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Hyperoxia induces glutamine-fuelled anaplerosis in retinal Muller cells.

ABSTRACT: Although supplemental oxygen is required to promote survival of severely premature infants, hyperoxia is simultaneously harmful to premature developing tissues such as in the retina. Here we report the effect of hyperoxia on central carbon metabolism in primary mouse Müller glial cells and a human Müller glia cell line (M10-M1 cells). We found decreased flux from glycolysis entering the tricarboxylic acid cycle in Müller cells accompanied by increased glutamine consumption in response to hyperoxia. In hyperoxia, anaplerotic catabolism of glutamine by Müller cells increased ammonium release two-fold. Hyperoxia induces glutamine-fueled anaplerosis that reverses basal Müller cell metabolism from production to consumption of glutamine.

SUBMITTER: Singh C

PROVIDER: S-EPMC7062830 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Hyperoxia induces glutamine-fuelled anaplerosis in retinal Müller cells.

Singh Charandeep C Tran Vincent V McCollum Leah L Bolok Youstina Y Allan Kristin K Yuan Alex A Hoppe George G Brunengraber Henri H Sears Jonathan E JE

Nature communications 20200309 1

Although supplemental oxygen is required to promote survival of severely premature infants, hyperoxia is simultaneously harmful to premature developing tissues such as in the retina. Here we report the effect of hyperoxia on central carbon metabolism in primary mouse Müller glial cells and a human Müller glia cell line (M10-M1 cells). We found decreased flux from glycolysis entering the tricarboxylic acid cycle in Müller cells accompanied by increased glutamine consumption in response to hyperox ...[more]

PMID: 32152301

Similar Datasets

Hyperoxia induces glutamine-fuelled anaplerosis in retinal Müller cells

Project description:Premature infants require oxygen supplementation to survive, but excess oxygen causes retinovascular growth suppression that underlies the leading cause of infant blindness known as retinopathy of prematurity (ROP). We analyzed changes in intermediary metabolism during hyperoxia in human retinal endothelial cells (RECs) and human retinal Müller glia, which coexist through glutamine consumption and production, respectively. Using a stable isotope labeling technique in human RECs and human Müller cells in culture, here we show that Müller cells in hyperoxia block entry of glycolytic carbon into the tricarboxylic acid (TCA) cycle and instead oxidize glutamine. In hyperoxia, catabolism of glutamine increased ammonium release by 2-fold. Hyperoxia induces glutamine-fueled anaplerosis that reverses basal Müller cell metabolism from production to consumption of glutamine.

2020-03-12 | MTBLS1228 | MetaboLights

High glucose induces an early and transient cytoprotective autophagy in retinal Muller cells.

Project description:PurposeWe investigated the autophagic response of rat Müller rMC-1 cells during a short-term high glucose challenge.MethodsrMC-1 cells were maintained in 5 mM glucose (LG) or exposed to 25 mM glucose (HG). Western blot analysis was used to evaluate the expression levels of markers of autophagy (LC3-II, p62) and glial activation (AQP4), as well as the activation of TRAF2/JNK, ERK and AKT pathways. Autophagic flux assessment was performed using the autophagy inhibitor chloroquine. ROS levels were measured by flow cytometry using dichlorofluorescein diacetate. ERK involvement in autophagy induction was addressed using the ERK inhibitor FR180204. The effect of autophagy inhibition on cell viability was evaluated by SRB assay.ResultsActivation of autophagy was observed in the first 2-6 h of HG exposure. This early autophagic response was transient, not accompanied by an increase in AQP4 or in the phospho-activation of JNK, a key mediator of cellular response to oxidative stress, and required ERK activity. Cells exposed to HG had a lower viability upon autophagy inhibition by chloroquine, as compared to those maintained in LG.ConclusionA short-term HG challenge triggers in rMC-1 cells a process improving the ability to cope with stressful conditions, which involves ERK and an early and transient autophagy activation.

| S-EPMC9325829 | biostudies-literature

Environmental cystine drives glutamine anaplerosis and sensitizes cancer cells to glutaminase inhibition.

Project description:Many mammalian cancer cell lines depend on glutamine as a major tri-carboxylic acid (TCA) cycle anaplerotic substrate to support proliferation. However, some cell lines that depend on glutamine anaplerosis in culture rely less on glutamine catabolism to proliferate in vivo. We sought to understand the environmental differences that cause differential dependence on glutamine for anaplerosis. We find that cells cultured in adult bovine serum, which better reflects nutrients available to cells in vivo, exhibit decreased glutamine catabolism and reduced reliance on glutamine anaplerosis compared to cells cultured in standard tissue culture conditions. We find that levels of a single nutrient, cystine, accounts for the differential dependence on glutamine in these different environmental contexts. Further, we show that cystine levels dictate glutamine dependence via the cystine/glutamate antiporter xCT/SLC7A11. Thus, xCT/SLC7A11 expression, in conjunction with environmental cystine, is necessary and sufficient to increase glutamine catabolism, defining important determinants of glutamine anaplerosis and glutaminase dependence in cancer.

| S-EPMC5589418 | biostudies-literature

Atoh7 promotes retinal Muller cell differentiation into retinal ganglion cells.

