Novel Mechanism Of Intercellular Communication Research Articles

Erythrocyte-derived extracellular vesicles from type 2 diabetes patients induce endothelial dysfunction through arginase 1

Abstract Background The mechanisms driving the development of cardiovascular injury in type 2 diabetes (T2D) remain incompletely understood. We recently demonstrated that red blood cells (RBCs) from patients with T2D (T2D-RBCs) act as mediators of endothelial dysfunction, but the mechanisms underlying this interaction are not clarified. We found that RBCs via upregulation of arginase 1 attenuate nitric oxide bioavailability and endothelial function. It is increasingly clear that extracellular vesicles (EVs) are actively secreted by practically all cell types, including RBCs, and represent a novel mechanism of intercellular communication. Purpose This study aimed to determine whether EVs derived from T2D-RBCs are involved as mediators in vascular injury through the signalling of arginase 1. Methods T2D-RBCs and RBCs from age-matched healthy controls (H-RBCs) were isolated and incubated with Krebs-Henseleit buffer (20% haematocrit). Following 18h incubation, the conditioned medium was collected for EV isolation using sequential ultracentrifugation and membrane affinity column. EV concentration was measured by nanoparticle tracking analysis. Aortas isolated from wild-type mice were incubated with EVs derived from T2D-RBCs and H-RBCs for 18h. Endothelium-dependent and -independent relaxations (EDR and EIDR, respectively) of the aortae were evaluated in a wire myograph. The involvement of arginase was investigated by the addition of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) either to the 18h co-incubation of EVs with the aortic segments to selectively investigate the contribution of EV-derived arginase (ABH, 10 mM) or to the aortae following the 18h co-incubation to selectively target vascular arginase (ABH, 100 µM). All animal experiments were performed according to the principles of laboratory animal care (NIH Publication no. 85-23 revised 1985) and human procedures according to the declaration of Helsinki and approved by the Swedish Ethical Review Authority. Results T2D-RBCs had a ten times lower EV concentration compared to H-RBCs. T2D-RBC-derived EVs isolated using both methods significantly impaired EDR (Fig. 1A-C), whereas EIDR was not affected. This effect was observed irrespective of if the same volume or concentration of EVs were administered. Inhibition of arginase with ABH during the co-incubation with EVs derived from T2D-RBCs completely prevented the impairment of EDR induced by the EVs (Fig. 1D). Administration of ABH to the aortae following the co-incubation also attenuated the impairment of EDR. Immunohistochemical staining revealed upregulation of arginase 1 (Fig. 2A-B) but not arginase 2 (Fig. 2C-D) in the vasculature following incubation with EVs from T2D-RBCs. Conclusion EVs derived from T2D-RBCs induce endothelial dysfunction, and arginase 1 derived from these EVs mediates this endothelial dysfunction. These results shed new important light on the mechanism underlying vascular injury mediated by RBCs in T2D.

TNFα induced by DNA-sensing in macrophage compromises retinal pigment epithelial (RPE) barrier function

Increasing evidence suggests that chronic inflammation plays an important role in the pathogenesis of age-related macular degeneration (AMD); however, the precise pathogenic stressors and sensors, and their impact on disease progression remain unclear. Several studies have demonstrated that type I interferon (IFN) response is activated in the retinal pigment epithelium (RPE) of AMD patients. Previously, we demonstrated that human RPE cells can initiate RNA-mediated type I IFN responses through RIG-I, yet are unable to directly sense and respond to DNA. In this study, we utilized a co-culture system combining primary human macrophage and iPS-derived RPE to study how each cell type responds to nucleic acids challenges and their effect on RPE barrier function in a homotypic and heterotypic manner. We find that DNA-induced macrophage activation induces an IFN response in the RPE, and compromises RPE barrier function via tight-junction remodeling. Investigation of the secreted cytokines responsible for RPE dysfunction following DNA-induced macrophages activation indicates that neutralization of macrophage-secreted TNFα, but not IFNβ, is sufficient to rescue RPE morphology and barrier function. Our data reveals a novel mechanism of intercellular communication by which DNA induces RPE dysfunction via macrophage-secreted TNFa, highlighting the complexity and potential pathological relevance of RPE and macrophage interactions.

New signaling kid on the block in the endocrine system: the role of extracellular vesicles.

