Biology subjects

Yamanaka, N.

Publications and source records attributed to Yamanaka, N..

11 recordsLinked to original sources

bioRxiv2025

Steroid hormone-dependent glial-neuronal interaction promotes brain development during Drosophila metamorphosis

Steroid hormones regulate various aspects of brain development in metazoans. In the fruit fly Drosophila melanogaster, the primary steroid hormone ecdysone enters the central nervous system (CNS) via Ecdysone Importer (EcI) in the blood-brain barrier (BBB) and induces brain development during metamorphosis. However, our understanding of the exact cell types that require ecdysone during CNS transformation is still limited. Here, we report that ecdysone-dependent glial-neuronal interaction promotes brain development during Drosophila metamorphosis. Unexpectedly, disrupting ecdysone signaling in glial cells caused more severe defects in CNS transformation than in neurons, suggesting an essential role of glia in ecdysone-dependent brain development. When ecdysone receptor was knocked down in mushroom body (MB) neurons, pruning of their larval-specific axonal lobes was disrupted as reported previously. In contrast, knockdown of EcI in the MB did not induce any discernible deficiency in neuronal remodeling, suggesting dispensability of EcI-mediated ecdysone entry into the MB. Consistent with this, the neuronal remodeling defects induced by EcI knockdown in the BBB were rescued by glial cell-specific overexpression of a transforming growth factor-{beta} ligand myoglianin and an engulfment receptor draper, both of which are upregulated in glial cells in an ecdysone-dependent manner. Collectively, our findings suggest that ecdysone is primarily required in glial cells for CNS transformation during metamorphosis, elucidating a hormone-dependent glial-neuronal interaction that drives brain development.

developmental biology↗

bioRxiv2025

Ion transport peptide regulates body water balance via a receptor guanylyl cyclase in the Drosophila hindgut

Maintaining internal water balance, including ionic and osmotic balance, is critical for animal development and survival. In insects, internal water balance is regulated through the Malpighian tubules and the hindgut, which transport water and ions across their epithelia under the regulation of multiple peptide hormones. One of these, ion transport peptide (ITP), a member of the highly conserved crustacean hyperglycemic hormone superfamily among ecdysozoans, is an anti-diuretic hormone in insects, but its mechanism of action remains largely unclear. Here, we show that the short amidated isoform of ITP (saITP), secreted from brain neurosecretory cells, regulates water absorption via the receptor guanylyl cyclase (rGC) Gyc76C in the hindgut of the fruit fly Drosophila melanogaster. Both ITP and Gyc76C are evolutionarily conserved and are essential for larval survival in D. melanogaster, as mutation or knockdown of either gene results in early larval lethality. In Drosophila S2 cells, synthetic saITP increases intracellular cyclic GMP (cGMP) in a Gyc76C-dependent manner, an effect abolished by deletion of its putative ligand-binding domain. Using the fluorescent cGMP biosensor RedcGull in ex vivo-cultured hindguts, we found that saITP increases epithelial cGMP levels, and this response requires Gyc76C. Consistently, saITP promotes hindgut water reabsorption via Gyc76C. Thus, saITP acts via Gyc76C in a brain-hindgut neuroendocrine axis that regulates internal water balance during development. Our study provides new insight into the neuroendocrine control of osmoregulation in ecdysozoans and supports a broader role for rGCs in peptide-hormone signaling.

physiology↗

bioRxiv2025

Two Cytochrome P450 epoxidases mediate juvenile hormone biosynthesis in Drosophila melanogaster

Juvenile hormones (JHs) mediate various biological processes such as development and reproduction in insects. Although pleiotropic functions of JHs are well investigated in the fruit fly Drosophila melanogaster, their biosynthetic mechanisms are less well understood, partly because many JH biosynthetic enzymes still remain unidentified in this important model species. Here we report that two cytochrome P450 (CYP) epoxidases mediate JH biosynthesis in D. melanogaster. In addition to previously reported Cyp6g2, a second epoxidase, Cyp6a13, also functions in the corpus allatum, the major JH biosynthetic endocrine gland. Combined mutations of the genes encoding these enzymes cause developmental and reproductive defects, which can be rescued by JH application. JH biosynthetic functions of these genes were further confirmed by using a heterologous expression system and ex vivo tissue culture. Collectively, our results indicate that these two CYP epoxidases function cooperatively to mediate JH biosynthesis in D. melanogaster. HighlightsO_LIDrosophila Cyp6g2 and Cyp6a13 are highly expressed in the corpus allatum. C_LIO_LICombined knockout mutants of the CYP genes exhibit developmental and reproductive defects. C_LIO_LIMutant phenotypes were rescued by feeding juvenile hormones. C_LIO_LIBoth Cyp6g2 and Cyp6a13 catalyze epoxidation of juvenile hormone precursors. C_LI

