Neuron-glia signaling in developing retina mediated by neurotransmitter spillover

Miniaturized Electrochemical Sensing Platforms for Quantitative Monitoring of Glutamate Dynamics in the Central Nervous System

Glutamate is one of the most important excitatory neurotransmitters within the mammalian central nervous system. The role of glutamate in regulating neural network signaling transmission through both synaptic and extra-synaptic paths highlights the importance of the real-time and continuous monitoring of its concentration and dynamics in living organisms. Progresses in multidisciplinary research have promoted the development of electrochemical glutamate sensors through the co-design of materials, interfaces, electronic devices, and integrated systems. This review summarizes recent works reporting various electrochemical sensor designs and their applicability as miniaturized neural probes to in vivo sensing within biological environments. We start with an overview of the role and physiological significance of glutamate, the metabolic routes, and its presence in various bodily fluids. Next, we discuss the design principles, commonly employed validation models/protocols, and successful demonstrations of multifunctional, compact, and bio-integrated devices in animal models. The final section provides an outlook on the development of the next generation glutamate sensors for neuroscience and neuroengineering, with the aim of offering practical guidance for future research.

Cone cell dysfunction attenuates retinal neovascularization in oxygen-induced retinopathy mouse model

Aberrant neovascularization is the most common feature in retinopathy of prematurity (ROP), which leads to the retinal detachment and visual defects in neonates with a low gestational age eventually. Understanding the regulation of inappropriate angiogenic signaling benefits individuals at-risk. Recently, neural activity originating from the specific neural activity has been considered to contribute to retinal angiogenesis. Here, we explored the impact of cone cell dysfunction on oxygen-induced retinopathy (OIR), a mouse model commonly employed to understand retinal diseases associated with abnormal blood vessel growth, using the Gnat2cpfl3 (cone photoreceptor function loss-3) strain of mice (regardless of the sex), which is known for its inherent cone cell dysfunction. We found that the retinal avascular area, hypoxic area, and neovascular area were significantly attenuated in Gnat2cpfl3 OIR mice compared to those in C57BL/6 OIR mice. Moreover, the HIF-1α/VEGF axis was also reduced in Gnat2cpfl3 OIR mice. Collectively, our results indicated that cone cell dysfunction, as observed in Gnat2cpfl3 OIR mice, leads to attenuated retinal neovascularization. This finding suggests that retinal neural activity may precede and potentially influence the onset of pathological neovascularization.

Multivesicular release favors short term synaptic depression in hippocampal autapses

Presynaptic terminals of the central nervous system can support univesicular and multivesicular synchronous release of neurotransmitters, however, the functional implications of the prevalence of one mechanism over the other are yet unresolved. Here, we took advantage of the expression of SF-iGluSnFR.S72A in the astrocytic feeder layer of autaptic hippocampal neuronal cultures to associate the liberation of glutamate to excitatory postsynaptic currents. The presence of the glutamate sensor in glial cells avoided any interference with the function of endogenous postsynaptic receptors. It was possible to optically detect changes in neurotransmitter release probability, which was heterogeneous among synaptic boutons studied. For each neuron investigated, the liberation of neurotransmitters occurred through a predominant mechanism. The prevalence of multivesicular over univesicular release increased synaptic strength and enhanced short-term synaptic depression. These results show that the preference of hippocampal boutons to synchronously release one or more vesicles determines the strength and low pass filtering properties of the synapses established.

Astrocytic Kir4.1 channels regulate locomotion by orchestrating neuronal rhythmicity in the spinal network

Neuronal rhythmogenesis in the spinal cord is correlated with variations in extracellular K⁺ levels ([K⁺ ]_e ). Astrocytes play important role in [K⁺ ]_e homeostasis and compute neuronal information. Yet it is unclear how neuronal oscillations are regulated by astrocytic K⁺ homeostasis. Here we identify the astrocytic inward-rectifying K⁺ channel Kir4.1 (a.k.a. Kcnj10) as a key molecular player for neuronal rhythmicity in the spinal central pattern generator (CPG). By combining two-photon calcium imaging with electrophysiology, immunohistochemistry and genetic tools, we report that astrocytes display Ca²⁺ transients before and during oscillations of neighboring neurons. Inhibition of astrocytic Ca²⁺ transients with BAPTA decreases the barium-sensitive Kir4.1 current responsible of K⁺ clearance. Finally, we show in mice that Kir4.1 knockdown in astrocytes progressively prevents neuronal oscillations and alters the locomotor pattern resulting in lower motor performances in challenging tasks. These data identify astroglial Kir4.1 channels as key regulators of neuronal rhythmogenesis in the CPG driving locomotion.

Long Non-coding RNA LINC01224 Promotes the Malignant Behaviors of Triple Negative Breast Cancer Cells via Regulating the miR-193a-5p/NUP210 Axis

Triple negative breast cancer (TNBC) is a prevalent malignant tumor in women and is characterized by high incidence and mortality. Current evidence has suggested that multiple long noncoding RNAs (lncRNAs) play regulatory roles in TNBC, while the specific mechanism of LINC01224 in TNBC remains unclear. In this study, LINC01224 was highly expressed in TNBC cells. Moreover, LINC01224 downregulation inhibited TNBC cell proliferation, migration, and invasion, and promoted cell apoptosis. Additionally, LINC01224 stabilized NUP210 mRNA through interaction with miR-193a-5p, thereby aggravating the malignant phenotypes of TNBC. Overall, LINC01224 functions as a tumor promoter for TNBC.

Brainstem serotonin neurons selectively gate retinal information flow to thalamus

Retinal ganglion cell (RGC) types relay parallel streams of visual feature information. We hypothesized that neuromodulators might efficiently control which visual information streams reach the cortex by selectively gating transmission from specific RGC axons in the thalamus. Using fiber photometry recordings, we found that optogenetic stimulation of serotonergic axons in primary visual thalamus of awake mice suppressed ongoing and visually evoked calcium activity and glutamate release from RGC boutons. Two-photon calcium imaging revealed that serotonin axon stimulation suppressed RGC boutons that responded strongly to global changes in luminance more than those responding only to local visual stimuli, while the converse was true for suppression induced by increases in arousal. Converging evidence suggests that differential expression of the 5-HT1B receptor on RGC presynaptic terminals, but not differential density of nearby serotonin axons, may contribute to the selective serotonergic gating of specific visual information streams before they can activate thalamocortical neurons.

CircMERTK modulates the suppressive capacity of tumor-associated macrophage via targeting IL-10 in colorectal cancer

Macrophages represent the major population in the tumor microenvironment (TME). Recent studies have demonstrated circular RNAs (circRNAs) are implicated in the development and progression of different immune responses and immune diseases. However, the role of circRNAs in the development of tumor-associated macrophages (TAM) remains unknown. Here, we used the circRNA sequencing to identify the differentially expressed circRNAs (DEcircRNAs) in TAM-like cell induced by culture medium of colorectal cancer cell lines. Of note, the expression of circMERTK was remarkably overexpressed in TAMs. The ISH assay displayed that the expressions of circMERTK were mainly overlapped with macrophages marker CD68, and the abundance of circMERTK in CRC tissues was much higher than that in matched normal tissues. Functionally, circMERTK knockdown resulted in attenuated CD8⁺ T cell apoptosis in the co-culture assay, indicating that circMERTK could have an impact on the immunosuppressive activity of TAM-like cell. Mechanically, TAM-like cell could exert immunosuppressive activity via circMERTK/miR-125a-3p/IL-10 axis. These data suggested that circMERTK could play an important role in TAM activation, and may serve as a potential therapeutic target for CRC.

Retinoschisin Deficiency Induces Persistent Aberrant Waves of Activity Affecting Neuroglial Signaling in the Retina

Genetic disorders that present during development make treatment strategies particularly challenging because there is a need to disentangle primary pathophysiology from downstream dysfunction caused at key developmental stages. To provide a deeper insight into this question, we studied a mouse model of X-linked juvenile retinoschisis, an early-onset inherited condition caused by mutations in the Rs1 gene encoding retinoschisin (RS1) and characterized by cystic retinal lesions and early visual deficits. Using an unbiased approach in expressing the fast intracellular calcium indicator GCaMP6f in neuronal, glial, and vascular cells of the retina of RS1-deficient male mice, we found that initial cyst formation is paralleled by the appearance of aberrant spontaneous neuroglial signals as early as postnatal day 15, when eyes normally open. These presented as glutamate-driven wavelets of neuronal activity and sporadic radial bursts of activity by Müller glia, spanning all retinal layers and disrupting light-induced signaling. This study confers a role to RS1 beyond its function as an adhesion molecule, identifies an early onset for dysfunction in the course of disease, establishing a potential window for disease diagnosis and therapeutic intervention.SIGNIFICANCE STATEMENT Developmental disorders make it difficult to distinguish pathophysiology due to ongoing disease from pathophysiology due to disrupted development. Here, we investigated a mouse model for X-linked retinoschisis, a well defined monogenic degenerative disease caused by mutations in the Rs1 gene, which codes for the protein retinoschisin. We evaluated the spontaneous activity of explanted retinas lacking retinoschisin at key stages of development using the unbiased approach of ubiquitously expressing GCaMP6f in all retinal neurons, vasculature, and glia. In mice lacking RS1, we found that an array of novel phenotypes, which present around eye opening, are linked to glutamatergic neurotransmission and affect visual processing. These data identify a novel pathophysiology linked to RS1, and define a window where treatments might be best targeted.

