# DNM1L Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- The *DNM1L* gene encodes dynamin-related protein 1 (DRP1), a GTPase essential for mitochondrial and peroxisomal fission, a process critical for cellular metabolism, apoptosis, and organelle quality control.
- Pathogenic variants in *DNM1L* lead to a spectrum of severe neurodevelopmental disorders, including encephalopathy, intractable epilepsy, and optic neuropathy, often presenting in infancy or childhood.
- DRP1 function is tightly regulated by post-translational modifications such as phosphorylation (e.g., Ser616, Ser637) and ubiquitination, which modulate its recruitment to and activity at organelle membranes.
- Small-molecule inhibitors like Mdivi-1 target DRP1 GTPase activity, showing therapeutic potential in preclinical models of neurodegeneration, ischemia-reperfusion injury, and various cancers by modulating mitochondrial dynamics.
- Dysregulation of DRP1 is implicated in numerous pathologies beyond neurodevelopmental disorders, including dilated cardiomyopathy, Parkinson's disease susceptibility, and multiple cancer types, highlighting its broad clinical significance.

---

## Executive Summary & Key Metadata

The *DNM1L* (Dynamin-1-Like) gene encodes dynamin-related protein 1 (DRP1), a large GTPase that serves as the master regulator of mitochondrial and peroxisomal fission. DRP1 is a cytosolic protein that is recruited to the outer mitochondrial membrane (OMM) where it oligomerizes into helical structures that constrict and sever the organelle in a GTP-hydrolysis-dependent manner. Beyond its canonical role in organelle division, DRP1 is now recognized as a central hub integrating cellular metabolism, apoptosis, calcium signaling, cell cycle progression, and immune responses. Pathogenic variants in *DNM1L* produce a spectrum of severe neurodevelopmental, epileptic, and neurodegenerative phenotypes, while dysregulated DRP1 expression is implicated in oncogenesis, cardiomyopathy, and metabolic disease.

| **Attribute** | **Detail** |
|---|---|
| **HGNC Symbol** | DNM1L |
| **UniProt Accession** | O00429 |
| **Representative PDB ID** | 4H1V (human DRP1 GMP-PCP-bound tetramer); 5WP9 (nucleotide-free dimer) |
| **Chromosomal Locus** | 12p11.21 |
| **Primary Molecular Function** | GTP-dependent mitochondrial and peroxisomal fission; regulation of mitochondrial dynamics, cristae morphology, and mitophagy |
| **Disease & Pathology Associations** | Encephalopathy due to defective mitochondrial and peroxisomal fission 1 (EMPF1, MIM #614388); dominant optic atrophy; dilated cardiomyopathy; Parkinson's disease susceptibility; multiple cancer types (hepatocellular, breast, lung, gastric, pancreatic, renal) |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Gene Structure

The *DNM1L* gene is located on the short arm of chromosome 12 at band 11.21 (12p11.21), spanning approximately 70 kilobases of genomic DNA. The gene is oriented on the minus strand (reverse orientation) and comprises 21 coding exons that produce a primary transcript of ~3.5 kb. The genomic coordinates (GRCh38/hg38) are chr12:32,679,301–32,749,582. The locus is gene-dense, with the *DDX11* (DEAD/H-box helicase 11) gene located in close proximity; both genes have been implicated in systemic lupus erythematosus susceptibility through expression quantitative trait loci (eQTL) analyses [1].

### 1.2 Promoter Architecture and Transcriptional Regulation

The *DNM1L* promoter region lacks a canonical TATA box but contains multiple GC-rich elements and CpG islands characteristic of constitutively expressed housekeeping genes. However, expression is tightly regulated in a cell-type- and context-dependent manner. Several transcription factor binding sites have been experimentally validated:

- **E2F1**: Directly binds the *DNM1L* promoter and drives transcription during the G1/S transition of the cell cycle, linking mitochondrial fission to proliferation.
- **p53**: Represses *DNM1L* transcription under conditions of genotoxic stress, providing a mechanism for apoptosis sensitization.
- **c-Myc**: Enhances *DNM1L* expression in transformed cells, contributing to the metabolic reprogramming of cancer.
- **ELK3**: A member of the ETS transcription factor family that regulates *DNM1L* expression in triple-negative breast cancer cells, where it modulates chemosensitivity to cisplatin by controlling mitochondrial dynamics [2].
- **CARM1**: The coactivator-associated arginine methyltransferase 1 promotes *DNM1L* expression through epigenetic mechanisms, driving mitochondrial fission during cellular senescence [3].

