Fos regulates macrophage infiltration against surrounding tissue resistance by a cortical actin-based mechanism in Drosophila

Functional analysis of BmTsp.C in modulating infection of BmNPV through apoptosis pathways in domestic silkworm (Bombyx mori)

The silkworm, Bombyx mori, is a crucial model insect in agriculture and biological research. Tetraspanins, known for their effects in regulating cellular functions like cell signalling, adhesion, migration and diffusion, take on a crucial role in viral dynamics, influencing both viral spread and entry into host cells. In this study, a tetraspanin gene called BmTsp.C from the silkworm genome was identified and investigated. Tissue profiles showed that BmTsp.C has the highest transcription level in midgut, with a marked increase following viral infection. The immunofluorescence localization suggested that BmTsp.C is primarily distributed on the cell membrane. Additionally, overexpression of BmTsp.C in BmN cells facilitated the proliferation of BmNPV. Meanwhile, siRNA-mediated knockdown of BmTsp.C could inhibit viral proliferation. In addition, knockdown of BmTsp.C at the individual level further validated the remarkable effect of BmTsp.C during viral infestation. Furthermore, overexpression of BmTsp.C could regulate the expression of apoptosis-related genes. Results from flow cytometry indicated a decrease in the number of apoptotic cells after overexpression of BmTsp.C. Taken together, our results demonstrated that BmTsp.C, as an important factor in the Tetraspanin-enriched microdomains, exerts a significant influence on the proliferation of BmNPV, most likely through the cellular apoptosis pathway.

Some molecular aspects of larval development in Paralithodes camtschaticus

The transcriptome of the red king crab, Paralithodes camtschaticus, was sequenced at four developmental stages: zoea I, zoea IV, glaucothoe, and juveniles. Based on our RNA-seq data and paired-end reads from 112 libraries obtained by other researchers earlier, the transcriptome assembly for P. camtschaticus that we obtained has proven to be the most complete of those reported to date. An analysis of enriched processes at different stages has shown, that some of adaptations, e.g., to elevated temperature and hypoxia, do not appear in early larvae. Thus, it is important to maintain optimal conditions for normal larval development and reduce mortality rates. According to the results of the expression profile clustering and transcription factor (TF) search, most TFs are associated with the development of various organs, metamorphosis, and immune responses. The data obtained provide an additional basis for deeper investigation into the mechanisms of the biphasic life cycle in decapods and can be helpful in commercial red king crab stock enhancement programs.

Single-cell RNA sequencing dissects the immunosuppressive signatures in Helicobacter pylori-infected human gastric ecosystem

Helicobacter pylori (H. pylori) manipulates the host immune system to establish a persistent colonization, posing a serious threat to human health, but the mechanisms remain poorly understood. Here we integrate single-cell RNA sequencing and TCR profiling for analyzing 187,192 cells from 11 H. pylori-negative and 12 H. pylori-positive individuals to describe the human gastric ecosystem reprogrammed by H. pylori infection, as manifested by impaired antigen presentation and phagocytosis function. We further delineate a monocyte-to-C1QC+ macrophage differentiation trajectory driven by H. pylori infection, while T cell responses exhibit broad functional impairment and hyporesponsiveness with restricted clonal expansion capacity. We also identify an HLA-DRs- and CTLA4-expressing T cell population residing in H. pylori-inhabited stomach that potentially contribute to immune evasion. Together, our findings provide single-cell resolution information into the immunosuppressive microenvironment shaped by H. pylori infection, offering critical insights for developing novel therapeutic approaches to eliminate this globally prevalent pathogen.

fos genes in mainly invertebrate model systems: A review of commonalities and some diversities

fos genes, transcription factors with a common basic region and leucine zipper domains binding to a consensus DNA sequence (TGA{}TCA), are evolutionarily conserved in eukaryotes. Homologs can be found in many different species from yeast to vertebrates. In yeast, the homologous GCN4 gene is required to mediate "emergency" situations like nutrient deprivation and the unfolded protein response. The C. elegans homolog fos-1 is required for reproduction and vulval development, as well as in adult homeostasis. In Drosophila melanogaster, there is also a sole fos homolog: the gene kayak, with five isoforms. The kayak locus has been studied in detail. It was originally described as embryonic lethal with a "dorsal open" phenotype. Since then, kayak has been shown to be required for oocyte maturation and as a source for piRNA; for early dorsoventral specification, macrophage function, dorsal closure, endoderm differentiation, and finally during metamorphosis in wing and eye-antennal development. In mammals there are multiple fos loci, each one with alternative splicing giving rise to multiple isoforms. Overall, mammalian fos genes are required for bone, cartilage and tooth formation, and in some instances for placental angiogenesis and retinal function. We review here mainly what is known about fos function in invertebrate model systems, especially during embryogenesis. We propose that fos genes, evolutionarily conserved transcription factors, evolved early during eukaryotic development, and from its inception as part of an environmental stress response machinery, were co-opted several times during development to regulate processes that may require similar cellular responses.