Mechanism of CREB1 in cardiac function of rats with heart failure via regulating the microRNA-376a-3p/TRAF6 axis

Heart failure (HF) is a complicated disease resulting from impaired heart function. CREB1 is a candidate target in heart-concerning diseases. This paper attempts to explore the role of CREB1 in HF. Initially, the HF rat model was established by constricted abdominal aortic surgery and the cardiac function of HF rats was assessed by ultrasonic cardiogram. Levels of CK-MB and LDH and activity of Caspase-3 and Caspase-9 in HF rats were determined. Subsequently, myocardium pathological injury and myocardium apoptosis were detected. Additionally, the interactions between CREB1 and miR-376a-3p and between miR-376a-3p and TRAF6 were verified. The roles of CREB1, miR-376a-3p, and TRAF6 in HF were evaluated. In HF rats, CREB1 and miR-376a-3p were both downregulated while TRAF6 was upregulated. Besides, HF rats had decreased values of EF and FS, elevated levels of CK-MB and LDH, inflammatory infiltration, promoted cardiomyocyte apoptosis, and elevated activity of Caspase-3 and Caspase-9, which were all reversed by CREB1. Additionally, CREB1 activated miR-376a-3p expression, and miR-376a-3p targeted TRAF6 transcription. Both miR-376a-3p knockdown and TRAF6 overexpression annulled the protective role of CREB1 overexpression in cardiac function of HF rats. CREB1 activated miR-376a-3p expression to suppress TRAF6, thereby promoting the cardiac function of HF rats.

Expansion of the RNAStructuromeDB to include secondary structural data spanning the human protein-coding transcriptome

RNA plays vital functional roles in almost every component of biology, and these functional roles are often influenced by its folding into secondary and tertiary structures. An important role of RNA secondary structure is in maintaining proper gene regulation; therefore, making accurate predictions of the structures involved in these processes is important. In this study, we have expanded on our previous work that led to the creation of the RNAStructuromeDB. Unlike this previous study that analyzed the human genome at low resolution, we have now scanned the protein-coding human transcriptome at high (single nt) resolution. This provides more robust structure predictions for over 100,000 isoforms of known protein-coding genes. Notably, we also utilize the motif identification tool, ScanFold, to model structures with high propensity for ordered/evolved stability. All data have been uploaded to the RNAStructuromeDB, allowing for easy searching of transcripts, visualization of data tracks (via the Integrative Genomics Viewer or IGV), and download of ScanFold data—including unique highly-ordered motifs. Herein, we provide an example analysis of MAT2A to demonstrate the utility of ScanFold at finding known and novel secondary structures, highlighting regions of potential functionality, and guiding generation of functional hypotheses through use of the data.

Targeting ferroptosis with miR-144-3p to attenuate pancreatic β cells dysfunction via regulating USP22/SIRT1 in type 2 diabetes

BACKGROUND

Recently, ferroptosis has been implicated in the pathologic process of several diseases including type 2 diabetes mellitus (T2DM). However, molecular mechanisms underlying ferroptosis in T2DM remain obscure.

METHODS

Twenty four mice were included in this study. T2DM model mice were established by a high-fat diet combined with streptozotocin injection. INS-1 cells were stimulated with high glucose (HG). Cell viability was detected by CCK-8 kit. The levels of GSH, MDA, iron, and lipid ROS, and SOD activity, were detected by the corresponding kits. The interaction between miR-144-3p and USP22 was validated by dual-luciferase reporter assay. The relationship between USP22 and its substrate was verified using Co-IP and ubiquitination assays. The mRNA and protein expressions were examined by RT-qPCR and western blot, respectively. The functions of β cells in vitro and in vivo were evaluated glucose-stimulated insulin secretion test and HOMA-β, respectively.

RESULTS

Ferroptosis occurred in the pancreas of T2DM mice and HG-induced INS-1 cells. Silencing miR-144-3p blocked the effect of HG on the cell viability and accumulation of lipid peroxides, thereby improving the insulin secretion in INS-1 cells. Mechanistically, USP22 is a direct target of miR-144-3p, which could stabilize SIRT1 expression, thereby suppressing ferroptosis. Overexpressing USP22 attenuated deleterious roles of HG in INS-1 cells; but its roles were reversed by up-regulating miR-144-3p. In vivo study demonstrated that miR-144-3p antagomir exerted an anti-hyperglycemic effect and regulated the ferroptosis-related proteins in the pancreas.

CONCLUSION

The up-regulation of miR-144-3p suppressed USP22/SIRT1 to induce ferroptosis, which causes pancreatic β cells dysfunction, thereby promoting T2DM development.

A deep learning method for miRNA/isomiR target detection

Accurate identification of microRNA (miRNA) targets at base-pair resolution has been an open problem for over a decade. The recent discovery of miRNA isoforms (isomiRs) adds more complexity to this problem. Despite the existence of many methods, none considers isomiRs, and their performance is still suboptimal. We hypothesize that by taking the isomiR-mRNA interactions into account and applying a deep learning model to study miRNA-mRNA interaction features, we may improve the accuracy of miRNA target predictions. We developed a deep learning tool called DMISO to capture the intricate features of miRNA/isomiR-mRNA interactions. Based on tenfold cross-validation, DMISO showed high precision (95%) and recall (90%). Evaluated on three independent datasets, DMISO had superior performance to five tools, including three popular conventional tools and two recently developed deep learning-based tools. By applying two popular feature interpretation strategies, we demonstrated the importance of the miRNA regions other than their seeds and the potential contribution of the RNA-binding motifs within miRNAs/isomiRs and mRNAs to the miRNA/isomiR-mRNA interactions.

Neuronal microRNAs safeguard ER Ca2+ homeostasis and attenuate the unfolded protein response upon stress

Ca2+ is a critical mediator of neurotransmitter release, synaptic plasticity, and gene expression, but also excitotoxicity. Ca2+ signaling and homeostasis are coordinated by an intricate network of channels, pumps, and calcium-binding proteins, which must be rapidly regulated at all expression levels. Τhe role of neuronal miRNAs in regulating ryanodine receptors (RyRs) and inositol 1,4,5-triphosphate receptors (IP3Rs) was investigated to understand the underlying mechanisms that modulate ER Ca2+ release. RyRs and IP3Rs are critical in mounting and propagating cytosolic Ca2+ signals by functionally linking the ER Ca2+ content, while excessive ER Ca2+ release via these receptors is central to the pathophysiology of a wide range of neurological diseases. Herein, two brain-restricted microRNAs, miR-124-3p and miR-153-3p, were found to bind to RyR1-3 and IP3R3 3'UTRs, and suppress their expression at both the mRNA and protein level. Ca2+ imaging studies revealed that overexpression of these miRNAs reduced ER Ca2+ release upon RyR/IP3R activation, but had no effect on [Ca2+]i under resting conditions. Interestingly, treatments that cause excessive ER Ca2+ release decreased expression of these miRNAs and increased expression of their target ER Ca2+ channels, indicating interdependence of miRNAs, RyRs, and IP3Rs in Ca2+ homeostasis. Furthermore, by maintaining the ER Ca2+ content, miR-124 and miR-153 reduced cytosolic Ca2+ overload and preserved protein-folding capacity by attenuating PERK signaling. Overall, this study shows that miR-124-3p and miR-153-3p fine-tune ER Ca2+ homeostasis and alleviate ER stress responses.

