Periodic Reporting for period 1 - MitoZebra (Activation of mitochondria during embryogenesis)
Período documentado: 2021-09-01 hasta 2023-08-31
Energy homeostasis is important for development, and mitochondria play a crucial role in its regulation. Mitochondria are only maternally inherited; their dysfunction has been linked to infertility and developmental disorders. An increasing number of women who have metabolic disorders such as diabetes or obesity are turning to IVF (in vitro fertilization) clinics to mitigate the adverse metabolic effects of mitochondrial dysfunction. Thus, advances in studying mitochondria during embryogenesis promise to provide novel avenues for the development of therapies and potential disease prevention. Despite decades of research into mitochondrial functions, it remains unclear how the respiratory chain is activated during embryogenesis. Here we addressed these question by systematically investigating the mitochondrial activation during embryogenesis using zebrafish as a model system. We showed that mitochondrial activation replicates findings in other species, which establishes zebrafish as a great model for studying mitochondrial biology in vertebrate development due to its external fertilization and accessibility of embryos. Furthermore, analysis of protein changes during development allowed us to identify two potential mechanisms of mitochondrial activation during development that we are currently exploring.
Characterization of the increase in mitochondrial respiratory activity during zebrafish embryogenesis.
Drawing from both existing literature and our own research findings, we hypothesized that mitochondrial translation is active in early embryogenesis and contributes to synthesis and assembly of new respiratory complexes, which in turn lead to the increase in the activity of mitochondrial respiratory chain complexes during embryogenesis. However, while our results indicate that mitochondrial ribosomes are capable of translation even during the early stages of embryogenesis, blue native polyacrylamide gel electrophoresis (BN-PAGE) showed revealed that all the respiratory chain complexes are present already in activated oocytes and their abundance remains steady during the early stages of embryogenesis.
In order to identify potential mechanism that might contribute to the increase in mitochondrial activity, we analyzed protein and phospho-protein composition of isolated mitochondria at different stages of embryogenesis. Based on our proteomics results we focused on two potential mechanisms that might contribute to the increase in mitochondrial activity. Firstly, we observed an upregulation of endoplasmic reticulum proteins and cytoplasmic ribosome subunits while the total levels of these proteins remained constant over time. Currently, we are exploring this lead further.
Secondly, we noted a downregulation of proteins associated with mitochondrial fission as development progressed. We are actively investigating whether changes in mitochondrial morphology contribute to the observed increase in mitochondrial activity during development.
Drawing from both existing literature and our own research findings, we hypothesized that mitochondrial translation is active in early embryogenesis and contributes to synthesis and assembly of new respiratory complexes, which in turn lead to the increase in the activity of mitochondrial respiratory chain complexes during embryogenesis. However, while our results indicate that mitochondrial ribosomes are capable of translation even during the early stages of embryogenesis, blue native polyacrylamide gel electrophoresis (BN-PAGE) showed revealed that all the respiratory chain complexes are present already in activated oocytes and their abundance remains steady during the early stages of embryogenesis.
In order to identify potential mechanism that might contribute to the increase in mitochondrial activity, we analyzed protein and phospho-protein composition of isolated mitochondria at different stages of embryogenesis. Based on our proteomics results we focused on two potential mechanisms that might contribute to the increase in mitochondrial activity. Firstly, we observed an upregulation of endoplasmic reticulum proteins and cytoplasmic ribosome subunits while the total levels of these proteins remained constant over time. Currently, we are exploring this lead further.
Secondly, we noted a downregulation of proteins associated with mitochondrial fission as development progressed. We are actively investigating whether changes in mitochondrial morphology contribute to the observed increase in mitochondrial activity during development.
We are currently in the process of preparing a manuscript for publication, which we will make openly accessible to the research community by posting it on bioRxiv and submitting it to a peer-reviewed journal.
This work has already been shared with the wider scientific community at four international meetings in the form of poster presentations: EMBO Mitochondrial homeostasis and human diseases, 2021; EMBO Molecular biology of mitochondrial gene maintenance and expression, 2022; Cell Symposium Multifaceted mitochondria, 2022; EMBO Inter-organelle contacts biology, 2023. No website has been developed for the project, but we will disseminate the results through twitter, social media platforms and the Pauli lab website.
This work has already been shared with the wider scientific community at four international meetings in the form of poster presentations: EMBO Mitochondrial homeostasis and human diseases, 2021; EMBO Molecular biology of mitochondrial gene maintenance and expression, 2022; Cell Symposium Multifaceted mitochondria, 2022; EMBO Inter-organelle contacts biology, 2023. No website has been developed for the project, but we will disseminate the results through twitter, social media platforms and the Pauli lab website.