Immune cells adapt to confined environments in vivo to optimise nuclear plasticity for migration

Cells navigating in complex 3D microenvironments frequently encounter narrow spaces that physically challenge migration. While in vitro studies identified nuclear stiffness as a key rate-limiting factor governing the movement of many cell types through artificial constraints, how cells migrating in vivo respond dynamically to confinement imposed by local tissue architecture, and whether these encounters trigger molecular adaptations, is unclear. Here, we establish an innovative in vivo model for mechanistic analysis of nuclear plasticity as Drosophila immune cells transition into increasingly confined microenvironments. Integrating live in vivo imaging with molecular genetic analyses, we demonstrate how rapid molecular adaptation upon environmental confinement (including fine-tuning of the nuclear lamina) primes leukocytes for enhanced nuclear deformation while curbing damage (including rupture and micronucleation), ultimately accelerating movement through complex tissues. We find nuclear dynamics in vivo are further impacted by large organelles (phagosomes) and the plasticity of neighbouring cells, which themselves deform during leukocyte passage. The biomechanics of cell migration in vivo are thus shaped both by factors intrinsic to individual immune cells and the malleability of the surrounding microenvironment.

The Circadian Rhythm Regulates the Hepato-ovarian Axis Linking Polycystic Ovary Syndrome and Non-alcoholic Fatty Liver Disease

This study aimed to identify shared gene expression related to circadian rhythm disruption in polycystic ovary syndrome (PCOS) and non-alcoholic fatty liver disease (NAFLD) to discover common diagnostic biomarkers. Visceral fat RNA samples were collected from 12 PCOS and 14 non-PCOS patients, a sample size representing the clinical situation and sufficient to capture PCOS gene expression profiles. Along with liver transcriptome profiles from NAFLD patients, these data were analyzed to identify crosstalk circadian rhythm-related genes (CRRGs) between the diseases. Single-sample and single-gene gene set enrichment analyses explored immune infiltration and pathways associated with CRRGs. Diagnostic biomarkers were identified using a random forest algorithm and validated through nomograms and a mouse model. Seven crosstalk CRRGs (FOS, ACHE, FOSB, EGR1, NR4A1, DUSP1, and EGR3) were associated with clinical features, immunoinflammatory microenvironment, and metabolic pathways in both diseases. EGR1, DUSP1, and NR4A1 were identified as diagnostic biomarkers, exhibiting robust diagnostic capacity (AUC = 0.7679 for PCOS, AUG = 0.9981 for NAFLD). Nomogram validation showed excellent calibration, and independent datasets confirmed their discriminatory ability (AUC = 0.6528 for PCOS, AUC = 0.8275 for NAFLD). Additionally, ceRNA networks and androgen receptor binding sites were identified, suggesting their regulatory roles. Mouse model validation confirmed significant downregulation of EGR1, DUSP1, and NR4A1 in liver tissues, consistent with sequencing data. This study identifies crosstalk CRRGs and diagnostic biomarkers shared between PCOS and NAFLD, highlighting their roles in immune and metabolic dysregulation. These biomarkers offer the potential for improving diagnosis and guiding targeted treatments for both diseases.

The filamins of Drosophila

The actin cytoskeleton is a dynamic mesh of filaments that provide structural support for cells and respond to external deformation forces. Active sensing of these forces is crucial for the function of the actin cytoskeleton, and some actin crosslinkers accomplish it. One such crosslinker is filamin, a highly conserved actin crosslinker dimeric protein with an elastic region capable of responding to mechanical changes in the actin cytoskeleton. Filamins are required across various cells and tissues. In Drosophila early and recent studies have provided many details about filamin functions. This review centers on the two Drosophila filamins encoded by the cheerio and jitterbu g genes. We examine the structural and evolutionary aspects of filamin genes in flies, contrasting them with those of other model organisms. Then, we synthesize phenotypic data across diverse cell types. Additionally, we outline the genetic tools available for both genes. We also propose to divide filamins into typical and atypical based on the number of actin-binding domains and their relationship with other filamins.