In recent years, there has been a growing interest in the role of Extracellular vesicles (EVs) in both normal and pathological physiology. These natural nanoparticles are now recognized as a novel mechanism for intercellular communication, allowing cells to exchange of biologically active molecules such as microRNAs (miRNAs). As is well acknowledged, the endocrine system regulates bodily operations through the emission of various hormones. Although the discovery of EVs took place approximately 80 years later than that of hormones, circulating EVs have attracted considerable interest and are expected to be the frontier in the endocrine system. Interestingly, the interplay between hormones and EVs is a complex phenomenon that involves both synergistic and antagonistic effects. Moreover, EVs facilitate communication between endocrine cells and contain miRNAs that may serve as valuable biomarkers for diagnosis and prognosis. This review aims to provide an overview of current research on physiological and pathological secretion of EVs from endocrine organs or tissues. Additionally, we examine the essential relationship between hormones and EVs in the endocrine system.

Exosomes derived from lung cancer cells: Isolation, characterization, and stability studies

Recent advances in nanomedicine have paved the way for developing targeted drug delivery systems. Nanoscale exosomes are present in almost every body fluid and represent a novel mechanism of intercellular communication. Because of their membrane origin, they easily fuse with cells, acting as a natural delivery system and maintaining the bioactivity and immunotolerance of cells. To develop a reconstitutable exosome-based drug candidate for clinical applications, quality assurance by preserving its physical and biological properties during storage is necessary. Therefore, this study aimed to determine the best storage conditions for exosomes derived from lung cancer cells (A549). This study established that the phosphate-buffered saline buffer enriched with 25 mM trehalose is an optimal cryoprotectant for A549-derived exosomes stored at −80°C. Under these conditions, the concentration, size distribution, zeta potential, and total cargo protein levels of the preserved exosomes remained constant.

Tunneling Nanotube-Mediated Communication: A Mechanism of Intercellular Nucleic Acid Transfer.

Tunneling nanotubes (TNTs) are thin, F-actin-based membranous protrusions that connect distant cells and can provide e a novel mechanism for intercellular communication. By establishing cytoplasmic continuity between interconnected cells, TNTs enable the bidirectional transfer of nuclear and cytoplasmic cargo, including organelles, nucleic acids, drugs, and pathogenic molecules. TNT-mediated nucleic acid transfer provides a unique opportunity for donor cells to directly alter the genome, transcriptome, and metabolome of recipient cells. TNTs have been reported to transport DNA, mitochondrial DNA, mRNA, viral RNA, and non-coding RNAs, such as miRNA and siRNA. This mechanism of transfer is observed in physiological as well as pathological conditions, and has been implicated in the progression of disease. Herein, we provide a concise overview of TNTs’ structure, mechanisms of biogenesis, and the functional effects of TNT-mediated intercellular transfer of nucleic acid cargo. Furthermore, we highlight the potential translational applications of TNT-mediated nucleic acid transfer in cancer, immunity, and neurological diseases.

Mitochondrial Transplantation as a Novel Therapeutic for Retinal Metabolic Dysfunction‐Driven Disease

Metabolic dysfunction and mitochondria defect are implicated in several age‐associated diseases including age‐related macular degeneration (AMD), a leading cause of blindness in the elderly. In AMD, mitochondrial oxidative stress in the retinal pigment epithelium (RPE) drives disease progression and growth of atrophic lesions. Mitochondria release and uptake has been recently identified as a novel mechanism of intercellular communication but its implication in ocular diseases such as AMD has never been investigated. Here, we examined the role of mitochondrial transfer as a new mechanism of metabolic crosstalk between RPE cells. Diseased mitochondria were purified from RPE cells treated with the AMD‐associated cytokine TNFα (10 ng/mL), administered to host RPE cells and the effects of MitoTNFA compared to MitoCtrl, isolated from control RPE, or exposure to exogenous TNFα. We showed that treatment of healthy RPE with MitoTNFA, and not MitoCtrl, triggers mitochondrial network fragmentation and transcriptional upregulation of inflammatory factors RelB, IL6, IL8, and repression of PGC1α, mirroring the effect of direct TNFα treatment. ELISA assay confirmed that the effects observed were not caused by presence of soluble TNFα within the mitochondrial fraction. Metabolic profiling using the Seahorse XFe96 bioanalyzer further validated the ability of MitoTNFA to phenocopy TNFα‐induced metabolic reprograming in RPE. Finally, we demonstrated that transfer of MitoCtrl improved the bioenergetic functions of both healthy and diseased RPE with significant increases in basal, maximal, and spare respiratory functions. Our results showed that mitochondria transfer recapitulates the context‐specific phenotype from donor to host cells in RPE. This new paradigm in RPE biology may not only explain the centrifugal expansion of RPE lesions in AMD but also presents a promising therapeutic avenue for mitochondria‐driven disorders such as AMD.

