Biology subjects

Gerards, M.

Publications and source records attributed to Gerards, M..

3 recordsLinked to original sources

bioRxiv2024

The curse of the red pearl: a fibroblast specific pearl-necklace mitochondrial phenotype caused by phototoxicity

The dynamic nature of mitochondria makes live cell imaging an important tool in mitochondrial research. Although imaging using fluorescent probes is the golden standard in studying mitochondrial morphology, these probes might introduce a-specific features. In this study, live cell fluorescent imaging was applied to investigate a pearl-necklace shaped mitochondrial phenotype that arises when mitochondrial fission is restricted. In this fibroblast specific pearl-necklace phenotype, constricted and expanded mitochondrial regions alternate. Imaging studies revealed that the formation time of this pearl-necklace phenotype differs between laser scanning confocal, widefield and spinning disk confocal microscopy. We found that the phenotype formation correlates with the excitation of the fluorescent probe and is the result of phototoxicity. Interestingly, the phenotype only arises in cells stained with red mitochondrial dyes. Serial section electron tomography pearl-necklace mitochondria revealed that the mitochondrial membranes remained intact, while the cristae structure was altered. Furthermore, filaments and ER were present at the constricted sites. This study illustrates the importance of considering experimental conditions for live cell imaging to prevent imaging artefacts that can have a major impact on the obtained results.

molecular biology↗

bioRxiv2024

The guardians of mitochondrial dynamics: a novel role for intermediate filament proteins

Mitochondria are dynamic organelles and the main source of cellular energy. Their dynamic nature is crucial to meet cellular requirements. However, the processes and proteins involved in mitochondrial dynamics are not fully understood. Using a computational protein-protein interaction approach, we identified ITPRIPL2, which caused mitochondrial elongation upon knockdown. ITPRIPL2 co-localizes with the intermediate filament protein vimentin and interacts with vimentin according to protein simulations. ITPRIPL2 knockdown alters vimentin processing, disrupts intermediate filaments and transcriptomics analysis revealed changes in vimentin-related pathways. Our data illustrates that ITPRIPL2 is essential for vimentin related intermediate filament structure. Interestingly, like ITPRIPL2 knockdown, vimentin knockdown results in mitochondrial elongation. Our data highlights ITPRIPL2 as a vimentin-associated protein and reveals a role for intermediate filaments in mitochondrial dynamics, improving our understanding of mitochondrial dynamics regulators. Moreover, our study demonstrates that protein- protein interaction analysis is a powerful approach for identifying novel mitochondrial dynamics proteins.

systems biology↗

bioRxiv2019

Tfam knockdown results in reduction of mtDNA copy number, OXPHOS deficiency and abnormalities in zebrafish embryos

High mitochondrial DNA (mtDNA) copy numbers are essential for oogenesis and embryogenesis and correlate with fertility of oocytes and viability of embryos. To understand the pathology and mechanisms associated with low mtDNA copy numbers, we knocked down mitochondrial transcription factor A (Tfam), a regulator of mtDNA replication, during early zebrafish development. Reduction of Tfam using a splice-modifying morpholino (MO) resulted in a 42%{+/-}4% decrease in mtDNA copy number in embryos at 4 days post fertilization. Morphant embryos displayed abnormal development of the eye, brain, heart and muscle, as well as a 50%{+/-}11% decrease in ATP production. Transcriptome analysis revealed a decrease in protein-encoding transcripts from the heavy strand of the mtDNA. In addition, various RNA translation pathways were increased, indicating an upregulation of nuclear and mitochondria-related translation. The developmental defects observed were supported by a decreased expression of pathways related to eye development and haematopoiesis. The increase in mRNA translation might serve as a compensation mechanism, but appears insufficient during prolonged periods of mtDNA depletion, highlighting the importance of high mtDNA copy numbers for early development in zebrafish. SUMMARY STATEMENTThe first tuneable zebrafish model used to characterize the effect of a reduced mtDNA copy number and resulting OXPHOS deficiency on zebrafish embryonic development.

developmental biology↗