Discovering mechanisms of macrophage tissue infiltration with Drosophila

Much is known about the importance of macrophages for regulating diverse aspects of organismal physiology, alongside their essential roles in inflammation. Relatively unexplored are the processes influencing macrophages' and monocytes' ability to invade into the tissues where they carry out these functions. Drosophila plasmatocytes, also called hemocytes, show similarities to vertebrate macrophages in their function and their molecular specification; they have recently been shown to also infiltrate into tissues during development and inflammation. Extravasation across vasculature, into tumors, the brain, and adipose tissue have all been observed. We discuss the striking parallels in some of these systems to vertebrate immune responses, including a requirement for tumor necrosis factor. Finally, we highlight the new pathways regulating infiltration found in the fly that remain as yet unexamined in a vertebrate context.

Mechanism underlying the role of integrin α3β1 in adhesive dysfunction between thyroid cells induced by diesel engine exhaust particles

The role and mechanisms of DEP exposure on thyroid injury are not yet clear. This study explores thyroid damage induced by in vivo DEP exposure using a mouse model. This study has observed alterations in thyroid follicular architecture, including rupture, colloid overflow, and the formation of voids. Additionally, there was a significant decrease in the expression levels of proteins involved in thyroid hormone synthesis, such as thyroid peroxidase and thyroglobulin, their trend of change is consistent with the damage to the thyroid structure. Serum levels of triiodothyronine and tetraiodothyronine were raise. However, the decrease in TSH expression suggests that the function of the HPT axis is unaffected. To delve deeper into the intrinsic mechanisms of thyroid injury, we performed KEGG pathway enrichment analysis, which revealed notable alterations in the cell adhesion signaling pathway. Our immunofluorescence results show that DEP exposure impairs thyroid adhesion, and integrin α3β1 plays an important role. CD151 binds to α3β1, promoting multimolecular complex formation and activating adhesion-dependent small GTPases. Our in vitro model has confirmed the pivotal role of integrin α3β1 in thyroid cell adhesion, which may be mediated by the CD151/α3β1/Rac1 pathway. In summary, exposure to DEP disrupts the structure and function of the thyroid, a process that likely involves the regulation of cell adhesion through the CD151/α3β1/Rac1 pathway, leading to glandular damage.

Filamin protects myofibrils from contractile damage through changes in its mechanosensory region

Filamins are mechanosensitive actin crosslinking proteins that organize the actin cytoskeleton in a variety of shapes and tissues. In muscles, filamin crosslinks actin filaments from opposing sarcomeres, the smallest contractile units of muscles. This happens at the Z-disc, the actin-organizing center of sarcomeres. In flies and vertebrates, filamin mutations lead to fragile muscles that appear ruptured, suggesting filamin helps counteract muscle rupturing during muscle contractions by providing elastic support and/or through signaling. An elastic region at the C-terminus of filamin is called the mechanosensitive region and has been proposed to sense and counteract contractile damage. Here we use molecularly defined mutants and microscopy analysis of the Drosophila indirect flight muscles to investigate the molecular details by which filamin provides cohesion to the Z-disc. We made novel filamin mutations affecting the C-terminal region to interrogate the mechanosensitive region and detected three Z-disc phenotypes: dissociation of actin filaments, Z-disc rupture, and Z-disc enlargement. We tested a constitutively closed filamin mutant, which prevents the elastic changes in the mechanosensitive region and results in ruptured Z-discs, and a constitutively open mutant which has the opposite elastic effect on the mechanosensitive region and gives rise to enlarged Z-discs. Finally, we show that muscle contraction is required for Z-disc rupture. We propose that filamin senses myofibril damage by elastic changes in its mechanosensory region, stabilizes the Z-disc, and counteracts contractile damage at the Z-disc.

Experience-dependent glial pruning of synaptic glomeruli during the critical period