LncRNA-encoded microproteins: A new form of cargo in cell culture-derived and circulating extracellular vesicles.

Advancements in omics‐based technologies over the past few years have led to the discovery of numerous biologically relevant peptides encoded by small open reading frames (smORFs) embedded in long noncoding RNA (lncRNA) transcripts (referred to as microproteins here) in a variety of species. However, the mechanisms and modes of action that underlie the roles of microproteins have yet to be fully characterized. Herein, we provide the first experimental evidence of abundant microproteins in extracellular vesicles (EVs) derived from glioma cancer cells, indicating that the EV‐mediated transfer of microproteins may represent a novel mechanism for intercellular communication. Intriguingly, when examining human plasma, 48, 11 and 3 microproteins were identified from purified EVs, whole plasma and EV‐free plasma, respectively, suggesting that circulating microproteins are primarily enriched in EVs. Most importantly, the preliminary data showed that the expression profile of EV microproteins in glioma patient diverged from the health donors, suggesting that the circulating microproteins in EVs might have potential diagnostic application in identifying patients with glioma.

Exosomes Derived From Heat Stroke Cases Carry miRNAs Associated With Inflammation and Coagulation Cascade.

The pathological mechanism underlying heat stroke (HS) is associated with the dysbalanced inflammation and coagulation cascade. Cell-derived circulating extracellular vesicles (EVs), as a novel pathway mediating intercellular communication, are associated with the immune response and inflammation in critical inflammatory syndromes, such as sepsis. Although these vesicles contain genetic material correlated with their biological function, their molecular cargo during HS remains unknown. In this study, we evaluate the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) associated with inflammatory responses and coagulation cascade in exosomes of patients with HS. Blood samples were collected from three patients with HS at the time of admission to the intensive care unit; three healthy volunteers were selected as control. Exosomes were isolated using ultracentrifugation, and their miRNA content was profiled using next-generation sequencing; mRNA content was evaluated using qPCR array. Compared with those from healthy volunteers, exosomes from patients with HS showed substantial changes in the expression of 202 exosomal miRNAs (154 upregulated and 48 downregulated miRNAs). The most upregulated miRNAs included miR-511-3p, miR-122-5p, miR-155-3p, miR-1290, and let7-5p, whereas the most downregulated ones included miR-150-3p, 146a-5p, and 151a-3p. Gene ontology enrichment of the miRNAs of patients with HS compared with control subjects were associated mostly with inflammatory response, including T cell activation, B cell receptor signaling, dendritic cell chemotaxis and leukocyte migration, and platelet activation and blood coagulation. The identified miRNAs were primarily enriched to the signal transduction pathways namely, T cell receptor signaling, Ras signaling, chemokine signaling, platelet activation, and leukocyte transendothelial migration, all of which are associated with inflammation and hemostasis. Multiple targeted mRNAs associated with the inflammatory response, blood coagulation, and platelet activation were further verified in serum exosomes. Exosomes from patients with HS convey miRNAs and mRNAs associated with pathogenic pathways, including inflammatory response and coagulation cascade. Exosomes may represent a novel mechanism for intercellular communication during HS.

Langerhans Cells Spy on Keratinocytes

Tunneling nanotubes (TNTs) have been described as a novel mechanism for intercellular communication. However, the ability of epidermal cells to utilize TNTs remains a mystery. In this issue, Su and Igyártó (2019) showed that Langerhans cells (LCs) obtain mRNA from keratinocytes (KC) in vivo presumably via TNTs. The demonstration of exchange of genetic material from KC to LC in vivo is an an unexpected method of antigen acquisition by LC and also an important consideration when analyzing transcriptomic data.

Tunneling nanotubes, a novel mode of tumor cell-macrophage communication in tumor cell invasion.

