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#cytoskeleton

1 post1 participant0 posts today
Public
Rxiv mechanobio

📰 "LUZP1 Regulates Dendritic Spine Maturation and Synaptic Plasticity in the Hippocampal Dentate Gyrus of Mice"
doi.org/doi:10.1523/JNEUROSCI.
pubmed.ncbi.nlm.nih.gov/401805
#Cytoskeleton #Dynamics

Journal of Neuroscience · LUZP1 Regulates Dendritic Spine Maturation and Synaptic Plasticity in the Hippocampal Dentate Gyrus of MiceLeucine zipper protein 1 (LUZP1) functions in the maintenance and dynamics of the cytoskeleton by interacting with actin and microtubules. Deficiency or mutation of LUZP1 is associated with brain developmental disorders, however, its precise role in brain function remains unclear. We showed that LUZP1 localizes to actin and is highly expressed in CaMKIIα-expressing neurons within the mouse hippocampal dentate gyrus. Depletion of LUZP1 impedes dendritic spine maturation, which is characterized by excess immature filopodia and loss of mature mushroom spines both in vitro and in vivo. LUZP1 knockdown reduces spontaneous electrical activity and synaptic plasticity in hippocampal neurons. Conditional deletion of LUZP1 in CaMKIIα-expressing neurons causes impaired learning and memory behavior in mice of both sexes. Mechanistically, LUZP1 control dendritic maturation by directly interacting with filamin A and modulating the Rac1-PAK1 signaling pathway. These findings shed light on the role of LUZP1 in regulating synaptic plasticity and brain function. Significance Statement Unraveling brain development and function is critical for understanding neurological disorders. The discovery of LUZP1 sheds light on cytoskeletal dynamics, crucial for brain health. LUZP1's interaction with actin and its link to brain disorders highlight its neural importance. LUZP1's presence in specific hippocampal neurons, notably CaMKIIα-expressing ones, provides insights into synaptic function. Depletion of LUZP1 hinders dendritic spine maturation, impacting synaptic activity and plasticity, crucial for neural connectivity. The association of LUZP1 with learning impairments upon deletion in neurons emphasizes its role in cognition. Its involvement in the Rac1-PAK1 pathway offers novel insights into dendritic maturation and synaptic plasticity regulation. These discoveries illuminate LUZP1's significant impact on synaptic plasticity and brain function, hinting at potential interventions for LUZP1-associated neurological disorders.
Public
Rxiv mechanobio

📰 "KIF20A cooperates with Myosin II to drive endosomal carriers fission and protein trafficking"
biorxiv.org/content/10.1101/20 #Cytoskeleton #Dynamics #Myosin

bioRxiv · KIF20A cooperates with Myosin II to drive endosomal carriers fission and protein traffickingFormation of membrane transport carrier relies on cytoskeleton coordination, however how microtubules and actin dynamics cooperate is still poorly understood. In this study, we reveal a novel mechanism by which a kinesin, KIF20A, regulates actomyosin and branched actin dynamics in coordination with Myosin II, facilitating the fission of transport intermediates at early endosomes. We demonstrate that KIF20A is required for maintaining endosomal homeostasis as its inhibition results in the enlargement of both early and late endosomes. Moreover, our findings demonstrate that KIF20A is required for the proper trafficking of Transferrin (Tf), and for ensuring the correct plasma membrane localization of β1 Integrin, a key protein that is critical for cell adhesion and migration. Collectively, these results highlight a new pivotal role of KIF20A as a key regulator of endosomal dynamics and function, contributing to metastatic potential. ### Competing Interest Statement The authors have declared no competing interest.
Public
Rxiv mechanobio

📰 "Nonequilibrium polysome dynamics promote chromosome segregation and its coupling to cell growth in Escherichia coli"
doi.org/doi:10.1101/2024.10.08
pubmed.ncbi.nlm.nih.gov/401618
#Cytoskeleton #Dynamics #Cell

bioRxiv · Nonequilibrium polysome dynamics promote chromosome segregation and its coupling to cell growth in Escherichia coliChromosome segregation is essential for cellular proliferation. Unlike eukaryotes, bacteria lack cytoskeleton-based machinery to segregate their chromosomal DNA (nucleoid). The bacterial ParABS system segregates the duplicated chromosomal regions near the origin of replication. However, this function does not explain how bacterial cells partition the rest (bulk) of the chromosomal material. Furthermore, some bacteria, including Escherichia coli, lack a ParABS system. Yet, E. coli faithfully segregates nucleoids across various growth rates. Here, we provide theoretical and experimental evidence that polysome production during chromosomal gene expression helps compact, split, segregate, and position nucleoids in E. coli through out-of-equilibrium dynamics and polysome exclusion from the DNA meshwork, inherently coupling these processes to biomass growth across nutritional conditions. Halting chromosomal gene expression and thus polysome production immediately stops sister nucleoid migration while ensuing polysome depletion gradually reverses nucleoid segregation. Redirecting gene expression away from the chromosome and toward plasmids causes ectopic polysome accumulations that are sufficient to drive aberrant nucleoid dynamics. Cell width enlargement suggest that the proximity of the DNA to the membrane along the radial axis is important to limit the exchange of polysomes across DNA-free regions, ensuring nucleoid segregation along the cell length. Our findings suggest a self-organizing mechanism for coupling nucleoid segregation to cell growth. ### Competing Interest Statement The authors have declared no competing interest.
Public
Rxiv mechanobio

