Expression and high glucose-mediated regulation of K+ channel interacting protein 3 (KChIP3) and KV4 channels in retinal Müller glial cells

Kv4/K channel-interacting protein (KChIP) potassium channels are a major class of rapidly inactivating K channels in brain and heart. Considering the importance of alternative splicing to the quantitative features of KChIP gating modulation, a previously uncharacterized splice form of KChIP1 was functionally characterized. The KChIP1b splice variant differs from the previously characterized KChIP1a splice form by the inclusion of a novel amino-terminal region that is encoded by an alternative exon that is conserved in mouse, rat, and human genes. The expression of KChIP1b mRNA was high in brain but undetectable in heart or liver by RT-PCR. In cerebellar tissue, KChIP1b and KChIP1a transcripts were expressed at nearly equal levels. Coexpression of KChIP1b or KChIP1a with Kv4.2 channels in oocytes slowed K current decay and destabilized open-inactivated channel gating. Like other KChIP subunits, KChIP1b increased Kv4.2 current amplitude and KChIP1b also shifted Kv4.2 conductance-voltage curves by —10 mV. The development of Kv4.2 channel inactivation accessed from closed gating states was faster with KChIP1b coexpression. Deletion of the novel amino-terminal region in KChIP1b selectively altered the subunit's modulation of Kv4.2 closed inactivation gating. The role of the KChIP1b NH2-terminal region was further confirmed by direct comparison of the properties of the NH2-terminal deletion mutant and the KChIP1a subunit, which is encoded by a transcript that lacks the novel exon. The features of KChIP1b modulation of Kv4 channels are likely to be conserved in mammals and demonstrate a role for the KChIP1 NH2-terminal region in the regulation of closed inactivation gating.

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670nm photobiomodulation modulates bioenergetics and oxidative stress, in rat Müller cells challenged with high glucose

PLoS ONE ◽

10.1371/journal.pone.0260968 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0260968

Author(s):

Hannah J. Nonarath ◽

Alexandria E. Hall ◽

Gopika SenthilKumar ◽

Betsy Abroe ◽

Janis T. Eells ◽

...

Keyword(s):

Oxidative Stress ◽

Glial Cells ◽

High Glucose ◽

Near Infrared ◽

Müller Cells ◽

Model System ◽

Light Treatment ◽

Muller Cells ◽

Müller Glial Cells

Diabetic retinopathy (DR), the most common complication of diabetes mellitus, is associated with oxidative stress, nuclear factor-κB (NFκB) activation, and excess production of vascular endothelial growth factor (VEGF) and intracellular adhesion molecule-1 (ICAM-1). Muller glial cells, spanning the entirety of the retina, are involved in DR inflammation. Mitigation of DR pathology currently occurs via invasive, frequently ineffective therapies which can cause adverse effects. The application of far-red to near-infrared (NIR) light (630-1000nm) reduces oxidative stress and inflammation in vitro and in vivo. Thus, we hypothesize that 670nm light treatment will diminish oxidative stress preventing downstream inflammatory mechanisms associated with DR initiated by Muller cells. In this study, we used an in vitro model system of rat Müller glial cells grown under normal (5 mM) or high (25 mM) glucose conditions and treated with a 670 nm light emitting diode array (LED) (4.5 J/cm2) or no light (sham) daily. We report that a single 670 nm light treatment diminished reactive oxygen species (ROS) production and preserved mitochondrial integrity in this in vitro model of early DR. Furthermore, treatment for 3 days in culture reduced NFκB activity to levels observed in normal glucose and prevented the subsequent increase in ICAM-1. The ability of 670nm light treatment to prevent early molecular changes in this in vitro high glucose model system suggests light treatment could mitigate early deleterious effects modulating inflammatory signaling and diminishing oxidative stress.

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Metabolic Imbalance Effect on Retinal Müller Glial Cells Reprogramming Capacity: Involvement of Histone Deacetylase SIRT6

Frontiers in Genetics ◽

10.3389/fgene.2021.769723 ◽

2021 ◽

Vol 12 ◽

Author(s):

L Francisco Sanhueza Salas ◽

Alfredo García-Venzor ◽

Natalia Beltramone ◽

Claudia Capurro ◽

Debra Toiber ◽

...

