Elsevier BV Acta Medica Okayama 1349-0079 68 1 2026 Dynamin 2 is involved in osteoblast migration by regulating the organization of F-actin 100720 EN Takumi Moriya Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University A. Surong Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Nanami Tatsumi Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Fumiko Takemoto Department of Orthodontics, Okayama University Hospital Hiroshi Kamioka Department of Orthodontics, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hirohiko Okamura Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Mika Ikegame Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Objectives: Dynamin, a GTPase that regulates membrane dynamics, has recently been implicated in actin cytoskeletal remodeling. This study aimed to elucidate the role of dynamin in osteoblast migration by examining the effects of dynamin inhibition on the localization and organization of F-actin and dynamin 2 in MC3T3-E1 cells.<br> Methods: MC3T3-E1 cells were treated with dynamin inhibitors (Dyngo 4a and Dynole 34-2), and cell migration was assessed using a wound-healing assay. Fluorescent staining was performed to analyze the intracellular localization of F-actin and dynamin 2.<br> Results: Dynamin inhibition significantly reduced the migration of MC3T3-E1 cells. Fluorescence analysis revealed a marked decrease in the accumulation and colocalization of F-actin and dynamin 2 at the protrusion edge. Additionally, dynamin inhibition suppressed the formation of lamellipodia and stress fibers while promoting the appearance of abnormal F-actin clusters in the cytoplasm.<br> Conclusions: These findings suggest that dynamin plays an essential role in osteoblast migration by regulating actin cytoskeletal remodeling, particularly through the formation of lamellipodia and stress fibers. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1661-6596 26 6 2025 Vesicular Glutamate Transporter 3 Is Involved in Glutamatergic Signalling in Podocytes 2485 EN Naoko Nishii Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomoko Kawai Department of Cell Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroki Yasuoka Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tadashi Abe Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Nanami Tatsumi Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yuika Harada Department of Genomics and Proteomics, Advanced Science Research Center, Okayama University Takaaki Miyaji Department of Genomics and Proteomics, Advanced Science Research Center, Okayama University Shunai Li Center for Innovative Clinical Medicine, Okayama University Hospital Moemi Tsukano Central Research Laboratory, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masami Watanabe Center for Innovative Clinical Medicine, Okayama University Hospital Daisuke Ogawa Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Jun Wada Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Kohji Takei Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroshi Yamada Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Glomerular podocytes act as a part of the filtration barrier in the kidney. The activity of this filter is regulated by ionotropic and metabotropic glutamate receptors. Adjacent podocytes can potentially release glutamate into the intercellular space; however, little is known about how podocytes release glutamate. Here, we demonstrated vesicular glutamate transporter 3 (VGLUT3)-dependent glutamate release from podocytes. Immunofluorescence analysis revealed that rat glomerular podocytes and an immortal mouse podocyte cell line (MPC) express VGLUT1 and VGLUT3. Consistent with this finding, quantitative RT-PCR revealed the expression of VGLUT1 and VGLUT3 mRNA in undifferentiated and differentiated MPCs. In addition, the exocytotic proteins vesicle-associated membrane protein 2, synapsin 1, and synaptophysin 1 were present in punctate patterns and colocalized with VGLUT3 in MPCs. Interestingly, approximately 30% of VGLUT3 colocalized with VGLUT1. By immunoelectron microscopy, VGLUT3 was often observed around clear vesicle-like structures in differentiated MPCs. Differentiated MPCs released glutamate following depolarization with high potassium levels and after stimulation with the muscarinic agonist pilocarpine. The depletion of VGLUT3 in MPCs by RNA interference reduced depolarization-dependent glutamate release. These results strongly suggest that VGLUT3 is involved in glutamatergic signalling in podocytes and may be a new drug target for various kidney diseases. