Oxidative Stress and Hypoxia Modify Mitochondrial Homeostasis During Glaucoma.
glaucoma; oxidative stress; hypoxia; glycolysis; HIF-1α; PGC-1α
Aims: Cellular response to hypoxia can include transition from respiration to glycolysis via upregulation of glycolytic enzymes and transporters, as well as mitophagy induction to eliminate surplus mitochondria. Our purpose was to evaluate the impact of hypoxia-inducible factor-1α (HIF-1α) stabilization on mitochondrial homeostasis and oxidative stress in a chronic model of glaucoma. Results: Retina and optic nerve (ON) were evaluated from young and aged DBA/2J (D2) glaucoma model mice and the control strain, the DBA/2- Gpnmb + . Hypoxic retinal ganglion cells (RGCs) were observed in young and aged D2 retina, with a significant increase in HIF-1α protein in the aged D2 retina. Reactive oxygen species observed in young D2 retina and ON were followed by significant decreases in antioxidant capacity in aged D2 retina and ON. HIF-1α targets such as neuron-specific glucose transporter-3 and lactate dehydrogenase were decreased or unchanged, respectively, in aged D2 retina despite an increased hypoxia response in RGCs. Mitochondrial mass was decreased in aged D2 retina concomitant with decreased mitochondrially encoded electron transport chain transcripts despite a stable nuclear-encoded TFAM (mitochondrial transcription factor), suggesting a breakdown in the nuclear-mitochondrial communication. Decreased mitophagy-associated proteins p62 and Rheb were observed in aged D2 retina, although p62 was significantly increased in the aged D2 ON. Innovation and Conclusion: The increased reactive oxygen species concomitant with HIF-1α upregulation despite reduced glucose transporters, mis-match of nuclear- and mitochondrial-encoded transcripts, and signs of reduced mitophagy suggest that retinas from D2 mice with chronic intraocular pressure elevation transition to pseudohypoxia without consistent metabolic reprogramming before significant RGC loss.
Jassim AH; Fan Y; Pappenhagen N; Nsiah NY; Inman DM
Antioxidants & Redox Signaling
2021
2021-04-29
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1089/ars.2020.8180" target="_blank" rel="noreferrer noopener">10.1089/ars.2020.8180</a>
A new LC-MS/MS technique for separation of gangliosides using a phenyl-hexyl column: Systematic separation according to sialic acid class and ceramide subclass
mass spectrometry; Gangliosides; HPLC-MS; LC-MS; MS; phenyl-hexyl column
A LC-MS/MS technique separated the bovine and mouse brain gangliosides monosialotetrahexosylgangliosides (GM1), disialotetrahexosylgangliosides (GD1a), trisialotetrahexosylgangliosides (GT1b) and tetrasialotetrahexosylgangliosides (GQ1b) using a phenyl-hexyl HPLC column and employing a linear methanol gradient in water, which is 0.028% in ammonium hydroxide. The gangliosides were separated according to sialic acid class, and within a particular class, gangliosides having different ceramide carbon chain lengths were also separated. All gangliosides of a particular sialic acid class eluted in characteristic retention time windows in the order of GQ1b, (earliest), GT1b, GD1a, and GM1 (latest). Within each specific retention time window for a particular ganglioside class, gangliosides were separated in the order of increasing ceramide carbon chain length. The phenyl-hexyl column separation of gangliosides is advantageous over established hydrophilic interaction and conventional reversed-phase chromatography techniques, in that the former separates gangliosides according to sialic acid class but not ceramide composition and the latter distributes all the sialic acid ganglioside classes throughout the entire chromatogram. The mechanism of separation of the ganglioside sialic acid classes is proposed to be a pi-electron repulsion of negatively-charged gangliosides by the column phenyl moiety.
Gobburi ALP; Kipruto EW; Inman DM; Anderson DJ
Journal Of Liquid Chromatography & Related Technologies
2021
2021-01-20
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1080/10826076.2020.1856136" target="_blank" rel="noreferrer noopener">10.1080/10826076.2020.1856136</a>
Transcorneal electrical stimulation reduces neurodegenerative process in a mouse model of glaucoma.
Glaucoma; Optic nerve; BDNF; Retina; p75NTR; Transcorneal electrical stimulation
Glaucoma is a neurodegenerative disease in which the retinal ganglion cell axons of the optic nerve degenerate concomitant with synaptic changes in the retina, leading finally to death of the retinal ganglion cells (RGCs). Electrical stimulation has been used to improve neural regeneration in a variety of systems, including in diseases of the retina. Therefore, the focus of this study was to investigate whether transcorneal electrical stimulation (TES) in the DBA2/J mouse model of glaucoma could improve retinal or optic nerve pathology and serve as a minimally invasive treatment option. Mice (10 months-old) received 21 sessions of TES over 8 weeks, after which we evaluated RGC number, axon number, and anterograde axonal transport using histology and immunohistochemistry. To gain insight into the mechanism of proposed protection, we also evaluated inflammation by quantifying CD3 + T-cells and Iba1 + microglia; perturbations in metabolism were shown via the ratio pAMPK to AMPK, and changes in trophic support were tested using protein capillary electrophoresis. We found that TES resulted in RGC axon protection, a reduction in inflammatory cells and their activation, improved energy homeostasis, and a reduction of the cell death-associated p75NTR. Collectively, the data indicated that TES maintained axons, decreased inflammation, and increased trophic factor support, in the form of receptor presence and energy homeostasis, suggesting that electrical stimulation impacts several facets of the neurodegenerative process in glaucoma.
Jassim, AH;Cavanaugh M;Shah JS;Willits R;Inman DM
Annals Of Biomedical Engineering
2020
2020-09-24
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1007/s10439-020-02608-8" target="_blank" rel="noreferrer noopener">10.1007/s10439-020-02608-8</a>