Project description:Glaucoma is one of the leading eye diseases due to the death of retinal ganglion cells. Increasing evidence suggests that retinal Müller cells exhibit the characteristics of retinal progenitor cells and can differentiate to neurons in injured retinas under certain conditions. However, the number of ganglion cells differentiated from retinal Müller cells falls far short of therapeutic needs. This study aimed to promote the differentiation of retinal Müller cells into ganglion cells by introducing Atoh7 into the stem cells dedifferentiated from retinal Müller cells. Rat retinal Müller cells were isolated and dedifferentiated into stem cells, which were transfected with PEGFP-N1 or PEGFP-N1-Atoh7 vector, and then further induced to differentiate into ganglion cells. The proportion of ganglion cells differentiated from Atoh7-tranfected stem cells was significantly higher than that of control transfected or untransfected cells. In summary, Atoh7 promotes the differentiation of retinal Müller cells into retinal ganglion cells. This may open a new avenue for gene therapy of glaucoma by promoting optic nerve regeneration.

| S-EPMC4754246 | biostudies-literature

Electrical Stimulation Induces Retinal Muller Cell Proliferation and Their Progenitor Cell Potential.

Project description:Non-invasive electrical stimulation (ES) is increasingly applied to improve vision in untreatable eye conditions, such as retinitis pigmentosa and age-related macular degeneration. Our previous study suggested that ES promoted retinal function and the proliferation of progenitor-like glial cells in mice with inherited photoreceptor degeneration; however, the underlying mechanism remains obscure. Müller cells (MCs) are thought to be dormant residential progenitor cells that possess a high potential for retinal neuron repair and functional plasticity. Here, we showed that ES with a ramp waveform of 20 Hz and 300 µA of current was effective at inducing mouse MC proliferation and enhancing their expression of progenitor cell markers, such as Crx (cone-rod homeobox) and Wnt7, as well as their production of trophic factors, including ciliary neurotrophic factor. RNA sequencing revealed that calcium signaling pathway activation was a key event, with a false discovery rate of 5.33 × 10-8 (p = 1.78 × 10-10) in ES-mediated gene profiling changes. Moreover, the calcium channel blocker, nifedipine, abolished the observed effects of ES on MC proliferation and progenitor cell gene induction, supporting a central role of ES-induced Ca2+ signaling in the MC changes. Our results suggest that low-current ES may present a convenient tool for manipulating MC behavior toward neuroregeneration and repair.

| S-EPMC7140850 | biostudies-literature

Dengue Virus Infection of Human Retinal Muller Glial Cells.

Project description:Retinopathy is a recently recognized complication of dengue, affecting up to 10% of hospitalized patients. Research on the pathogenesis has focused largely on effects of dengue virus (DENV) at the blood-retinal barrier. Involvement of retinal Müller glial cells has received little attention, although this cell population contributes to the pathology of other intraocular infections. The goal of our work was to establish the susceptibility of Müller cells to infection with DENV and to identify characteristics of the cellular antiviral, inflammatory, and immunomodulatory responses to DENV infection in vitro. Primary human Müller cell isolates and the MIO-M1 human Müller cell line were infected with the laboratory-adapted Mon601 strain and DENV serotype 1 and 2 field isolates, and cell-DENV interactions were investigated by immunolabelling and quantitative real-time polymerase chain reaction. Müller cells were susceptible to DENV infection, but experiments involving primary cell isolates indicated inter-individual variation. Viral infection induced an inflammatory response (including tumour necrosis factor-α, interleukin [IL]-1β, and IL-6) and an immunomodulatory response (including programmed death-ligand [PD-L]1 and PD-L2). The type I interferon response was muted in the Müller cell line compared to primary cell isolates. The highest infectivity and cell responses were observed in the laboratory-adapted strain, and overall, infectivity and cell responses were stronger in DENV2 strains. This work demonstrates that Müller cells mount an antiviral and immune response to DENV infection, and that this response varies across cell isolates and DENV strain. The research provides a direction for future efforts to understand the role of human retinal Müller glial cells in dengue retinopathy.

| S-EPMC10385653 | biostudies-literature

Glucose-dependent anaplerosis in cancer cells is required for cellular redox balance in the absence of glutamine.

Project description:Cancer cells have altered metabolism compared to normal cells, including dependence on glutamine (GLN) for survival, known as GLN addiction. However, some cancer cell lines do not require GLN for survival and the basis for this discrepancy is not well understood. GLN is a precursor for antioxidants such as glutathione (GSH) and NADPH, and GLN deprivation is therefore predicted to deplete antioxidants and increase reactive oxygen species (ROS). Using diverse human cancer cell lines we show that this occurs only in cells that rely on GLN for survival. Thus, the preference for GLN as a dominant antioxidant source defines GLN addiction. We show that despite increased glucose uptake, GLN addicted cells do not metabolize glucose via the TCA cycle when GLN is depleted, as revealed by (13)C-glucose labeling. In contrast, GLN independent cells can compensate by diverting glucose-derived pyruvate into the TCA cycle. GLN addicted cells exhibit reduced PDH activity, increased PDK1 expression, and PDK inhibition partially rescues GLN starvation-induced ROS and cell death. Finally, we show that combining GLN starvation with pro-oxidants selectively kills GLN addicted cells. These data highlight a major role for GLN in maintaining redox balance in cancer cells that lack glucose-dependent anaplerosis.

