Drosophila immune cells transport oxygen through PPO2 protein phase transition.

Insect respiration has long been thought to be solely dependent on an elaborate tracheal system without assistance from the circulatory system or immune cells1,2. Here we describe that Drosophila crystal cells-myeloid-like immune cells called haemocytes-control respiration by oxygenating Prophenoloxidase 2 (PPO2) proteins. Crystal cells direct the movement of haemocytes between the trachea of the larval body wall and the circulation to collect oxygen. Aided by copper and a neutral pH, oxygen is trapped in the crystalline structures of PPO2 in crystal cells. Conversely, PPO2 crystals can be dissolved when carbonic anhydrase lowers the intracellular pH and then reassembled into crystals in cellulo by adhering to the trachea. Physiologically, larvae lacking crystal cells or PPO2, or those expressing a copper-binding mutant of PPO2, display hypoxic responses under normoxic conditions and are susceptible to hypoxia. These hypoxic phenotypes can be rescued by hyperoxia, expression of arthropod haemocyanin or prevention of larval burrowing activity to expose their respiratory organs. Thus, we propose that insect immune cells collaborate with the tracheal system to reserve and transport oxygen through the phase transition of PPO2 crystals, facilitating internal oxygen homeostasis in a process that is comparable to vertebrate respiration.

Olfactory control of blood progenitor maintenance.

Drosophila hematopoietic progenitor maintenance involves both near neighbor and systemic interactions. This study shows that olfactory receptor neurons (ORNs) function upstream of a small set of neurosecretory cells that express GABA. Upon olfactory stimulation, GABA from these neurosecretory cells is secreted into the circulating hemolymph and binds to metabotropic GABAB receptors expressed on blood progenitors within the hematopoietic organ, the lymph gland. The resulting GABA signal causes high cytosolic Ca(2+), which is necessary and sufficient for progenitor maintenance. Thus, the activation of an odorant receptor is essential for blood progenitor maintenance, and consequently, larvae raised on minimal odor environments fail to sustain a pool of hematopoietic progenitors. This study links sensory perception and the effects of its deprivation on the integrity of the hematopoietic and innate immune systems in Drosophila. PAPERCLIP:

Molecular traces of Drosophila hemocytes reveal transcriptomic conservation with vertebrate myeloid cells.

Drosophila hemocytes serve as the primary defense system against harmful threats, allowing the animals to thrive. Hemocytes are often compared to vertebrate innate immune system cells due to the observed functional similarities between the two. However, the similarities have primarily been established based on a limited number of genes and their functional homologies. Thus, a systematic analysis using transcriptomic data could offer novel insights into Drosophila hemocyte function and provide new perspectives on the evolution of the immune system. Here, we performed cross-species comparative analyses using single-cell RNA sequencing data from Drosophila and vertebrate immune cells. We found several conserved markers for the cluster of differentiation (CD) genes in Drosophila hemocytes and validated the role of CG8501 (CD59) in phagocytosis by plasmatocytes, which function much like macrophages in vertebrates. By comparing whole transcriptome profiles in both supervised and unsupervised analyses, we showed that Drosophila hemocytes are largely homologous to vertebrate myeloid cells, especially plasmatocytes to monocytes/macrophages and prohemocyte 1 (PH1) to hematopoietic stem cells. Furthermore, a small subset of prohemocytes with hematopoietic potential displayed homology with hematopoietic progenitor populations in vertebrates. Overall, our results provide a deeper understanding of molecular conservation in the Drosophila immune system.

Inter-organ regulation by the brain in Drosophila development and physiology.

The brain plays an essential role in regulating physiological homeostasis by communicating with other organs. Neuronal cells either directly innervate target tissues and transmit signals or secrete systemic factors into the hemolymph to regulate bodily functions, including physiology, development, metabolism, and immunity. In this review, we discuss the systemic functions of inter-organ communication mediated by the brain in four distinct categories: (1) nutrient sensing and feeding, (2) gastrointestinal activity and metabolism, (3) development and metamorphosis, and (4) immunity and hematopoiesis. First, we describe how chemosensory signals are sensed and transmitted to the brain in Drosophila and how the brain stimulates or modifies feeding behavior. Second, we summarize the brain-organ axis that regulates appetite activities and neuroendocrine pathways that maintain metabolic homeostasis. Third, we discuss how overall development in Drosophila is achieved by insulin and how it affects ecdysone signaling to initiate pupariation. Finally, we discuss how the central or peripheral nervous system controls hematopoiesis and innate immunity in Drosophila larvae. Given the functional parallels between Drosophila and humans, homologous pathways are likely to be conserved in human development and disease models, and the fly model system will continue to provide mechanistic insights into understanding complex interactions.

