Christina Vagena-Pantoula, Hajime Fukui and Julien Vermot : Manipulating Mechanical Forces in the Developing Zebrafish Heart Using Magnetic Beads, Journal of visualized experiments : JoVE, 2025-January, 215, 2025.
(要約)
Mechanical forces continuously provide feedback to heart valve morphogenetic programs. In zebrafish, cardiac valve development relies on heart contraction and physical stimuli generated by the beating heart. Intracardiac hemodynamics, driven by blood flow, emerge as fundamental information shaping the development of the embryonic heart. Here, we describe an effective method to manipulate mechanical forces in vivo by grafting a 30 µm to 60 µm diameter magnetic bead in the cardiac lumen. The insertion of the bead is conducted through microsurgery in anesthetized larvae without perturbing heart function and enables artificial alteration of the boundary conditions, thereby modifying flow forces in the system. As a result, the presence of the bead amplifies the mechanical forces experienced by endocardial cells and can directly trigger mechanical stimulus-dependent calcium influx. This approach facilitates the investigation of mechanotransduction pathways that govern heart development and can provide insights into the role of mechanical forces in cardiac valve morphogenesis.
Ayano Chiba, Takuya Yamamoto, Hajime Fukui, Moe Fukumoto, Manabu Shirai, Hiroyuki Nakajima and Naoki Mochizuki : Zonated Wnt/β-catenin signal-activated cardiomyocytes at the atrioventricular canal promote coronary vessel formation in zebrafish, Developmental Cell, 60, 1, 21-29.e8, 2024.
(要約)
Cells functioning at a specific zone by clustering according to gene expression are recognized as zonated cells. Here, we demonstrate anatomical and functional zones in the zebrafish heart. The cardiomyocytes (CMs) at the atrioventricular canal between the atrium and ventricle could be grouped into three zones according to the localization of signal-activated CMs: Wnt/β-catenin signal+, Bmp signal+, and Tbx2b+ zones. Endocardial endothelial cells (ECs) changed their characteristics, penetrated the Wnt/β-catenin signal+ CM zone, and became coronary ECs covering the heart. Coronary vessel length was reduced when the Wnt/β-catenin signal+ CMs were depleted. Collectively, we demonstrate the importance of anatomical and functional zonation of CMs in the zebrafish heart.
Mathilde Lebas, Giorgia Chinigò, Evan Courmont, Louay Bettaieb, Amani Machmouchi, Jermaine Goveia, Aleksandar Beatovic, Job Kerckhove Van, Cyril Robil, Silva Fabiola Angulo, Mauro Vedelago, Alina Errerd, Lucas Treps, Vance Gao, C.Delgado la Herrán Hilda De, Alicia Mayeuf-Louchart, Laurent L'homme, Mohamed Chamlali, Camille Dejos, Valérie Gouyer, Srikanth Venkata Naga Garikipati, Dhanendra Tomar, Hao Yin, Hajime Fukui, Stefan Vinckier, Anneke Stolte, Christin Lena Conradi, Fabrice Infanti, Loic Lemonnier, Elisabeth Zeisberg, Yonglun Luo, Lin Lin, Luc Jean Desseyn, Geoffrey J. Pickering, Raj Kishore, Muniswamy Madesh, David Dombrowicz, Fabiana Perocchi, Bart Staels, Fiorio Alessandra Pla, Dimitra Gkika and Rita Anna Cantelmo : Integrated single-cell RNA-seq analysis reveals mitochondrial calcium signaling as a modulator of endothelial-to- mesenchymal transition, Science Advances, 10, 32, eadp6182, 2024.
(要約)
Endothelial cells (ECs) are highly plastic, capable of differentiating into various cell types. Endothelial-to-mesenchymal transition (EndMT) is crucial during embryonic development and contributes substantially to vascular dysfunction in many cardiovascular diseases (CVDs). While targeting EndMT holds therapeutic promise, understanding its mechanisms and modulating its pathways remain challenging. Using single-cell RNA sequencing on three in vitro EndMT models, we identified conserved gene signatures. We validated original regulators in vitro and in vivo during embryonic heart development and peripheral artery disease. EndMT induction led to global expression changes in all EC subtypes rather than in mesenchymal clusters. We identified mitochondrial calcium uptake as a key driver of EndMT; inhibiting mitochondrial calcium uniporter (MCU) prevented EndMT in vitro, and conditional Mcu deletion in ECs blocked mesenchymal activation in a hind limb ischemia model. Tissues from patients with critical limb ischemia with EndMT features exhibited significantly elevated endothelial MCU. These findings highlight MCU as a regulator of EndMT and a potential therapeutic target.