Harnessing the Neuroprotective Behaviors of Müller Glia for Retinal Repair

Progressive and irreversible vision loss in mature and aging adults creates a health and economic burden, worldwide. Despite the advancements of many contemporary therapies to restore vision, few approaches have considered the innate benefits of gliosis, the endogenous processes of retinal repair that precede vision loss. Retinal gliosis is fundamentally driven by Müller glia (MG) and is characterized by three primary cellular mechanisms: hypertrophy, proliferation, and migration. In early stages of gliosis, these processes have neuroprotective potential to halt the progression of disease and encourage synaptic activity among neurons. Later stages, however, can lead to glial scarring, which is a hallmark of disease progression and blindness. As a result, the neuroprotective abilities of MG have remained incompletely explored and poorly integrated into current treatment regimens. Bioengineering studies of the intrinsic behaviors of MG hold promise to exploit glial reparative ability, while repressing neuro-disruptive MG responses. In particular, recent in vitro systems have become primary models to analyze individual gliotic processes and provide a stepping stone for in vivo strategies. This review highlights recent studies of MG gliosis seeking to harness MG neuroprotective ability for regeneration using contemporary biotechnologies. We emphasize the importance of studying gliosis as a reparative mechanism, rather than disregarding it as an unfortunate clinical prognosis in diseased retina.

Fine mapping and candidate gene analysis of a dravet syndrome modifier locus on mouse chromosome 11

Pathogenic variants in SCN1A result in a spectrum of phenotypes ranging from mild febrile seizures to Dravet syndrome, a severe infant-onset epileptic encephalopathy. Individuals with Dravet syndrome have developmental delays, elevated risk for sudden unexpected death in epilepsy (SUDEP), and have multiple seizure types that are often refractory to treatment. Although most Dravet syndrome variants arise de novo, there are cases where an SCN1A variant was inherited from mildly affected parents, as well as some individuals with de novo loss-of-function or truncation mutations that presented with milder phenotypes. This suggests that disease severity is influenced by other factors that modify expressivity of the primary mutation, which likely includes genetic modifiers. Consistent with this, the Scn1a^+/- mouse model of Dravet syndrome exhibits strain-dependent variable phenotype severity. Scn1a^+/- mice on the 129S6/SvEvTac (129) strain have no overt phenotype and a normal lifespan, while [C57BL/6Jx129]F1.Scn1a^+/- mice have severe epilepsy with high rates of premature death. Low resolution genetic mapping identified several Dravet syndrome modifier (Dsm) loci responsible for the strain-dependent difference in survival of Scn1a^+/- mice. To confirm the Dsm5 locus and refine its position, we generated interval-specific congenic strains carrying 129-derived chromosome 11 alleles on the C57BL/6J strain and localized Dsm5 to a 5.9 Mb minimal region. We then performed candidate gene analysis in the modifier region. Consideration of brain-expressed genes with expression or coding sequence differences between strains along with gene function suggested numerous strong candidates, including several protein coding genes and two miRNAs that may regulate Scn1a transcript.

Developmental neural activity requires neuron-astrocyte interactions

Developmental neural activity is a common feature of neural circuit assembly. Although glia have established roles in synapse development, the contribution of neuron-glia interactions to developmental activity remains largely unexplored. Here we show that astrocytes are necessary for developmental activity during synaptogenesis in Drosophila. Using wide-field epifluorescence and two-photon imaging, we show that the glia of the central nervous system participate in developmental activity with type-specific patterns of intracellular calcium dynamics. Genetic ablation of astrocytes, but not of cortex or ensheathing glia, leads to severe attenuation of neuronal activity. Similarly, inhibition of neuronal activity results in the loss of astrocyte calcium dynamics. By altering these dynamics, we show that astrocytic calcium cycles can influence neuronal activity but are not necessary per se. Taken together, our results indicate that, in addition to their recognized role in the structural maturation of synapses, astrocytes are also necessary for the function of synapses during development.

Targeting HIF1-alpha/miR-326/ITGA5 axis potentiates chemotherapy response in triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer that is frequently treated with chemotherapy. However, many patients exhibit either de novo chemoresistance or ultimately develop resistance to chemotherapy, leading to significantly high mortality rates. Therefore, increasing the efficacy of chemotherapy has potential to improve patient outcomes.

METHODS

Here, we performed whole transcriptome sequencing (both RNA and small RNA-sequencing), coupled with network simulations and patient survival data analyses to build a novel miRNA-mRNA interaction network governing chemoresistance in TNBC. We performed cell proliferation assay, Western blotting, RNAi/miRNA mimic experiments, FN coating, 3D cultures, and ChIP assays to validate the interactions in the network, and their functional roles in chemoresistance. We developed xenograft models to test the therapeutic potential of the identified key miRNA/proteins in potentiating chemoresponse in vivo. We also analyzed several patient datasets to evaluate the clinical relevance of our findings.

RESULTS

We identified fibronectin (FN1) as a central chemoresistance driver gene. Overexpressing miR-326 reversed FN1-driven chemoresistance by targeting FN1 receptor, ITGA5. miR-326 was downregulated by increased hypoxia/HIF1A and ECM stiffness in chemoresistant tumors, leading to upregulation of ITGA5 and activation of the downstream FAK/Src signaling pathways. Overexpression of miR-326 or inhibition of ITGA5 overcame FN1-driven chemotherapy resistance in vitro by inhibiting FAK/Src pathway and potentiated the efficacy of chemotherapy in vivo. Importantly, lower expression of miR-326 or higher levels of predicted miR-326 target genes was significantly associated with worse overall survival in chemotherapy-treated TNBC patients.

CONCLUSION

FN1 is central in chemoresistance. In chemoresistant tumors, hypoxia and resulting ECM stiffness repress the expression of the tumor suppressor miRNA, miR-326. Hence, re-expression of miR-326 or inhibition of its target ITGA5 reverses FN1-driven chemoresistance making them attractive therapeutic approaches to enhance chemotherapy response in TNBCs.

Exosome-derived miR-200a promotes esophageal cancer cell proliferation and migration via the mediating Keap1 expression

Previous studies have reported that exosomes bearing certain microRNAs (miRNAs) are related to the physiological functions of different types of cancer cells. Our study aimed to elucidate the role of miR-200a in esophageal squamous cell carcinoma (ESCC). We observed that miR-200a expression is higher in esophageal carcinoma cells, tissues, and exosomes than in normal cells and healthy tissues. We showed that exosome-shuttled miR-200a promotes the proliferation, migration, and invasion of esophageal cells and inhibits apoptosis, thereby leading to the progression of ESCC. We showed that miR-200a exerts its effects through its interaction with Keap1, thus altering the Keap1/Nrf2 signaling pathway. Our results suggest that exosome-shuttled miR-200a might be useful as a biomarker for prognosis in patients with ESCC.

Müller Glia in Retinal Development: From Specification to Circuit Integration

Müller glia of the retina share many features with astroglia located throughout the brain including maintenance of homeostasis, modulation of neurotransmitter spillover, and robust response to injury. Here we present the molecular factors and signaling events that govern Müller glial specification, patterning, and differentiation. Next, we discuss the various roles of Müller glia in retinal development, which include maintaining retinal organization and integrity as well as promoting neuronal survival, synaptogenesis, and phagocytosis of debris. Finally, we review the mechanisms by which Müller glia integrate into retinal circuits and actively participate in neuronal signaling during development.

Glia Regulate the Development, Function, and Plasticity of the Visual System From Retina to Cortex

Visual experience is mediated through a relay of finely-tuned neural circuits extending from the retina, to retinorecipient nuclei in the midbrain and thalamus, to the cortex which work together to translate light information entering our eyes into a complex and dynamic spatio-temporal representation of the world. While the experience-dependent developmental refinement and mature function of neurons in each major stage of the vertebrate visual system have been extensively characterized, the contributions of the glial cells populating each region are comparatively understudied despite important findings demonstrating that they mediate crucial processes related to the development, function, and plasticity of the system. In this article we review the mechanisms for neuron-glia communication throughout the vertebrate visual system, as well as functional roles attributed to astrocytes and microglia in visual system development and processing. We will also discuss important aspects of glial function that remain unclear, integrating the knowns and unknowns about glia in the visual system to advance new hypotheses to guide future experimental work.

LncRNA NEAT1 Promotes TLR4 Expression to Regulate Lipopolysaccharide-Induced Trophoblastic Cell Pyroptosis as a Molecular Sponge of miR-302b-3p

Pyroptosis is an inflammation-triggered cell death caused by certain inflammasomes, and long non-coding RNAs (lncRNAs) are related to cell pyroptosis. This study evaluated the mechanism of lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) on lipopolysaccharide (LPS)-induced trophoblastic cells pyroptosis. HTR-8/Svneo trophoblastic cells were treated with LPS. The expression of lncRNA NEAT1 was decreased using siRNAs, followed by the evaluation of cell proliferation, Caspase-1 activity, levels of Cleaved Caspase-1 and gasdermin D-N, and the concentrations of Interleukin (IL)-1β and IL-18. We found that LPS promoted the pyroptosis of HTR-8/Svneo cells, and lncRNA NEAT1 was highly expressed in LPS-treated HTR-8/Svneo cells while silencing lncRNA NEAT1 inhibited LPS-induced trophoblastic cells pyroptosis. The subcellular localization of lncRNA NEAT1 was detected. Dual-luciferase gene experiment and RNA pull-down assay detected that lncRNA NEAT1 bound to miR-302b-3p and could inhibit miR-302b-3p, and toll-like receptor 4 (TLR4) was the target gene of miR-302b-3p. Then, a joint experiment was designed for detection, which found that miR-302b-3p downregulation partially reversed the inhibition of silencing lncRNA NEAT1 on LPS-induced trophoblastic cells pyroptosis and overexpression of TLR4 annulled the inhibition of silencing lncRNA NEAT1 on LPS-induced trophoblastic cells pyroptosis. Therefore, lncRNA NEAT1 promoted the transcription of TLR4 by competitively binding to miR-302b-3p, thus promoting LPS-induced trophoblastic cells pyroptosis.