Development of Korea Neuroethics Guidelines.

BACKGROUND: Advances in neuroscience and neurotechnology provide great benefits to humans though unknown challenges may arise. We should address these challenges using new standards as well as existing ones. Novel standards should include ethical, legal, and social aspects which would be appropriate for advancing neuroscience and technology. Therefore, the Korea Neuroethics Guidelines were developed by stakeholders related to neuroscience and neurotechnology, including experts, policy makers, and the public in the Republic of Korea. METHOD: The guidelines were drafted by neuroethics experts, were disclosed at a public hearing, and were subsequently revised by opinions of various stakeholders. RESULTS: The guidelines are composed of twelve issues; humanity or human dignity, individual personality and identity, social justice, safety, sociocultural prejudice and public communication, misuse of technology, responsibility for the use of neuroscience and technology, specificity according to the purpose of using neurotechnology, autonomy, privacy and personal information, research, and enhancement. CONCLUSION: Although the guidelines may require a more detailed discussion after future advances in neuroscience and technology or changes in socio-cultural milieu, the development of the Korea Neuroethics Guidelines is a milestone for the scientific community and society in general for the ongoing development in neuroscience and neurotechnology.

Menstrual Cycle Control - A Controversial Example of Human Enhancement in Relation to Women's Body and Psyche.

By discussing the position of bio-conservatism and transhumanism, we question if the women menstrual cycle control would represent a new way toward a more responsive relation with one's own physical and mental health, a choice of freedom from undesired physiological conditions, a medicalization of a natural physiological event or an innovative carrier of social stigma against the women. We argue that the advancement of medical science may allow women a choice if to regulate own menstrual cycle, offering them as well a right to intervene responsibly on their own body and psyche. Accordingly, a post-human society could provide a suitable coexistence between women who claim menstruation as the biological essence and those who claim it as an option.

Graf regulates hematopoiesis through GEEC endocytosis of EGFR.

GTPase regulator associated with focal adhesion kinase 1 (GRAF1) is an essential component of the GPI-enriched endocytic compartment (GEEC) endocytosis pathway. Mutations in the human GRAF1 gene are associated with acute myeloid leukemia, but its normal role in myeloid cell development remains unclear. We show that Graf, the Drosophila ortholog of GRAF1, is expressed and specifically localizes to GEEC endocytic membranes in macrophage-like plasmatocytes. We also find that loss of Graf impairs GEEC endocytosis, enhances EGFR signaling and induces a plasmatocyte overproliferation phenotype that requires the EGFR signaling cascade. Mechanistically, Graf-dependent GEEC endocytosis serves as a major route for EGFR internalization at high, but not low, doses of the predominant Drosophila EGFR ligand Spitz (Spi), and is indispensable for efficient EGFR degradation and signal attenuation. Finally, Graf interacts directly with EGFR in a receptor ubiquitylation-dependent manner, suggesting a mechanism by which Graf promotes GEEC endocytosis of EGFR at high Spi. Based on our findings, we propose a model in which Graf functions to downregulate EGFR signaling by facilitating Spi-induced receptor internalization through GEEC endocytosis, thereby restraining plasmatocyte proliferation.

Nutritional regulation of stem and progenitor cells in Drosophila.

Stem cells and their progenitors are maintained within a microenvironment, termed the niche, through local cell-cell communication. Systemic signals originating outside the niche also affect stem cell and progenitor behavior. This review summarizes studies that pertain to nutritional effects on stem and progenitor cell maintenance and proliferation in Drosophila. Multiple tissue types are discussed that utilize the insulin-related signaling pathway to convey nutritional information either directly to these progenitors or via other cell types within the niche. The concept of systemic control of these cell types is not limited to Drosophila and may be functional in vertebrate systems, including mammals.