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1661-6596 25 22 2024 Distribution and Incorporation of Extracellular Vesicles into Chondrocytes and Synoviocytes 11942 EN Takashi Ohtsuki Department of Medical Technology, Graduate School of Health Sciences, Okayama University Ikumi Sato Department of Medical Technology, Graduate School of Health Sciences, Okayama University Ren Takashita Department of Medical Technology, Graduate School of Health Sciences, Okayama University Shintaro Kodama Department of Medical Technology, Graduate School of Health Sciences, Okayama University Kentaro Ikemura Department of Medical Technology, Graduate School of Health Sciences, Okayama University Gabriel Opoku Department of Medical Technology, Graduate School of Health Sciences, Okayama University Shogo Watanabe Department of Medical Technology, Graduate School of Health Sciences, Okayama University Takayuki Furumatsu Department of Orthopedic Surgery, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Hiroshi Yamada Department of Neuroscience, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Mitsuru Ando Laboratory of Biomaterials, Institute for Life and Medical Sciences, Kyoto University Kazunari Akiyoshi Department of Immunology, Graduate School of Medicine, Kyoto University Keiichiro Nishida Department of Orthopedic Surgery, Dentistry and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Satoshi Hirohata Department of Medical Technology, Graduate School of Health Sciences, Okayama University Osteoarthritis (OA) is a chronic disease affecting over 500 million people worldwide. As the population ages and obesity rates rise, the societal burden of OA is increasing. Pro-inflammatory cytokines, particularly interleukin-1β, are implicated in the pathogenesis of OA. Recent studies suggest that crosstalk between cartilage and synovium contributes to OA development, but the mechanisms remain unclear. Extracellular vesicles (EVs) were purified from cell culture-conditioned medium via ultracentrifugation and confirmed using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. We demonstrated that EVs were taken up by human synoviocytes and chondrocytes in vitro, while in vivo experiments revealed that fluorescent-labelled EVs injected into mouse joints were incorporated into chondrocytes and synoviocytes. EV uptake was significantly inhibited by dynamin-mediated endocytosis inhibitors, indicating that endocytosis plays a major role in this process. Additionally, co-culture experiments with HEK-293 cells expressing red fluorescent protein (RFP)-tagged CD9 and the chondrocytic cell line OUMS-27 confirmed the transfer of RFP-positive EVs across a 600-nm but not a 30-nm filter. These findings suggest that EVs from chondrocytes are released into joint fluid and taken up by cells within the cartilage, potentially facilitating communication between cartilage and synovium. The results underscore the importance of EVs in OA pathophysiology. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 2073-4409 13 16 2024 Direct Binding of Synaptopodin 2-Like Protein to Alpha-Actinin Contributes to Actin Bundle Formation in Cardiomyocytes 1373 EN Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hirona Osaka Graduate School of Science, Nagoya University Nanami Tatsumi Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Miu Araki Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tadashi Abe Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Keiko Kaihara Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ken Takahashi Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Eizo Takashima Division of Malaria Research, Proteo-Science Center, Ehime University Takayuki Uchihashi Graduate School of Science, Nagoya University Keiji Naruse Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kohji Takei Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Synaptopodin 2-like protein (SYNPO2L) is localized in the sarcomere of cardiomyocytes and is involved in heart morphogenesis. However, the molecular function of SYNPO2L in the heart is not fully understood. We investigated the interaction of SYNPO2L with sarcomeric alpha-actinin and actin filaments in cultured mouse cardiomyocytes. Immunofluorescence studies showed that SYNPO2L colocalized with alpha-actinin and actin filaments at the Z-discs of the sarcomere. Recombinant SYNPO2La or SYNPO2Lb caused a bundling of the actin filaments in the absence of alpha-actinin and enhanced the alpha-actinin-dependent formation of actin bundles. In addition, high-speed atomic force microscopy revealed that SYNPO2La directly bound to alpha-actinin via its globular ends. The interaction between alpha-actinin and SYNPO2La fixed the movements of the two proteins on the actin filaments. These results strongly suggest that SYNPO2L cooperates with alpha-actinin during actin bundle formation to facilitate sarcomere formation and maintenance. No potential conflict of interest relevant to this article was reported.

岡山医学会 Acta Medica Okayama 0030-1558 135 2 2023 オートファジー 92 94 EN Kohji Takei Department of Neurosience, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroshi Yamada Department of Neurosience, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University No potential conflict of interest relevant to this article was reported.

