Intercellular Signaling Molecules Research Articles

Tumor Cell Communications as Promising Supramolecular Targets for Cancer Chemotherapy: A Possible Strategy

Fifty-two years have passed since President Nixon launched the “War on Cancer”. Despite unparalleled efforts and funds allocated worldwide, the outlined goals were not achieved because cancer treatment approaches such as chemotherapy, radiation therapy, hormonal and targeted therapies have not fully met the expectations. Based on the recent literature, a new direction in cancer therapy can be proposed which targets connections between cancer cells and their microenvironment by chemical means. Cancer–stromal synapses such as immunological synapses between cancer and immune cells provide an attractive target for this approach. Such synapses form ligand–receptor clusters on the interface of the interacting cells. They share a common property of involving intercellular clusters of spatially proximate and cooperatively acting proteins. Synapses provide the space for the focused intercellular signaling molecules exchange. Thus, the disassembly of cancer–stromal synapses may potentially cause the collapse of various tumors. Additionally, the clustered arrangement of synapse components offers opportunities to enhance treatment safety and precision by using targeted crosslinking chemical agents which may inactivate cancer synapses even in reduced concentrations. Furthermore, attaching a cleavable cell-permeable toxic agent(s) to a crosslinker may further enhance the anti-cancer effect of such therapeutics. The highlighted approach promises to be universal, relatively simple and cost-efficient. We also hope that, unlike chemotherapeutic and immune drugs that interact with a single target, by using supramolecular large clusters that include many different components as a target, the emergence of a resistance characteristic of chemo- and immunotherapy is extremely unlikely.

Exploring neuroglial signaling: diversity of molecules implicated in microglia-to-astrocyte neuroimmune communication.

Effective communication between different cell types is essential for brain health, and dysregulation of this process leads to neuropathologies. Brain glial cells, including microglia and astrocytes, orchestrate immune defense and neuroimmune responses under pathological conditions during which interglial communication is indispensable. Our appreciation of the complexity of these processes is rapidly increasing due to recent advances in molecular biology techniques, which have identified numerous phenotypic states of both microglia and astrocytes. This review focuses on microglia-to-astrocyte communication facilitated by secreted neuroimmune modulators. The combinations of interleukin (IL)-1α, tumor necrosis factor (TNF), plus complement component C1q as well as IL-1β plus TNF are already well-established microglia-derived stimuli that induce reactive phenotypes in astrocytes. However, given the large number of inflammatory mediators secreted by microglia and the rapidly increasing number of distinct functional states recognized in astrocytes, it can be hypothesized that many more intercellular signaling molecules exist. This review identifies the following group of cytokines and gliotransmitters that, while not established as interglial mediators yet, are known to be released by microglia and elicit functional responses in astrocytes: IL-10, IL-12, IL-18, transforming growth factor (TGF)-β, interferon (IFN)-γ, C-C motif chemokine ligand (CCL)5, adenosine triphosphate (ATP), l-glutamate, and prostaglandin E2 (PGE2). The review of molecular mechanisms engaged by these mediators reveals complex, partially overlapping signaling pathways implicated in numerous neuropathologies. Additionally, lack of human-specific studies is identified as a significant knowledge gap. Further research on microglia-to-astrocyte communication is warranted, as it could discover novel interglial signaling-targeted therapies for diverse neurological disorders.

Pattern Formation and Bistability in a Synthetic Intercellular Genetic Toggle.

Differentiation within multicellular organisms is a complex process that helps to establish spatial patterning and tissue formation within the body. Often, the differentiation of cells is governed by morphogens and intercellular signaling molecules that guide the fate of each cell, frequently using toggle-like regulatory components. Synthetic biologists have long sought to recapitulate patterned differentiation with engineered cellular communities, and various methods for differentiating bacteria have been invented. Here, we couple a synthetic corepressive toggle switch with intercellular signaling pathways to create a "quorum-sensing toggle". We show that this circuit not only exhibits population-wide bistability in a well-mixed liquid environment but also generates patterns of differentiation in colonies grown on agar containing an externally supplied morphogen. If coupled to other metabolic processes, circuits such as the one described here would allow for the engineering of spatially patterned, differentiated bacteria for use in biomaterials and bioelectronics.