The interaction between tumor cells and macrophages is crucial in promoting tumor invasion and metastasis. In this study, we examined a novel mechanism of intercellular communication, namely membranous actin-based tunneling nanotubes (TNTs), that occurs between macrophages and tumor cells in the promotion of macrophage-dependent tumor cell invasion. The presence of heterotypic TNTs between macrophages and tumor cells induced invasive tumor cell morphology, which was dependent on EGF-EGFR signaling. Furthermore, reduction of a protein involved in TNT formation, M-Sec (TNFAIP2), in macrophages inhibited tumor cell elongation, blocked the ability of tumor cells to invade in 3D and reduced macrophage-dependent long-distance tumor cell streaming in vitro Using an in vivo zebrafish model that recreates macrophage-mediated tumor cell invasion, we observed TNT-mediated macrophage-dependent tumor cell invasion, distant metastatic foci and areas of metastatic spread. Overall, our studies support a role for TNTs as a novel means of interaction between tumor cells and macrophages that leads to tumor progression and metastasis.

Specialized Intercellular Communications via Cytonemes and Nanotubes.

In recent years, thin membrane protrusions such as cytonemes and tunneling nanotubes have emerged as a novel mechanism of intercellular communication. Protrusion-based cellular interactions allow for specific communication between participating cells and have a distinct spectrum of advantages compared to secretion- and diffusion-based intercellular communication. Identification of protrusion-based signaling in diverse systems suggests that this mechanism is a ubiquitous and prevailing means of communication employed by many cell types. Moreover, accumulating evidence indicates that protrusion-based intercellular communication is often involved in pathogenesis, including cancers and infections. Here we review our current understanding of protrusion-based intercellular communication.

Abstract 969: Tunneling nanotubes, a novel mode of tumor cell-macrophage communication in tumor cell invasion

Abstract The interaction between tumor cells and macrophages is crucial in promoting tumor invasion and metastasis. These two cell types are engaged in a mutual interaction in which tumor-associated macrophages produce epidermal growth factor (EGF) to activate tumor cells. In turn, tumor cells produce colony-stimulating factor-1 (CSF-1) that stimulates macrophages. The tumor cell - macrophage pairs formed in response to this paracrine signaling are then attracted toward blood vessels under an endothelial cell produced HGF gradient. This mutual signaling interaction leads to the co-migration and invasion of both cell types as imaged both in vitro and in vivo. . Recent studies have revealed an additional novel mechanism of intercellular communication between macrophages that can transmit signals over long distances through membranous actin-based tunneling nanotubes (TNTs). Our data demonstrates that heterotypic TNTs form between macrophages and tumor cells in co-culture. This novel interaction induced changes in tumor cell morphology consistent with a more invasive phenotype which was dependent on EGF-EGFR signaling. Moreover, the presence of these heterotypic TNTs was important for tumor cell invasion in an in vitro 3D invasion assay. Furthermore, reduction of M-Sec (TNFAIP2) in macrophages, a protein involved in TNT formation, inhibited tumor cell elongation and blocked the ability of tumor cells to invade. Using a modified 1D assay that mimics macrophage-dependent tumor cell streaming observed in vivo, we show a significant increase in long distance directional migration of tumor cells towards an endothelial-coated bead in a TNT dependent manner. We also employed an in vivo zebrafish model that recreates macrophage mediated tumor cell invasion in a more physiological fashion. The presence of macrophages increased tumor spread from the injection site, number of metastatic foci, and the distance of metastatic spread in a macrophage TNT-dependent manner. Overall, our studies support a role for TNTs as a novel means of interaction between tumor cells and macrophages that may lead to tumor progression and metastasis. Citation Format: Samer Hanna, Kessler McCoy-Simandle, Edison Leung, John Condeelis, Dianne Cox. Tunneling nanotubes, a novel mode of tumor cell-macrophage communication in tumor cell invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 969.

Exosomes from patients with septic shock convey miRNAs related to inflammation and cell cycle regulation: new signaling pathways in sepsis?