Jiahong Raymond Zhang, Julien Vermot, Riccardo Gherardi, Hajime Fukui and Wei-Yan Renee Chow : Calcium Signal Analysis in the Zebrafish Heart via Phase Matching of the Cardiac Cycle., Bio-protocol, 14, 10, 2024.
(要約)
Calcium signalling in the endocardium is critical for heart valve development. Calcium ion pulses in the endocardium are generated in response to mechanical forces due to blood flow and can be visualised in the beating zebrafish heart using a genetically encoded calcium indicator such as GCaMP7a. Analysing these pulses is challenging because of the rapid movement of the heart during heartbeat. This protocol outlines an imaging analysis method used to phase-match the cardiac cycle in single z-slice movies of the beating heart, allowing easy measurement of the calcium signal. Key features • Software to synchronise and analyse frames from movies of the beating heart corresponding to a user-defined phase of the cardiac cycle. • Software to measure the fluorescence intensity of the beating heart corresponding to a user-defined region of interest.
Hiroyuki Nakajima, Hiroyuki Ishikawa, Takuya Yamamoto, Ayano Chiba, Hajime Fukui, Keisuke Sako, Moe Fukumoto, Kenny Mattonet, Hyouk-Bum Kwon, P Subhra Hui, D Gergana Dobreva, Kazu Kikuchi, M Christian S Helker, R Didier Y Stainier and Naoki Mochizuki : Endoderm-derived islet1-expressing cells differentiate into endothelial cells to function as the vascular HSPC niche in zebrafish., Developmental Cell, 58, 3, 224-238.e7, 2023.
(要約)
Endothelial cells (ECs) line blood vessels and serve as a niche for hematopoietic stem and progenitor cells (HSPCs). Recent data point to tissue-specific EC specialization as well as heterogeneity; however, it remains unclear how ECs acquire these properties. Here, by combining live-imaging-based lineage-tracing and single-cell transcriptomics in zebrafish embryos, we identify an unexpected origin for part of the vascular HSPC niche. We find that islet1 (isl1)-expressing cells are the progenitors of the venous ECs that constitute the majority of the HSPC niche. These isl1-expressing cells surprisingly originate from the endoderm and differentiate into ECs in a process dependent on Bmp-Smad signaling and subsequently requiring npas4l (cloche) function. Single-cell RNA sequencing analyses show that isl1-derived ECs express a set of genes that reflect their distinct origin. This study demonstrates that endothelial specialization in the HSPC niche is determined at least in part by the origin of the ECs.
Hélène Vignes, Christina Vagena-Pantoula, Mangal Prakash, Hajime Fukui, Caren Norden, Naoki Mochizuki, Florian Jug and Julien Vermot : Extracellular mechanical forces drive endocardial cell volume decrease during zebrafish cardiac valve morphogenesis., Developmental Cell, 57, 5, 598-609.e5, 2022.
(要約)
Organ morphogenesis involves dynamic changes of tissue properties while cells adapt to their mechanical environment through mechanosensitive pathways. How mechanical cues influence cell behaviors during morphogenesis remains unclear. Here, we studied the formation of the zebrafish atrioventricular canal (AVC) where cardiac valves develop. We show that the AVC forms within a zone of tissue convergence associated with the increased activation of the actomyosin meshwork and cell-orientation changes. We demonstrate that tissue convergence occurs with a reduction of cell volume triggered by mechanical forces and the mechanosensitive channel TRPP2/TRPV4. Finally, we show that the extracellular matrix component hyaluronic acid controls cell volume changes. Together, our data suggest that multiple force-sensitive signaling pathways converge to modulate cell volume. We conclude that cell volume reduction is a key cellular feature activated by mechanotransduction during cardiovascular morphogenesis. This work further identifies how mechanical forces and extracellular matrix influence tissue remodeling in developing organs.