Frontiers Media Acta Medica Okayama 2235-2988 12 2022 Recruitment of Irgb6 to the membrane is a direct trigger for membrane deformation 992198 EN Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tadashi Abe Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hikaru Nagaoka Division of Malaria Research, Proteo-Science Center, Ehime University Eizo Takashima Division of Malaria Research, Proteo-Science Center, Ehime University Ryo Nitta Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine Masahiro Yamamoto Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University Kohji Takei Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Irgb6 is a member of interferon gamma-induced immunity related GTPase (IRG), and one of twenty "effector" IRGs, which coordinately attack parasitophorous vacuole membrane (PVM), causing death of intracellular pathogen. Although Irgb6 plays a pivotal role as a pioneer in the process of PVM disruption, the direct effect of Irgb6 on membrane remained to be elucidated. Here, we utilized artificial lipid membranes to reconstitute Irgb6-membrane interaction in vitro, and revealed that Irgb6 directly deformed the membranes. Liposomes incubated with recombinant Irgb6 were drastically deformed generating massive tubular protrusions in the absence of guanine nucleotide, or with GMP-PNP. Liposome deformation was abolished by incubating with Irgb6-K275A/R371A, point mutations at membrane targeting residues. The membrane tubules generated by Irgb6 were mostly disappeared by the addition of GTP or GDP, which are caused by detachment of Irgb6 from membrane. Binding of Irgb6 to the membrane, which was reconstituted in vitro using lipid monolayer, was stimulated at GTP-bound state. Irgb6 GTPase activity was stimulated by the presence of liposomes more than eightfold. Irgb6 GTPase activity in the absence of membrane was also slightly stimulated, by lowering ionic strength, or by increasing protein concentration, indicating synergistic stimulation of the GTPase activity. These results suggest that membrane targeting of Irgb6 and resulting membrane deformation does not require GTP, but converting into GTP-bound state is crucial for detaching Irgb6 from the membrane, which might coincident with local membrane disruption. No potential conflict of interest relevant to this article was reported.

Frontiers Media SA Acta Medica Okayama 2296-634X 10 2022 The Lipid-Binding Defective Dynamin 2 Mutant in Charcot-Marie-Tooth Disease Impairs Proper Actin Bundling and Actin Organization in Glomerular Podocytes 884509 EN Eriko Hamasaki Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Natsuki Wakita Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroki Yasuoka Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hikaru Nagaoka Division of Malaria Research, Proteo-Science Center, Ehime University Masayuki Morita Division of Malaria Research, Proteo-Science Center, Ehime University Eizo Takashima Division of Malaria Research, Proteo-Science Center, Ehime University Takayuki Uchihashi Department of Physics, Nagoya University Tetsuya Takeda Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tadashi Abe Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Ji-Won Lee Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University Tadahiro Iimura Department of Pharmacology, Faculty and Graduate School of Dental Medicine, Hokkaido University Moin A. Saleem Bristol Renal, Translational Health Sciences, Bristol Medical School, University of Bristol Naohisa Ogo Center for Drug Discovery, Graduate School of Pharmaceutical Sciences, University of Shizuoka Akira Asai Center for Drug Discovery, Graduate School of Pharmaceutical Sciences, University of Shizuoka Akihiro Narita Graduate School of Science, Nagoya University Kohji Takei Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Dynamin is an endocytic protein that functions in vesicle formation by scission of invaginated membranes. Dynamin maintains the structure of foot processes in glomerular podocytes by directly and indirectly interacting with actin filaments. However, molecular mechanisms underlying dynamin-mediated actin regulation are largely unknown. Here, biochemical and cell biological experiments were conducted to uncover how dynamin modulates interactions between membranes and actin in human podocytes. Actin-bundling, membrane tubulating, and GTPase activities of dynamin were examined in vitro using recombinant dynamin 2-wild-type (WT) or dynamin 2-K562E, which is a mutant found in Charcot-Marie-Tooth patients. Dynamin 2-WT and dynamin 2-K562E led to the formation of prominent actin bundles with constant diameters. Whereas liposomes incubated with dynamin 2-WT resulted in tubule formation, dynamin 2-K562E reduced tubulation. Actin filaments and liposomes stimulated dynamin 2-WT GTPase activity by 6- and 20-fold, respectively. Actin-filaments, but not liposomes, stimulated dynamin 2-K562E GTPase activity by 4-fold. Self-assembly-dependent GTPase activity of dynamin 2-K562E was reduced to one-third compared to that of dynamin 2-WT. Incubation of liposomes and actin with dynamin 2-WT led to the formation of thick actin bundles, which often bound to liposomes. The interaction between lipid membranes and actin bundles by dynamin 2-K562E was lower than that by dynamin 2-WT. Dynamin 2-WT partially colocalized with stress fibers and actin bundles based on double immunofluorescence of human podocytes. Dynamin 2-K562E expression resulted in decreased stress fiber density and the formation of aberrant actin clusters. Dynamin 2-K562E colocalized with alpha-actinin-4 in aberrant actin clusters. Reformation of stress fibers after cytochalasin D-induced actin depolymerization and washout was less effective in dynamin 2-K562E-expressing cells than that in dynamin 2-WT. Bis-T-23, a dynamin self-assembly enhancer, was unable to rescue the decreased focal adhesion numbers and reduced stress fiber density induced by dynamin 2-K562E expression. These results suggest that the low affinity of the K562E mutant for lipid membranes, and atypical self-assembling properties, lead to actin disorganization in HPCs. Moreover, lipid-binding and self-assembly of dynamin 2 along actin filaments are required for podocyte morphology and functions. Finally, dynamin 2-mediated interactions between actin and membranes are critical for actin bundle formation in HPCs. No potential conflict of interest relevant to this article was reported.