Biologics Agents in Periodontal Regeneration:A Review

The field of periodontology and dental implantology has witnessed significant advancements in the use of molecular mediators and biologic agents over the past decade. Periodontal regeneration, which involves the complete restoration of cementum, bone, and connective tissue following removal of epithelial tissues, is considered superior to tissue repair. Recent research has focused on utilizing biologic materials as complementary therapies to enhance regeneration by accelerating wound healing. These biologic agents were investigated using the following search terms: tissue engineering, intercellular signaling molecules, and biological factors. Enamel matrix derivative (EMD), platelet-derived growth factor (PDGF), platelet-rich plasma, bone morphogenetic proteins (BMPs), fibroblast growth factor (FGF), and parathyroid hormone (PTH) have demonstrated the capacity to stimulate both hard and soft tissue regeneration. However, no single biologic agent is universally effective, necessitating a case-by-case evaluation for optimal treatment selection. Currently, EMD and PDGF are the only biologic therapies approved by the FDA for periodontal regeneration, while BMP-2 is indicated for bone augmentation. Due to a lack of FDA approval for periodontal applications, the clinical use of FGF and PTH in this context is not recommended.

Carbon Nanotube Sensor Platforms for the Detection of Cellular Nitric Oxide Efflux Gradients

Cell communication is the ability to receive, process, and transmit signals from the environment and within cells to ensure functional coordination during physiological events. Cells communicate between themselves using waves of chemical concentration that change in both direction and time. Nitric oxide (NO) is a gaseous, ubiquitous, intra - and inter-cellular signaling molecule. NO’s small size and lipophilic nature allows it to diffuse through cell membranes and reach intracellular compartments of nearby cells. However, NO detection in biological systems represents a challenge due to NO’s short half-life (in the range of seconds) before breaking down into different subproducts. The lack of spatial NO detection, not an upstream or downstream indicator of NO, has hindered understanding of the extracellular NO dynamic signaling during both physiological and pathological events. However, single wall carbon nanotube (SWNT)-based fluorescent sensors allow for the detection of NO, and when immobilized onto a glass substrate, they can be used to quantify extracellular NO in a spatial-temporal manner. We detected changes in extracellular NO efflux from different macrophage cell lines known for their NO production under inflammatory responses, specifically human THP-1 monocytes and murine macrophage RAW 264.7. The cells were seeded on the SWNT platform and treated with Liposaccharides (LPS) 24 h to increase their NO release. The SWNT platform’s sensing response to NO was detected by changes in fluorescence intensity. Fluorescence data was collected on a custom-built hyperspectral microscope to give us near infrared (nIR) signal quantification with spatial resolution. Images were collected before and after the respective NO induction method. To analyze the extracellular NO mappings, bright field images of the cells were used to extract the cell coordinates and translate them to fluorescent images. Hyperspectral image analysis was performed with MATLAB to determine SWNT fluorescence below each cell and its surrounding area. To validate that the change in the fluorescence response was attributed to NO and not from cellular interaction with the SWNT sensor, we added 2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO), a NO scavenger, after visualizing the SWNT quenching to recover the initial fluorescence signal, showing that the cells didn’t affect SWNT functionality. Through fluorescence intensity changes with pixel specificity on the image acquisition, we were able to spatially quantify NO released by cells with dynamic diffusion gradients. The newly developed platform provides the means to quantify extracellular NO. In this study, only two cell lines were studied, but the platforms will allow for the quantification of NO for other cell types as well. By comparing extracellular NO concentrations for different types of cells, we will be able to better understand physiological and pathological patterns of NO release, leading to a better understanding of cellular signaling.