Extracellular vesicles carry miR-27a-3p to promote drug resistance of glioblastoma to temozolomide by targeting BTG2

OBJECTIVE

Glioblastoma (GBM) is the most common central nervous system tumor. Temozolomide (TMZ) is a commonly used drug for GBM management. This study explored the mechanism of extracellular vesicles (EVs) regulating TMZ-resistance in GBM.

METHODS

LN229 cells were inducted into TMZ-resistant LN229r strain by stepwise induction. After the intervention of miR-27a-3p expression, cell viability of GBM cells treated with different concentrations of TMZ was detected by MTT and IC50 value was calculated. Cell proliferation and apoptosis were detected by colony formation and flow cytometry. EVs extracted from LN18 cells were identified and the internalization of EVs by LN229r cells was evaluated. The 100 μmol/L TMZ-treated LN229r cells were treated with EVs or EVs with downregulated miR-27a-3p to verify the effect of EVs-carried miR-27a-3p on TMZ resistance. The binding relation between BTG2 and miR-27a-3p was verified. miR-27a-3p and BTG2 expressions in GBM cells and EVs were detected by RT-qPCR. The BTG2 effect on TMZ-resistance in GBM was verified. The xenograft tumor nude mouse model was established by injecting LN229r cells and treated with EVs and 100 μmol/L TMZ.

RESULTS

miR-27a-3p was highly expressed in LN229r cells. IC50 value and proliferation of LN229r cells with silenced miR-27a-3p were decreased and apoptosis was increased, indicating that miR-27a-3p silencing reduced the drug-resistant cell LN229r resistance to TMZ. LN18-derived EVs could be internalized by LN229r cells, and release its encapsulated miR-27a-3p into LN229r cells and increase miR-27a-3p expression. EV treatment increased LN229r cell proliferation and reduced apoptosis, while EVs with silenced miR-27a-3p showed the opposite trend. miR-27a-3p targeted BTG2. BTG2 overexpression reduced LN229r cell resistance to TMZ. In vivo, after EVs treatment, tumor volume and weight, Ki67-positive rate, and miR-27a-3p were increased, while BTG2 expression was decreased.

CONCLUSION

GBM-derived EVs were internalized by GBM cells, released miR-27a-3p into GBM cells, upregulated miR-27a-3p expression, and targeted BTG2, thus promoting TMZ resistance.

Müller Cell Molecular Heterogeneity: Facts and Predictions

The retina was historically considered as an “approachable part of the brain”; advantageous, for its simplicity, to use as a model organ for deciphering cellular and molecular mechanisms underlying physiology and pathology of the nervous system. However, the most relevant discoveries arise precisely from unveiling the complexity of the retina. A complexity that partially relies on the layered organization of an extended variety of specialized neuronal and glial cellular types and subtypes. Based on functional, morphological or transcriptome data, over 40 subtypes of retinal ganglion cells or 60 subtypes of retinal amacrine cells have been described. A high degree of specialization, that may lead to segregation into functionally diverse subtypes, is also conceivable for Müller cells, a pleiotropic glial component of all vertebrate retinas. The essential role of Müller glia in retinal homeostasis maintenance involves participation in structural, metabolic and intercellular communication processes. Additionally, they are the only retinal cells that possess regenerative potential in response to injury or disease, and thus may be considered as therapeutic tools. In the assumption that functional heterogeneity might be driven by molecular heterogeneity this review aims to compile emerging evidence that could broaden our understanding of Müller cell biology and retinal physiology.

Summary statement

Müller glial cells exert multiple essential functions in retinal physiology and retinopathies reflecting perhaps the existence of distinct Müller cellular subpopulations. Harnessing Müller cell heterogeneity may serve to enhance new therapeutic approaches for retinal disease.

The Intrinsic Blue Light Responses of Avian Müller Glial Cells Imply Calcium Release from Internal Stores

The retina of vertebrates is responsible for capturing light through visual (cones and rods) and non-visual photoreceptors (intrinsically photosensitive retinal ganglion cells and horizontal cells) triggering a number of essential activities associated to image- and non-image forming functions (photic entrainment of daily rhythms, pupillary light reflexes, pineal melatonin inhibition, among others). Although the retina contains diverse types of neuronal based-photoreceptors cells, originally classified as ciliary- or rhabdomeric-like types, in recent years, it has been shown that the major glial cell type of the retina, the Müller glial cells (MC), express blue photopigments as Opn3 (encephalopsin) and Opn5 (neuropsin) and display light responses associated to intracellular Ca2 + mobilization. These findings strongly propose MC as novel retinal photodetectors (Rios et al., 2019). Herein, we further investigated the intrinsic light responses of primary cultures of MC from embryonic chicken retinas specially focused on Ca2 + mobilization by fluorescence imaging and the identity of the internal Ca2 + stores responsible for blue light responses. Results clearly demonstrated that light responses were specific to blue light of long time exposure, and that the main Ca2 + reservoir to trigger downstream responses came from intracellular stores localized in the endoplasmic reticulum These observations bring more complexity to the intrinsic photosensitivity of retinal cells, particularly with regard to the detection of light in the blue range of visible spectra, and add novel functions to glial cells cooperating with other photoreceptors to detect and integrate ambient light in the retinal circuit and participate in cell to cell communication.

Summary statement:

Non-neuronal cells in the vertebrate retina, Muller glial cells, express non-canonical photopigments and sense blue light causing calcium release from intracellular stores strongly suggesting a novel intrinsic photosensitivity and new regulatory events mediating light-driven processes with yet unknown physiological implications.

Excitatory neurotransmission activates compartmentalized calcium transients in Müller glia without affecting lateral process motility

Neural activity has been implicated in the motility and outgrowth of glial cell processes throughout the central nervous system. Here, we explore this phenomenon in Müller glia, which are specialized radial astroglia that are the predominant glial type of the vertebrate retina. Müller glia extend fine filopodia-like processes into retinal synaptic layers, in similar fashion to brain astrocytes and radial glia that exhibit perisynaptic processes. Using two-photon volumetric imaging, we found that during the second postnatal week, Müller glial processes were highly dynamic, with rapid extensions and retractions that were mediated by cytoskeletal rearrangements. During this same stage of development, retinal waves led to increases in cytosolic calcium within Müller glial lateral processes and stalks. These regions comprised distinct calcium compartments, distinguished by variable participation in waves, timing, and sensitivity to an M1 muscarinic acetylcholine receptor antagonist. However, we found that motility of lateral processes was unaffected by the presence of pharmacological agents that enhanced or blocked wave-associated calcium transients. Finally, we found that mice lacking normal cholinergic waves in the first postnatal week also exhibited normal Müller glial process morphology. Hence, outgrowth of Müller glial lateral processes into synaptic layers is determined by factors that are independent of neuronal activity.

When it comes to studying the nervous system, neurons often steal the limelight; yet, they can only work properly thanks to an ensemble cast of cell types whose roles are only just emerging.

For example, ‘glial cells’ – their name derives from the Greek word for glue – were once thought to play only a passive, supporting function in nervous tissues. Now, growing evidence shows that they are, in fact, integrated into neural circuits: their activity is influenced by neurons, and, in turn, they help neurons to function properly.

The role of glial cells is becoming clear in the retina, the thin, light-sensitive layer that lines the back of the eye and relays visual information to the brain. There, beautifully intricate Müller glial cells display fine protrusions (or ‘processes') that intermingle with synapses, the busy space between neurons where chemical messengers are exchanged. These messengers can act on Müller cells, triggering cascades of molecular events that may influence the structure and function of glia. This is of particular interest during development: as Müller cells mature, they are exposed to chemicals released by more fully formed retinal neurons.