In the clinic, most cases of congenital heart valve defects are thought to arise through errors that occur after the endothelial-mesenchymal transition (EndoMT) stage of valve development. Although mechanical forces caused by heartbeat are essential modulators of cardiovascular development, their role in these later developmental events is poorly understood. To address this question, we used the zebrafish superior atrioventricular valve (AV) as a model. We found that cellularized cushions of the superior atrioventricular canal (AVC) morph into valve leaflets via mesenchymal-endothelial transition (MEndoT) and tissue sheet delamination. Defects in delamination result in thickened, hyperplastic valves, and reduced heart function. Mechanical, chemical, and genetic perturbation of cardiac forces showed that mechanical stimuli are important regulators of valve delamination. Mechanistically, we show that forces modulate Nfatc activity to control delamination. Together, our results establish the cellular and molecular signature of cardiac valve delamination in vivo and demonstrate the continuous regulatory role of mechanical forces and blood flow during valve formation.
Hajime Fukui, Wei-Yan Renee Chow, Jing Xie, Yin Yoke Foo, Hwai Choon Yap, Nicolas Minc, Naoki Mochizuki and Julien Vermot : Bioelectric signaling and the control of cardiac cell identity in response to mechanical forces., Science, 374, 6565, 351-354, 2021.
(要約)
-Nfatc1–mechanosensitive pathway to generate positional information and control valve formation.
R Rita Ferreira, Guillaume Pakula, Lhéanna Klaeyle, Hajime Fukui, Andrej Vilfan, Willy Supatto and Julien Vermot : Chiral Cilia Orientation in the Left-Right Organizer., Cell Reports, 25, 8, 2008-2016.e4, 2018.
(要約)
Chirality is a property of asymmetry between an object and its mirror image. Most biomolecules and many cell types are chiral. In the left-right organizer (LRO), cilia-driven flows transfer such chirality to the body scale. However, the existence of cellular chirality within tissues remains unknown. Here, we investigate this question in Kupffer's vesicle (KV), the zebrafish LRO. Quantitative live imaging reveals that cilia populating the KV display asymmetric orientation between the right and left sides, resulting in a chiral structure, which is different from the chiral cilia rotation. This KV chirality establishment is dynamic and depends on planar cell polarity. While its impact on left-right (LR) symmetry breaking remains unclear, we show that this asymmetry does not depend on the LR signaling pathway or flow. This work identifies a different type of tissue asymmetry and sheds light on chirality genesis in developing tissues.
Hajime Fukui, Takahiro Miyazaki, Wei-Yan Renee Chow, Hiroyuki Ishikawa, Hiroyuki Nakajima, Julien Vermot and Naoki Mochizuki : Hippo signaling determines the number of venous pole cells that originate from the anterior lateral plate mesoderm in zebrafish., eLife, 7, 2018.
(要約)
, a key transcription factor that is involved in the differentiation of atrial cardiomyocytes. Collectively, these results demonstrate that Hippo signaling defines venous pole cardiomyocyte number by modulating both the number and the identity of the ALPM cells that will populate the atrium of the heart.
Hiroyuki Nakajima, Kimiko Yamamoto, Sobhika Agarwala, Kenta Terai, Hajime Fukui, Shigetomo Fukuhara, Koji Ando, Takahiro Miyazaki, Yasuhiro Yokota, Etienne Schmelzer, Georg Heinz Belting, Markus Affolter, Virginie Lecaudey and Naoki Mochizuki : Flow-Dependent Endothelial YAP Regulation Contributes to Vessel Maintenance, Developmental Cell, 40, 6, 523-536.e6, 2017.
(要約)
Endothelial cells (ECs) line the inside of blood vessels and respond to mechanical cues generated by blood flow. Mechanical stimuli regulate the localization of YAP by reorganizing the actin cytoskeleton. Here we demonstrate blood-flow-mediated regulation of endothelial YAP in vivo. We indirectly monitored transcriptional activity of Yap1 (zebrafish YAP) and its spatiotemporal localization in living zebrafish and found that Yap1 entered the nucleus and promoted transcription in response to blood flow. In cultured human ECs, laminar shear stress induced nuclear import of YAP and its transcriptional activity in a manner independent of Hippo signaling. We uncovered a molecular mechanism by which flow induced the nuclear translocation of YAP through the regulation of filamentous actin and angiomotin. Yap1 mutant zebrafish showed a defect in vascular stability, indicating an essential role for Yap1 in blood vessels. Our data imply that endothelial Yap1 functions in response to flow to maintain blood vessels.