Enigmatic Nodal and Lefty gene repertoire discrepancy: Latent evolutionary history revealed by vertebrate-wide phylogeny.

Homology in vertebrate body plans is traditionally ascribed to the high-level conservation of regulatory components within the genetic programs governing them, particularly during the "phylotypic stage." However, advancements in embryology and molecular phylogeny have unveiled the dynamic nature of gene repertoires responsible for early development. Notably, the Nodal and Lefty genes, members of the transforming growth factor-beta superfamily producing intercellular signaling molecules and crucial for left-right (L-R) symmetry breaking, exhibit distinctive features within their gene repertoires. These features encompass among-species gene repertoire variations resulting from gene gain and loss, as well as gene conversion. Despite their significance, these features have been largely unexplored in a phylogenetic context, but accumulating genome-wide sequence information is allowing the scrutiny of these features. It has exposed hidden paralogy between Nodal1 and Nodal2 genes resulting from differential gene loss in amniotes. In parallel, the tandem cluster of Lefty1 and Lefty2 genes, which was thought to be confined to mammals, is observed in sharks and rays, with an unexpected phylogenetic pattern. This article provides a comprehensive review of the current understanding of the origins of these vertebrate gene repertoires and proposes a revised nomenclature based on the elucidated history of vertebrate genome evolution.

Monocarboxylate transporter 4 deficiency enhances high-intensity interval training-induced metabolic adaptations in skeletal muscle.

High-intensity exercise stimulates glycolysis, subsequently leading to elevated lactate production within skeletal muscle. While lactate produced within the muscle is predominantly released into the circulation via the monocarboxylate transporter 4 (MCT4), recent research underscores lactate's function as an intercellular and intertissue signalling molecule. However, its specific intracellular roles within muscle cells remains less defined. In this study, our objective was to elucidate the effects of increased intramuscular lactate accumulation on skeletal muscle adaptation to training. To achieve this, we developed MCT4 knockout mice and confirmed that a lack of MCT4 indeed results in pronounced lactate accumulation in skeletal muscle during high-intensity exercise. A key finding was the significant enhancement in endurance exercise capacity at high intensities when MCT4 deficiency was paired with high-intensity interval training (HIIT). Furthermore, metabolic adaptations supportive of this enhanced exercise capacity were evident with the combination of MCT4 deficiency and HIIT. Specifically, we observed a substantial uptick in the activity of glycolytic enzymes, notably hexokinase, glycogen phosphorylase and pyruvate kinase. The mitochondria also exhibited heightened pyruvate oxidation capabilities, as evidenced by an increase in oxygen consumption when pyruvate served as the substrate. This mitochondrial adaptation was further substantiated by elevated pyruvate dehydrogenase activity, increased activity of isocitrate dehydrogenase - the rate-limiting enzyme in the TCA cycle - and enhanced function of cytochrome c oxidase, pivotal to the electron transport chain. Our findings provide new insights into the physiological consequences of lactate accumulation in skeletal muscle during high-intensity exercises, deepening our grasp of the molecular intricacies underpinning exercise adaptation. KEY POINTS: We pioneered a unique line of monocarboxylate transporter 4 (MCT4) knockout mice specifically tailored to the ICR strain, an optimal background for high-intensity exercise studies. A deficiency in MCT4 exacerbates the accumulation of lactate in skeletal muscle during high-intensity exercise. Pairing MCT4 deficiency with high-intensity interval training (HIIT) results in a synergistic boost in high-intensity exercise capacity, observable both at the organismal level (via a treadmill running test) and at the muscle tissue level (through an ex vivo muscle contractile function test). Coordinating MCT4 deficiency with HIIT enhances both the glycolytic enzyme activities and mitochondrial capacity to oxidize pyruvate.

FGF21 Induces Skeletal Muscle Atrophy and Increases Amino Acids in Female Mice: A Potential Role for Glucocorticoids.