| S-EPMC5015067 | biostudies-literature

In vivo assessment of glutamine anaplerosis into the TCA cycle in human pre-malignant and malignant clonal plasma cells

Project description:Background Overexpression of c-Myc is required for the progression of pre-malignant plasma cells in monoclonal gammopathy of undetermined significance (MGUS) to malignant plasma cells in multiple myeloma (MM). c-Myc also increases glutamine anaplerosis into the tricarboxylic acid (TCA) cycle within cancer cells. Whether increased glutamine anaplerosis is associated with the progression of pre-malignant to malignant plasma cells is unknown. Methods Human volunteers (N =?7) and patients with MGUS (N =?11) and MM (N =?12) were prospectively recruited to undergo an intravenous infusion of 13C-labeled glutamine followed by a bone marrow aspiration to obtain bone marrow cells and plasma. Results Despite notable heterogeneity, stable isotope-resolved metabolomics (SIRM) revealed that the mean 13C-labeled glutamine anaplerosis into the TCA cycle was higher in malignant compared to pre-malignant bone marrow plasma cells relative to the remainder of their paired bone marrow mononuclear cells. RNA sequencing demonstrated a higher relative mRNA expression of c-Myc and glutamine transporters such as ASCT2 and SN2 in malignant compared to pre-malignant bone marrow plasma cells. Finally, higher quantitative levels of TCA cycle intermediates in the bone marrow plasma differentiated MM from MGUS patients. Conclusion Measurement of the in vivo activity of glutamine anaplerosis into the TCA cycle provides novel insight into the metabolic changes associated with the transformation of pre-malignant plasma cells in MGUS to malignant plasma cells in MM. Trial registration NCT03384108 and NCT03119883

| S-EPMC7731537 | biostudies-literature

Atoh7 promotes the differentiation of retinal stem cells derived from Muller cells into retinal ganglion cells by inhibiting Notch signaling.

Project description:INTRODUCTION: Retinal Müller cells exhibit the characteristics of retinal progenitor cells, and differentiate into ganglion cells under certain conditions. However, the number of ganglion cells differentiated from retinal Müller cells falls far short of therapeutic needs. This study aimed to develop a novel protocol to promote the differentiation of retinal Müller cells into ganglion cells and explore the underlying signaling mechanisms. METHODS: Müller cells were isolated and purified from rat retina and induced to dedifferentiate into retinal stem cells. Next the stem cells were transfected with lentivirus PGC-FU-GFP or lentivirus PGC-FU-Atoh7-GFP. In addition, the stem cells were transfected with Brn-3b siRNA or Isl-1 siRNA or treated with Notch inhibitor gamma-secretase inhibitor (GSI). RESULTS: The proportion of ganglion cells differentiated from Atoh7-tranfected stem cells was significantly higher than that of controls. Knockdown of Brn-3b or Isl-1 inhibited, while GSI promoted, the differentiation into retinal ganglion cells. Atoh7 promoted the expression of Brn-3b and Isl-1 but inhibited the expression of Notch1. CONCLUSIONS: Atoh7 promotes the differentiation of Müller cells-derived retinal stem cells into retinal ganglion cells by inhibiting Notch signaling, thus opening up a new avenue for gene therapy and optic nerve regeneration in glaucoma.

| S-EPMC3854761 | biostudies-literature

Reprogramming of Adult Retinal Muller Glial Cells into Human-Induced Pluripotent Stem Cells as an Efficient Source of Retinal Cells.

Project description:The reprogramming of human somatic cells to induced pluripotent stem cells (iPSCs) has broad applications in regenerative medicine. The generation of self-organized retinal structures from these iPSCs offers the opportunity to study retinal development and model-specific retinal disease with patient-specific iPSCs and provides the basis for cell replacement strategies. In this study, we demonstrated that the major type of glial cells of the human retina, Müller cells, can be reprogrammed into iPSCs that acquire classical signature of pluripotent stem cells. These Müller glial cell-derived iPSCs were able to differentiate toward retinal fate and generate concomitantly retinal pigmented epithelial cells and self-forming retinal organoid structures containing retinal progenitor cells. Retinal organoids recapitulated retinal neurogenesis with differentiation of retinal progenitor cells into all retinal cell types in a sequential overlapping order. With a modified retinal maturation protocol characterized by the presence of serum and high glucose levels, our study revealed that the retinal organoids contained pseudolaminated neural retina with important features reminiscent of mature photoreceptors, both rod and cone subtypes. This advanced maturation of photoreceptors not only supports the possibility to use 3D retinal organoids for studying photoreceptor development but also offers a novel opportunity for disease modeling, particularly for inherited retinal diseases.

| S-EPMC6664555 | biostudies-literature

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