Journal Club – September 2023

Featured Articles

  • Eren et al⁠. Structure, 2023.
    HIV-1 Rev is a crucial protein that plays a role in transporting specific viral mRNAs from the nucleus to the cytoplasm, which is essential for the production of viral structural proteins. As it moves between the nucleus and cytoplasm, Rev
    collaborates with various host proteins, leveraging the cell’s machinery for the virus’s benefit. Here, Eren et al. present a detailed 3.5 Å cryo-EM structure of a complex formed between Rev and tubulin. The structure reveals that Rev’s arginine-rich motif (ARM) interacts with specific parts of the tubulin protein. This interaction is similar to that of another protein, kinesin-13, and significantly impacts the stability of microtubules, even in small amounts. When Rev is expressed in specific cell types, it can alter the microtubule structure within the cell. This study uncovers a previously unknown function of the Rev protein in
    regulating the cell’s structural framework.
    Read the article

  • Cisterna et al⁠. bioRxiv 2023.
    This study investigates the role of Profilin 1 (PFN1) in regulating microtubules in cells. PFN1 is already known for its role in actin assembly, but its specific impact on microtubules is not fully understood. The researchers manipulated levels of PFN1, actin filament assembly, and actomyosin contractility to observe their effects on microtubules. They found that reducing any of these factors led to an increase in the number and acetylation of microtubules, especially in neuronal processes. Importantly, these changes were reversible when actomyosin contractility was restored, suggesting that PFN1 primarily regulates microtubules through its action on actin. Altered microtubules due to PFN1 depletion led to significant changes in microtubule-based transport, resembling conditions seen in neurodegenerative diseases. The study concludes that defects in actin dynamics can trigger compensatory responses in other components of the cell’s cytoskeleton, which can have significant implications for cellular function.
    Read the article

  • Grichine et all⁠. Blood Advances 2023.
    Grichine et al. explore the changes in blood platelets’ cytoskeleton and energy production mechanisms when they are activated, particularly during clot formation and retraction. Platelets undergo significant structural changes when activated, requiring a lot of energy. While resting platelets have only 5-8 individual mitochondria and primarily produce energy through oxidative phosphorylation, the study aimed to understand how this changes in activated platelets, which are larger in size. Using expansion microscopy, live imaging, and Focused Ion Beam-Scanning Electron Microscopy, the researchers found that the number of mitochondria increases in activated, spread platelets. They also discovered that mitochondrial fission occurs during platelet activation, which is dependent on Drp1. In Drp1-deficient platelets, the mitochondria are fused rather than separated.
    The study also found that activated platelets shift to a more glycolytic energy production during clot retraction. Drp1-deficient platelets showed a defect in clot retraction, suggesting that mitochondrial fission and the shift to glycolytic energy production are crucial for effective clot retraction.
    Read the article

 

 

Featured Articles

  • Eren et al⁠. Structure, 2023.
    HIV-1 Rev is a crucial protein that plays a role in transporting specific viral mRNAs from the nucleus to the cytoplasm, which is essential for the production of viral structural proteins. As it moves between the nucleus and cytoplasm, Rev collaborates with various host proteins, leveraging the cell’s machinery for the virus’s benefit. Here, Eren et al. present a detailed 3.5 Å cryo-EM structure of a complex formed between Rev and tubulin. The structure reveals that Rev’s arginine-rich motif (ARM) interacts with specific parts of the tubulin protein. This interaction is similar to that of another protein, kinesin-13, and significantly impacts the stability of microtubules, even in small amounts. When Rev is expressed in specific cell types, it can alter the microtubule structure within the cell. This study uncovers a previously unknown function of the Rev protein in regulating the cell’s structural framework. Read the article

  • Cisterna et al⁠. bioRxiv 2023.
    This study investigates the role of Profilin 1 (PFN1) in regulating microtubules in cells. PFN1 is already known for its role in actin assembly, but its specific impact on microtubules is not fully understood. The researchers manipulated levels of PFN1, actin filament assembly, and actomyosin contractility to observe their effects on microtubules. They found that reducing any of these factors led to an increase in the number and acetylation of microtubules, especially in neuronal processes. Importantly, these changes were reversible when actomyosin contractility was restored, suggesting that PFN1 primarily regulates microtubules through its action on actin. Altered microtubules due to PFN1 depletion led to significant changes in microtubule-based transport, resembling conditions seen in neurodegenerative diseases. The study concludes that defects in actin dynamics can trigger compensatory responses in other components of the cell’s cytoskeleton, which can have significant implications for cellular function.
    Read the article

  • Grichine et all⁠. Blood Advances 2023.
    Grichine et al. explore the changes in blood platelets’ cytoskeleton and energy production mechanisms when they are activated, particularly during clot formation and retraction. Platelets undergo significant structural changes when activated, requiring a lot of energy. While resting platelets have only 5-8 individual mitochondria and primarily produce energy through oxidative phosphorylation, the study aimed to understand how this changes in activated platelets, which are larger in size. Using expansion microscopy, live imaging, and Focused Ion Beam-Scanning Electron Microscopy, the researchers found that the number of mitochondria increases in activated, spread platelets. They also discovered that mitochondrial fission occurs during platelet activation, which is dependent on Drp1. In Drp1-deficient platelets, the mitochondria are fused rather than separated. The study also found that activated platelets shift to a more glycolytic energy production during clot retraction. Drp1-deficient platelets showed a defect in clot retraction, suggesting that mitochondrial fission and the shift to glycolytic energy production are crucial for effective clot retraction.
    Read the article

Notable Retractions

Former Stanford president retracts 1999 cell paper.
Read the article.

Extras

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