developmental biology↗

bioRxiv2025

Long-read RNA sequencing identifies isoform switching of a novel long non-coding RNA that promotes somatic cell reprogramming

Development of long-read RNA sequencing technologies has paved the way to the exploration of RNA isoform diversity and its relevance in regulating cell fate. However, identifying new functional isoforms is still very difficult. Here, we leverage long-read RNA sequencing to study changes in isoforms during somatic cell reprogramming and identify novel isoforms occurring throughout cell state transitions. We demonstrate tight regulation of non-coding isoforms and show that isoform switching plays previously overlooked functional roles and outcomes in gene regulation and cell fate changes. We uncover a novel long non-coding RNA, Snhg26, that undergoes isoform switching during reprogramming to enhance the conversion of differentiated cells towards the pluripotent state. Knock-down of Snhg26 in mouse and human pluripotency models reveals that it is important for pluripotency acquisition. Together, our study provides a resource to study full-length isoform usage during cell fate change. It also demonstrates the power of long-read sequencing to identify functionally relevant gene isoforms in the context of cell plasticity.

cell biology↗

bioRxiv2025

Functional characterization of eicosanoid signaling in Drosophila development

20-carbon fatty acid-derived eicosanoids are versatile signaling oxylipins in mammals. In particular, a group of eicosanoids termed prostanoids are involved in multiple physiological processes, such as reproduction and immune responses. Although some eicosanoids such as prostaglandin E2 (PGE2) have been detected in some insect species, molecular mechanisms of eicosanoid synthesis and signal transduction in insects have not been thoroughly investigated. Our phylogenetic analysis indicated that, in clear contrast to the presence of numerous receptors for oxylipins and other lipid mediators in humans, the Drosophila genome only possesses a single ortholog of such receptors, which is homologous to human prostanoid receptors. This G protein-coupled receptor, named Prostaglandin Receptor or PGR, is activated by PGE2 and its isomer PGD2 in Drosophila S2 cells. PGR mutant flies die as pharate adults with insufficient tracheal development, which can be rescued by supplying high oxygen. Consistent with this, through a comprehensive mutagenesis approach, we identified a Drosophila PGE synthase whose mutants show similar pharate adult lethality with hypoxia responses. Drosophila thus has a highly simplified eicosanoid signaling pathway as compared to humans, and it may provide an ideal model system for investigating evolutionarily conserved aspects of eicosanoid signaling. Author SummaryThere are numerous bioactive lipids that control animal physiology, and some of them are commonly observed in both humans and insects. Well-studied insects such as fruit flies can therefore be an excellent gateway to learn about lipid molecules that have common functions in various animal species. In this study, we analyzed the fruit fly genome to look for genes that encode sensors (or receptors) for such lipid molecules called lipid mediators and found that the fruit fly only has one such receptor, as compared to [~]50 receptors in humans. Interestingly, the fly receptor we found was similar to human receptors for lipid molecules called prostanoids. Our work on the fruit fly prostanoid receptor further revealed that it is important for development of the fly respiratory system, and we showed that flies can also synthesize prostanoids in their body just like humans. Prostanoids are clinically important due to their pro-inflammatory functions, and some widely used drugs such as ibuprofen target enzymes that synthesize prostanoids. Our study on fruit fly prostanoids therefore provides a solid basis for using this simple organism to reveal common prostanoid functions in animals, which may provide important insights into animal health in general.

developmental biology↗

bioRxiv2024

Aging-associated vacuolation of multi-ciliated cells in the distal mouse oviduct reflects unique cell identity and luminal microenvironment