Ayano Chiba, Haruko Watanabe-Takano, Kenta Terai, Hajime Fukui, Takahiro Miyazaki, Mami Uemura, Hisashi Hashimoto, Masahiko Hibi, Shigetomo Fukuhara and Naoki Mochizuki : Osteocrin, a peptide secreted from the heart and other tissues, contributes to cranial osteogenesis and chondrogenesis in zebrafish, Development, 144, 2, 334-344, 2016.
(要約)
The heart is an endocrine organ, as cardiomyocytes (CMs) secrete natriuretic peptide (NP) hormones. Since the discovery of NPs, no other peptide hormones that affect remote organs have been identified from the heart. We identified osteocrin (Ostn) as an osteogenesis/chondrogenesis regulatory hormone secreted from CMs in zebrafish. ostn mutant larvae exhibit impaired membranous and chondral bone formation. The impaired bones were recovered by CM-specific overexpression of OSTN. We analyzed the parasphenoid (ps) as a representative of membranous bones. In the shortened ps of ostn morphants, nuclear Yap1/Wwtr1-dependent transcription was increased, suggesting that Ostn might induce the nuclear export of Yap1/Wwtr1 in osteoblasts. Although OSTN is proposed to bind to NPR3 (clearance receptor for NPs) to enhance the binding of NPs to NPR1 or NPR2, OSTN enhanced C-type NP (CNP)-dependent nuclear export of YAP1/WWTR1 of cultured mouse osteoblasts stimulated with saturable CNP. OSTN might therefore activate unidentified receptors that augment protein kinase G signaling mediated by a CNP-NPR2 signaling axis. These data demonstrate that Ostn secreted from the heart contributes to bone formation as an endocrine hormone.
Koji Ando, Shigetomo Fukuhara, Nanae Izumi, Hiroyuki Nakajima, Hajime Fukui, N Robert Kelsh and Naoki Mochizuki : Clarification of mural cell coverage of vascular endothelial cells by live imaging of zebrafish., Development, 143, 8, 1328-1339, 2016.
(要約)
Mural cells (MCs) consisting of vascular smooth muscle cells and pericytes cover the endothelial cells (ECs) to regulate vascular stability and homeostasis. Here, we clarified the mechanism by which MCs develop and cover ECs by generating transgenic zebrafish lines that allow live imaging of MCs and by lineage tracing in vivo To cover cranial vessels, MCs derived from either neural crest cells or mesoderm emerged around the preformed EC tubes, proliferated and migrated along EC tubes. During their migration, the MCs moved forward by extending their processes along the inter-EC junctions, suggesting a role for inter-EC junctions as a scaffold for MC migration. In the trunk vasculature, MCs derived from mesoderm covered the ventral side of the dorsal aorta (DA), but not the posterior cardinal vein. Furthermore, the MCs migrating from the DA or emerging around intersegmental vessels (ISVs) preferentially covered arterial ISVs rather than venous ISVs, indicating that MCs mostly cover arteries during vascular development. Thus, live imaging and lineage tracing enabled us to clarify precisely how MCs cover the EC tubes and to identify the origins of MCs.
Jun-Dal Kim, Kyung-Eui Park, Junji Ishida, Koichiro Kako, Juri Hamada, Shuichi Kani, Miki Takeuchi, Kana Namiki, Hajime Fukui, Shigetomo Fukuhara, Masahiko Hibi, Makoto Kobayashi, Yasunori Kanaho, Yoshitoshi Kasuya, Naoki Mochizuki and Akiyoshi Fukamizu : PRMT8 as a phospholipase regulates Purkinje cell dendritic arborization and motor coordination., Science Advances, 1, 11, 2015.
(要約)
The development of vertebrate neurons requires a change in membrane phosphatidylcholine (PC) metabolism. Although PC hydrolysis is essential for enhanced axonal outgrowth mediated by phospholipase D (PLD), less is known about the determinants of PC metabolism on dendritic arborization. We show that protein arginine methyltransferase 8 (PRMT8) acts as a phospholipase that directly hydrolyzes PC, generating choline and phosphatidic acid. We found that PRMT8 knockout mice (prmt8 (-/-)) displayed abnormal motor behaviors, including hindlimb clasping and hyperactivity. Moreover, prmt8 (-/-) mice and TALEN-induced zebrafish prmt8 mutants and morphants showed abnormal phenotypes, including the development of dendritic trees in Purkinje cells and altered cerebellar structure. Choline and acetylcholine levels were significantly decreased, whereas PC levels were increased, in the cerebellum of prmt8 (-/-) mice. Our findings suggest that PRMT8 acts both as an arginine methyltransferase and as a PC-hydrolyzing PLD that is essential for proper neurological functions.
