MARCH5 (Membrane Associated Ring-CH-Type Finger 5, also known as MARCHF5 or MITOL) encodes a mitochondrial outer membrane E3 ubiquitin ligase that plays critical roles in mitochondrial quality control, dynamics, and innate immune signaling. MARCH5 ubiquitinates misfolded proteins on the mitochondrial surface, regulates mitochondrial fission by targeting DRP1 and MFN1/2, and controls MAVS-dependent antiviral signaling. In the context of neurodegeneration, MARCH5 is essential for clearing aggregation-prone proteins that accumulate on mitochondria, and its dysfunction contributes to mitochondrial fragmentation and neuronal death in Parkinson's disease and Alzheimer's disease.
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| Full Name | Membrane Associated Ring-CH-Type Finger 5 |
| Gene Symbol | MARCH5 (MARCHF5, MITOL) |
| Chromosomal Location | 10q23.33 |
| NCBI Gene ID | [54708](https://www.ncbi.nlm.nih.gov/gene/54708) |
| Ensembl ID | [ENSG00000148627](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000148627) |
| UniProt ID | [Q9NX47](https://www.uniprot.org/uniprot/Q9NX47) |
| Protein | [MARCH5 Protein](/proteins/march5-protein) |
| Associated Diseases | [PD](/diseases/parkinsons-disease), [AD](/diseases/alzheimers-disease), [ALS](/diseases/amyotrophic-lateral-sclerosis) |
MARCH5 is the primary E3 ubiquitin ligase for outer mitochondrial membrane (OMM) protein quality control:
- Ubiquitinates misfolded or damaged OMM proteins, targeting them for proteasomal degradation (mitochondria-associated degradation, MAD)
- Substrates include mislocalized tail-anchored proteins, oxidatively damaged membrane proteins, and aggregation-prone substrates
- Works with the AAA-ATPase VCP/p97 to extract ubiquitinated OMM proteins for proteasomal degradation
MARCH5 regulates the balance between mitochondrial fission and fusion:
- Fission: Ubiquitinates DRP1 (Dynamin-related protein 1) to modulate its activity and turnover at mitochondrial fission sites
- Fusion: Ubiquitinates and regulates turnover of MFN1 and MFN2 (Mitofusins) on the OMM
- Net effect: MARCH5 loss causes excessive mitochondrial fragmentation due to uncontrolled DRP1 accumulation and reduced fusogenic capacity
MARCH5 ubiquitinates MAVS (mitochondrial antiviral signaling protein) to terminate RIG-I-mediated antiviral signaling:
- K48-linked ubiquitination of MAVS targets it for proteasomal degradation
- This prevents chronic type I interferon production from mitochondrial damage
- Relevant to neuroinflammation: MARCH5 deficiency prolongs MAVS-dependent IFN-β signaling, contributing to sterile inflammation
MARCH5 ubiquitinates disease-associated proteins that accumulate on mitochondria:
- Expanded polyQ huntingtin fragments that associate with the OMM
- Mutant SOD1 aggregates on mitochondria in ALS
- α-Synuclein fragments imported into mitochondria
- MARCH5 cooperates with PINK1/Parkin in mitophagy: MARCH5 performs initial ubiquitination of OMM proteins on damaged mitochondria, while Parkin amplifies the ubiquitin signal
- MARCH5 loss impairs mitophagy initiation, leading to accumulation of dysfunctional mitochondria in dopaminergic neurons
- α-Synuclein overexpression reduces MARCH5 levels in neuronal cells, creating a feed-forward mitochondrial dysfunction loop
- MARCH5 ubiquitinates mutant LRRK2 (G2019S) on mitochondria, promoting its clearance
- Amyloid-beta oligomers localize to mitochondrial membranes; MARCH5 helps clear Aβ-associated mitochondrial damage
- MARCH5 expression is reduced in AD hippocampal neurons, correlating with mitochondrial fragmentation
- MARCH5 deficiency exacerbates tau-induced mitochondrial dysfunction through DRP1 dysregulation
- MARCH5 overexpression rescues Aβ-induced mitochondrial morphology defects in neuronal cultures
- Mutant SOD1 (G93A, A4V) misfolds and accumulates on the OMM; MARCH5 ubiquitinates misfolded SOD1 for proteasomal clearance
- MARCH5 depletion in motor neurons accelerates mutant SOD1 aggregation and cell death
- TDP-43 C-terminal fragments also accumulate on mitochondria and are MARCH5 substrates
- Mutant HTT polyQ fragments associate with mitochondria and impair function
- MARCH5 ubiquitinates mutant HTT fragments on the OMM, promoting their degradation
- MARCH5 overexpression reduces mitochondria-associated polyQ aggregation in HD models
- Neurons: Moderate expression; essential for neuronal mitochondrial quality control
- Brain regions: Enriched in substantia nigra, hippocampus, and cortex — regions with high mitochondrial metabolic demand
- Heart and muscle: High expression; critical for cardiac mitochondrial homeostasis
- Microglia: Low-moderate expression
- MARCH5 upregulation: Gene therapy or small molecule MARCH5 inducers could enhance mitochondrial protein quality control
- Substrate-specific approaches: Enhancing MARCH5 activity toward disease-specific substrates (mutant SOD1, α-synuclein, Aβ-associated damage)
- Combination with mitophagy enhancers: MARCH5 + PINK1/Parkin activation for synergistic mitochondrial clearance
- USP30 inhibition: The deubiquitinase USP30 opposes MARCH5/Parkin-mediated ubiquitination; USP30 inhibitors enhance mitochondrial quality control