Fibroblast growth factor-21 (FGF21) is an intercellular signaling molecule secreted by metabolic organs, including skeletal muscle, in response to intracellular stress. FGF21 crosses the blood-brain barrier and acts via the nervous system to coordinate aspects of the adaptive starvation response, including increased lipolysis, gluconeogenesis, fatty acid oxidation, and activation of the hypothalamic-pituitary-adrenocortical (HPA) axis. Given its beneficial effects for hepatic lipid metabolism, pharmaceutical FGF21 analogues are used in clinical trials treatment of fatty liver disease. We predicted pharmacologic treatment with FGF21 increases HPA axis activity and skeletal muscle glucocorticoid signaling and induces skeletal muscle atrophy in mice. Here we found a short course of systemic FGF21 treatment decreased muscle protein synthesis and reduced tibialis anterior weight; this was driven primarily by its effect in female mice. Similarly, intracerebroventricular FGF21 reduced tibialis anterior muscle fiber cross-sectional area; this was more apparent among female mice than male littermates. In agreement with the reduced muscle mass, the topmost enriched metabolic pathways in plasma collected from FGF21-treated females were related to amino acid metabolism, and the relative abundance of plasma proteinogenic amino acids was increased up to 3-fold. FGF21 treatment increased hypothalamic Crh mRNA, plasma corticosterone, and adrenal weight, and increased expression of glucocorticoid receptor target genes known to reduce muscle protein synthesis and/or promote degradation. Given the proposed use of FGF21 analogues for the treatment of metabolic disease, the study is both physiologically relevant and may have important clinical implications.

Enhancement of mast cells activation by ATP via P2X4 receptor

Adenosine-5'-triphosphate (ATP) is an important intracellular energy currency, but it is released extracellularly in response to various stimuli and acts as an intercellular signaling molecule by stimulating various P2 receptors. ATP and ADP are stored in synaptic vesicles and secretory granules, and are released extracellularly upon stimulation, playing important roles in neurotransmission and platelet aggregation. Furthermore, considerable amount of ATP is released by mechanical stimuli such as skin scraping or by cell damage, which in turn activates immune cells to promote inflammatory responses. Mast cells (MCs) are derived from hematopoietic stem cells and play a central role in type I allergic reactions. MCs are activated by IgE-mediated antigen recognition, leading to type I allergic reactions. MCs express P2X7 receptors that are activated by high concentrations of ATP (>0.5 ‍mM), and reported to aggravate inflammatory bowel disease and dermatitis. In contrast, role of MC P2 receptors that respond to lower concentrations of ATP remains to be investigated. We investigated in detail the effects of ATP in mouse bone marrow-derived MCs, and found that lower concentrations of ATP (<100 ‍μM) promotes IgE-dependent and GPCR-mediated degranulation via the ionotropic P2X4 receptor. In mouse allergic models, P2X4 receptor signal promote MC-mediated allergic responses through comprehensively increasing the sensitivity of MCs to different stimuli. Since ATP is known to be released from various cells upon mechanical stimuli such as cell damage or scratching, inhibition of P2X4 receptor signaling may represent a novel strategy to abrogate allergic reaction.

Paper-Based Coculture Platform to Evaluate the Effects of Fibroblasts on Estrogen Signaling in ER+ Breast Cancers.