Takeru Kashiwada, Shigetomo Fukuhara, Kenta Terai, Toru Tanaka, Yuki Wakayama, Koji Ando, Hiroyuki Nakajima, Hajime Fukui, Shinya Yuge, Yoshinobu Saito, Akihiko Gemma and Naoki Mochizuki : β-catenin-dependent transcription is central to bmp-mediated formation of venous vessels, Development, 142, 3, 497-509, 2015.
(要約)
β-catenin regulates the transcription of genes involved in diverse biological processes, including embryogenesis, tissue homeostasis and regeneration. Endothelial cell (EC)-specific gene-targeting analyses in mice have revealed that β-catenin is required for vascular development. However, the precise function of β-catenin-mediated gene regulation in vascular development is not well understood, since β-catenin regulates not only gene expression but also the formation of cell-cell junctions. To address this question, we have developed a novel transgenic zebrafish line that allows the visualization of β-catenin transcriptional activity specifically in ECs and discovered that β-catenin-dependent transcription is central to the bone morphogenetic protein (Bmp)-mediated formation of venous vessels. During caudal vein (CV) formation, Bmp induces the expression of aggf1, a putative causative gene for Klippel-Trenaunay syndrome, which is characterized by venous malformation and hypertrophy of bones and soft tissues. Subsequently, Aggf1 potentiates β-catenin transcriptional activity by acting as a transcriptional co-factor, suggesting that Bmp evokes β-catenin-mediated gene expression through Aggf1 expression. Bmp-mediated activation of β-catenin induces the expression of Nr2f2 (also known as Coup-TFII), a member of the nuclear receptor superfamily, to promote the differentiation of venous ECs, thereby contributing to CV formation. Furthermore, β-catenin stimulated by Bmp promotes the survival of venous ECs, but not that of arterial ECs. Collectively, these results indicate that Bmp-induced activation of β-catenin through Aggf1 regulates CV development by promoting the Nr2f2-dependent differentiation of venous ECs and their survival. This study demonstrates, for the first time, a crucial role of β-catenin-mediated gene expression in the development of venous vessels.
To form the primary heart tube in zebrafish, bilateral cardiac precursor cells (CPCs) migrate toward the midline beneath the endoderm. Mutants lacking endoderm and fish with defective sphingosine 1-phosphate (S1P) signaling exhibit cardia bifida. Endoderm defects lead to the lack of foothold for the CPCs, whereas the cause of cardia bifida in S1P signaling mutants remains unclear. Here we show that S1P signaling regulates CPC migration through Yes-associated protein 1 (Yap1)-dependent endoderm survival. Cardia bifida seen in spns2 (S1P transporter) morphants and s1pr2 (S1P receptor-2) morphants could be rescued by endodermal expression of nuclear localized form of yap1. yap1 morphants had decreased expression of the Yap1/Tead target connective tissue growth factor a (Ctgfa) and consequently increased endodermal cell apoptosis. Consistently, ctgfa morphants showed defects of the endodermal sheet and cardia bifida. Collectively, we show that S1pr2/Yap1-regulated ctgfa expression is essential for the proper endoderm formation required for CPC migration.
Hajime Fukui, Dai Shiba, Kazuhide Asakawa, Koichi Kawakami and Takahiko Yokoyama : The ciliary protein Nek8/Nphp9 acts downstream of Inv/Nphp2 during pronephros morphogenesis and left-right establishment in zebrafish., FEBS Letters, 586, 16, 2273-2279, 2012.
(要約)
Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease. Among 12 reported Nphp gene products, Inv/Nphp2, Nphp3 and Nek8/Nphp9 are localized to the proximal segment in the primary cilium. However, the functional relationships are unknown. This study focused on phenotype analysis of nek8 knockdown embryos and the genetic relationship between nek8 and inv in zebrafish. Knockdown of nek8 produced both pronephric cysts and abnormal cardiac looping. Simultaneous knockdown of nek8 and inv synergistically increased the incidence of these defects. Interestingly, nek8 mRNA rescued inv morphant phenotypes, although inv mRNA could not rescue nek8 morphant phenotypes. These results suggest that Nek8 acts downstream of Inv function.