The female reproductive organs present with the earliest aging characteristics, such as a decline in fertility and estrous cyclicity. While age-related changes in the ovary are well-documented, it is unclear if any age-associated changes occur in the other female reproductive organs, such as the oviduct/fallopian tube. The recent recognition of the distal end of the fallopian tube as the tissue of origin of high-grade serous tubal ovarian carcinomas (HGSCs), and that its patient demographic is strongly biased to postmenopausal women, motivated us to investigate age-associated changes in this organ. At the distal end of aged oviducts in mice, we found vacuolated multi-ciliated cells (MCCs) with a severely apically displaced and deformed nucleus. This phenotype was unique to the distal oviduct epithelium -infundibulum (INF) and ampulla (AMP). Ovariectomy did not affect the timeline of MCC vacuolation, suggesting little involvement of ovulation and hormonal regulation. MCC vacuolation was induced in hypoxia or hydroxyurea treatments in in vitro organotypic culture of all oviduct regions, not limited to the INF/AMP epithelium. This suggests high oxygen demand in MCCs, compared to other cell types, and a uniquely stressed INF/AMP epithelial microenvironment in vivo. We found that the blood circulation of INF/AMP depended on the ovarian artery, different from the rest of the oviduct epithelium and its circulation declined along with ovarian activities. We conclude that a decline in local blood circulation and distinct cellular identity of the INF/AMP epithelium caused age-associated MCC vacuolation, reflecting its mild, chronically stressed microenvironment.

physiology↗

bioRxiv2021

Essential functions of mosquito ecdysone importers in development and reproduction

The primary insect steroid hormone ecdysone requires a membrane transporter to enter its target cells. Although an organic anion-transporting polypeptide (OATP) named Ecdysone Importer (EcI) serves this role in the fruit fly Drosophila melanogaster and most likely in other arthropod species, this highly conserved transporter is apparently missing in mosquitoes. Here we report three additional OATPs that facilitate cellular incorporation of ecdysone in Drosophila and the yellow fever mosquito Aedes aegypti. These additional ecdysone importers (EcI-2, 3, and 4) are dispensable for development and reproduction in Drosophila, consistent with the predominant role of EcI. In contrast, in Aedes, EcI-2 is indispensable for ecdysone-mediated development, whereas EcI-4 is critical for vitellogenesis induced by ecdysone in adult females. Altogether, our results indicate unique and essential functions of these additional ecdysone importers in mosquito development and reproduction, making them attractive molecular targets for species- and stage-specific control of ecdysone signaling in mosquitoes.

developmental biology↗

bioRxiv2021

Modeling High-grade serous ovarian carcinoma using a combination of in vivo electroporation and CRISPR/Cas9 mediated genome editing

Ovarian cancer remains the most lethal gynecological cancer today. High-grade serous ovarian carcinoma (HGSC) is the most common and lethal type of ovarian cancer and is most frequently diagnosed at advanced stages. Here, we developed a novel strategy to generate somatic ovarian cancer mouse models using a combination of in vivo electroporation and CRISPR/Cas9 mediated genome editing. We mutated tumor suppressor genes associated with HGSC in two different combinations; Brca1, Tp53, Pten with/without Lkb1 and successfully generated HGSC, however, with different latencies and pathophysiology. By utilizing Cre lineage tracing in our system, we visualized peritoneal micrometastases in an immune-competent environment. Because our strategy is flexible in selecting mutation combinations and targeting areas, it would be useful for generating ovarian cancer mouse models. Significance StatementHigh grade serous ovarian cancer (HGSC) is the most common ovarian malignancy but our knowledge of early tumorigenesis is still quite limited due to late diagnosis of patients. We developed a new strategy of generating mouse ovarian cancer models using a combination of in vivo electroporation and CRISPR-mediated genome editing. We demonstrated that a combination of three tumor suppressor gene mutations (Brca1, Tp53 and Pten) is sufficient to develop HGSCs. Interesting, an additional mutation in Lkb1 drastically changed tumor latency, penetrance and pathophysiology through changing its cell-of-origin. Our strategy is highly flexible in selection of mutation combinations and targeting areas in immune competent mice and useful to study early tumorigenesis of ovarian cancer.