Cell-based assays enable molecular-level studies of cellular responses to drug candidates or potential toxins. Transactivation assays quantify the activation or inhibition of nuclear receptors, key transcriptional regulators of gene targets in mamalian cells. One such assay couples the expression of luciferase to the transcriptional activity of estrogen receptor-alpha (ERα). While this assay is regularly used to screen for agonists and antagonists of the estrogen signaling pathway, the setup relies on monolayer cultures in which cells are plated directly onto the surface of cell-compatible plasticware. The tumor microenvironment is more than a collection of cancerous cells and is profoundly influenced by tissue architecture, the presence of extracellular matrices, and intercellular signaling molecules produced by non-cancerous neighboring cells (e.g., fibroblasts). There exists a need for three-dimensional culture platforms that can be rapidly prototyped to assess new configurations and readily produced in the large numbers needed for translational studies and screening applications. Here, we demonstrate the utility of the paper-based culture platform to probe the effects of intercellular signaling between two cell types. We used paper scaffolds to generate tumor-like environments, forming a defined volume of breast cancer cells suspended in collagen. By placing the paper scaffolds in commercial 96-well plates, we compared monocultures of only breast cancer cells with coculture configurations containing fibroblasts in different locations that mimicked the stages of breast cancer progression. We show that ERα transactivation in the T47D-KBluc cell line is affected by the presence, number, and proximity of fibroblasts, and is a consequence of intercellular signaling molecules. After screening a small library of fibroblast-secreted signaling molecules, we showed that interleukin-6 (IL-6) was the primary driver of reduced estradiol sensitivity. These effects were mitigated in the coculture configurations by the addition of an IL-6 neutralizing antibody. We also assessed estrogen receptor expression and transcriptional regulation, further demonstrating the utility of the paper-based platform for detailed mechanistic studies.

MicroRNA Profile, Putative Diagnostic Biomarkers and RNA-Based Therapies in the Inherited Lipid Storage Disease Niemann-Pick Type C.

Lipids are essential for cellular function and are tightly controlled at the transcriptional and post-transcriptional levels. Dysregulation of these pathways is associated with vascular diseases, diabetes, cancer, and several inherited metabolic disorders. MicroRNAs (miRNAs), in particular, are a family of post-transcriptional gene repressors associated with the regulation of many genes that encode proteins involved in multiple lipid metabolism pathways, thereby influencing their homeostasis. Thus, this class of non-coding RNAs (ncRNAs) has emerged as a promising therapeutic target for the treatment of lipid-related metabolic alterations. Most of these miRNAs act at an intracellular level, but in the past few years, a role for miRNAs as intercellular signaling molecules has also been uncovered since they can be transported in bodily fluids and used as potential biomarkers of lipid metabolic alterations. In this review, we point out the current knowledge on the miRNA signature in a lysosomal storage disorder associated with lipid dysfunction, Niemann-Pick type C, and discuss the potential use of miRNAs as biomarkers and therapeutic targets for RNA-based therapies.

Platelets as a source of biomolecules for enhancing chemotaxis of human neural stem cells

In the modern era, tissue engineering is actively developing based on the utilization and enhancement of endogenous repair resources. Due to neurodegenerative processes that occur in traumatic brain injuries, vascular diseases of the central nervous system, and natural aging, the percentage of disability is steadily increasing, particularly in developed countries. The most pressing task today is to find optimal measures for prevention and therapy. Changes in neurodynamics, ischemia, inflammation, accumulation of toxic products, activation of catabolism, and a decrease in the activity of anabolic processes have both local and systemic implications. Neurons of nervous tissue are particularly sensitive. It is known that nervous tissue is capable of regeneration, but spontaneous regenerative processes do not fully restore the structure and function of the central nervous system. Contemporary research indicates that chemokines play a crucial role in regulating the viability, self-renewal, and attraction of stem cells. The dynamic interaction between neural stem cells is regulated by the chemokine CXCL12 (C-X-C motif chemokine 12) and its receptor CXCR4 (C-X-C motif chemokine receptor 4). Elevated levels of CXCL12 create conditions for the active recruitment of neural progenitor cells to sites of injury. Platelets serve as an endogenous reservoir for more than 1500 biofactors that influence various metabolic processes in the body's cells. Many of them exhibit neurotrophic activity. Powerful intercellular signaling molecules, such as CCL5 and the chemokine ligand CXCL4 (PF4), are present in alpha granules. In vivo, platelet activation is believed to lead to the release of factors that stimulate recovery, including through PF4 (CXCL4). These platelet properties explain the attention given to these cells as potential endogenous enhancers of chemotaxis of neuronal cells and recovery in pathological conditions.