Seika Mitsui, Kan Torii, Hajime Fukui, Kunio Tsujimura, Akira Maeda, Mitsuhiko Nose, Akito Nagatsu, Hajime Mizukami and Akimichi Morita : The herbal medicine compound falcarindiol from notopterygii rhizoma suppresses dendritic cell maturation, The Journal of Pharmacology and Experimental Therapeutics, 333, 3, 954-960, 2010.
(要約)
Dendritic cells (DCs) are important for regulating the immune response. We report an herbal medicine compound called falcarindiol that affects DC function. Ethanol extracts of 99 crude drugs that are the main components of 210 traditional Japanese medicines (Kampo medicine) approved by the Ministry of Health, Labor and Welfare in Japan were prepared and screened using the murine epidermal-derived Langerhans cell line XS106. Notopterygii Rhizoma strongly suppressed major histocompatibility complex (MHC) class II expression in XS106 cells. Activity-guided fractionation led to the isolation and identification of falcarindiol as a principal active compound in Notopterygii Rhizoma. Falcarindiol (1-5 microM) dose-dependently suppressed MHC II expression in XS106 cells. Fresh-isolated bone marrow-derived DCs were examined for the production of MHC II, CD80, CD86, interleukin (IL)-12p70, and IL-10. Treatment of bone marrow-derived DCs with 5 muM falcarindiol significantly inhibited lipopolysaccharide-induced phenotype activation and cytokine secretion and inhibited MHC II expression by CD40 ligation, but not phorbol 12-myristate 13-acetate + ionomycin or IL-12. Falcarindiol inhibited DC maturation by blocking the canonical pathway of nuclear factor-kappaB and phosphorylated p38. Topical application of 0.002 and 0.01% falcarindiol before sensitization dose-dependently suppressed delayed-type hypersensitivity to ovalbumin (p < 0.01). Falcarindiol induces immunosuppressive effects in vitro and in vivo and might be a novel therapy for autoimmune or allergic diseases.
(キーワード)
Administration, Topical / Animals / Apiaceae / Bone Marrow Cells / Cell Line / Cytokines / Dendritic Cells / Diynes / Drugs, Chinese Herbal / Fatty Alcohols / Female / Flow Cytometry / Fluorescein-5-isothiocyanate / Fluorescent Dyes / Hypersensitivity, Delayed / Japan / Magnetic Resonance Spectroscopy / Mice / Mice, Inbred BALB C / Mice, Inbred C57BL / Mitogen-Activated Protein Kinases / NF-kappa B / Plant Extracts / Protein Transport
Hajime Fukui, Ryuki Hanaoka and Atsuo Kawahara : Noncanonical activity of seryl-tRNA synthetase is involved in vascular development., Circulation Research, 104, 11, 1253-1259, 2009.
(要約)
Vascular endothelial growth factor (Vegf) plays central roles in the establishment of stereotypic vascular patterning in vertebrates. However, it is not fully understood how the network of blood vessels is established and maintained during vascular development. A zebrafish ko095 mutant presented the disorganized vessels with abnormal branching of the established intersegmental vessels (ISVs) after 60 hours postfertilization. The gene responsible for ko095 encodes seryl-tRNA synthetase (Sars) with a nonsense mutation. The abnormal branching of ISVs in ko095 mutant was suppressed by the introduction of either wild-type Sars or a mutant Sars (T429A) lacking the enzymatic activity that catalyzes aminoacylation of transfer RNA for serine (canonical activity), suggesting that the abnormal branching is attributable to the loss of function of Sars besides its canonical activity. We further found the increased expression of vegfa in ko095 mutant at 72 hours postfertilization, which was also reversed by the introduction of Sars (T429A). Furthermore, the abnormal branching of ISVs in the mutant was suppressed by knockdown of vegfa or vegfr2 (kdra and kdrb). Knockdown of vegfc or vegfr3 rescued the abnormal ISV branching in ko095 mutant. These results suggest that the abnormal ISV branching in ko095 mutant is caused by the activated Vegfa-Vegfr2 signal and requires the Vegfc-Vegfr3 signal, because the latter is needed for general angiogenesis. Hence, we conclude that noncanonical activity of Sars is involved in vascular development presumably by modulating the expression of vegfa.