### 1.3 Enhancer Elements and Chromatin Architecture

Chromatin immunoprecipitation followed by sequencing (ChIP-seq) data from the ENCODE project reveal multiple enhancer-associated histone marks (H3K27ac, H3K4me1) in intronic regions of *DNM1L*, particularly within introns 2 and 15. These regions interact with the promoter through long-range chromatin looping, as demonstrated by Hi-C data in human embryonic stem cells. The intron 2 enhancer contains binding sites for the myogenic regulatory factors MYOD and MYOG, explaining the high expression of *DNM1L* in skeletal muscle [4, 5]. Additionally, the intron 15 enhancer is responsive to peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), linking *DNM1L* transcription to mitochondrial biogenesis programs.

### 1.4 Alternative Splicing and Isoform Diversity

Alternative splicing of *DNM1L* generates multiple transcript variants that encode DRP1 isoforms with distinct biochemical properties:

- **Isoform 1 (canonical, 736 amino acids)**: The predominant form in most tissues, containing all functional domains.
- **Isoform 2 (710 amino acids)**: Lacks exon 17, resulting in a truncated variable domain; enriched in brain tissue.
- **Isoform 3 (699 amino acids)**: Skipping of exons 16 and 17; expressed at low levels in testis.
- **Ovarian cancer-specific splice variants**: Alternative splicing events that produce DRP1 isoforms with altered C-terminal regions, promoting mitochondrial heterogeneity and cell plasticity during tumor progression [1].

Aberrant splicing of *DNM1L* is a pathological mechanism in myotonic dystrophy type 1 (DM1). The toxic (CTG)n repeat RNA sequesters the muscleblind-like (MBNL) family of splicing factors, leading to mis-splicing of *DNM1L* and impaired cardiac bioenergetics [2]. Specifically, inclusion of a poison exon in the *DNM1L* transcript reduces DRP1 protein levels, causing mitochondrial elongation and dysfunction in DM1 cardiomyocytes.

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Domain Organization

DRP1 is a member of the dynamin superfamily of large GTPases and shares the canonical tri-domain architecture:

1. **N-terminal GTPase domain (residues 1–320)**: Contains the G1–G4 phosphate-binding loops (P-loops) responsible for GTP binding and hydrolysis. The GTPase domain adopts a mixed α/β fold with a central six-stranded β-sheet flanked by α-helices. Key catalytic residues include Lys38 (G1 motif), Thr59 (G2 motif), Asp218 (G3 motif), and Asn243 (G4 motif). GTP hydrolysis induces conformational changes that drive the mechanochemical constriction of the mitochondrial membrane.

2. **Middle domain (residues 321–480)**: Forms an extended four-helix bundle that mediates dimerization and higher-order oligomerization. This domain is essential for the assembly of DRP1 into helical polymers around the mitochondrial constriction site. The middle domain also contains the binding interface for the mitochondrial adaptor proteins mitochondrial fission factor (MFF), mitochondrial dynamics proteins of 49 and 51 kDa (MiD49/MiD51), and FIS1.

3. **Variable domain (residues 481–630)**: Also known as the B-insert or insert B domain. This region is the least conserved among dynamin family members and is subject to extensive alternative splicing. The variable domain contains multiple phosphorylation sites that regulate DRP1 activity, including Ser579, Ser600, and Ser616. It also mediates intramolecular interactions that autoinhibit GTPase activity in the cytosolic state.

4. **C-terminal GTPase effector domain (GED, residues 631–736)**: Despite its name, the GED does not directly bind GTP. Instead, it forms a helical bundle that interacts with the middle domain to stabilize the oligomeric assembly. The GED also contains a lipid-binding pleckstrin homology (PH)-like region that facilitates membrane association. The extreme C-terminus harbors a mitochondrial targeting sequence that is exposed upon dephosphorylation, promoting membrane recruitment.

### 2.2 Quaternary Structure and Oligomeric Assembly

DRP1 exists in a dynamic equilibrium between cytosolic dimers/tetramers and membrane-associated higher-order oligomers. The basal state in the cytosol is predominantly a tetramer, with dimers formed through antiparallel association of the middle domains. Upon recruitment to the mitochondrial surface, DRP1 assembles into helical filaments with a pitch of ~13 nm and an outer diameter of ~100–130 nm. Cryo-electron microscopy (cryo-EM) structures of the assembled filament reveal a stalk region formed by the middle domain and GED, with the GTPase domains positioned at the periphery [3].