Japan Society for Cell Biology Acta Medica Okayama 0386-7196 45 2 2020 Internalization of AMPA-type Glutamate Receptor in the MIN6 Pancreatic β-cell Line 121 130 EN The Mon La Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Hiroshi Yamada Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Sayaka Seiriki Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shun-AI Li Center for Innovative Clinical Medicine, Okayama University Hospital Kenshiro Fujise Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Natsuho Katsumi Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tadashi Abe Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masami Watanabe Center for Innovative Clinical Medicine, Okayama University Hospital Kohji Takei Department of Neuroscience, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences The activity of AMPA-type glutamate receptor is involved in insulin release from pancreatic β-cells. However, the mechanism and dynamics that underlie AMPA receptor-mediated insulin release in β-cells is largely unknown. Here, we show that AMPA induces internalization of glutamate receptor 2/3 (GluR2/3), AMPA receptor subtype, in the mouse β-cell line MIN6. Immunofluorescence experiments showed that GluR2/3 appeared as fine dots that were distributed throughout MIN6 cells. Intracellular GluR2/3 co-localized with AP2 and clathrin, markers for clathrin-coated pits and vesicles. Immunoelectron microscopy revealed that GluR2/3 was also localized at plasma membrane. Surface biotinylation and immunofluorescence measurements showed that addition of AMPA caused an approximate 1.8-fold increase in GluR2/3 internalization under low-glucose conditions. Furthermore, internalized GluR2 largely co-localized with EEA1, an early endosome marker. In addition, GluR2/3 co-immunoprecipitated with cortactin, a F-actin binding protein. Depletion of cortactin by RNAi in MIN6 cells altered the intracellular distribution of GluR2/3, suggesting that cortactin is involved in internalization of GluR2/3 in MIN6 cells. Taken together, our results suggest that pancreatic β-cells adjust the amount of AMPA-type GluR2/3 on the cell surface to regulate the receptive capability of the cell for glutamate. No potential conflict of interest relevant to this article was reported.

Wiley Acta Medica Okayama 0892-6638 34 12 2020 Dynamin 1 is important for microtubule organization and stabilization in glomerular podocytes 16449 16463 EN The Mon La Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiromi Tachibana Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Shun-Ai Li Center for Innovative Clinical Medicine, Okayama University Hospital Tadashi Abe Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Sayaka Seiriki Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hikaru Nagaoka Division of Malaria Research, Proteo-Science Center, Ehime University Eizo Takashima Division of Malaria Research, Proteo-Science Center, Ehime University Tetsuya Takeda Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Daisuke Ogawa Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Shin-Ichi Makino Department of Nephrology, Graduate School of Medicine, Chiba University Katsuhiko Asanuma Department of Nephrology, Graduate School of Medicine, Chiba University Masami Watanabe Center for Innovative Clinical Medicine, Okayama University Hospital Xuefei Tian Department of Internal Medicine, Section of Nephrology, Yale University School of Medicine Shuta Ishibe Department of Internal Medicine, Section of Nephrology, Yale University School of Medicine Ayuko Sakane Department of Biochemistry, Tokushima University Graduate School of Medical Sciences Takuya Sasaki Department of Biochemistry, Tokushima University Graduate School of Medical Sciences Jun Wada Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kohji Takei Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Dynamin 1 is a neuronal endocytic protein that participates in vesicle formation by scission of invaginated membranes. Dynamin 1 is also expressed in the kidney; however, its physiological significance to this organ remains unknown. Here, we show that dynamin 1 is crucial for microtubule organization and stabilization in glomerular podocytes. By immunofluorescence and immunoelectron microscopy, dynamin 1 was concentrated at microtubules at primary processes in rat podocytes. By immunofluorescence of differentiated mouse podocytes (MPCs), dynamin 1 was often colocalized with microtubule bundles, which radially arranged toward periphery of expanded podocyte. In dynamin 1-depleted MPCs by RNAi, alpha-tubulin showed a dispersed linear filament-like localization, and microtubule bundles were rarely observed. Furthermore, dynamin 1 depletion resulted in the formation of discontinuous, short acetylated alpha-tubulin fragments, and the decrease of microtubule-rich protrusions. Dynamins 1 and 2 double-knockout podocytes showed dispersed acetylated alpha-tubulin and rare protrusions. In vitro, dynamin 1 polymerized around microtubules and cross-linked them into bundles, and increased their resistance to the disassembly-inducing reagents Ca(2+)and podophyllotoxin. In addition, overexpression and depletion of dynamin 1 in MPCs increased and decreased the nocodazole resistance of microtubules, respectively. These results suggest that dynamin 1 supports the microtubule bundle formation and participates in the stabilization of microtubules. No potential conflict of interest relevant to this article was reported.