Atsuo Kawahara, Tsuyoshi Nishi, Yu Hisano, Hajime Fukui, Akihito Yamaguchi and Naoki Mochizuki : The sphingolipid transporter spns2 functions in migration of zebrafish myocardial precursors., Science, 323, 5913, 524-527, 2008.
(要約)
Sphingosine-1-phosphate (S1P) is a secreted lipid mediator that functions in vascular development; however, it remains unclear how S1P secretion is regulated during embryogenesis. We identified a zebrafish mutant, ko157, that displays cardia bifida (two hearts) resembling that in the S1P receptor-2 mutant. A migration defect of myocardial precursors in the ko157 mutant is due to a mutation in a multipass transmembrane protein, Spns2, and can be rescued by S1P injection. We show that the export of S1P from cells requires Spns2. spns2 is expressed in the extraembryonic tissue yolk syncytial layer (YSL), and the introduction of spns2 mRNA in the YSL restored the cardiac defect in the ko157 mutant. Thus, Spns2 in the YSL functions as a S1P transporter in S1P secretion, thereby regulating myocardial precursor migration.
Hajime Fukui, Seika Mitsui, Nobue Harima, Mitsuhiko Nose, Kunio Tsujimura, Hajime Mizukami and Akimichi Morita : Novel functions of herbal medicines in dendritic cells: Role of amomi semen in tumor immunity, Microbiology and Immunology, 51, 11, 1121-1133, 2007.
(要約)
Dendritic cells (DCs) have a major role in regulating immune responses, including tumor immunity and peripheral tolerance. In the present study, we identified novel functions of herbal medicines in DCs by screening 99 herbal medicines, most of which are among the 210 Chinese medicines approved by the Ministry of Health, Labour, and Welfare, Japan. Ethanol extracts were prepared, and a murine epidermal-derived Langerhans cell line, XS106, was used to screen the 99 extracts by analyzing major histocompatibility complex (MHC) class II expression. Amomi Semen (amomum seed), Polyporus (polyporus sclerotium), and Plantaginis Semen (plantago seed) potently activated XS106 and were selected for further analysis. The effects of these extracts on bone marrow-derived DCs (BM-DCs) generated in vitro were then analyzed using surface phenotype (MHC class II, CD80, and CD86) and interleukin (IL)-12p70 production as indicators. BM-DCs treated with Amomi Semen extract exhibited activated phenotypes and secreted IL-12p70. The activation level was similar to that induced by lipopolysaccharides. Finally, an E.G7-OVA tumor model (E.L4-OVA transfectant) was used to examine the anti-tumor effects of Amomi Semen extract. Vaccination of mice with a subcutaneous injection of BM-DCs treated with Amomi Semen extract and OVA peptide significantly inhibited the growth of tumor cells and prolonged survival time compared to controls. Furthermore, therapeutic effects were observed on established tumors. The inhibition rates for both the prophylactic and therapeutic protocols were comparable to those of lipopolysaccharides. These results indicate that Amomi Semen extract potently activate DCs and is potentially useful for DC vaccination.
Hajime Fukui, Yan Renee Wei Chow, Hwai Choon Yap and Julien Vermot : Rhythmic forces shaping the zebrafish cardiac system, Trends in Cell Biology, 35, 2, 166-176, Dec. 2024.
(要約)
The structural development of the heart depends heavily on mechanical forces, and rhythmic contractions generate essential physical stimuli during morphogenesis. Cardiac cells play a critical role in coordinating this process by sensing and responding to these mechanical forces. In vivo, cells experience rhythmic spatial and temporal variations in deformation-related stresses throughout heart development. What impact do these mechanical forces have on heart morphogenesis? Recent work in zebrafish (Danio rerio) offers important insights into this question. This review focuses on endocardial (EdCs) and myocardial cells (cardiomyocytes, CMs), key cell types in the heart, and provides a comprehensive overview of forces and tissue mechanics in zebrafish and their direct influence on cardiac cell identity.
(キーワード)
cardiac valve / Danio rerio / endothelial to mesenchymal transition / finite element modeling / tissue mechanics / trabeculation
Rita Ferreira R, Hajime Fukui, Renee Chow, Andrej Vilfan and Julien Vermot : The cilium as a force sensor-myth versus reality., Journal of Cell Science, 132, 14, Jul. 2019.
