Inducible and Inhibitory Organelles in Neurodegeneration DOJINDO LABORATORIES

Previous Science Note

In neurodegeneration, dysfunctional mitochondria contribute to oxidative stress and energy deficits in neurons. Lysosomes, responsible for the disposal of cellular waste, may be impaired, leading to the accumulation of damaged organelles, including mitochondria. At the same time, abnormal lipid metabolism and accumulation of lipid droplets have been implicated in neurodegenerative diseases, potentially exacerbating neuronal dysfunction and contributing to disease progression. The intricate relationships between dysfunctional mitochondria, impaired lysosomal function and abnormal lipid metabolism underscore the complex pathophysiology of neurodegeneration.

Messenger RNA transport on lysosomal vesicles maintains axonal mitochondrial homeostasis and prevents axonal degeneration
Click here for the original article: Raffaella De Pace, et. al., Nature Neuroscience, 2024.

Point of Interest

- Lysosome–kinesin adaptor related complex (BORC) KO depletes axonal mRNAs mainly encoding ribosomal and mitochondrial/oxidative phosphorylation proteins.

- This depletion leads to mitochondrial defects and ultimately to axonal degeneration in neurons.

- A mechanistic connection of BORC deficiency may accelerate common neurodegenerative disorders.

APOE4/4 is linked to damaging lipid droplets in Alzheimer’s disease microglia
Click here for the original article: Michael S. Haney,et. al., Nature, 2024.

Point of Interest

- Lipid droplet-associated enzyme ACSL1-positive microglia was most abundant in patients with AD having the APOE4/4 genotype.

- In microglia, fibrillar Aβ induces ACSL1 expression, triglyceride synthesis and lipid droplet accumulation depending on APOE.

- Conditioned media from lipid droplet-containing microglia lead to Tau phosphorylation and neurotoxicity depending on APOE in neurons.

Loss of WIPI4 in neurodegeneration causes autophagy-independent ferroptosis
Click here for the original article: Ye Zhu, et. al., Nature Cell Biology, 2024.
Point of Interest

- WIPI4 deficiency causes β-Propeller protein-associated neurodegeneration, which induces ferroptosis via an autophagy-independent mechanism in cell culture and in zebrafish.

- WIPI4 depletion increases the localization of ATG2A at ER-mitochondrial contact sites, which enhances phosphatidylserine import into mitochondria.

- This leads to increased mitochondrial synthesis of phosphatidylethanolamine, a major lipid prone to peroxidation and ultimately to ferroptosis.

Related Techniques

Mitochondrial or internal lipid peroxide detection

MitoPeDPP, Liperfluo

Mitochondrial or internal iron detection

Mito-FerroGreen, FerroOrange

Mitophagy or autophagy detection

Mitophagy Detection Kit, Autophagic Flux Assay Kit

Glycolysis/Oxidative phosphorylation Assay

Extracellular OCR Plate Assay Kit, Glycolysis/OXPHOS Assay Kit

Lipid droplets detection

Lipi-Blue/Green/Red/Deep Red

Lysosome staining

pH-dependent (pHLys Red) and pH resistance (LysoPrime Green/Deep Red) probes

Lysosomal acidic pH detection

Lysosoml Acidic pH Detection Kit-Green/Red and Green/Deep Red

Related Applications

The simultaneous detection of lysosomal function with Mitochondrial ROS and intracellular Fe²⁺

Lysosomal Function and Iron Homeostasis

Recent reports suggest that lysosomal neutralization can result in iron depletion, consequently leading to the disruption of cell viability. To verify this, HeLa cells were labeled with FerroOrange for Fe²⁺ detection, and the lysosomal mass and pH were separately detected with LysoPrime DeepRed and pHLys Green (a product currently under development). Co-staining with FerroOrange and Lysosomal dyes demonstrated that Bafilomycin A1 (Baf. A1), an inhibitor of lysosomal acidification, causes iron depletion consistent with the findings reported in the article. Interestingly, the iron chelator, Deferiprone (DFP), did not impact lysosomal pH, suggesting that lysosomal function plays a key role in managing iron homeostasis.

Reference: Ross A Weber, et. al., Mol Cell (2020)

Products in Use
- FerroOrange
- pHLys Green*
- LysoPrime Deep Red

*pHLys Green is included as a component of the "Lysosomal Acidic pH Detection Kit-Green/Deep Red".

Lysosomal Function and Mitochondrial ROS

CCCP and Antimycin are recognized inducers of mitochondrial ROS, linked to the loss of mitochondrial membrane potential. Recent studies have shown that CCCP induces not only mitochondrial ROS but also lysosomal dysfunction. To observe mitochondrial ROS, HeLa cells were labeled with MitoBright ROS Deep Red for Mitochondrial Superoxide Detection, and the lysosomal mass and pH were independently detected with LysoPrime Green and pHLys Red. Co-staining with MitoBright ROS and Lysosomal dyes revealed that CCCP, unlike Antimycin, triggers concurrent lysosomal neutralization and mitochondrial ROS induction.

Reference: Benjamin S Padman, et. al., Autophagy (2013)

Products in Use
- LysoPrime Green
- pHLys Red
- Lysosomal Acidic pH Detection Kit
- MitoBright ROS Deep Red - Mitochondrial Superoxide Detection

Related Products
- Mitophagy Detection Kit and Mtphagy Dye