Determination of oxylipins and their precursors in breast milk by solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry

Oxylipins and their precursors (long-chain polyunsaturated fatty acids, LCPUFAs) are key intercellular signaling molecules influencing the inflammatory response. Each oxylipin has pro- and/or anti-inflammatory effects, and the relative abundance of different oxylipins can alter the inflammatory balance, making it important to clarify the oxylipin profile of breast milk for optimal infant health. The extraction, identification, and simultaneous quantification of oxylipins in breast milk are challenging due to the structural similarity, limited stability, and the low endogenous concentration of oxylipins and the complex matrix of breast milk. This study aimed to develop a solid phase extraction-ultra high performance liquid chromatography-triple quadrupole tandem mass spectrometry (SPE-UPLC-MS/MS) method for the comprehensive and specific quantification of oxylipins and their precursors in breast milk. The LC conditions (including column, mobile phase, and gradient conditions) and SPE procedure (including SPE cartridges, elution solvent, and elution volume) were optimized to achieve accurate quantification and better analyte recovery. A single 18-minute chromatographic run allows for the quantification of 20 oxylipins and 5 PUFAs. The results showed good linearity (R2 > 0.99) over the concentration range of 2 to 100 ng/mL, with the instrument detection limits ranging from 0.01 to 0.90 ng/mL for oxylipins and 0.02 to 0.59 ng/mL for PUFAs. The method is rapid, sensitive, and reproducible (RSD ≤ 10%) and is suitable for the quantitative analysis of oxylipins and their precursors in infant formula samples.

Control of Tissue Development by Morphogens.

Intercellular signaling molecules, known as morphogens, act at a long range in developing tissues to provide spatial information and control properties such as cell fate and tissue growth. The production, transport, and removal of morphogens shape their concentration profiles in time and space. Downstream signaling cascades and gene regulatory networks within cells then convert the spatiotemporal morphogen profiles into distinct cellular responses. Current challenges are to understand the diverse molecular and cellular mechanisms underlying morphogen gradient formation, as well as the logic of downstream regulatory circuits involved in morphogen interpretation. This knowledge, combining experimental and theoretical results, is essential to understand emerging properties of morphogen-controlled systems, such as robustness and scaling.

Inhibitory Effects of Epithelial Cells on Fibrosis Mechanics of Microtissue and Their Spatiotemporal Dependence on the Epithelial-Fibroblast Interaction.

Cell-generated contraction force is the primary physical drive for fibrotic densification of biological tissues. Previous studies using two-dimensional culture models have shown that epithelial cells inhibit the myofibroblast-derived contraction force via the regulation of the fibroblast/myofibroblast transition (FMT). However, it remains unclear how epithelial cells interact with fibroblasts and myofibroblasts to determine the mechanical consequences and spatiotemporal regulation of fibrosis development. In this study, we established a three-dimensional microtissue model using an NIH/3T3 fibroblast-laden collagen hydrogel, incorporated with a microstring-based force sensor, to assess fibrosis mechanics. When Madin-Darby canine kidney epithelial cells were cocultured on the microtissue's surface, the densification, stiffness, and contraction force of the microtissue greatly decreased compared to the monocultured microtissue without epithelial cells. The key fibrotic features, such as enhanced protein expression of α-smooth muscle actin, fibronectin, and collagen indicating FMT and matrix deposition, respectively, were also significantly reduced. The antifibrotic effects of epithelial cells on the microtissue were dependent on the intercellular signaling molecule prostaglandin E2 (PGE2) with an effective concentration of 10 μM and their proximity to the fibroblasts, indicating paracrine cellular signaling between the two types of cells during tissue fibrosis. The effect of PGE2 on microtissue contraction was also dependent on the time point when PGE2 was delivered or blocked, suggesting that the presence of epithelial cells at an early stage is critical for preventing or treating advanced fibrosis. Taken together, this study provides insights into the spatiotemporal regulation of mechanical properties of fibrosis by epithelial cells, and the cocultured microtissue model incorporated with a real-time and sensitive force sensor will be a suitable system for evaluating fibrosis and drug screening.