(要約)
Cells need to sense their mechanical environment during the growth of developing tissues and maintenance of adult tissues. The concept of force-sensing mechanisms that act through cell-cell and cell-matrix adhesions is now well established and accepted. Additionally, it is widely believed that force sensing can be mediated through cilia. Yet, this hypothesis is still debated. By using primary cilia sensing as a paradigm, we describe the physical requirements for cilium-mediated mechanical sensing and discuss the different hypotheses of how this could work. We review the different mechanosensitive channels within the cilium, their potential mode of action and their biological implications. In addition, we describe the biological contexts in which cilia are acting - in particular, the left-right organizer - and discuss the challenges to discriminate between cilium-mediated chemosensitivity and mechanosensitivity. Throughout, we provide perspectives on how quantitative analysis and physics-based arguments might help to better understand the biological mechanisms by which cells use cilia to probe their mechanical environment.
Hajime Fukui, Ayano Chiba, Takahiro Miyazaki, Haruko Takano, Hiroyuki Ishikawa, Toyonori Omori and Naoki Mochiuzki : Spatial Allocation and Specification of Cardiomyocytes during Zebrafish Embryogenesis., Korean Circulation Journal, 47, 2, 160-167, Mar. 2017.
(要約)
Incomplete development and severe malformation of the heart result in miscarriage of embryos because of its malfunction as a pump for circulation. During cardiogenesis, development of the heart is precisely coordinated by the genetically-primed program that is revealed by the sequential expression of transcription factors. It is important to investigate how spatial allocation of the heart containing cardiomyocytes and other mesoderm-derived cells is determined. In addition, the molecular mechanism underlying cardiomyocyte differentiation still remains elusive. The location of ectoderm-, mesoderm-, and endoderm-derived organs is determined by their initial allocation and subsequent mutual cell-cell interactions or paracrine-based regulation. In the present work, we provide an overview of cardiac development controlled by the germ layers and discuss the points that should be uncovered in future for understanding cardiogenesis.
Shigetomo Fukuhara, Hajime Fukui, Yuki Wakayama, Koji Ando, Hiroyuki Nakajima and Naoki Mochizuki : Looking back and moving forward: recent advances in understanding of cardiovascular development by imaging of zebrafish., Development Growth & Differentiation, 57, 4, 333-340, Apr. 2015.
(要約)
Development requires cell proliferation, migration, differentiation, apoptosis, and many kinds of cell responses. Cells prepare intracellular conditions to respond to extracellular cues from neighboring cells. We have studied the development of the cardiovascular system (CVS) by visualizing morphology and signaling simultaneously using zebrafish, which express probes for both. Endodermal sheet is required for the bilateral cardiac precursor cell (CPC) migration toward the midline. Endothelial cells (ECs) proliferate specifically in the certain regions of blood vessels. Bone morphogenetic proteins (BMP) induce the remodeling of the caudal vein plexus (CVP) to form the caudal vein (CV). Our findings point to the pre-existing neighboring cells as the cells exhibiting certain responses during the development of CVS. In this review, we introduce recent results of our research on angiogenesis and cardiogenesis by spotlighting the mechanism by which ECs and CPCs are regulated by the cells next to themselves. In addition, we discuss the unanswered questions that should be clarified in the future in the field of CVS development.
(キーワード)
Animals / Cardiovascular System / Cell Movement / Cell Proliferation / Transcriptional Activation / Zebrafish
Hajime Fukui : Blood flow-dependent physical parameters instruct the cardiac lumen morphogenesis, APPW 2025, Mar. 2025.
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Hajime Fukui : Blood flow-dependent physical parameters instruct the cardiac lumen morphogenesis, 2024 Team Meeting for Transformative (A), Dec. 2024.
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Hajime Fukui : Blood flow-dependent force parameters instruct endocardial cell identity for the cardiac lumen morphogenesis, The 47th Conference on Molecular Biology Society of Japan, Nov. 2024.
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Hajime Fukui : Blood flow-dependent force parameters instruct endocardial cell identity for the cardiac lumen morphogenesis, The 19th International Symposium of the Institute Network for Biomedical Sciences, Oct. 2024.
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Hajime Fukui : Blood flow-dependent force parameters instruct endocardial cell identity for the cardiac lumen morphogenesis, The 52nd Naito Conference on Frontiers of Physical and Mechanical Biology, Oct. 2024.