cancer biology↗

bioRxiv2021

Parasitic nematode fatty acid- and retinol-binding proteins compromise host immunity by interfering with host lipid signaling pathways

Parasitic nematodes cause significant morbidity and mortality globally. Excretory/secretory products (ESPs) such as fatty acid- and retinol- binding proteins (FARs) are hypothesized to suppress host immunity during infection, yet little is known about their interactions with host tissues. Leveraging the insect parasitic nematode, Steinernema carpocapsae, we provide the first in vivo study that shows FARs modulate animal immunity, causing an increase in susceptibility to bacterial infection. Next we determined that FARs dampen various aspects of the fly immune response including the phenoloxidase cascade and antimicrobial peptide (AMP) production. Finally, we found that FARs deplete lipid signaling precursors in vivo as well as bind to these fatty acids in vitro, suggesting that FARs elicit their immunomodulatory effects by altering the availability of lipid signaling molecules necessary for a functional immune response. Collectively, these data reveal a complex role for FARs in immunosuppression and provide detailed mechanistic insight into parasitism in phylum Nematoda. SignificanceA central aspect of parasitic nematode success is their ability to modify host biology, including evasion and/or subversion of host immunity. Modulation of host biology and the pathology caused by parasitic nematodes is largely effected through the release of proteins and small molecules. There are hundreds of proteins released by nematodes during an infection and few have been studied in detail. Fatty acid- and retinol-binding proteins (FARs) are a unique protein family released during infection. We report that nematode FARs from S. carpocapsae, C. elegans and A. ceylanicum dampen fly immunity decreasing resistance to infection. Mechanistically, this is achieved through modulation of the phenoloxidase cascade and antimicrobial peptide production. Furthermore, FARs alter the availability of lipid immune signaling precursors in vivo and show binding specificity in vitro. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=187 SRC="FIGDIR/small/436866v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@48f582org.highwire.dtl.DTLVardef@1ee4292org.highwire.dtl.DTLVardef@1548248org.highwire.dtl.DTLVardef@13574d6_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

molecular biology↗

bioRxiv2020

Anatomical and cellular heterogeneity in the mouse oviduct-- its potential roles in reproduction and preimplantation development

The oviduct/fallopian tube is a tube-like structure that extends from the uterus to the ovary. It is an essential reproductive tissue that provides an environment for internal fertilization and preimplantation development. However, our knowledge of its regional and cellular heterogeneity is still limited. Here, we examined the anatomical complexity of mouse oviducts using modern imaging techniques and fluorescence reporter lines. We found that there are basic coiling patterns and turning points in the coiled mouse oviduct can serve as reliable landmarks for luminal morphological regionalities. We identified previously unrecognized anatomical structures in the isthmus and uterotubal junction (UTJ) that likely play important roles in reproduction. Interestingly, during ovulation, the isthmus was transiently plugged by a thick mucus, keeping the oocytes within the ampulla. Preimplantation embryos travelled along the oviduct and formed a queue within small compartments of the UTJ before uterine entry. Taken together, the oviduct luminal epithelium had highly diverse luminal structures with distinct cell populations reflecting its complex functions in reproduction.

physiology↗

bioRxiv2020

Oviduct epithelial cells constitute two developmentally distinct lineages that are spatially separated along the distal-proximal axis

Owing to technical advances in single cell biology, the appreciation of cellular heterogeneity has increased, which has aided our understanding of organ function, homeostasis and disease progression. The oviduct (also known as the fallopian tube in humans) is the distal-most portion of the female reproductive tract. It is essential for reproduction and the proposed origin of high grade serous ovarian carcinoma (HGSOC). In mammals, the oviduct is morphologically segmented along the ovary-uterus axis into four evolutionally conserved regions. It is unknown however if there is a diversification of epithelial cell characteristics between these regions. In this study, we identified transcriptionally distinct populations of secretory and multiciliated cells restricted to the distal and proximal regions of the oviduct. We demonstrated that these distal and proximal populations are distinct lineages specified early in Mullerian duct development and are maintained separately. These results aid our understanding of epithelial development, homeostasis and initiation of disease from the oviduct.

developmental biology↗