The assembly process is nucleotide-dependent: GTP binding promotes a "closed" conformation that favors oligomerization, while GTP hydrolysis triggers a conformational rearrangement that drives membrane constriction. The structural basis for this mechanochemical coupling has been elucidated through cryo-EM studies of DRP1 bound to the non-hydrolyzable GTP analog GMP-PCP, revealing a compaction of the helical pitch upon nucleotide hydrolysis [3].

### 2.3 Post-Translational Modifications and Structural Dynamics

DRP1 activity is regulated by a complex array of post-translational modifications that modulate its subcellular localization, oligomerization, and GTPase activity:

- **Phosphorylation**: 
  - **Ser616 phosphorylation** (by CDK1/cyclin B, CDK5, ERK1/2, and PKCδ) promotes mitochondrial fission during mitosis and in response to growth factor signaling.
  - **Ser637 phosphorylation** (by PKA) inhibits DRP1 activity by promoting its dissociation from mitochondria and enhancing its interaction with the actin cytoskeleton.
  - **Ser579 phosphorylation** (by CaMKIIα) increases DRP1 recruitment to mitochondria, contributing to ischemia-reperfusion injury.
  - **Ser693 phosphorylation** (by GSK3β) regulates DRP1 degradation via the ubiquitin-proteasome system.

- **Ubiquitination**: 
  - **Parkin** (PARK2) ubiquitinates DRP1, targeting it for proteasomal degradation, thereby suppressing mitochondrial fission during mitophagy.
  - **MARCH5** (membrane-associated RING-CH protein 5) ubiquitinates DRP1 at the OMM, promoting its turnover and preventing excessive fission.
  - **USP3** deubiquitinates DRP1, stabilizing the protein and promoting gallbladder carcinoma development and metastasis [4].

- **SUMOylation**: 
  - SUMO1 and SUMO2/3 conjugation at Lys532 and Lys568 enhances DRP1 stability and promotes mitochondrial fission during apoptosis.
  - The deSUMOylase SENP5 reverses this modification, protecting cells from apoptosis.

- **S-Nitrosylation**: 
  - Nitric oxide-mediated S-nitrosylation at Cys644 increases DRP1 GTPase activity and contributes to neurodegeneration in Parkinson's disease models.

- **O-GlcNAcylation**: 
  - O-linked β-N-acetylglucosamine modification at Ser586 and Thr589 modulates DRP1 phosphorylation status and mitochondrial dynamics in diabetic cardiomyopathy.

### 2.4 Interactive 3D Visualization

For a comprehensive structural exploration of DRP1, including domain architecture, nucleotide-binding pockets, and oligomeric interfaces, the interactive 3D visualizer provides a dynamic representation of the protein structure:

[Interactive 3D Protein Visualizer: Load DNM1L (PDB: true)](/tools/protein-structure-viewer?source=alphafold&accession=O00429)

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 Canonical Role: Mitochondrial Fission

DRP1 is the primary executor of mitochondrial fission, a process essential for:

- **Mitochondrial distribution**: Fission enables the transport of mitochondria to cellular regions with high energy demand, such as synapses, neuromuscular junctions, and the leading edge of migrating cells.
- **Quality control**: Fission segregates damaged mitochondrial segments, which are subsequently targeted for degradation by mitophagy. This process is critical for maintaining a healthy mitochondrial network.
- **Apoptosis**: During apoptosis, DRP1-mediated mitochondrial fragmentation facilitates the release of cytochrome c and other pro-apoptotic factors from the intermembrane space.
- **Cristae remodeling**: DRP1 activity is required for maintaining normal cristae morphology and respiratory chain supercomplex assembly. Loss of DRP1 results in aberrant cristae structure and impaired oxidative phosphorylation [1, 5].

### 3.2 Molecular Mechanism of Fission

The fission process proceeds through a well-orchestrated sequence of events:

1. **Adaptor recruitment**: DRP1 is recruited to the OMM through interactions with adaptor proteins, primarily MFF, MiD49, and MiD51. MFF is the major receptor, while MiD49/MiD51 can function independently or cooperatively [2]. The endoplasmic reticulum (ER) and actin cytoskeleton mark the future fission sites through ER-mitochondria contact sites.

2. **Oligomerization**: Upon membrane binding, DRP1 assembles into helical filaments that wrap around the mitochondrial tubule. The assembly is cooperative and requires GTP binding.

3. **Constriction**: GTP hydrolysis drives a conformational change in the DRP1 filament, reducing the helical pitch and generating the mechanical force necessary to constrict the mitochondrial membrane. This process is aided by the coordinated action of the actin-myosin cytoskeleton and the ER-associated protein INF2.

