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Gemini-Based Lipoplexes Complement the Mitochondrial Phenotype in MFN1-Knockout Mouse Embryonic Fibroblasts
Mónica Muñoz-Úbeda1, Andrés Tolosa-Díaz1,2, Santanu Bhattacharya3
1Instituto de Investigación Hospital Doce de Octubre (i+12), Avenida de Córdoba s/n, 28041 Madrid, Spain.
Abstract:
Mitochondria form a dynamic network of constantly dividing and fusing organelles. The balance between these antagonistic processes is crucial for normal cellular function and requires the action of specialized proteins. The mitochondrial membrane proteins mitofusin 1 (Mfn1) and mitofusin 2 (Mfn2) are responsible for the fusion of the outer membrane of adjacent mitochondria. Mutations within Mfn1 or Mfn2 impair mitochondrial fusion and lead to some severe mitochondrial dysfunctions and mitochondrial diseases (MDs). A characteristic phenotype of cells carrying defective Mfn1 or Mfn2 is the presence of a highly fragmented mitochondrial network. Here, we use a biocompatible mixture of lipids, consisting on synthetic gemini cationic lipids (GCLs) and the zwitterionic phospholipid (DOPE), to complex, transport, and deliver intact copies of MFN1 gene into MFN1-Knockout mouse embryonic fibroblasts (MFN1-KO MEFs). We demonstrate that the GCL/DOPE-DNA lipoplexes are able to introduce the intact MFN1 gene into the cells and ectopically produce functional Mfn1. A four-fold increase of the Mfn1 levels is necessary to revert the MFN1-KO phenotype and to partially restore a mitochondrial network. This phenotype complementation was correlated with the transfection of GCL/DOPE-MFN1 lipoplexes that exhibited a high proportion of highly packaged hexagonal phase. GCL/DOPE-DNA lipoplexes are formulated as efficient therapeutic agents against MDs.
Insights
Synthetic gemini cationic lipids (GCLs) and DOPE effectively deliver the MFN1 gene into cells, restoring mitochondrial networks. This breakthrough offers a promising therapeutic strategy for mitochondrial diseases (MDs).
Area of Science:
- Cell Biology
- Genetics
- Biotechnology
Background:
- Mitochondria are dynamic organelles crucial for cellular function, requiring a balance of division and fusion.
- Mitofusin proteins (Mfn1 and Mfn2) regulate mitochondrial outer membrane fusion; mutations cause dysfunction and mitochondrial diseases (MDs).
- Defective Mfn1 or Mfn2 leads to a fragmented mitochondrial network, a hallmark of cellular dysfunction.
Purpose of the Study:
- To develop a novel gene delivery system for restoring functional Mfn1 in MFN1-knockout cells.
- To investigate the therapeutic potential of GCL/DOPE-DNA lipoplexes for treating mitochondrial diseases.
Main Methods:
- Utilized a biocompatible mixture of synthetic gemini cationic lipids (GCLs) and DOPE to create lipoplexes.
- Complexed and delivered intact MFN1 gene copies into MFN1-Knockout mouse embryonic fibroblasts (MFN1-KO MEFs).
- Assessed Mfn1 levels, mitochondrial network structure, and lipoplex characteristics (hexagonal phase).
Main Results:
- GCL/DOPE-DNA lipoplexes successfully delivered the MFN1 gene, leading to ectopic production of functional Mfn1.
- A four-fold increase in Mfn1 levels was sufficient to revert the MFN1-KO phenotype and partially restore mitochondrial networks.
- Successful phenotype complementation correlated with lipoplexes exhibiting a high proportion of hexagonal phase.
Conclusions:
- GCL/DOPE-DNA lipoplexes are effective agents for delivering the MFN1 gene and restoring mitochondrial function.
- This approach shows significant promise as a therapeutic strategy for mitochondrial diseases caused by Mfn1 deficiency.
- The hexagonal phase characteristics of the lipoplexes are linked to their transfection efficiency and therapeutic efficacy.
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