Identification of three elevenin receptors and roles of elevenin disulfide bond and residues in receptor activation in Aplysia californica

Neuropeptides are ubiquitous intercellular signaling molecules in the CNS and play diverse roles in modulating physiological functions by acting on specific G-protein coupled receptors (GPCRs). Among them, the elevenin signaling system is now believed to be present primarily in protostomes. Although elevenin was first identified from the L11 neuron of the abdominal ganglion in mollusc Aplysia californica, no receptors have been described in Aplysia, nor in any other molluscs. Here, using two elevenin receptors in annelid Platynereis dumerilii, we found three putative elevenin GPCRs in Aplysia. We cloned the three receptors and tentatively named them apElevR1, apElevR2, and apElevR3. Using an inositol monophosphate (IP1) accumulation assay, we demonstrated that Aplysia elevenin with the disulfide bond activated the three putative receptors with low EC50 values (ranging from 1.2 to 25 nM), supporting that they are true receptors for elevenin. In contrast, elevenin without the disulfide bond could not activate the receptors, indicating that the disulfide bond is required for receptor activity. Using alanine substitution of individual conserved residues other than the two cysteines, we showed that these residues appear to be critical to receptor activity, and the three different receptors had different sensitivities to the single residue substitution. Finally, we examined the roles of those residues outside the disulfide bond ring by removing these residues and found that they also appeared to be important to receptor activity. Thus, our study provides an important basis for further study of the functions of elevenin and its receptors in Aplysia and other molluscs.

Characterizing purinergic receptors in the gastrointestinal epithelium and immune cells

Background: Extracellular release of nucleotides (e.g., ATP, ADP, UTP, UDP) are well established as potent intercellular signaling molecules during homeostasis but are also released from cells during pathogenic microbial infection and tissue injury to serve as danger signals. These important extracellular signaling molecules activate purinergic receptors, of which there are 19 different purinergic receptor subtypes that are classified into P1 and P2 receptors. P1 receptor subtypes are activated by adenosine, while P2 receptors are differentially activated by ATP, ADP, UTP, UDP, and UP-glucose. P2 receptors are further divided into P2Y receptors (P2YRs) and P2X receptors (P2XRs) based on their structures and distinct signal-transduction mechanisms. Several studies have revealed crucial roles for P2 receptors during inflammatory and infectious diseases, yet the majority of work to date has focused on purinergic signaling in immune cells. Our group has previously identified a role for P2Y1 in mediating ADP-driven calcium waves during rotavirus infection. While purinergic signaling is a well-established mode of signaling in the enteric nervous system, the functional roles of purinergic signaling in the gastrointestinal tract remain incompletely understood. Hypothesis: Since epithelial cells serve as the first barrier against irritants and infection, we hypothesized that gut epithelium express multiple purinergic receptors that regulate cellular responses to extracellular nucleotide signals. Methods &amp; Results: Using the Human Protein Atlas, we queried single cell RNA sequencing data for the P2 purinergic receptors. We examined these receptors along the length of the gastrointestinal tract, including esophagus, small intestine, colon, and rectum as well as in flow-sorted immune cells, peripheral blood mononuclear cells and and bone marrow derived immune cells. In silico analysis revealed high expression of P2Y1, P2Y2, P2Y11 and P2X4 among the purinergic receptors throughout the gastrointestinal tract. Interestingly, P2Y1 showed highest expression in esophageal epithelial cells, small intestinal enterocytes, and goblet cells. P2Y6 was also observed in promixal enterocytes of the small intestine, but was largely absent from the colon and rectum. In contrast, we found that immune cells from bone marrow, peripheral blood and flow sorted cells had relatively high expression of P2X1 and P2X4. We noted P2X5 expression in plasma cells and B -cells in all sets. Pathway analysis from the Reactome database revealed P2Y receptors are associated with signal transduction, metabolism and hemostasis pathways, while P2X receptors were primarily involved in immune response and infectious disease pathways. Conclusions: These findings confirm that the gastrointestinal tract possess robust P2Y1, P2Y2, P2Y11 and P2X4 receptor expression and can participate in purinergic signaling pathways. R01 DK115507 (Hyser); R01 AI158683 (Hyser); APS Postdoctoral Fellowship (Engevik); F32 DK130288 (Engevik) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Engineering Controllable Pulse Generation for Molecular Communication via Genetic Circuits