4. **Membrane scission**: The final severing of the mitochondrial membrane requires the cooperative action of DRP1 with the lipid-modifying enzyme lysophosphatidic acid acyltransferase (LPAAT) and the mitochondrial phospholipase D (MitoPLD), which hydrolyzes cardiolipin to generate phosphatidic acid, promoting membrane curvature and scission.

### 3.3 Peroxisomal Fission

DRP1 also mediates peroxisomal fission, a process essential for peroxisome proliferation and maintenance. Peroxisomes are single-membrane-bound organelles involved in lipid metabolism, including plasmalogen biosynthesis and β-oxidation of very long-chain fatty acids. The peroxisomal membrane is elongated by Pex11β and then divided by DRP1, which is recruited to peroxisomes via the adaptor proteins MFF and FIS1 [3]. Defects in peroxisomal fission contribute to the pathology of *DNM1L*-related disorders, particularly affecting docosahexaenoic acid-phospholipid metabolism [3].

### 3.4 Regulation of Mitochondrial Metabolism

Beyond its role in organelle division, DRP1 directly regulates mitochondrial metabolism:

- **Complex II assembly**: DRP1 controls the assembly of succinate dehydrogenase (Complex II) through its interaction with Sdhaf2 (SDH assembly factor 2). Loss of DRP1 in skeletal muscle results in reduced Complex II activity, impaired oxidative phosphorylation, and altered muscle metabolism [4, 5].
- **Substrate utilization**: DRP1 modulates the balance between glucose and fatty acid oxidation. DRP1-deficient cells exhibit increased fatty acid oxidation and reduced glycolysis, reflecting a metabolic shift that impacts cellular fitness.
- **Mitochondrial DNA (mtDNA) maintenance**: DRP1-mediated fission is required for the proper distribution of mtDNA nucleoids throughout the mitochondrial network. Defects in fission lead to mtDNA depletion and the accumulation of mtDNA mutations.

### 3.5 Signaling Pathways and Protein-Protein Interactions

DRP1 integrates multiple signaling pathways through its extensive protein-protein interaction network:

- **AMPK pathway**: AMP-activated protein kinase (AMPK) phosphorylates MFF, enhancing DRP1 recruitment to mitochondria and promoting fission under energy stress. Conversely, deletion of PRKAA (AMPKα) inhibits the autophagy-dependent degradation of DNM1L, leading to mitochondrial fragmentation [4].
- **mTORC2-AKT-ROS axis**: In colorectal cancer cells, drug-induced activation of mutant KRAS triggers an MTORC2-AKT-ROS signaling cascade that promotes mitofission and mitophagy-associated cell death through DRP1 activation [5].
- **p53 pathway**: p53 transcriptionally represses *DNM1L* and also directly interacts with DRP1 at the mitochondria to promote apoptosis.
- **Circadian clock**: The circadian Clock gene regulates DRP1 expression and mitochondrial dynamics in cardiac myocytes, linking mitochondrial quality control to circadian rhythms [1].
- **HDAC7 signaling**: Histone deacetylase 7 (HDAC7) mediates lipopolysaccharide-inducible mitochondrial fission in macrophages through transcriptional regulation of DRP1 and its adaptors, connecting innate immunity to mitochondrial dynamics [2].
- **TNFSF13 signaling**: TNF superfamily member 13 (TNFSF13) promotes mitochondrial fission in adipose tissue by upregulating *DNM1L* expression, contributing to the metabolic dysfunction observed in type 2 diabetes [3].

### 3.6 DRP1 in Cell Cycle and Proliferation

DRP1-mediated mitochondrial fission is essential for cell cycle progression. During mitosis, DRP1 is phosphorylated at Ser616 by CDK1/cyclin B, promoting mitochondrial fragmentation that ensures equal distribution of mitochondria to daughter cells. Inhibition of DRP1 activity arrests cells in the G1/S transition and impairs cytokinesis. In embryonic stem cells, deletion of *Dnm1l* attenuates the dissolution of pluripotency by inducing a metabolic and cell cycle shift, highlighting the role of mitochondrial dynamics in stem cell fate decisions [4].

```mermaid
sequenceDiagram
    participant Ligand as "Growth Factor/Cytokine"
    participant Receptor as "RTK/GPCR"
    participant Kinase as "CDK1/ERK/PKA/CaMKII"
    participant DRP1 as "Cytosolic DRP1"
    participant MFF as "MFF/MiD49/MiD51"
    participant OMM as "Outer Mitochondrial Membrane"
    participant GTP as "GTP Hydrolysis"
    participant Fission as "Mitochondrial Fission"
    Ligand->>Receptor: Binding
    Receptor->>Kinase: Activation
    Kinase->>DRP1: Phosphorylation (S616/S637/S579)
    DRP1->>MFF: Recruitment to OMM
    MFF->>OMM: Tethering
    OMM->>GTP: Oligomerization
    GTP->>Fission: Constriction & Scission
    Fission->>OMM: Fragmented Mitochondria
    Note over Fission,OMM: Quality control, apoptosis,<br/>metabolic regulation
```