Tworig et al. explored how neuronal messengers can influence the way Müller cells grow their processes. To do so, they tracked mouse retinal glial cells ‘live’ during development, showing that they were growing fine, highly dynamic processes in a region rich in synapses just as neurons and glia increased their communication. However, using drugs to disrupt this messaging for a short period did not seem to impact how the processes grew. Extending the blockade over a longer timeframe also did not change the way Müller cells developed, with the cells still acquiring their characteristic elaborate process networks. Taken together, these results suggest that the structural maturation of Müller glial cells is not impacted by neuronal signaling, giving a more refined understanding of how glia form in the retina and potentially in the brain.

MiR-30b-5p attenuates neuropathic pain by the CYP24A1-Wnt/β-catenin signaling in CCI rats

MicroRNAs (miRNAs) has been reported to act as key regulators of neuronal function. Increasing evidence has showed that miRNAs exert significant effects in neuropathic pain. We explored the role of miR-30b-5p in neuropathic pain by establishing a rat model of chronic constrictive injury (CCI). The sciatic nerve of CCI rats was used to induce chronic neuropathic pain. The expression and cellular distribution of miR-30b-5p were determined by RT-qPCR and FISH. The mRNA level, protein level, and cellular distribution of CYP24A1 were detected by RT-qPCR, western blot, and immunofluorescence staining assays, respectively. The interaction between miR-30b-5p and CYP24A1 was examined by a luciferase reporter assay. The behavioral effects of miR-30b-5p were assessed after intrathecal administration. Mechanical stimuli and radiant heat were applied to assess mechanical allodynia and thermal hyperalgesia of rats. ELISA was performed to measure the concentration of inflammatory cytokines. MiR-30b-5p expression was significantly downregulated in the spinal cord tissues and of CCI rats. Overexpression of miR-30b-5p attenuated symptoms of neuropathic pain, including mechanical allodynia and thermal hyperalgesia. Additionally, miR-30b-5p overexpression suppressed neuroinflammation by reducing the levels of IL-6, TNF-α and COX2 and elevating the levels of IL-10 in CCI rats. Mechanistically, CYP24A1 was a target of miR-30b-5p, and its expression was negatively regulated by miR-30b-5p. Moreover, CYP24A1 expression was upregulated in CCI rats and knockdown of CYP24A1 attenuated neuropathic pain and neuroinflammation. Furthermore, miR-30b-5p reduced the levels of the Wnt pathway-related genes in CCI rats by downregulating CYP24A1. Rescue assays showed that overexpression of CYP24A1 or activation of Wnt pathway reduced the alleviative effects of miR-30b-5p overexpression on neuropathic pain in CCI rats. Overall, miR-30b-5p inhibits neuropathic pain progression in CCI rats by inhibiting the CYP24A1-Wnt/β-catenin pathway.

Neuroepithelial progenitors generate and propagate non-neuronal action potentials across the spinal cord

In the developing central nervous system, electrical signaling is thought to rely exclusively on differentiating neurons as they acquire the ability to generate and propagate action potentials. Accordingly, neuroepithelial progenitors (NEPs), which give rise to all neurons and glial cells during development, have been reported to remain electrically passive. Here, we investigated the physiological properties of NEPs at the onset of spontaneous neural activity (SNA) initiating motor behavior in mouse embryonic spinal cord. Using patch-clamp recordings, we discovered that spinal NEPs exhibit spontaneous membrane depolarizations during episodes of SNA. These rhythmic depolarizations exhibited a ventral-to-dorsal gradient with the highest amplitude located in the floor plate, the ventral-most part of the neuroepithelium. Paired recordings revealed that NEPs are coupled via gap junctions and form an electrical syncytium. Although other NEPs were electrically passive, we discovered that floor-plate NEPs generated large Na⁺/Ca²⁺ action potentials. Unlike in neurons, floor-plate action potentials relied primarily on the activation of voltage-gated T-type calcium channels (TTCCs). In situ hybridization showed that all 3 known subtypes of TTCCs are predominantly expressed in the floor plate. During SNA, we found that acetylcholine released by motoneurons rhythmically triggers floor-plate action potentials by acting through nicotinic acetylcholine receptors. Finally, by expressing the genetically encoded calcium indicator GCaMP6f in the floor plate, we demonstrated that neuroepithelial action potentials are associated with calcium waves and propagate along the entire length of the spinal cord. Our work reveals a novel physiological mechanism to generate and propagate electrical signals across a neural structure independently from neurons.

The "Neuro-Glial-Vascular" Unit: The Role of Glia in Neurovascular Unit Formation and Dysfunction

The neurovascular unit (NVU) is a complex multi-cellular structure consisting of endothelial cells (ECs), neurons, glia, smooth muscle cells (SMCs), and pericytes. Each component is closely linked to each other, establishing a structural and functional unit, regulating central nervous system (CNS) blood flow and energy metabolism as well as forming the blood-brain barrier (BBB) and inner blood-retina barrier (BRB). As the name suggests, the “neuro” and “vascular” components of the NVU are well recognized and neurovascular coupling is the key function of the NVU. However, the NVU consists of multiple cell types and its functionality goes beyond the resulting neurovascular coupling, with cross-component links of signaling, metabolism, and homeostasis. Within the NVU, glia cells have gained increased attention and it is increasingly clear that they fulfill various multi-level functions in the NVU. Glial dysfunctions were shown to precede neuronal and vascular pathologies suggesting central roles for glia in NVU functionality and pathogenesis of disease. In this review, we take a “glio-centric” view on NVU development and function in the retina and brain, how these change in disease, and how advancing experimental techniques will help us address unanswered questions.

MiR-519d-3p enhances the sensitivity of non-small-cell lung cancer to tyrosine kinase inhibitors

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. Tyrosine kinase inhibitors (TKIs) are currently the most effective chemotherapy for NSCLC. However, most cancer patients develop TKI resistance at tumor relapse stage. We firstly measured the expression change of miR-519d-3p in TKI resistance NSCLC cells. We then ectopically expressed miR-519-3p in TKI resistant cells to study its functional impact on cell proliferation, migration, invasion and cell sensitivity to gefitinib. The downstream target of miR-519-3p was identified by bioinformatics and validated in luciferase reporter assay and western blotting analysis. We also studied the reversing effect of the candidate target in NSCLC cells expressing miR-519d-3p. Lastly, we compared the miR-519d-3p level in NSCLC patients with good or poor response to gefitinib. miR-519d-3p level was downregulated in TKI resistant NSCLC cells. The restoration of miR-519d-3p in these NSCLC cells inhibited cell proliferation, invasion and migration; enhanced cell sensitivity to gefitinib. EPAS1 was identified and validated as downstream target of miR-519d-3p. Co-expressing EPAS1 antagonized the inhibitory effect of miR-519d-3p on NSCLC cells. MiR-519d-3p was downregulated in NSCLC patients with poor response to gefitinib. Targeting miR-519d-3p/EPAS1 axis may provide alternative treatment for TKI-resistant NSCLC.

Mobius strip in pancreatic cancer: biogenesis, function and clinical significance of circular RNAs

Pancreatic cancer (PC) is a kind of common digestive system cancer with the worst prognosis for its insidious symptoms and high invasiveness. Circular RNAs (circRNAs) are endogenous non-coding RNAs with covalently closed circular structure, which are more stable and conservative than linear RNAs and process major functions of microRNA (miRNA) sponge, RNA binding protein (RBP) sponge and polypeptide translation template. Incremental researches have proved that circRNAs express aberrantly and play a vital role in various types of cancer. Hence, we reviewed the biogenesis, degradation, characteristics, and biological functions of circRNAs and summarized the roles circRNAs played in the proliferation, invasion, metastasis, chemoresistance and exosome-mediated intercellular communication of PC. We then summed up a workflow regarding circRNA research in cancer and relative specific databases and experimental methods. In the future, more efforts ought to be put into circRNAs research in PC, including basic research of discovering and testifying circRNAs centered ceRNA networks, and clinical research of exploiting exosomal or circulating circRNAs as a diagnostic biomarker, chemotherapy sensitivity predictor and prognostic predictor.