Synthetic biology provides the engineering community with a tool to build biological entities that are capable of carrying out desired signal processing functionalities. The design and study of genetic circuits that exhibit natural behavior can be helpful for an improved understanding of the principles and kinetics behind the gene expression behavior, as well as for engineering cellular systems for synthetic biology. In this paper, we propose a synthetic biology system capable of generating a pulse-shaped signal, which is a prevalent behavior in natural environment. In particular, our proposed pulse generation system divides the pulse generation functions into different cells which are connected by intercellular signaling molecules. More specifically, the system is consisted of three engineered cells with different digital logic functionalities, and the pulse generation exploits the alteration in logic state. To quantitatively describe the generated pulse, we not only analyze the individual behavior of each cell using Shea-Ackers formalism but also derive the intercellular signaling channel. Simulation results demonstrate that the pulse-shaped signal can be produced in a controllable manner by arranging cells in different spatial configurations.

Retinoic Acid and POU Genes in Developing Amphioxus: A Focus on Neural Development.

POU genes are a family of evolutionarily conserved transcription factors with key functions in cell type specification and neurogenesis. In vitro experiments have indicated that the expression of some POU genes is controlled by the intercellular signaling molecule retinoic acid (RA). In this work, we aimed to characterize the roles of RA signaling in the regulation of POU genes in vivo. To do so, we studied POU genes during the development of the cephalochordate amphioxus, an animal model crucial for understanding the evolutionary origins of vertebrates. The expression patterns of amphioxus POU genes were assessed at different developmental stages by chromogenic in situ hybridization and hybridization chain reaction. Expression was further assessed in embryos subjected to pharmacological manipulation of endogenous RA signaling activity. In addition to a detailed description of the effects of these treatments on amphioxus POU gene expression, our survey included the first description of Pou2 and Pou6 expression in amphioxus embryos. We found that Pit-1, Pou2, Pou3l, and Pou6 expression are not affected by alterations of endogenous RA signaling levels. In contrast, our experiments indicated that Brn1/2/4 and Pou4 expression are regulated by RA signaling in the endoderm and the nerve cord, respectively. The effects of the treatments on Pou4 expression in the nerve cord revealed that, in developing amphioxus, RA signaling plays a dual role by (1) providing anteroposterior patterning information to neural cells and (2) specifying neural cell types. This finding is coherent with a terminal selector function of Pou4 for GABAergic neurons in amphioxus and represents the first description of RA-induced changes in POU gene expression in vivo.

CEACAMS 1, 5, and 6 in disease and cancer: interactions with pathogens.

The CEA family comprises 18 genes and 11 pseudogenes located at chromosome 19q13.2 and is divided into two main groups: cell surface anchored CEA-related cell adhesion molecules (CEACAMs) and the secreted pregnancy-specific glycoproteins (PSGs). CEACAMs are highly glycosylated cell surface anchored, intracellular, and intercellular signaling molecules with diverse functions, from cell differentiation and transformation to modulating immune responses associated with infection, inflammation, and cancer. In this review, we explore current knowledge surrounding CEACAM1, CEACAM5, and CEACAM6, highlight their pathological significance in the areas of cancer biology, immunology, and inflammatory disease, and describe the utility of murine models in exploring questions related to these proteins.