📰 "Microtubule-dependent cell polarity regulates skin-resident macrophage phagocytosis and directed cell migration"
doi.org/doi:10.1101/2025.03.13
pubmed.ncbi.nlm.nih.gov/401618
#CellMigration #Cytoskeleton #Microtubule

bioRxiv · Microtubule-dependent cell polarity regulates skin-resident macrophage phagocytosis and directed cell migrationImmune cells rapidly respond to tissue damage through dynamic properties of the cytoskeleton. How microtubules control immune cell functions during injury responses remains poorly understood. Within skin, tissue-resident macrophages known as Langerhans cells use dynamic dendrites to surveil the epidermis for damage and migrate through a densely packed epithelium to wounds. Here, we use Langerhans cells within the adult zebrafish epidermis as a model to investigate roles for microtubules in immune cell tissue surveillance, phagocytosis, and directed migration. We describe microtubule organization within Langerhans cells, and show that depolymerizing the microtubule cytoskeleton alters dendrite morphology, debris engulfment, and migration efficiency. We find that the microtubule organizing center positions adjacent to engulfed debris and that its position correlates with navigational pathfinding during directed cell migration. Stabilizing microtubules prevents Langerhans cell motility during directed cell migration by impairing navigation around cellular obstacles. Collectively, our work demonstrates requirements for microtubules in the dynamic actions of tissue-resident macrophages during epithelial surveillance and wound repair. ### Competing Interest Statement The authors have declared no competing interest.
Public
Rxiv mechanobio

📰 "Root hair growth phases are coordinated by cytoskeleton, nucleus dynamics and cell mechanics in Arabidopsis"
biorxiv.org/content/10.1101/20 #Cytoskeleton #Dynamics #Cell

bioRxiv · Root hair growth phases are coordinated by cytoskeleton, nucleus dynamics and cell mechanics in ArabidopsisPolar cell growth is a fundamental process across organisms, yet its coordination with nuclear movement and cytoskeleton dynamics remains underexplored. Focusing on Arabidopsis thaliana root hairs, we investigate these processes using high-resolution live imaging within microfluidics-based experiments. By incorporating data on cytoskeletal dynamics, nuclear positioning, and tip growth into a mathematical model, we analyse how their interactions shape the different growth phases that we reveal for the first time in this study. Chemical treatments and mutant analyses further support our model, revealing that timely cytoskeletal changes drive transitions between these growth phases, and correlate with shifts in nuclear movement and morphology. This regulation suggests a microtubule-actin crosstalk in the root hair subapical region. Additionally, we present novel findings on vacuole movement and cell stiffness, further refining our understanding of tip growth dynamics. Collectively, our work provides a comprehensive framework for understanding how transitions between growth phases are orchestrated in plant tip-growing cells. ### Competing Interest Statement The authors have declared no competing interest.
Public
Rxiv mechanobio

📰 "Microtubule-dependent cell polarity regulates skin-resident macrophage phagocytosis and directed cell migration"
biorxiv.org/content/10.1101/20 #CellMigration #Cytoskeleton #Microtubule

bioRxiv · Microtubule-dependent cell polarity regulates skin-resident macrophage phagocytosis and directed cell migrationImmune cells rapidly respond to tissue damage through dynamic properties of the cytoskeleton. How microtubules control immune cell functions during injury responses remains poorly understood. Within skin, tissue-resident macrophages known as Langerhans cells use dynamic dendrites to surveil the epidermis for damage and migrate through a densely packed epithelium to wounds. Here, we use Langerhans cells within the adult zebrafish epidermis as a model to investigate roles for microtubules in immune cell tissue surveillance, phagocytosis, and directed migration. We describe microtubule organization within Langerhans cells, and show that depolymerizing the microtubule cytoskeleton alters dendrite morphology, debris engulfment, and migration efficiency. We find that the microtubule organizing center positions adjacent to engulfed debris and that its position correlates with navigational pathfinding during directed cell migration. Stabilizing microtubules prevents Langerhans cell motility during directed cell migration by impairing navigation around cellular obstacles. Collectively, our work demonstrates requirements for microtubules in the dynamic actions of tissue-resident macrophages during epithelial surveillance and wound repair. ### Competing Interest Statement The authors have declared no competing interest.
Public
mechanochemistry

New preprint from the Balasubramanian lab

"Fluorescent protein tags for human tropomyosin isoform comparison”

doi.org/10.1101/2025.02.25.640

bioRxiv · Fluorescent protein tags for human tropomyosin isoform comparisonTropomyosin is an important actin cytoskeletal protein underpinning processes such as muscle contraction, cell shape and cell division. Defects in tropomyosin function can lead to diseases, including some myopathies and allergies. In cells, tropomyosin molecules form coiled-coil dimers, which then polymerise end-to-end with other dimers for actin association. Tropomyosin is challenging to tag for in vivo fluorescence microscopy without perturbing its polymerisation interfaces. We recently developed a fluorescent tag comprising a forty amino acid flexible linker capable of detecting tropomyosin in S. pombe actin cables and the actomyosin ring, and in patch-like structures that were previously unappreciated. We also used this strategy successfully to tag human TPM2.2, a prominent human muscle isoform. Here, we expand this tool to visualise eight other human tropomyosin isoforms, using mNeonGreen, mCherry and mStayGold tags. All show typical tropomyosin fluorescence, no signs of cytotoxicity and are compatible with super-resolution microscopy. These tools singly or in combination should aid detailed mechanistic investigations of tropomyosin isoforms. ### Competing Interest Statement The authors have declared no competing interest.
#CellBiology#Microscopy#Cytoskeleton
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