Two distinct skeletal muscle microRNA signatures revealing the complex mechanism of sporadic ALS

Skeletal muscle pathology is thought to have an important role in the onset and/or progression of amyotrophic lateral sclerosis (ALS), which is a neurodegenerative disorder characterized by progressive muscle weakness. Since miRNAs are recognized as important regulatory factors of essential biological processes, we aimed to identify differentially expressed miRNAs in the skeletal muscle of sporadic ALS patients through the combination of molecular-omic technologies and bioinformatic tools. We analyzed the miRnome profiles of skeletal muscle biopsies acquired from ten sALS patients and five controls with Affymetrix GeneChip miRNA 4.0 Array. To find out differentially expressed miRNAs in patients, data were analyzed by The Institute for Genomic Research-Multi Experiment Viewer (MeV) and miRNAs whose expression difference were statistically significant were identified as candidates. The potential target genes of these miRNAs were predicted by miRWalk 2.0 and were functionally enriched by gene ontology (GO) analysis. The expression level of priority candidates was validated by quantitative real-time PCR (qRT-PCR) analysis. We identified ten differentially expressed miRNAs in patients with a fold change threshold ≥ 2.0, FDR = 0. We identified ten differentially expressed miRNAs in patients with a fold change threshold ≥ 2.0, FDR = 0. Nine out of the ten miRNAs were found to be related to top three enriched ALS-related terms. Based on the qRT-PCR validation of candidate miRNAs, patients were separated into two groups: those with upregulated miR-4429 and miR-1825 expression and those with downregulated miR-638 expression. The different muscle-specific miRNA profiles in sALS patients may indicate the involvement of etiologic heterogeneity, which may allow the development of novel therapeutic strategies.

miR-637 Prevents Glioblastoma Progression by Interrupting ZEB2/WNT/β-catenin Cascades

Glioblastomas (GBMs) are the most frequent primary malignancies in the central nervous system. Aberrant activation of WNT/β-catenin signaling pathways is critical for GBM malignancy. However, the regulation of WNT/β-catenin signaling cascades remains unclear. Presently, we observed the increased expression of ZEB2 and the decreased expression of miR-637 in GBM. The expression of miR-637 was negatively correlated with ZEB2 expression. miR-637 overexpression overcame the ZEB2-enhanced cell proliferation and G1/S phase transition. Besides, miR-637 suppressed the canonical WNT/β-catenin pathways by targeting WNT7A directly. Gain- and loss-of-function experiments with U251 mice demonstrated that miR-637 inhibited cell proliferation and arrested the G1/S phase transition, leading to tumor growth suppression. The collective findings suggest that ZEB2 and WNT/β-catenin cascades merge at miR-637, and the ectopic expression of miR-637 disturbs ZEB2/WNT/β-catenin-mediated GBM growth. The findings provide new clues for improving β-catenin-targeted therapy against GBM.

Building a circuit through correlated spontaneous neuronal activity in the developing vertebrate and invertebrate visual systems

During the development of the vertebrate nervous systems, genetic programs assemble an immature circuit that is subsequently refined by neuronal activity evoked by external stimuli. However, prior to sensory experience, the intrinsic property of the developing nervous system also triggers correlated network-level neuronal activity, with retinal waves in the developing vertebrate retina being the best documented example. Spontaneous activity has also been found in the visual system of Drosophila Here, we compare the spontaneous activity of the developing visual system between mammalian and Drosophila and suggest that Drosophila is an emerging model for mechanistic and functional studies of correlated spontaneous activity.

Identification of miR-17, miR-21, miR-27a, miR-106b and miR-222 as endoplasmic reticulum stress-related potential biomarkers in circulation of patients with atherosclerosis

Atherosclerosis and related cardiovascular diseases are among the most common causes of death worldwide. Unfolded protein response, also known as Endoplasmic reticulum stress, has a critical role in many diseases including atherosclerosis. Small non-coding microRNAs (miRNA), which generally suppress gene expression, regulate UPR signalling and they may also be involved in the progression of atherosclerosis. We aim to investigate the expression levels of miR-17, miR-21, miR-27a, miR-106b, miR-222 and CHOP gene in circulation of atherosclerosis patients compared to healthy controls to establish a link between ER stress and atherosclerosis. miRNA containing whole RNA was isolated from blood samples of 25 patients with atherosclerosis and 26 healthy controls. Expression levels of miRNAs and CHOP were measured via Real Time PCR method. miR-17 and miR-106b were significantly increased while miR-21, miR-27a, and miR-222 were significantly decreased in patients compared to controls. CHOP gene was also dramatically and significantly induced in patient samples. miR-17, miR-21, miR-27a, miR-106b, miR-222 and CHOP were significantly differentially expressed in patients with atherosclerosis. Each miRNA and CHOP might regulate atherosclerotic plaque progression and they can be used as a biomarker in the diagnosis and follow-up of atherosclerosis-related cardiovascular diseases.

MiR-103/miR-107 inhibits enterovirus 71 replication and facilitates type I interferon response by regulating SOCS3/STAT3 pathway

BACKGROUND

Enterovirus71 (EV71), the major cause of hand, foot, and-mouth disease (HFMD), has increasingly become a public health challenge. Type I interferons (IFNs) can regulate innate and adaptive immune responses to pathogens. MicroRNAs (miRNAs) play regulatory roles in host innate immune responses to viral infections. However, the roles of miR-103 and miR-107 in EV71 infection remain unclear.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to determine the expression of miR-103, miR-107, suppressor of cytokine signaling 3 (SOCS3), VP1, IFN-α, and IFN-β. Virus titers were measured by 50% tissue culture infectious dose (TCID₅₀) assay. Western blot assay was conducted to detect the protein levels of VP1, IFN-α, IFN-β, SOCS3, signal transducer and activator of transcription 3 (STAT3), and phospho-STAT3 (p-STAT3). Immunofluorescence assay was used to detect the protein level of VP1. The concentrations of IFN-α and IFN-β were examined by Enzyme-linked immunosorbent assay (ELISA). The interaction between SOCS3 and miR-103/miR-107 was predicted by starBase and verified by dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

MiR-103 and miR-107 were downregulated and SOCS3 was upregulated in serum from patients with EV71 and EV71-infected cells. Overexpression of miR-103 and miR-107 repressed EV71 replication by inhibiting EV71 titers and VP1 expression. Moreover, upregulation of miR-103 and miR-107 enhanced EV71-triggered the production of type I IFNs. In addition, miR-103 and miR-107 directly targeted SOCS3, and SOCS3 upregulation reversed the effects of miR-103 and miR-107 on EV71 replication and type I IFN response. Importantly, miR-103 and miR-107 increased STAT3 phosphorylation by targeting SOCS3 after EV71 infection.

CONCLUSION

MiR-103 and miR-107 suppressed EV71 replication and increased the production of type I IFNs by regulating SOCS3/STAT3 pathway, which might provide a novel strategy for developing effective antiviral therapy.

Identification of genetic variants in m6A modification genes associated with pancreatic cancer risk in the Chinese population

N6-Methyladenosine (m⁶A) is the most prevalent modification of RNA in eukaryotes, and is associated with many cellular processes and even the development of cancers. We hypothesized that single-nucleotide polymorphisms (SNPs) in m⁶A modification genes, including its "writers", "erasers" and "readers", might affect the m⁶A functions and associate with the susceptibility to pancreatic ductal adenocarcinoma (PDAC). We first conducted a two-stage case-control study in Chinese population to interrogate all SNPs in 22 m⁶A modification genes. In the discovery stage, a total of 2735 SNPs were genotyped in 980 patients and 1991 controls. Then, the promising SNP was replicated in another independent population consisting of 858 cases and 2084 controls. As a result, we found the rs7495 in 3'UTR of hnRNPC was significantly associated with increased risk of PDAC in both stages (combined odds ratio = 1.22, 95% confidence interval = 1.12-1.32, P = 2.39 × 10^-6). To further reveal the biological function of rs7495 and hnRNPC, we performed a series of biochemical experiments. Luciferase reporter assays indicated that rs7495G allele promoted hnRNPC expression through disrupting a putative binding site for has-miR-183-3p. Cell viability assay demonstrated that knockdown of hnRNPC suppressed the proliferation of PDAC cells. RNA-seq analysis suggested that as an m⁶A "reader", hnRNPC played an important role in RNA biological processes. In conclusion, our findings elucidated that rs7495G could confer higher risk of PDAC via promoting the expression of hnRNPC through a miRNA-mediated manner. These results provided a novel insight into the critical role of m⁶A modification in tumorigenesis.

The circular RNA circSlc7a11 promotes bone cancer pain pathogenesis in rats by modulating LLC-WRC 256 cell proliferation and apoptosis

Treatment of bone cancer pain (BCP) caused by bone metastasis in advanced cancers remains a challenge in clinical oncology, and the underlying mechanisms of BCP are poorly understood. This study aimed to investigate the pathogenic roles of circular RNAs (circRNAs) in regulating cancer cell proliferation and BCP development. Eight differentially expressed circRNAs in the rat spinal cord were validated by agarose gel electrophoresis and Sanger sequencing. Expression of circRNAs and mRNAs was detected by quantitative RT-PCR. MTS assay and flow cytometry were performed to analyze cell proliferation and apoptosis, respectively. Differentially expressed mRNA profiles were characterized by deep RNA sequencing, hierarchical clustering, and functional categorization. The interactions among circRNAs, microRNAs (miRNAs), and mRNAs were predicted using TargetScan. Additionally, western blot was performed to determine the protein levels of Pax8, Isg15, and Cxcl10. Multiple circRNAs were differentially expressed in the spinal cords of BCP model rats; of these, circSlc7a11 showed the greatest increase in expression. The overexpression of circSlc7a11 significantly promoted cell proliferation and repressed apoptosis of LLC-WRC 256 and UMR-106 cells, whereas circSlc7a11 silencing produced the opposite effects. Altered expression of circSlc7a11 also induced substantial changes in the mRNA expression profiles of LLC-WRC 256 cells; these changes were linked to multiple apoptotic processes and signaling pathways, such as the chemokine signaling pathway, and formed a complex circRNA/miRNA/mRNA network. Additionally, Pax8, Isg15, and Cxc110 protein level in LLC-WRC 256 cells was consistent with the mRNA results. The circRNA circSlc7a11 regulates rat BCP development by modulating LLC-WRC 256 cell proliferation and apoptosis through multiple-signaling mechanisms.