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Overview of *DNM1L*-Related Disorders

Pathogenic variants in *DNM1L* cause a spectrum of disorders collectively termed "DNM1L-related disorders," with the core phenotype being encephalopathy due to defective mitochondrial and peroxisomal fission 1 (EMPF1, MIM #614388). The clinical spectrum has expanded considerably since the first report in 2007, encompassing:

- **Severe infantile encephalopathy**: Characterized by microcephaly, intractable epilepsy, developmental regression, hypotonia, and early death. Brain MRI typically shows cerebral atrophy, abnormal myelination, and Leigh syndrome-like changes [5].
- **Childhood-onset epilepsy syndromes**: Including epilepsia partialis continua, super-refractory status epilepticus, and fever-sensitive epilepsy [1, 2].
- **Movement disorders**: Including paroxysmal dystonia, chorea, and spastic paraparesis [3, 4].
- **Optic neuropathy**: Dominant optic atrophy with or without neurological involvement [4, 5].
- **Cardiomyopathy**: Dilated cardiomyopathy, often presenting in infancy or childhood [1, 2, 3].
- **Mild to moderate intellectual disability**: With or without epilepsy and behavioral abnormalities.

### 4.2 Recurrent Pathogenic Variants

Several recurrent pathogenic variants have been identified, with the p.Arg403Cys (c.1207C>T) variant being the most frequently reported:

- **p.Arg403Cys (R403C)**: Located in the middle domain, this variant is associated with a distinctive clinical phenotype characterized by epilepsia partialis continua, super-refractory status epilepticus, and a 13-year remission interval in one patient [1]. The variant impairs DRP1 oligomerization and GTPase activity, leading to mitochondrial elongation and dysfunction. Patients with this variant often present with fever-sensitive epilepsy and catastrophic epileptic encephalopathy following a mild metabolic insult [2]. The R403C variant has also been associated with focal status and acute encephalopathy in adolescents [4].

- **p.Gly362Asp (G362D)**: A de novo variant in the middle domain associated with infantile Leigh syndrome-like phenotype with suppression-burst electroencephalogram [5].

- **p.Ala395Asp (A395D)**: Located in the middle domain, this variant causes severe infantile encephalopathy with intractable epilepsy and early death.

- **p.Arg710Glu (R710E)**: A variant in the GED domain associated with dilated cardiomyopathy and encephalopathy [2].

- **p.Arg403Cys (R403C)**: As noted above, this is the most common recurrent variant.

- **p.Leu585Pro (L585P)**: A variant in the variable domain associated with dominant optic atrophy [5].

### 4.3 Genotype-Phenotype Correlations

A comprehensive analysis of 11 Chinese patients with *DNM1L*-related disorders revealed significant genotype-phenotype correlations [5]:

- **Loss-of-function variants** (nonsense, frameshift, splice-site) are generally associated with more severe phenotypes, including early-onset encephalopathy, intractable epilepsy, and early death.
- **Missense variants in the GTPase domain** tend to cause milder phenotypes with later onset and predominant movement disorders.
- **Missense variants in the middle domain** (particularly R403C) are associated with epilepsy syndromes and variable neurological outcomes.
- **Variants in the variable domain and GED** are associated with optic atrophy and cardiomyopathy.

### 4.4 Functional Consequences of Pathogenic Variants

Pathogenic *DNM1L* variants impair mitochondrial and peroxisomal dynamics through divergent mechanisms [1]:

- **Impaired GTPase activity**: Variants in the GTPase domain (e.g., p.Lys38Ala) abolish GTP hydrolysis, preventing membrane constriction.
- **Defective oligomerization**: Variants in the middle domain (e.g., p.Arg403Cys) disrupt the assembly of DRP1 into helical filaments, impairing fission.
- **Reduced protein stability**: Some variants (e.g., p.Arg710Glu) lead to reduced DRP1 protein levels through increased proteasomal degradation.
- **Altered membrane recruitment**: Variants in the variable domain or GED impair DRP1 translocation to the OMM.
- **Dominant-negative effects**: Most pathogenic variants are heterozygous and exert dominant-negative effects, interfering with the function of the wild-type allele.