Critical periods are temporally-restricted, early-life windows when sensory experience remodels synaptic connectivity to optimize environmental input. In the Drosophila juvenile brain, critical period experience drives synapse elimination, which is transiently reversible. Within olfactory sensory neuron (OSN) classes synapsing onto single projection neurons extending to brain learning/memory centers, we find glia mediate experience-dependent pruning of OSN synaptic glomeruli downstream of critical period odorant exposure. We find glial projections infiltrate brain neuropil in response to critical period experience, and use Draper (MEGF10) engulfment receptors to prune synaptic glomeruli. Downstream, we find antagonistic Basket (JNK) and Puckered (DUSP) signaling is required for the experience-dependent translocation of activated Basket into glial nuclei. Dependent on this signaling, we find critical period experience drives expression of the F-actin linking signaling scaffold Cheerio (FLNA), which is absolutely essential for the synaptic glomeruli pruning. We find Cheerio mediates experience-dependent regulation of the glial F-actin cytoskeleton for critical period remodeling. These results define a sequential pathway for experience-dependent brain synaptic glomeruli pruning in a strictly-defined critical period; input experience drives neuropil infiltration of glial projections, Draper/MEGF10 receptors activate a Basket/JNK signaling cascade for transcriptional activation, and Cheerio/FLNA induction regulates the glial actin cytoskeleton to mediate targeted synapse phagocytosis.

Hemolymph exosomes inhibit Spiroplasma eriocheiris infection by promoting Tetraspanin-mediated hemocyte phagocytosis in crab

Exosomes released from infected cells are thought to play an important role in the dissemination of pathogens, as well as in host-derived immune molecules during infection. As an intracellular pathogen, Spiroplasma eriocheiris is harmful to multiple crustaceans. However, the immune mechanism of exosomes during Spiroplasma infection has not been investigated. Here, we found exosomes derived from S. eriocheiris-infected crabs could facilitate phagocytosis and apoptosis of hemocytes, resulting in increased crab survival and suppression of Spiroplasma intracellular replication. Proteomic analysis revealed the altered abundance of EsTetraspanin may confer resistance to S. eriocheiris, possibly by mediating hemocyte phagocytosis in Eriocheir sinensis. Specifically, knockdown of EsTetraspanin in E. sinensis increased susceptibility to S. eriocheiris infection and displayed compromised phagocytic ability, whereas overexpression of EsTetraspanin in Drosophila S2 cells inhibited S. eriocheiris infection. Further, it was confirmed that intramuscular injection of recombinant LEL domain of EsTetraspanin reduced the mortality of S. eriocheiris-infected crabs. Blockade with anti-EsTetraspanin serum could exacerbate S. eriocheiris invasion of hemocytes and impair hemocyte phagocytic activity. Taken together, our findings prove for the first time that exosomes modulate phagocytosis to resist pathogenic infection in invertebrates, which is proposed to be mediated by exosomal Tetraspanin, supporting the development of preventative strategies against Spiroplasma infection.

Biophysical Control of the Glioblastoma Immunosuppressive Microenvironment: Opportunities for Immunotherapy

GBM is the most aggressive and common form of primary brain cancer with a dismal prognosis. Current GBM treatments have not improved patient survival, due to the propensity for tumor cell adaptation and immune evasion, leading to a persistent progression of the disease. In recent years, the tumor microenvironment (TME) has been identified as a critical regulator of these pro-tumorigenic changes, providing a complex array of biomolecular and biophysical signals that facilitate evasion strategies by modulating tumor cells, stromal cells, and immune populations. Efforts to unravel these complex TME interactions are necessary to improve GBM therapy. Immunotherapy is a promising treatment strategy that utilizes a patient's own immune system for tumor eradication and has exhibited exciting results in many cancer types; however, the highly immunosuppressive interactions between the immune cell populations and the GBM TME continue to present challenges. In order to elucidate these interactions, novel bioengineering models are being employed to decipher the mechanisms of immunologically "cold" GBMs. Additionally, these data are being leveraged to develop cell engineering strategies to bolster immunotherapy efficacy. This review presents an in-depth analysis of the biophysical interactions of the GBM TME and immune cell populations as well as the systems used to elucidate the underlying immunosuppressive mechanisms for improving current therapies.

Nuclear lamin facilitates collective border cell invasion into confined spaces in vivo

Cells migrate collectively through confined environments during development and cancer metastasis. The nucleus, a stiff organelle, impedes single cells from squeezing into narrow channels within artificial environments. However, how nuclei affect collective migration into compact tissues is unknown. Here, we use border cells in the fly ovary to study nuclear dynamics in collective, confined in vivo migration. Border cells delaminate from the follicular epithelium and squeeze into tiny spaces between cells called nurse cells. The lead cell nucleus transiently deforms within the lead cell protrusion, which then widens. The nuclei of follower cells deform less. Depletion of the Drosophila B-type lamin, Lam, compromises nuclear integrity, hinders expansion of leading protrusions, and impedes border cell movement. In wildtype, cortical myosin II accumulates behind the nucleus and pushes it into the protrusion, whereas in Lam-depleted cells, myosin accumulates but does not move the nucleus. These data suggest that the nucleus stabilizes lead cell protrusions, helping to wedge open spaces between nurse cells.