Comprehensive upstream and downstream regulatory analyses identify miR-675-3p as a potential prognostic biomarker in melanoma

This study assessed miR-675-3p-related regulatory mechanisms in melanoma and the clinical relevance of such regulatory activities. We downloaded miRNA mature strand expression RNA-Seq, phenotypic, and DNA methylation data pertaining to the TCGA Melanoma cohort. Differentially expressed miRNAs (DEMs) between metastatic and primary melanoma patient tissues were then identified, and miR-675-3p expression in melanoma patient peripheral blood was confirmed using the GSE20994 GEO dataset, while its expression in melanoma cell lines was evaluated via qRT-RCR. The clinical and prognostic implications of miR-675-3p in melanoma were assessed, and miR-675-3p target genes were identified using bioinformatics tools. Functional roles of this miRNA were explored via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. We identified 3 and 22 miRNAs that were up- and downregulated, respectively, in metastatic melanoma samples relative to primary melanoma samples. Upregulation of miR-675-3p was associated with poorer overall patient survival, tumor histologic grade, and Clark's level. Consistently, miR-675-3p was also overexpressed in the peripheral blood of melanoma patients relative to healthy controls, and in melanoma cell lines relative to control cells. Gene regulatory networks indicated that 32 transcription factors control miR-675-3p expression, and that it, in turn, regulates 10 target genes. KEGG analyses indicated that these genes were associated with cell cycle, transcriptional misregulation in cancer, TGF-beta signaling, and HIF-1 signaling pathways. Gain-of-function assays revealed that miR-675-3p could promote cell proliferation via accelerating cell cycle progression. Western blotting results indicated that miR-675-3p could active TGF-beta and HIF-1 signaling. Through upstream and downstream analyses of miR-675-3p-related regulatory activity, we confirmed that this miRNA participates in key melanoma-related processes and offers value as a prognostic biomarker in melanoma patients.

MMP1 3'UTR facilitates the proliferation and migration of human oral squamous cell carcinoma by sponging miR-188-5p to up-regulate SOX4 and CDK4

Growing evidence indicates that the non-coding 3'-untranslated region (3'UTR) of genes acts as competing endogenous RNAs (ceRNAs) to exert their roles in a number of diseases, including cancer. In the present study, MMP1 messenger RNA was identified to be significantly up-regulated in oral squamous cell carcinoma (OSCC) tissues, and both MMP1 and its 3'UTR promoted tumor growth and cell motility. Further mechanism investigations indicated that MMP1 3'UTR was able to antagonize miR-188-5p; in addition, overexpression of MMP1 3'UTR up-regulated the expression level of SOX4 and CDK4, target genes of miR-188-5p, which have also been identified as oncogenic driver genes in OSCC. Therefore, a ceRNA regulatory network among MMP1, SOX4, and CDK4 mediated via competing for binding to miR-188-5p was proved. Taken together, the present study demonstrates for the first time that MMP1 mRNA participates in the development of OSCC via ceRNA regulatory mechanism and genes involved in the ceRNA network may provide a novel avenue for target therapy.

Cell Calcium Imaging as a Reliable Method to Study Neuron-Glial Circuits

Complex dynamic cellular networks have been studied in physiological and pathological processes under the light of single-cell calcium imaging (SCCI), a method that correlates functional data based on calcium shifts operated by different intracellular and extracellular mechanisms integrated with their cell phenotypes. From the classic synaptic structure to tripartite astrocytic model or the recent quadripartite microglia added ensemble, as well as other physiological tissues, it is possible to follow how cells signal spatiotemporally to cellular patterns. This methodology has been used broadly due to the universal properties of calcium as a second messenger. In general, at least two types of receptor operate through calcium permeation: a fast-acting ionotropic receptor channel and a slow-activating metabotropic receptor, added to exchangers/transporters/pumps and intracellular Ca²⁺ release activated by messengers. These prototypes have gained an enormous amount of information in dynamic signaling circuits. SCCI has also been used as a method to associate phenotypic markers during development and stage transitions in progenitors, stem, vascular cells, neuro- and glioblasts, neurons, astrocytes, oligodendrocytes, and microglia that operate through ion channels, transporters, and receptors. Also, cancer cells or inducible cell lines from human organoids characterized by transition stages are currently being used to model diseases or reconfigure healthy cells in terms of the expression of calcium-binding/permeable molecules and shed light on therapy.

Overexpression of miR-669m inhibits erythroblast differentiation

MicroRNAs (miRNAs), one of small non-coding RNAs, regulate many cell functions through their post-transcriptionally downregulation of target genes. Accumulated studies have revealed that miRNAs are involved in hematopoiesis. In the present study, we investigated effects of miR-669m overexpression on hematopoiesis in mouse in vivo, and found that erythroid differentiation was inhibited by the overexpression. Our bioinformatic analyses showed that candidate targets of miR-669m which are involved in the erythropoiesis inhibition are A-kinase anchoring protein 7 (Akap7) and X-linked Kx blood group (Xk) genes. These two genes were predicted as targets of miR-669m by two different in silico methods and were upregulated in late erythroblasts in a public RNA-seq data, which was confirmed with qPCR. Further, miR-669m suppressed luciferase reporters for 3′ untranslated regions of Akap7 and Xk genes, which supports these genes are direct targets of miR-669m. Physiologically, miR-669m was not expressed in the erythroblast. In conclusion, using miR-669m, we found Akap7 and Xk, which may be involved in erythroid differentiation, implying that manipulating these genes could be a therapeutic way for diseases associated with erythropoiesis dysfunction.

Müller Glial Cells Participate in Retinal Waves via Glutamate Transporters and AMPA Receptors

Retinal waves, the spontaneous patterned neural activities propagating among developing retinal ganglion cells (RGCs), instruct the activity-dependent refinement of visuotopic maps. Although it is known that the wave is initiated successively by amacrine cells and bipolar cells, the behavior and function of glia in retinal waves remain unclear. Using multiple in vivo methods in larval zebrafish, we found that Müller glial cells (MGCs) display wave-like spontaneous activities, which start at MGC processes within the inner plexiform layer, vertically spread to their somata and endfeet, and horizontally propagate into neighboring MGCs. MGC waves depend on glutamatergic signaling derived from bipolar cells. Moreover, MGCs express both glia-specific glutamate transporters and the AMPA subtype of glutamate receptors. The AMPA receptors mediate MGC calcium activities during retinal waves, whereas the glutamate transporters modulate the occurrence of retinal waves. Thus, MGCs can sense and regulate retinal waves via AMPA receptors and glutamate transporters, respectively.

miR-4634 augments the anti-tumor effects of RAD001 and associates well with clinical prognosis of non-small cell lung cancer

MicroRNA (miRNA) is involved in the physiological and pathological processes of various malignancies. In this study, miRNA microarray analysis showed that miR-4634 levels in A549 cells increased significantly after everolimus (RAD001) treatment. Decreased expression of miR-4634 was also found in non-small-cell lung carcinoma (NSCLC) cell lines and patients’ tumors by qPCR. Additionally, a combination of miR-4634 and RAD001 exerted synergistic antitumor efficacy by inhibiting cell proliferation, migration, and colony formation. High expression of miR-4634 was significantly more common in non-cancerous lung tissue than adenocarcinoma or squamous cell carcinoma tissue (72.8%, 45.7%, and 50.9%, respectively; P < 0.001). Furthermore, high expression of miR-4634 was found to be more frequent in patients without lymph node metastasis (P = 0.037) by in-situ hybridization. Importantly, through univariate and multivariate analysis, high miR-4634 expression was associated with better prognosis of NSCLC patients. In conclusion, miR-4634 may act as a tumor suppressor in NSCLC, and to augment the efficacy of RAD001, co-treatment of miR-4634 and RAD001 might be a potential mTOR-targeted cancer therapy strategy for NSCLC patients. High expression of miR-4634 could be an independent good prognostic biomarker for NSCLC.