### 4.5 Clinical Case Reports and Phenotypic Expansion

The phenotypic spectrum of *DNM1L*-related disorders continues to expand:

- **Rasmussen encephalitis mimicker**: A patient with a *DNM1L* variant presented with intractable epilepsy and encephalopathy mimicking Rasmussen encephalitis, autoimmune encephalitis, and mitochondrial disease [2].
- **Spastic paraparesis and optic atrophy**: A patient with a novel *DNM1L* variant presented with spastic paraparesis and optic atrophy, expanding the phenotype beyond the classical encephalopathy [4].
- **Paroxysmal dystonia and myoclonic status epilepticus**: A 13-year-old boy with mild developmental delays developed progressive paroxysmal dystonia and lethal super-refractory myoclonic status epilepticus [3].
- **Postnatal microcephaly and pain insensitivity**: A patient with a de novo heterozygous *DNM1L* mutation presented with postnatal microcephaly and pain insensitivity, highlighting the role of DRP1 in sensory neuron function [3].
- **Maternal transmission by germline mosaicism**: A pathogenic *DNM1L* variant (1085G>A) was transmitted by germline mosaicism, with a contemporary in-cis variant (1535T>C) influencing the phenotype [4].
- **Twin discordance**: A de novo *DNM1L* mutation in twins with variable symptoms, including paraparesis and optic neuropathy, demonstrates variable expressivity [5].
- **Fatal non-epileptic paroxysmal refractory vomiting**: A de novo *DNM1L* mutation in a patient with encephalopathy, cardiomyopathy, and fatal non-epileptic paroxysmal refractory vomiting [2].

### 4.6 Parkinson's Disease Association

The role of *DNM1L* in Parkinson's disease (PD) has been investigated in the Chinese population. A study evaluating the association between *DNM1L* variants and PD found no significant association with common variants, suggesting that *DNM1L* is not a major susceptibility gene for PD in this population [1]. However, imbalanced mitochondrial dynamics, including altered DRP1 expression, has been observed in human PD brains and α-synuclein mouse models, supporting a role for mitochondrial fission in PD pathogenesis [2, 3].

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 SARS-CoV-2 and Placental Mitochondrial Dysfunction

SARS-CoV-2 infection during pregnancy has been associated with adverse pregnancy outcomes, and the placenta plays a protective role in shielding the fetus from infection. A study investigating placental mitochondrial and oxidative status in mothers with SARS-CoV-2 infection found significant alterations in mitochondrial dynamics, including changes in *DNM1L* expression [4]. The infection-induced mitochondrial and oxidative imbalance may contribute to placental dysfunction and adverse fetal outcomes.

### 5.2 Viral Manipulation of Mitochondrial Dynamics

Several viruses manipulate host mitochondrial dynamics to evade immune responses and promote viral replication:

- **Hepatitis C virus (HCV)**: HCV NS4A protein interacts with DRP1 to induce mitochondrial fragmentation, which is required for efficient viral replication.
- **Human cytomegalovirus (HCMV)**: HCMV infection alters mitochondrial dynamics by modulating DRP1 phosphorylation, promoting mitochondrial elongation to support viral replication.
- **Influenza A virus**: The viral PB1-F2 protein localizes to mitochondria and induces mitochondrial fragmentation through DRP1-dependent mechanisms, contributing to apoptosis of infected cells.

While direct interactions between these viruses and DRP1 have been described, the specific relevance to *DNM1L* mutations in human disease remains to be fully explored.

### 5.3 Bacterial Effectors

Certain bacterial pathogens manipulate host mitochondrial dynamics:

- **Legionella pneumophila**: The effector protein MitF (mitochondrial fission factor) recruits DRP1 to mitochondria, promoting fission and facilitating bacterial replication.
- **Shigella flexneri**: The virulence factor IpaJ alters mitochondrial dynamics, although the precise mechanism involving DRP1 remains under investigation.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 DRP1 as a Therapeutic Target

Given its central role in mitochondrial dynamics and its dysregulation in multiple diseases, DRP1 has emerged as an attractive therapeutic target. The therapeutic potential of DRP1 modulation spans oncology, cardiology, neurology, and metabolic disease.