Spandidos Acta Medica Okayama 1019-6439 49 3 2016 Actin bundling by dynamin 2 and cortactin is implicated in cell migration by stabilizing filopodia in human non-small cell lung carcinoma cells 877 886 EN Hiroshi Yamada Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tetsuya Takeda Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Hiroyuki Michiue Department of Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Tadashi Abe Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Kohji Takei Department of Neuroscience, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University The endocytic protein dynamin participates in the formation of actin-based membrane protrusions such as podosomes, pseudopodia, and invadopodia, which facilitate cancer cell migration, invasion, and metastasis. However, the role of dynamin in the formation of actin-based membrane protrusions at the leading edge of cancer cells is unclear. In this study, we demonstrate that the ubiquitously expressed dynamin 2 isoform facilitates cell migration by stabilizing F-actin bundles in filopodia of the lung cancer cell line H1299. Pharmacological inhibition of dynamin 2 decreased cell migration and filopodial formation. Furthermore, dynamin 2 and cortactin mostly colocalized along F-actin bundles in filopodia of serum-stimulated H1299 cells by immunofluorescent and immunoelectron microscopy. Knockdown of dynamin 2 or cortactin inhibited the formation of filopodia in serum-stimulated H1299 cells, concomitant with a loss of F-actin bundles. Expression of wild-type cortactin rescued the punctate-like localization of dynamin 2 and filopodial formation. The incubation of dynamin 2 and cortactin with F-actin induced the formation of long and thick actin bundles, with these proteins colocalizing at F-actin bundles. A depolymerization assay revealed that dynamin 2 and cortactin increased the stability of F-actin bundles. These results indicate that dynamin 2 and cortactin participate in cell migration by stabilizing F-actin bundles in filopodia. Taken together, these findings suggest that dynamin might be a possible molecular target for anticancer therapy. No potential conflict of interest relevant to this article was reported.

岡山医学会 Acta Medica Okayama 0030-1558 123 1 2011 アンフィファイジンとN-WASPのダイナミックな相互作用は，アクチン重合を制御する 1 11 EN Hiroshi Yamada Sergi Padilla-Parra Sun Joo Park Toshiki Itoh Mathilde Chaineau Ilaria Monaldi Ottavio Cremona Fabio Benfenati Pietro De Camilli Maïté Coppey-Moisan Marc Tramier Thierry Galli Kohji Takei No potential conflict of interest relevant to this article was reported.

The Company of Biologists Limited Acta Medica Okayama 0022-0949 203 1 2001 Synaptic-like microvesicles, synaptic vesicle counterparts in endocrine cells, are involved in a novel regulatory mechanism for the synthesis and secretion of hormones 117 125 EN Yoshinori Moriyama Mitsuko Hayashi Hiroshi Yamada Shouki Yatsushiro Shougo Ishio Akitsugu Yamamoto Microvesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H+-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate L-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use L-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 62 6 2008 Dynamin 2 Cooperates with Amphiphysin 1 in Phagocytosis in Sertoli Cells 385 391 EN Akira Nakanishi Tadashi Abe Masami Watanabe Kohji Takei Hiroshi Yamada Original Article 10.18926/AMO/30954 <p>Testicular Sertoli cells highly express dynamin 2 and amphiphysin 1. Here we demonstrate that dynamin 2 is implicated in phosphatidylserine (PS)-dependent phagocytosis in Sertoli cells. Immunofluorescence and dual-live imaging revealed that dynamin 2 and amphiphysin 1 accumulate simultaneously at ruffles. These proteins are specifically bound <i>in vitro</i>. Over-expression of dominant negative dynamin 2 (K44A) inhibits liposome-uptake and leads to the mis-localization of amphiphysin 1. Thus, the cooperative function of dynamin 2 and amphiphysin 1 in PS-dependent phagocytosis is strongly suggested.</p> No potential conflict of interest relevant to this article was reported.