S-nitrosylation-triggered unfolded protein response maintains hematopoietic progenitors in Drosophila.

The Drosophila lymph gland houses blood progenitors that give rise to myeloid-like blood cells. Initially, blood progenitors proliferate, but later, they become quiescent to maintain multipotency before differentiation. Despite the identification of various factors involved in multipotency maintenance, the cellular mechanism controlling blood progenitor quiescence remains elusive. Here, we identify the expression of nitric oxide synthase in blood progenitors, generating nitric oxide for post-translational S-nitrosylation of protein cysteine residues. S-nitrosylation activates the Ire1-Xbp1-mediated unfolded protein response, leading to G2 cell-cycle arrest. Specifically, we identify the epidermal growth factor receptor as a target of S-nitrosylation, resulting in its retention within the endoplasmic reticulum and blockade of its receptor function. Overall, our findings highlight developmentally programmed S-nitrosylation as a critical mechanism that induces protein quality control in blood progenitors, maintaining their undifferentiated state by inhibiting cell-cycle progression and rendering them unresponsive to paracrine factors.

Stabilization of RNT-1 protein, runt-related transcription factor (RUNX) protein homolog of Caenorhabditis elegans, by oxidative stress through mitogen-activated protein kinase pathway.

RUNX proteins are evolutionarily conserved transcription factors known to be involved in various developmental processes. Here we report a new role for a RUNX protein: a role in stress response. We show that RNT-1, the Caenorhabditis elegans RUNX homolog, is constantly produced and degraded by the ubiquitination-proteasome pathway in the intestine of the nematode. RNT-1 was rapidly stabilized by oxidative stress, and the rnt-1-mutant animals were more sensitive to oxidative stress, indicating that rapid RNT-1 stabilization is a defense response against the oxidative stress. The MAP kinase pathway is required for RNT-1 stabilization, and RNT-1 was phosphorylated by SEK-1/PMK-1 in vitro. ChIP-sequencing analysis revealed a feedback loop mechanism of the MAP kinase pathway by the VHP-1 phosphatase in the RNT-1-mediated oxidative stress response. We propose that rnt-1 is regulated at the protein level for its role in the immediate response to environmental challenges in the intestine.

Oxidative stress in the haematopoietic niche regulates the cellular immune response in Drosophila.

Oxidative stress induced by high levels of reactive oxygen species (ROS) is associated with the development of different pathological conditions, including cancers and autoimmune diseases. We analysed whether oxidatively challenged tissue can have systemic effects on the development of cellular immune responses using Drosophila as a model system. Indeed, the haematopoietic niche that normally maintains blood progenitors can sense oxidative stress and regulate the cellular immune response. Pathogen infection induces ROS in the niche cells, resulting in the secretion of an epidermal growth factor-like cytokine signal that leads to the differentiation of specialized cells involved in innate immune responses.

An XYZ-axis Matrix Approach for the Integration of Neuroscience and Neuroethics.

The recent, unprecedented advancement in neuroscience has led to new discoveries about the human brain and its function. Yet at the same time, it has spurred novel ethical and regulatory issues, and the field of neuroethics has emerged as an interdisciplinary endeavor to address these issues. Across the globe, extensive efforts have been underway to achieve the integration of neuroscience and Neuroethics, with active engagement not only from academia but also from the government, the public, and industry. However, in some countries, integrating neuroscience and neuroethics has proved to be a particularly challenging task. For example, in South Korea, the government has primarily driven the integration effort, and only a small group of researchers is properly trained for conducting an interdisciplinary evaluation of ethical, legal, social, and cultural implications (ELSCI) of neurotechnology. On the basis of the last few years of experience pursuing a government-funded neuroethics project in South Korea, we developed a new operational framework to provide practical guidance on ELSCI research. This framework consists of the X, Y, and Z axes; the X-axis represents a target neurotechnology, the Y-axis represents different developmental stages of the technology, and the Z-axis represents ELSCI issues that may arise from the development and use of the neurotechnology. Here we also present a step-by-step workflow to apply this matrix framework, from organizing a panel for a target neurotechnology to facilitating stakeholder discussion through public hearings. This framework will enable meaningful integration of neuroscience and neuroethics to promote responsible innovation in neuroscience and neurotechnology.