Keyword(s):

Oxidative Stress ◽

Histone Deacetylase ◽

Glial Cells ◽

High Glucose ◽

Müller Cells ◽

Enrichment Analysis ◽

Regulatory Elements ◽

Muller Cells ◽

Müller Glial Cells ◽

And Oxidative Stress

Retinal Müller glial cells (MGs) are among the first to demonstrate metabolic changes during retinal disease and are a potential source of regenerative cells. In response to a harmful stimulus, they can dedifferentiate acquiring neural stem cells properties, proliferate and migrate to the damaged retinal layer and differentiate into lost neurons. However, it is not yet known how this reprogramming process is regulated in mammals. Since glucose and oxygen are important regulatory elements that may help directing stem cell fate, we aimed to study the effect of glucose variations and oxidative stress in Müller cells reprogramming capacity and analyze the participation the histone deacetylase SIRT6, as an epigenetic modulator of this process. We found that the combination of high glucose and oxidative stress induced a decrease in the levels of the marker glutamine synthetase, and an increase in the migration capacity of the cells suggesting that these experimental conditions could induce some degree of dedifferentiation and favor the migration ability. High glucose induced an increase in the levels of the pluripotent factor SOX9 and a decrease in SIRT6 levels accompanied by the increase in the acetylation levels of H3K9. Inhibiting SIRT6 expression by siRNA rendered an increase in SOX9 levels. We also determined SOX9 levels in retinas from mice with a conditional deletion of SIRT6 in the CNS. To further understand the mechanisms that regulate MGs response under metabolic impaired conditions, we evaluated the gene expression profile and performed Gene Ontology enrichment analysis of Müller cells from a murine model of Diabetes. We found several differentially expressed genes and observed that the transcriptomic change involved the enrichment of genes associated with glucose metabolism, cell migration, development and pluripotency. We found that many functional categories affected in cells of diabetic animals were directly related to SIRT6 function. Transcription factors enrichment analysis allowed us to predict several factors, including SOX9, that may be involved in the modulation of the differential expression program observed in diabetic MGs. Our results underline the heterogeneity of Müller cells response and the challenge that the study of metabolic impairment in vivo represents.

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Epo inhibits the fibrosis and migration of Müller glial cells induced by TGF-β and high glucose

Graefe s Archive for Clinical and Experimental Ophthalmology ◽

10.1007/s00417-016-3290-5 ◽

2016 ◽

Vol 254 (5) ◽

pp. 881-890 ◽

Cited By ~ 9

Author(s):

Wentao Luo ◽

Liumei Hu ◽

Weiye Li ◽

Guotong Xu ◽

Linxinyu Xu ◽

...

Keyword(s):

Glial Cells ◽

High Glucose ◽

Müller Glial Cells ◽

And Migration

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High glucose treatment promotes extracellular matrix proteome remodeling in Müller glial cells

PeerJ ◽

10.7717/peerj.11316 ◽

2021 ◽

Vol 9 ◽

pp. e11316

Author(s):

Sandra Sagmeister ◽

Juliane Merl-Pham ◽

Agnese Petrera ◽

Cornelia A. Deeg ◽

Stefanie M. Hauck

Keyword(s):

Extracellular Matrix ◽

Glial Cells ◽

High Glucose ◽

Current Knowledge ◽

Explant Culture ◽

Cell Swelling ◽

Short Term ◽

Müller Glial Cells ◽

Glucose Treatment

Background The underlying pathomechanisms in diabetic retinopathy (DR) remain incompletely understood. The aim of this study was to add to the current knowledge about the particular role of retinal Müller glial cells (RMG) in the initial processes of DR. Methods Applying a quantitative proteomic workflow, we investigated changes of primary porcine RMG under short term high glucose treatment as well as glycolysis inhibition treatment. Results We revealed significant changes in RMG proteome primarily in proteins building the extracellular matrix (ECM) indicating fundamental remodeling processes of ECM as novel rapid response to high glucose treatment. Among others, Osteopontin (SPP1) as well as its interacting integrins were significantly downregulated and organotypic retinal explant culture confirmed the selective loss of SPP1 in RMG upon treatment. Since SPP1 in the retina has been described neuroprotective for photoreceptors and functions against experimentally induced cell swelling, it’s rapid loss under diabetic conditions may point to a direct involvement of RMG to the early neurodegenerative processes driving DR. Data are available via ProteomeXchange with identifier PXD015879.

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