The macrophage genetic cassette inr/dtor/pvf2 is a nutritional status checkpoint for developmental timing

A small number of signaling molecules, used reiteratively, control differentiation programs, but the mechanisms that adapt developmental timing to environmental cues are less understood. We report here that a macrophage inr/dtor/pvf2 genetic cassette is a developmental timing checkpoint in Drosophila, which either licenses or delays biosynthesis of the steroid hormone in the endocrine gland and metamorphosis according to the larval nutritional status. Insulin receptor/dTor signaling in macrophages is required and sufficient for production of the PDGF/VEGF family growth factor Pvf2, which turns on transcription of the sterol biosynthesis Halloween genes in the prothoracic gland via its receptor Pvr. In response to a starvation event or genetic manipulation, low Pvf2 signal delays steroid biosynthesis until it becomes Pvr-independent, thereby prolonging larval growth before pupariation. The significance of this developmental timing checkpoint for host fitness is illustrated by the observation that it regulates the size of the pupae and adult flies.

Cell-matrix and cell-cell interaction mechanics in guiding migration

Physical properties of tissue are increasingly recognised as major regulatory cues affecting cell behaviours, particularly cell migration. While these properties of the extracellular matrix have been extensively discussed, the contribution from the cellular components that make up the tissue are still poorly appreciated. In this mini-review, we will discuss two major physical components: stiffness and topology with a stronger focus on cell-cell interactions and how these can impact cell migration.

Emerging concepts on the mechanical interplay between migrating cells and microenvironment in vivo

During embryogenesis, tissues develop into elaborate collectives through a myriad of active mechanisms, with cell migration being one of the most common. As cells migrate, they squeeze through crowded microenvironments to reach the positions where they ultimately execute their function. Much of our knowledge of cell migration has been based on cells' ability to navigate in vitro and how cells respond to the mechanical properties of the extracellular matrix (ECM). These simplified and largely passive surroundings contrast with the complexity of the tissue environments in vivo, where different cells and ECM make up the milieu cells migrate in. Due to this complexity, comparatively little is known about how the physical interactions between migrating cells and their tissue environment instruct cell movement in vivo. Work in different model organisms has been instrumental in addressing this question. Here, we explore various examples of cell migration in vivo and describe how the physical interplay between migrating cells and the neighboring microenvironment controls cell behavior. Understanding this mechanical cooperation in vivo will provide key insights into organ development, regeneration, and disease.

Cell division in tissues enables macrophage infiltration

Cells migrate through crowded microenvironments within tissues during normal development, immune response, and cancer metastasis. Although migration through pores and tracks in the extracellular matrix (ECM) has been well studied, little is known about cellular traversal into confining cell-dense tissues. We find that embryonic tissue invasion by Drosophila macrophages requires division of an epithelial ectodermal cell at the site of entry. Dividing ectodermal cells disassemble ECM attachment formed by integrin-mediated focal adhesions next to mesodermal cells, allowing macrophages to move their nuclei ahead and invade between two immediately adjacent tissues. Invasion efficiency depends on division frequency, but reduction of adhesion strength allows macrophage entry independently of division. This work demonstrates that tissue dynamics can regulate cellular infiltration.

Macrophage mitochondrial bioenergetics and tissue invasion are boosted by an Atossa-Porthos axis in Drosophila

Cellular metabolism must adapt to changing demands to enable homeostasis. During immune responses or cancer metastasis, cells leading migration into challenging environments require an energy boost, but what controls this capacity is unclear. Here, we study a previously uncharacterized nuclear protein, Atossa (encoded by CG9005), which supports macrophage invasion into the germband of Drosophila by controlling cellular metabolism. First, nuclear Atossa increases mRNA levels of Porthos, a DEAD‐box protein, and of two metabolic enzymes, lysine‐α‐ketoglutarate reductase (LKR/SDH) and NADPH glyoxylate reductase (GR/HPR), thus enhancing mitochondrial bioenergetics. Then Porthos supports ribosome assembly and thereby raises the translational efficiency of a subset of mRNAs, including those affecting mitochondrial functions, the electron transport chain, and metabolism. Mitochondrial respiration measurements, metabolomics, and live imaging indicate that Atossa and Porthos power up OxPhos and energy production to promote the forging of a path into tissues by leading macrophages. Since many crucial physiological responses require increases in mitochondrial energy output, this previously undescribed genetic program may modulate a wide range of cellular behaviors.