Neuronal regulation of the blood-brain barrier and neurovascular coupling

To continuously process neural activity underlying sensation, movement and cognition, the CNS requires a homeostatic microenvironment that is not only enriched in nutrients to meet its high metabolic demands but that is also devoid of toxins that might harm the sensitive neural tissues. This highly regulated microenvironment is made possible by two unique features of CNS vasculature absent in the peripheral organs. First, the blood-blood barrier, which partitions the circulating blood from the CNS, acts as a gatekeeper to facilitate the selective trafficking of substances between the blood and the parenchyma. Second, neurovascular coupling ensures that, following local neural activation, regional blood flow is increased to quickly supply more nutrients and remove metabolic waste. Here, we review how neural and vascular activity act on one another with regard to these two properties.

A Robust Model System for Retinal Hypoxia: Live Imaging of Calcium Dynamics and Gene Expression Studies in Primary Human Mixed Retinal Culture

The detailed mechanisms underlying oxidative stress that leads to neuroinflammation and neurodegeneration in retinal vascular conditions, including diabetic retinopathy, retinopathy of prematurity etc., remain largely unexplored mainly due to a lack of suitable disease models that can simulate the inherent neuron-glia interactions in human retina. Specifically, establishment of a mixed retinal culture (MRC) containing both neuron and glial cell types remains a challenge due to different conditions required for their optimal growth and differentiation. Here, we establish a novel primary MRC model system containing neurons, astrocytes, Müller glia, and microglia from human donor retina that can be used to study the neuromodulatory effects of glial cells under the stress. The cell characterization based on immunostaining with individual cell type-specific markers and their presence in close vicinity to each other further underscores their utility for studying their cross talk. To the best of our knowledge, this is the first instance of an in vitro model obtained from human donor retina containing four major cell types. Next, we induce hypoxic stress to MRC to investigate if hypoxia activated neuroglia modulates altered gene expression for inflammatory, apoptotic, and angiogenic markers and Ca²⁺ transients by live cell imaging. Further, we performed k-means clustering of the Ca²⁺ responses to identify the modification of clustering pattern in stressed condition. Finally, we provide the evidence that the altered Ca²⁺ transient correlates to differential expression of genes shown to be involved in neuroinflammation, angiogenesis, and neurodegeneration under the hypoxic conditions as seen earlier in human cell lines and animal models of diabetic retinopathy. The major features of the hypoxic conditions in the proposed human MRC model included: increase in microglia activity, chemokine and cytokine expression, and percentage of cells having higher amplitude and frequency of Ca²⁺ transients. Thus, the proposed experimental system can potentially serve as an ideal in vitro model for studying the neuroinflammatory and neurodegenerative changes in the retina and identifying newer drug targets.

Satellite glial cells modulate cholinergic transmission between sympathetic neurons

Postganglionic sympathetic neurons and satellite glial cells are the two major cell types of the peripheral sympathetic ganglia. Sympathetic neurons project to and provide neural control of peripheral organs and have been implicated in human disorders ranging from cardiovascular disease to peripheral neuropathies. Here we show that satellite glia regulate synaptic activity of cultured postnatal sympathetic neurons, providing evidence for local ganglionic control of sympathetic drive. In addition to modulating neuron-to-neuron cholinergic neurotransmission, satellite glia promote synapse formation and contribute to neuronal survival. Examination of the cellular architecture of the rat sympathetic ganglia in vivo shows this regulation of neuronal properties takes place during a developmental period in which neuronal morphology and density are actively changing and satellite glia enwrap sympathetic neuronal somata. Cultured satellite glia make and release factors that promote neuronal activity and that can partially rescue the neurons from cell death following nerve growth factor deprivation. Thus, satellite glia play an early and ongoing role within the postnatal sympathetic ganglia, expanding our understanding of the contributions of local and target-derived factors in the regulation of sympathetic neuron function.

Expression of Non-visual Opsins Opn3 and Opn5 in the Developing Inner Retinal Cells of Birds. Light-Responses in Müller Glial Cells

The avian retina is composed of different types of photoreceptors responsible for image and non-image forming tasks: the visual photoreceptor cells (cones and rods), the melanopsin-expressing intrinsically photoresponsive retinal ganglion cells (ipRGCs) and horizontal cells. Furthermore, the non-visual opsins Opn3 (encephalopsin/panaopsin) and Opn5 (neuropsin) have been shown to be expressed in the vertebrate inner retina, responding to blue (BL) and UV light, respectively. Here we investigated the expression and localization of Opn3 and Opn5 in the developing chick retina at different embryonic days (E) as well as in primary cultures of retinal Müller glial cells (MCs). Opn3 and Opn5 mRNAs and proteins appeared as early as E10 although traces of Opn3- and Opn5-like proteins were seen earlier by E7 in the forming RGC layer and in glial cells extending throughout the developing nuclear layer. Later on, at postnatal days 1–10 (PN1–10) a significant expression of Opn3 was observed in inner retinal cells and processes in plexiform layers, together with expression of the glial markers glutamine synthetase (GS) and the glial fibrillary acidic protein (GFAP). Opn3 and Opn5 were found to be expressed in primary MC cultures prepared at E8 and kept for 2 weeks. In addition, significant effects of BL exposure on Opn3 expression and subcellular localization were observed in MCs as BL significantly increased its levels and modified its nuclear location when compared with dark controls, through a mechanism dependent on protein synthesis. More importantly, a subpopulation of MCs responded to brief BL pulses by increasing intracellular Ca²⁺ levels; whereas light-responses were completely abolished with the retinal bleacher hydroxylamine pretreatment. Taken together, our findings show that these two opsins are expressed in inner retinal cells and MCs of the chicken retina at early developmental phases and remain expressed in the mature retina at PN days. In addition, the novel photic responses seen in MCs may suggest another important role for the glia in retinal physiology.

Cholinergic neural activity directs retinal layer-specific angiogenesis and blood retinal barrier formation

Blood vessels in the central nervous system (CNS) develop unique features, but the contribution of CNS neurons to regulating those features is not fully understood. We report that inhibiting spontaneous cholinergic activity or reducing starburst amacrine cell numbers prevents invasion of endothelial cells into the deep layers of the retina and causes blood-retinal-barrier (BRB) dysfunction in mice. Vascular endothelial growth factor (VEGF), which drives angiogenesis, and Norrin, a Wnt ligand that induces BRB properties, are decreased after activity blockade. Exogenous VEGF restores vessel growth but not BRB function, whereas stabilizing beta-catenin in endothelial cells rescues BRB dysfunction but not vessel formation. We further identify that inhibiting cholinergic activity reduces angiogenesis during oxygen-induced retinopathy. Our findings demonstrate that neural activity lies upstream of VEGF and Norrin, coordinating angiogenesis and BRB formation. Neural activity originating from specific neural circuits may be a general mechanism for driving regional angiogenesis and barrier formation across CNS development.

During retinal development, waves of cholinergic neural activity play a role in retinal circuit development. Here, the authors show that this activity also contributes to layer-specific angiogenesis and formation of the blood-retinal barrier.

Synaptic Functions of Hemichannels and Pannexons: A Double-Edged Sword

The classical view of synapses as the functional contact between presynaptic and postsynaptic neurons has been challenged in recent years by the emerging regulatory role of glial cells. Astrocytes, traditionally considered merely supportive elements are now recognized as active modulators of synaptic transmission and plasticity at the now so-called "tripartite synapse." In addition, an increasing body of evidence indicates that beyond immune functions microglia also participate in various processes aimed to shape synaptic plasticity. Release of neuroactive compounds of glial origin, -process known as gliotransmission-, constitute a widespread mechanism through which glial cells can either potentiate or reduce the synaptic strength. The prevailing vision states that gliotransmission depends on an intracellular Ca²⁺/exocytotic-mediated release; notwithstanding, growing evidence is pointing at hemichannels (connexons) and pannexin channels (pannexons) as alternative non-vesicular routes for gliotransmitters efflux. In concurrence with this novel concept, both hemichannels and pannexons are known to mediate the transfer of ions and signaling molecules -such as ATP and glutamate- between the cytoplasm and the extracellular milieu. Importantly, recent reports show that glial hemichannels and pannexons are capable to perceive synaptic activity and to respond to it through changes in their functional state. In this article, we will review the current information supporting the "double edge sword" role of hemichannels and pannexons in the function of central and peripheral synapses. At one end, available data support the idea that these channels are chief components of a feedback control mechanism through which gliotransmitters adjust the synaptic gain in either resting or stimulated conditions. At the other end, we will discuss how the excitotoxic release of gliotransmitters and [Ca²⁺]_i overload linked to the opening of hemichannels/pannexons might impact cell function and survival in the nervous system.