Modulation of mTOR Within Retinal Pigment Epithelium Affects Cell Viability and Mitochondrial Pathology

Area of Science:

• Cell Biology
• Ophthalmology
• Biochemistry

Background:

• Mitochondrial integrity is crucial for retinal pigment epithelium (RPE) health.
• Dysfunctional mitochondria are implicated in age-related macular degeneration (AMD).
• The mechanistic target of rapamycin (mTOR) pathway influences mitochondrial health and AMD pathogenesis.

Purpose of the Study:

• To investigate the impact of mTOR modulation on RPE cell mitochondrial status.
• To explore the therapeutic potential of mTOR inhibitors in preventing RPE degeneration.

Main Methods:

• Light and electron microscopy were used to assess RPE mitochondrial morphology.
• MitoTracker dyes and mitochondrial immunohistochemistry quantified mitochondrial mass and integrity.
• In situ mitochondrial morphometry and autophagy/mTOR activity assays were performed.
• Compounds like 3-methyladenine (3-MA), curcumin, and rapamycin were administered to modulate mTOR.

Main Results:

• 3-MA activated mTOR, causing RPE cell death, increased membrane permeability, and altered ZO-1 expression.
• 3-MA treatment reduced healthy mitochondria, increased damaged mitochondria, and affected key mitochondrial proteins (Tomm20, Pink1, Parkin).
• Curcumin and rapamycin counteracted mTOR activation, preserved mitochondrial status, prevented RPE cell loss, and maintained ZO-1 expression.

Conclusions:

• mTOR pathway activation is detrimental to RPE mitochondrial health and integrity.
• Inhibition of mTOR by curcumin and rapamycin offers a protective strategy against RPE degeneration.
• Targeting mTOR may be a viable therapeutic approach for mitochondrial dysfunction in retinal diseases like AMD.