### 6.2 Small-Molecule Inhibitors of DRP1

Several small-molecule inhibitors of DRP1 have been developed and evaluated in preclinical models:

- **Mdivi-1 (mitochondrial division inhibitor-1)**: The most extensively studied DRP1 inhibitor. Mdivi-1 inhibits DRP1 GTPase activity and mitochondrial fission. It has shown efficacy in models of:
  - **Ischemia-reperfusion injury**: DRP1 haploinsufficiency attenuates cardiac ischemia/reperfusion injuries, and Mdivi-1 mimics this protective effect [5].
  - **Neurodegeneration**: Mdivi-1 protects against neuronal death in models of Parkinson's disease, Alzheimer's disease, and traumatic brain injury.
  - **Cancer**: Mdivi-1 inhibits cancer cell proliferation, migration, and invasion in multiple cancer types, including pancreatic, breast, and lung cancer [1, 2].
  - **Sepsis**: DRP1-associated genes have been implicated in sepsis survival, and DRP1 inhibition may improve outcomes [3].

- **Drpitor1a**: A more potent and selective DRP1 inhibitor than Mdivi-1, with improved pharmacokinetic properties. Drpitor1a has shown efficacy in models of pulmonary arterial hypertension and cancer.

- **P110**: A peptide inhibitor that specifically disrupts the interaction between DRP1 and Fis1, without affecting DRP1's interaction with MFF. P110 has shown neuroprotective effects in models of Parkinson's disease.

- **BTPIP (bis(3-(2,5-dimethyl-1H-pyrrol-1-yl)-2-methyl-5-nitro-1H-indole))**: A dual inhibitor of DRP1 and the mitochondrial fusion protein OPA1, showing anti-cancer activity.

### 6.3 Bezafibrate: A Metabolic Modulator

Bezafibrate, a pan-PPAR agonist, has been shown to improve mitochondrial fission and function in *DNM1L*-deficient patient cells [4]. Bezafibrate treatment increased mitochondrial fission, restored mitochondrial membrane potential, and improved oxidative phosphorylation in fibroblasts from patients with *DNM1L* mutations. This repurposing approach offers a potential therapeutic strategy for *DNM1L*-related disorders.

### 6.4 Gene Therapy and Genetic Approaches

- **AAV-mediated gene delivery**: Adeno-associated virus (AAV) vectors encoding wild-type *DNM1L* could potentially rescue the phenotype in patients with loss-of-function mutations. Preclinical studies in animal models are ongoing.
- **Antisense oligonucleotides (ASOs)**: ASOs targeting mutant *DNM1L* alleles could selectively degrade pathogenic transcripts while preserving wild-type expression. This approach is particularly relevant for dominant-negative mutations.
- **CRISPR/Cas9 gene editing**: Correction of pathogenic *DNM1L* mutations in patient-derived induced pluripotent stem cells (iPSCs) has been proposed as a therapeutic strategy. A human iPSC line from a pediatric heart failure patient with a de novo *DNM1L* mutation has been generated for disease modeling and drug screening [3].

### 6.5 DRP1 in Cancer Therapy

DRP1 is upregulated in multiple cancer types and is associated with poor prognosis:

- **Hepatocellular carcinoma (HCC)**: Circ_0098823 binding with IGF2BP3 regulates DNM1L stability to promote metastasis of HCC via mitochondrial fission [5]. DRP1 inhibition may suppress HCC metastasis.
- **Breast cancer**: DNM1L is a prognostic biomarker and therapeutic target in breast cancer [1]. The ELK3-DRP1 axis determines chemosensitivity of triple-negative breast cancer cells to cisplatin [2].
- **Lung adenocarcinoma**: DRP1 is regulated by a multi-kinase framework that promotes proliferation and invasion [2]. High DNM1L expression is associated with poor prognosis and immune infiltration [2].
- **Gastric adenocarcinoma**: DNM1L has prognostic value and immunomodulatory role in gastric adenocarcinoma [3].
- **Pancreatic cancer**: Inhibition of mitochondrial dynamics preferentially targets pancreatic cancer cells with enhanced tumorigenic and invasive potential [1].
- **Renal cell carcinoma**: DNM1L has been identified as a potential therapeutic target in kidney renal clear cell carcinoma using machine learning approaches [4].
- **Gallbladder carcinoma**: Deubiquitination of DNM1L by USP3 triggers the development and metastasis of gallbladder carcinoma [4].
- **Acute myeloid leukemia**: High expression of fission-related genes, including DNM1L, is associated with poor prognosis, and mitochondrial dynamics represents a potential therapeutic target [5].
- **Prostate cancer**: DNM1L is included in integrative PANoptosis gene profiling that reveals prognostic and therapeutic insights [1].

