Related Experiment Video
Updated: Jul 9, 2025
Determination of Mitochondrial Respiration and Glycolysis in Ex Vivo Retinal Tissue Samples
Published on: August 4, 2021
In vivo measurement of mitochondrial ROS production in mouse models of photoreceptor degeneration
Katja E Menger1, Angela Logan2, Ulrich F O Luhmann1
1UCL Institute of Ophthalmology, Bath St, London, EC1V 9EL, UK.
Abstract:
Retinitis pigmentosa (RP) is a disease characterised by photoreceptor cell death. It can be initiated by mutations in a number of different genes, primarily affecting rods, which will die first, resulting in loss of night vision. The secondary death of cones then leads to loss of visual acuity and blindness. We set out to investigate whether increased mitochondrial reactive oxygen species (ROS) formation, plays a role in this sequential photoreceptor degeneration. To do this we measured mitochondrial H2O2 production within mouse eyes in vivo using the mass spectrometric probe MitoB. We found higher levels of mitochondrial ROS that preceded photoreceptor loss in four mouse models of RP: Pde6b; Prhp2; RPGR; Cln6. In contrast, there was no increase in mitochondrial ROS in loss of function models of vision loss (GNAT, OGC), or where vision loss was not due to photoreceptor death (Cln3). Upregulation of Nrf2 transcriptional activity with dimethylfumarate (DMF) lowered mitochondrial ROS in RPGR mice. These findings have important implications for the mechanism and treatment of RP.
Insights
Mitochondrial reactive oxygen species (ROS) increase before photoreceptor death in many forms of retinitis pigmentosa (RP). Lowering ROS with dimethylfumarate may offer a new treatment for RP.
Area of Science:
- Ophthalmology
- Genetics
- Cell Biology
Background:
- Retinitis pigmentosa (RP) causes progressive photoreceptor cell death, leading to vision loss and blindness.
- RP is genetically heterogeneous, with mutations primarily affecting rod cells first, followed by cone cells.
- The precise mechanisms driving sequential photoreceptor degeneration in RP remain incompletely understood.
Purpose of the Study:
- To investigate the role of mitochondrial reactive oxygen species (ROS) in the pathogenesis of retinitis pigmentosa (RP).
- To determine if elevated mitochondrial ROS levels precede photoreceptor cell death in various RP mouse models.
- To explore potential therapeutic interventions targeting mitochondrial ROS in RP.
Main Methods:
- Measurement of mitochondrial hydrogen peroxide (H2O2) production in mouse eyes using the MitoB mass spectrometric probe.
- In vivo assessment of mitochondrial ROS levels in four distinct mouse models of RP (Pde6b, Prhp2, RPGR, Cln6).
- Evaluation of mitochondrial ROS in control and non-RP vision loss models (GNAT, OGC, Cln3).
- Assessment of Nrf2 transcriptional activity modulation using dimethylfumarate (DMF) in RPGR mice.
Main Results:
- Increased mitochondrial ROS levels were observed preceding photoreceptor loss in Pde6b, Prhp2, RPGR, and Cln6 mouse models of RP.
- No significant increase in mitochondrial ROS was detected in GNAT and OGC loss-of-function models or the Cln3 model where vision loss is not due to photoreceptor death.
- Upregulation of Nrf2 activity with DMF treatment successfully reduced mitochondrial ROS levels in RPGR mice.
Conclusions:
- Elevated mitochondrial ROS formation is a key factor in the sequential photoreceptor degeneration observed in multiple forms of retinitis pigmentosa.
- Targeting mitochondrial ROS, potentially through Nrf2 activation, represents a promising therapeutic strategy for retinitis pigmentosa.
- These findings provide critical insights into the molecular mechanisms underlying RP and suggest new avenues for treatment development.