A Novel Interaction between MFN2/Marf and MARK4/PAR-1 Is Implicated in Synaptic Defects and Mitochondrial Dysfunction.

As cellular energy powerhouses, mitochondria undergo constant fission and fusion to maintain functional homeostasis. The conserved dynamin-like GTPase, Mitofusin2 (MFN2)/mitochondrial assembly regulatory factor (Marf), plays a role in mitochondrial fusion, mutations of which are implicated in age-related human diseases, including several neurodegenerative disorders. However, the regulation of MFN2/Marf-mediated mitochondrial fusion, as well as the pathologic mechanism of neurodegeneration, is not clearly understood. Here, we identified a novel interaction between MFN2/Marf and microtubule affinity-regulating kinase 4 (MARK4)/PAR-1. In the Drosophila larval neuromuscular junction, muscle-specific overexpression of MFN2/Marf decreased the number of synaptic boutons, and the loss of MARK4/PAR-1 alleviated the synaptic defects of MFN2/Marf overexpression. Downregulation of MARK4/PAR-1 rescued the mitochondrial hyperfusion phenotype caused by MFN2/Marf overexpression in the Drosophila muscles as well as in the cultured cells. In addition, knockdown of MARK4/PAR-1 rescued the respiratory dysfunction of mitochondria induced by MFN2/Marf overexpression in mammalian cells. Together, our results indicate that the interaction between MFN2/Marf and MARK4/PAR-1 is fine-tuned to maintain synaptic integrity and mitochondrial homeostasis, and its dysregulation may be implicated in neurologic pathogenesis.

A new role for Hif-1α.

A gene normally involved in responding to hypoxia helps to protect insect muscles during migratory flight in a non-oxygen dependent manner.

Measures to Use Electroceuticals and Secure Social Reliability in Korea: A Narrative Review.

Background: The purpose of this study was to present a plan for utilizing electroceuticals to secure social reliability in Korea by investigating and analyzing the trends of humanities and social science research in Korea regarding electroceuticals. Methods: The present situation of academic papers in the fields of humanities and social sciences that had researched electroceuticals in Korea and the topics that were directly related to electroceuticals had been reviewed and analyzed. Results: Regarding researches related to electroceuticals in the fields of humanities and social sciences in Korea, they were insufficient quantitatively. Qualitatively, they had leaned too much toward theoretical and abstract discourses regarding neuroethics and neurophilosophy. Conclusion: If researches in the fields of humanities and social sciences known to play a role in preparing practical guidelines could be carried out sufficiently while preparing a base for solving actual problems raised by electroceuticals, they could actually help plan a specific electroceuticals policy and a law to secure social reliability. Among principles of general life medical ethics (principles of biomedical ethics), when considering the principle of justice, the investment by the Korean government regarding research and development of electroceuticals, the rationalization of electroceuticals regulations, the application of electroceuticals of public health insurance benefit, and voluntary efforts of electroceuticals corporations are important in order to have strong plans for securing the social reliability of electroceuticals.

Intrinsic and Extrinsic Regulation of Hematopoiesis in Drosophila.

Drosophila melanogaster lymph gland, the primary site of hematopoiesis, contains myeloid-like progenitor cells that differentiate into functional hemocytes in the circulation of pupae and adults. Fly hemocytes are dynamic and plastic, and they play diverse roles in the innate immune response and wound healing. Various hematopoietic regulators in the lymph gland ensure the developmental and functional balance between progenitors and mature blood cells. In addition, systemic factors, such as nutrient availability and sensory inputs, integrate environmental variabilities to synchronize the blood development in the lymph gland with larval growth, physiology, and immunity. This review examines the intrinsic and extrinsic factors determining the progenitor states during hemocyte development in the lymph gland and provides new insights for further studies that may extend the frontier of our collective knowledge on hematopoiesis and innate immunity.