BackgroundExosomes isolated from plasma of patients with sepsis may induce vascular apoptosis and myocardial dysfunction by mechanisms related to inflammation and oxidative stress. Despite previous studies demonstrating that these vesicles contain genetic material related to cellular communication, their molecular cargo during sepsis is relatively unknown. In this study, we evaluated the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) related to inflammatory response and redox metabolism in exosomes of patients with septic shock.MethodsBlood samples were collected from 24 patients with septic shock at ICU admission and after 7 days of treatment. Twelve healthy volunteers were used as control subjects. Exosomes were isolated by ultracentrifugation, and their miRNA and mRNA content was evaluated by qRT-PCR array.ResultsAs compared with healthy volunteers, exosomes from patients with sepsis had significant changes in 65 exosomal miRNAs. Twenty-eight miRNAs were differentially expressed, both at enrollment and after 7 days, with similar kinetics (18 miRNAs upregulated and 10 downregulated). At enrollment, 35 differentially expressed miRNAs clustered patients with sepsis according to survival. The pathways enriched by the miRNAs of patients with sepsis compared with control subjects were related mostly to inflammatory response. The comparison of miRNAs from patients with sepsis according to hospital survival demonstrated pathways related mostly to cell cycle regulation. At enrollment, sepsis was associated with significant increases in the expression of mRNAs related to redox metabolism (myeloperoxidase, 64-fold; PRDX3, 2.6-fold; SOD2, 2.2-fold) and redox-responsive genes (FOXM1, 21-fold; SELS, 16-fold; GLRX2, 3.4-fold). The expression of myeloperoxidase mRNA remained elevated after 7 days (65-fold).ConclusionsExosomes from patients with septic shock convey miRNAs and mRNAs related to pathogenic pathways, including inflammatory response, oxidative stress, and cell cycle regulation. Exosomes may represent a novel mechanism for intercellular communication during sepsis.

Extracellular vesicles as a target for the development of anti-helminth vaccines.

There is a rapidly growing body of evidence that production of extracellular vesicles (EVs) is a universal feature of cellular life. More recently, EVs have been identified in a broad range of both unicellular and multicellular parasites where they play roles in parasite-parasite intercommunication as well as parasite-host interactions. Parasitic helminth-derived EVs traverse host target cell membranes whereupon they offload their molecular cargo - proteins, lipids, and genetic information such as mRNAs and miRNAs - which are thought to hijack the target cell and modulate its gene expression to promote parasite survival. As such, EVs represent a novel mechanism of intercellular communication that could be targeted for vaccine-mediated interruption, given the abundance of surface antigens expressed on helminth EVs, and the ability of antibodies to block their uptake by target cells. In this Perspective article, we review recent developments in the field of helminth-derived EVs and highlight their roles in helminth vaccine discovery and development.

Stromal cells control the epithelial residence of DCs and memory T cells by regulated activation of TGF-β.

Cells of the immune system that reside in barrier epithelia provide a first line of defense against pathogens. Langerhans cells (LCs) and CD8(+) tissue-resident memory T cells (TRM cells) require active transforming growth factor-β1 (TGF-β) for epidermal residence. Here we found that integrins αvβ6 and αvβ8 were expressed in non-overlapping patterns by keratinocytes (KCs) and maintained the epidermal residence of LCs and TRM cells by activating latent TGF-β. Similarly, the residence of dendritic cells and TRM cells in the small intestine epithelium also required αvβ6. Treatment of the skin with ultraviolet irradiation decreased integrin expression on KCs and reduced the availability of active TGF-β, which resulted in LC migration. Our data demonstrated that regulated activation of TGF-β by stromal cells was able to directly control epithelial residence of cells of the immune system through a novel mechanism of intercellular communication.

Neuroprotective properties of extracellular vesicles derived from mesenchymal stem cells.

Extracellular vesicles (EVs) provide a novel mechanism of intercellular communication via the transfer of proteins, lipids, and miRNAs between cells. It is now widely accepted that cargo content of EVs depends on cell type and its physiological state. Accordingly, EVs derived from healthy cells may have a comparable therapeutic potential as cells themselves. Indeed, several studies confirmed this notion and demonstrated therapeutic potential of EVs in different clinical settings. Exosomes represent a class of EVs, that can cross blood-brain barrier (Alvarez-Erviti et al., 2011), therefore they can be delivered into the CNS using intravenous, or intranasal routes avoiding the need for neurosurgical interventions. This property makes them particularly attractive as a new tool for the neuroregenerative therapies. However, new protocols require large amounts of EVs which can be obtained only from cells expanded in vitro. In this respect human mesenchymal stem cells (MSCs) represent one of the most promising cellular sources of EVs.

