of the ribosome-inactivating protein saporin with EGF in exosomes using our simple electroporation method produces superior cytotoxicity via the enhanced cellular uptake of exosomes. Our findings contribute to the biological, pharmaceutical, and medical research fields in terms of understanding the macropinocytosis-mediated cellular uptake of exosomes with applications for exosomal delivery systems.
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http://dx.doi.org/10.1038/srep10300DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4453128PMC
June 2015
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