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MAM-Localized MANF Counteracts Microinflammatory Stress to Attenuate Mitochondrial Dysfunction and Cataractogenesis
Xin Liu1,2,3,4, Hao Li1,5, Ching Kang1,2,3,4
1Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China.
Abstract:
Chronic microinflammation drives tissue degeneration, particularly in age-related and metabolic diseases, yet how it disrupts inter-organelle communication that leads to cellular failure remains largely unexplored. Utilizing highly myopic cataract (HMC) as a paradigm, we uncover a non-canonical defense mechanism centered on mitochondria-associated endoplasmic reticulum membranes (MAMs). Under microinflammatory stress, mesencephalic astrocyte-derived neurotrophic factor (MANF), conventionally recognized as an ER-resident protein, specifically localizes to MAMs in lens epithelial cells (LECs). At this critical interface, MANF acts as a metabolic sensor that safeguards calcium homeostasis by directly promoting the ubiquitin-mediated degradation of the sarco/endoplasmic reticulum Ca2 +-ATPase 2 (SERCA2). Microinflammation-induced MANF deficiency triggers pathological SERCA2 accumulation, MAM hyperassembly, disrupted ER-to-mitochondria calcium coupling, profound oxidative stress, and mitochondrial bioenergetic collapse, culminating in LEC apoptosis. We validate this pathogenic cascade using human HMC specimens, a unilateral defocus-induced high myopia model, and a novel lens-specific Manf conditional knockdown mouse. Strikingly, in vivo AAV2-mediated MANF gene delivery successfully normalizes MAM architecture, rescues mitochondrial function, and prevents cataractogenesis, demonstrating therapeutic reversibility. In summary, this study establishes the MANF-SERCA2 axis at the MAM interface as a critical pathway linking microinflammation to organelle dysfunction and proposes this interaction as a promising therapeutic target for cataractogenesis and other microinflammation-driven degenerations.
Insights
Chronic microinflammation causes cellular failure via disrupted organelle communication. A novel defense mechanism involving MANF protein at mitochondria-associated ER membranes (MAMs) protects against this, offering a therapeutic target for diseases like cataracts.
Area of Science:
- Cell Biology
- Ophthalmology
- Neuroscience
Background:
- Chronic microinflammation contributes to tissue degeneration in aging and metabolic diseases.
- Disruption of inter-organelle communication is a key factor in cellular failure.
- The role of microinflammation in disrupting organelle communication remains largely unexplored.
Purpose of the Study:
- To investigate the role of mitochondria-associated endoplasmic reticulum membranes (MAMs) in cellular defense against microinflammation.
- To identify novel mechanisms linking microinflammation to organelle dysfunction and cellular failure.
- To explore therapeutic strategies for microinflammation-driven diseases, using highly myopic cataract (HMC) as a model.
Main Methods:
- Utilized highly myopic cataract (HMC) as a model system.
- Investigated the localization and function of mesencephalic astrocyte-derived neurotrophic factor (MANF) at MAMs in lens epithelial cells (LECs).
- Examined the impact of microinflammation-induced MANF deficiency on calcium homeostasis, MAM structure, oxidative stress, and mitochondrial function.
- Validated findings in human HMC specimens, a myopia model, and a lens-specific Manf conditional knockdown mouse.
- Assessed the therapeutic potential of AAV2-mediated MANF gene delivery in vivo.
Main Results:
- MANF specifically localizes to MAMs under microinflammatory stress, acting as a metabolic sensor.
- MANF promotes the degradation of SERCA2, safeguarding calcium homeostasis.
- MANF deficiency leads to SERCA2 accumulation, MAM hyperassembly, disrupted calcium coupling, oxidative stress, and mitochondrial dysfunction.
- MANF gene delivery successfully normalized MAMs, rescued mitochondrial function, and prevented cataractogenesis in vivo.
- Established the MANF-SERCA2 axis at the MAM interface as a critical pathway linking microinflammation to organelle dysfunction.
Conclusions:
- The MANF-SERCA2 axis at MAMs is a critical pathway in microinflammation-induced cellular degeneration.
- MANF plays a crucial role in maintaining organelle communication and function under stress.
- Targeting the MANF-SERCA2 interaction at MAMs presents a promising therapeutic strategy for cataracts and other microinflammation-driven diseases.