A Comparative Study on Intention to Use Digital Therapeutics: MZ Generation and Baby Boomers' Digital Therapeutics Use Intention in Korea.

PURPOSE: The aim of this study lies in articulating the relationship between digital literacy and private concern as a predictor of intention to use digital therapeutics. MATERIALS AND METHODS: An online survey was conducted through a research company among 600 panels. The survey questionnaire consists of items of digital literacy, privacy concern, perceptions, and intention to use digital therapeutics, and the participants were asked to fill out the questions online. A structural equation model was established, and the difference in paths between the MZ generation and the baby boomers were examined. RESULTS: Public perception of digital therapeutics was categorized into seven factors and the dimension of digital literacy as categorized into three factors. For the MZ generation, digital literacy and privacy concern both directly and indirectly affect the digital therapeutics use intention, in that higher the level of digital literacy and the lower the privacy concern, digital therapeutics perception and digital therapeutics use intention becomes intensified. For the baby boomers, digital literacy and privacy concern positively affect digital therapeutics perception, and as digital therapeutics perception becomes more positive, digital therapeutics use intention also increases. Direct effects of digital literacy and privacy concern to digital therapeutics use intention were not found for the baby boomers. CONCLUSION: In order to promote the use of digital therapeutics, it is common for the MZ generation and baby boomers to develop a positive perception toward digital therapeutics by cultivating digital literacy. For the MZ generation, privacy concerns need to be cautiously considered as they negatively affect the intention to use digital therapeutics.

Fly Cell Atlas: A single-nucleus transcriptomic atlas of the adult fruit fly.

For more than 100 years, the fruit fly Drosophila melanogaster has been one of the most studied model organisms. Here, we present a single-cell atlas of the adult fly, Tabula Drosophilae, that includes 580,000 nuclei from 15 individually dissected sexed tissues as well as the entire head and body, annotated to >250 distinct cell types. We provide an in-depth analysis of cell type-related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types between tissues, such as blood and muscle cells, reveals rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the Drosophila community and serves as a reference to study genetic perturbations and disease models at single-cell resolution.

Chk2-p53 and JNK in irradiation-induced cell death of hematopoietic progenitors and differentiated cells in Drosophila larval lymph gland.

Ionizing radiation (IR) induces DNA double-strand breaks that activate the DNA damage response (DDR), which leads to cell cycle arrest, senescence, or apoptotic cell death. Understanding the DDR of stem cells is critical to tissue homeostasis and the survival of the organism. Drosophila hematopoiesis serves as a model system for sensing stress and environmental changes; however, their response to DNA damage remains largely unexplored. The Drosophila lymph gland is the larval hematopoietic organ, where stem-like progenitors proliferate and differentiate into mature blood cells called hemocytes. We found that apoptotic cell death was induced in progenitors and hemocytes after 40 Gy irradiation, with progenitors showing more resistance to IR-induced cell death compared to hemocytes at a lower dose. Furthermore, we found that Drosophila ATM (tefu), Chk2 (lok), p53, and reaper were necessary for IR-induced cell death in the progenitors. Notably, IR-induced cell death in mature hemocytes required tefu, Drosophila JNK (bsk), and reaper, but not lok or p53. In summary, we found that DNA damage induces apoptotic cell death in the late third instar larval lymph gland and identified lok/p53-dependent and -independent cell death pathways in progenitors and mature hemocytes, respectively.

The Role of Lozenge in Drosophila Hematopoiesis.

Drosophila hematopoiesis is comparable to mammalian differentiation of myeloid lineages, and therefore, has been a useful model organism in illustrating the molecular and genetic basis for hematopoiesis. Multiple novel regulators and signals have been uncovered using the tools of Drosophila genetics. A Runt domain protein, lozenge, is one of the first players recognized and closely studied in the hematopoietic lineage specification. Here, we explore the role of lozenge in determination of prohemocytes into a special class of hemocyte, namely the crystal cell, and discuss molecules and signals controlling the lozenge function and its implication in immunity and stress response. Given the highly conserved nature of Runt domain in both invertebrates and vertebrates, studies in Drosophila will enlighten our perspectives on Runx-mediated development and pathologies.