Extracellular vesicles from neural stem cells transfer the IFN-γ/IFNGR1 complex to activate Stat1-dependent signalling in target cells

Advances in stem cell biology have raised great expectations that diseases of the central nervous system may be ameliorated by the development of nonhaematopoietic stem cell medicines. Yet, the application of stem cells as therapeutics is challenging and the interpretation of some of the outcomes ambiguous. The initial idea that stem cell transplants work only via structural cell replacement has been challenged by the observation of consistent intercellular information exchange between the graft and the host. Here, we focused on defining whether the form of cellular signalling mediated by extracellular membrane vesicles (EVs) exists for neural stem/precursor cells (NPCs), and on its molecular signature and functional relevance on target cells. We also investigated whether the EV cargo molecules are modulated by extracellular pro- or anti-inflammatory cytokines, and determined the key elements responsible for this novel mechanism of EV-mediated intercellular communication. We show that NPC EVs primarily consist of exosomes and observe novel cytokine-regulated pathways that sort specific proteins and mRNAs into EVs. We describe a highly specific induction of IFN-gamma pathways in parental NPCs exposed to Th1 pro-inflammatory cytokines that is mirrored in EVs and exosomes. We finally demonstrate the activation of Stat1-dependent signalling in target cells through intercellular transfer of IFN-gamma bound to IFNGR1-enriched EVs. While confirming the intrinsic signalling properties of EVs, our study identifies a novel mechanism of intercellular communication regulated by IFN-gamma/IFNGR1 complex, which stem cell grafts may use to signal to the host immune system.

Tetraspanins in extracellular vesicle formation and function.

Extracellular vesicles (EVs) represent a novel mechanism of intercellular communication as vehicles for intercellular transfer of functional membrane and cytosolic proteins, lipids, and RNAs. Microvesicles, ectosomes, shedding vesicles, microparticles, and exosomes are the most common terms to refer to the different kinds of EVs based on their origin, composition, size, and density. Exosomes have an endosomal origin and are released by many different cell types, participating in different physiological and/or pathological processes. Depending on their origin, they can alter the fate of recipient cells according to the information transferred. In the last two decades, EVs have become the focus of many studies because of their putative use as non-invasive biomarkers and their potential in bioengineering and clinical applications. In order to exploit this ability of EVs many aspects of their biology should be deciphered. Here, we review the mechanisms involved in EV biogenesis, assembly, recruitment of selected proteins, and genetic material as well as the uptake mechanisms by target cells in an effort to understand EV functions and their utility in clinical applications. In these contexts, the role of proteins from the tetraspanin superfamily, which are among the most abundant membrane proteins of EVs, will be highlighted.

Intercellular Transfer of GPRC5B via Exosomes Drives HGF-Mediated Outward Growth

How cells communicate during development and regeneration is a critical question. One mechanism of intercellular communication is via exosomes, extracellular vesicles that originate by the fusion of multivesicular endosomes with the plasma membrane [1-8]. To model exosome-based intercellular communication, we used Madin-Darby canine kidney (MDCK) cell cysts grown in 3D gels of extracellular matrix, which form tubules in response to hepatocyte growth factor (HGF). We report that GPRC5B, an orphan G protein coupled receptor, is in exosomes produced by HGF-treated cysts and released into the cyst lumen. Exosomal GPRC5B is taken up by nearby cells and together with HGF promotes extracellular signal-regulated kinase 1/2 (ERK1/2) activation and tubulogenesis, even under conditions where tubulogenesis would otherwise not occur. Recovery from injury, such as acute kidney injury (AKI), often recapitulates developmental processes. Here, we show that GPRC5B is elevated in urinary exosomes from patients with AKI. Our results elucidate how GPRC5B is carried by exosomes and augments HGF-induced morphogenesis. The unexpected role of exosomes in transporting GPRC5B between cells during morphogenesis and the ability of GPRC5B to predict the disease state of AKI elucidate a novel mechanism for intercellular communication during development and repair.

Epididymosomes Convey Different Repertoires of MicroRNAs Throughout the Bovine Epididymis1

Epididymosomes are small membrane vesicles that are secreted by epididymal epithelial cells and are involved in posttesticular sperm maturation. Although their role in protein transfer to the sperm membrane is well documented, we report their capacity to transport microRNAs (miRNAs), which are potent regulators of posttranscriptional gene expression. Using a microperfusion technique combined with a global microarray approach, we demonstrated that epididymosomes from two discrete bovine epididymal regions (caput and cauda) possess distinct miRNA signatures. In addition, we also established that miRNA repertoires contained within epididymosomes differ from those of their parent epithelial cells, suggesting that miRNA populations released from the cells may be selectively sorted. Binding of DilC12-labeled epididymosomes to primary cultured epididymal cells was measured by flow cytometry, and the results indicated that epididymosomes from the median caput and their miRNA content may be incorporated into distal caput epithelial cells. Overall, these findings reveal that distinct miRNA repertoires are released into the intraluminal fluid in a region-specific manner and could be involved in a novel mechanism of intercellular communication throughout the epididymis via epididymosomes.