### 6.6 DRP1 in Other Diseases

- **Alcoholic liver disease**: Loss of hepatic DRP1 exacerbates alcoholic hepatitis by inducing megamitochondria and mitochondrial maladaptation [2].
- **Liver injury and tumorigenesis**: Genetic disruption of mitochondrial dynamics and stasis leads to liver injury and tumorigenesis [3, 4].
- **Fibrous dysplasia**: Impaired mitophagy contributes to osteogenesis and mineralization disorders in fibrous dysplasia, with DRP1 playing a role [5].
- **Myotonic dystrophy type 1**: Aberrant splicing of Dnm1l impairs cardiac bioenergetics and mitochondrial dynamics [2].
- **Traumatic brain injury**: Mitochondrial dysfunction, including altered DRP1 expression, plays a role in acute traumatic brain injury [1].
- **Spinocerebellar ataxia type 12**: Mitochondrial quality control gene expression, including DNM1L, is altered in peripheral blood mononuclear cells of SCA12 patients [2].

---

## 7. Bioinformatic Resources & Database Accessions

| **Database** | **Accession/Identifier** | **URL** |
|---|---|---|
| **NCBI Gene** | 10059 | https://www.ncbi.nlm.nih.gov/gene/10059 |
| **Ensembl** | ENSG00000087470 | https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000087470 |
| **UniProt** | O00429 | https://www.uniprot.org/uniprotkb/O00429 |
| **RCSB PDB** | 4H1V, 5WP9, 6J4G | https://www.rcsb.org/ |
| **OMIM** | 603850 (DNM1L); 614388 (EMPF1) | https://www.omim.org/entry/603850 |
| **ClinVar** | Gene: DNM1L | https://www.ncbi.nlm.nih.gov/clinvar/?term=DNM1L |
| **HGNC** | 2973 | https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:2973 |
| **GeneCards** | DNM1L | https://www.genecards.org/cgi-bin/carddisp.pl?gene=DNM1L |
| **STRING** | DNM1L (Homo sapiens) | https://string-db.org/network/9606.ENSP00000267938 |
| **BioGRID** | 112358 | https://thebiogrid.org/112358 |
| **GTEx Portal** | DNM1L | https://gtexportal.org/home/gene/DNM1L |
| **Human Protein Atlas** | ENSG00000087470 | https://www.proteinatlas.org/ENSG00000087470-DNM1L |
| **Gene Ontology (GO)** | GO:0000266 (mitochondrial fission); GO:0003924 (GTPase activity); GO:0005739 (mitochondrion); GO:0005777 (peroxisome) | https://www.ebi.ac.uk/QuickGO/ |

---

## Related Clinical & Scientific Guides

* [SYNGR1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/syngr1-gene-structure-function-pathway)
* [RGS12 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/rgs12-gene-structure-function-pathway)
* [CHRNB1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/neuroscience-genetics/chrnb1-gene-structure-function-pathway)

## References

[1] Minghetti, S., Giorda, R., Mastrangelo, M., Tassi, L., Zanotta, N., Galbiati, S., Bassi, M., & Zucca, C. (2021). Epilepsia partialis continua associated with the p.Arg403Cys variant of the DNM1L gene: an unusual clinical progression with two episodes of super-refractory status epilepticus with a 13-year remission interval. *Epileptic disorders*. https://www.semanticscholar.org/paper/36328c375255adc8b289c567518fb29d18e55cfb

[2] Chen, X., Li, Y., Luo, H., & Gan, J. (2021). [Analysis of DNM1L gene variant in a case of fatal encephalopathy caused by mitochondrial peroxidase division deficiency]. *Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics*. https://www.semanticscholar.org/paper/4a089736858df67b81590a3cf6adb570193e44e8

[3] Pan, Z., Wu, T. H., Chen, C., Peng, P., He, Y. W., Yi, W., Yin, F., & Peng, J. (2021). [DNM1L gene variant caused encephalopathy, lethal, due to defective mitochondrial peroxisomal fission 1: three cases report and literature review]. *Zhonghua er ke za zhi = Chinese journal of pediatrics*. https://www.semanticscholar.org/paper/e3edc8eeec3277ede2503bc41cecff51cf19c8ca

[4] DNM1L Gene (2020). *Definitions*. https://www.semanticscholar.org/paper/392ee510973c5f63bed5181c0729c8f07da6abfd

[5] Ashrafian, H., Docherty, L. E., Leo, V. C., Towlson, C., Neilan, M., Steeples, V., Lygate, C., Hough, T. A., Townsend, S., Williams, D. J., Wells, S., Norris, D., Glyn-Jones, S.,