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1. Mitochondrial nucleoids

   https://doi.org/10.1016/j.cub.2024.09.078  

   Kakudji, Eve V; Lewis, Samantha C (November 2024, Current Biology)

   Eve Kakudji and Samantha Lewis discuss the structure and function of mitochondrial nucleoids - large nucleoprotein complexes containing mitochondrial DNA and the regulatory factors necessary for its packaging, replication, transcription, and repair. 

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2. Mitochondrial Connexins and Mitochondrial Contact Sites with Gap Junction Structure

   https://doi.org/10.3390/ijms24109036  

   Cetin-Ferra, Selma; Francis, Sharon C.; Cooper, Anthonya T.; Neikirk, Kit; Marshall, Andrea G.; Hinton, Antentor; Murray, Sandra A. (May 2023, International Journal of Molecular Sciences)

   Mitochondria contain connexins, a family of proteins that is known to form gap junction channels. Connexins are synthesized in the endoplasmic reticulum and oligomerized in the Golgi to form hemichannels. Hemichannels from adjacent cells dock with one another to form gap junction channels that aggregate into plaques and allow cell–cell communication. Cell–cell communication was once thought to be the only function of connexins and their gap junction channels. In the mitochondria, however, connexins have been identified as monomers and assembled into hemichannels, thus questioning their role solely as cell–cell communication channels. Accordingly, mitochondrial connexins have been suggested to play critical roles in the regulation of mitochondrial functions, including potassium fluxes and respiration. However, while much is known about plasma membrane gap junction channel connexins, the presence and function of mitochondrial connexins remain poorly understood. In this review, the presence and role of mitochondrial connexins and mitochondrial/connexin-containing structure contact sites will be discussed. An understanding of the significance of mitochondrial connexins and their connexin contact sites is essential to our knowledge of connexins’ functions in normal and pathological conditions, and this information may aid in the development of therapeutic interventions in diseases linked to mitochondria. 

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3. Phosphorylation of mitochondrial transcription factor B2 controls mitochondrial DNA binding and transcription

   https://doi.org/10.1016/j.bbrc.2020.05.141  

   Bostwick, Alicia M.; Moya, Gonzalo E.; Senti, Mackenna L.; Basu, Urmimala; Shen, Jiayu; Patel, Smita S.; Dittenhafer-Reed, Kristin E. (July 2020, Biochemical and Biophysical Research Communications)
4. Mitochondrial regulation in spermatogenesis

   https://doi.org/10.1530/REP-21-0431  

   Zhang, Zhaoran; Miao, Junru; Wang, Yuan (April 2022, Reproduction)

   The classic roles of mitochondria in energy production, metabolism, and apoptosis have been well defined. However, a growing body of evidence suggests that mitochondria are also active players in regulating stem cell fate decision and lineage commitment via signaling transduction, protein modification, and epigenetic modulations. This is particularly interesting for spermatogenesis, during which germ cells demonstrate changing metabolic requirements across various stages of development. It is increasingly recognized that proper male fertility depends on exquisitely controlled plasticity of mitochondrial features, activities, and functional states. The unique role of mitochondria in germ cell ncRNA processing further adds another layer of complexity to mitochondrial regulation during spermatogenesis. In this review, we will discuss potential regulatory mechanisms of how mitochondria swiftly reshape their features, activities, and functions to support critical germ cell fate transitions during spermatogenesis. In addition, we will also review recent findings of how mitochondrial regulators coordinate with germline proteins to participate in germ cell-specific activities. 

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5. Geometric instability catalyzes mitochondrial fission

   https://doi.org/10.1091/mbc.E18-01-0018  

   Irajizad, Ehsan; Ramachandran, Rajesh; Agrawal, Ashutosh; Bassereau, Patricía (January 2019, Molecular Biology of the Cell)

   The mitochondrial membrane undergoes extreme remodeling during fission. While a few membrane-squeezing proteins are recognized as the key drivers of fission, there is a growing body of evidence that strongly suggests that conical lipids play a critical role in regulating mitochondrial morphology and fission. However, the mechanisms by which proteins and lipids cooperate to execute fission have not been quantitatively investigated. Here, we computationally model the squeezing of the largely tubular mitochondrion and show that proteins and conical lipids can act synergistically to trigger buckling instability and achieve extreme constriction. More remarkably, the study reveals that the conical lipids can act with different fission proteins to induce hierarchical instabilities and create increasingly narrow and stable constrictions. We reason that this geometric plasticity imparts significant robustness to the fission reaction by arresting the elastic tendency of the membrane to rebound during protein polymerization and depolymerization cycles. Our in vitro study validates protein–lipid cooperativity in constricting membrane tubules. Overall, our work presents a general mechanism for achieving drastic topological remodeling in cellular membranes. 

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