Mitofusin 2 Shapes Circadian Rhythms via SCN VIP Neurons
Publication Title: Mitofusin 2 controls mitochondrial and synaptic dynamics of suprachiasmatic VIP neurons and related circadian rhythms
Summary
- Question
- This study examined the role of mitofusin 2 (Mfn2), a protein responsible for mitochondrial fusion, in regulating circadian rhythms through its effects on suprachiasmatic nucleus (SCN) vasoactive intestinal peptide (VIP) neurons. The researchers aimed to understand how mitochondrial dynamics in VIP neurons influence the synchronization of biological rhythms, including sleep-wake cycles, locomotor activity, and core body temperature.
- Why it Matters
- Circadian rhythms, which are biological processes that follow a roughly 24-hour cycle, are essential for maintaining health and coordinating sleep, metabolism, and body temperature with environmental light-dark cues. Disruptions in these rhythms are linked to various conditions, such as sleep disorders, metabolic syndromes, and age-related neurodegenerative diseases. This research highlights the critical role of mitochondrial dynamics in SCN VIP neurons in sustaining these rhythms, offering insights into mechanisms that could be targeted for therapeutic interventions in circadian-related disorders.
- Methods
- The researchers used genetically modified mice with VIP neurons lacking Mfn2 to study its effects on mitochondrial and synaptic dynamics. Behavioral and physiological data were collected, including wheel-running activity, body temperature measurements, and sleep-wake patterns. The study also included microscopic analysis of neuronal structures and electrophysiological recordings to assess synaptic function and neuronal activity.
- Key Findings
- Mfn2 deficiency in VIP neurons disrupted the normal oscillations of mitochondrial and synaptic organization, leading to desynchronization of circadian rhythms. Mfn2-deficient mice showed altered activity onset, advanced phase shifts in locomotor rhythms, and irregular sleep-wake patterns, particularly during transitions between light and dark phases. Additionally, these mice exhibited impaired core body temperature regulation and reduced mitochondrial adaptability in VIP neurons.
- Implications
- The findings suggest that proper mitochondrial dynamics in SCN VIP neurons are essential for maintaining synchronized biological rhythms. Disruptions in mitochondrial function may contribute to circadian rhythm disorders, highlighting potential therapeutic targets for conditions like sleep disturbances, metabolic dysregulation, and age-related neurodegenerative diseases. This study also underscores the broader importance of mitochondrial health in circadian regulation.
- Next Steps
Future research should explore how Mfn2-regulated mitochondrial dynamics interact with other cellular processes in SCN neurons. Additionally, investigations into how mitochondrial dysfunction affects circadian rhythms in aging and neurodegenerative diseases could provide further therapeutic insights.
- Funding Information
- This research was supported by the National Institutes of Health (awards DK120891, DK126447, AG067329, AG051459, AG082190, DK127800, DK132647, DK090625, and AG065988). Additional funding was provided by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (PID2021-125193OA-I00), the Fondo Europeo de Desarrollo Regional, and the Ministerio de Ciencia e Innovación/Contrato Ramón y Cajal (RYC2022-038155-I). Yale University also provided funding and support for this research.
Full Citation
Stoiljkovic M, Song J, Hong H, Endle H, Varela L, Gao X, Liu Z, Sotonyi P, Diano S, Cedernaes J, Bass J, Horvath T. Mitofusin 2 controls mitochondrial and synaptic dynamics of suprachiasmatic VIP neurons and related circadian rhythms. Journal Of Clinical Investigation 2025, 135: e185000. PMID: 40590229, PMCID: PMC12208536, DOI: 10.1172/jci185000.
This AI-assisted summary has been reviewed and approved by at least one of the study's authors to ensure it accurately reflects the research.
Authors
Milan Stoiljkovic, MD, PhD
First AuthorAssociate Professor Adjunct
Tamas Horvath, DVM, PhD
Last AuthorJean and David W. Wallace Professor of Comparative Medicine and Professor of Neuroscience and of Obstetrics, Gynecology, and Reproductive Sciences