scholarly journals Identification of microtubule growth deceleration and its regulation by conserved and novel proteins

2016 ◽  
Vol 27 (9) ◽  
pp. 1479-1487 ◽  
Author(s):  
Benjamin Lacroix ◽  
Joël Ryan ◽  
Julien Dumont ◽  
Paul S. Maddox ◽  
Amy S. Maddox
Keyword(s):  
Dynamic Instability ◽  
Cell Periphery ◽  
Dynamic Parameters ◽  
Cell Type ◽  
Cellular Functions ◽  
Novel Proteins ◽  
Muscle Cell Type ◽  
Rate Deceleration ◽  
Cilia And Flagella ◽  
Growth Deceleration

Microtubules (MTs) are cytoskeletal polymers that participate in diverse cellular functions, including cell division, intracellular trafficking, and templating of cilia and flagella. MTs undergo dynamic instability, alternating between growth and shortening via catastrophe and rescue events. The rates and frequencies of MT dynamic parameters appear to be characteristic for a given cell type. We recently reported that all MT dynamic parameters vary throughout differentiation of a smooth muscle cell type in intact Caenorhabditis elegans. Here we describe local differences in MT dynamics and a novel MT behavior: an abrupt change in growth rate (deceleration) of single MTs occurring in the cell periphery of these cells. MT deceleration occurs where there is a decrease in local soluble tubulin concentration at the cell periphery. This local regulation of tubulin concentration and MT deceleration are dependent on two novel homologues of human cylicin. These novel ORFs, which we name cylc-1 and -2, share sequence homology with stathmins and encode small, very basic proteins containing several KKD/E repeats. The TOG domain–containing protein ZYG-9TOGp is responsible for the faster polymerization rate within the cell body. Thus we have defined two contributors to the molecular regulation for this novel MT behavior.

scholarly journals Tubulin glycylation controls axonemal dynein activity, flagellar beat, and male fertility

Science ◽  
2021 ◽  
Vol 371 (6525) ◽  
pp. eabd4914
Author(s):  
Sudarshan Gadadhar ◽  
Gonzalo Alvarez Viar ◽  
Jan Niklas Hansen ◽  
An Gong ◽  
Aleksandr Kostarev ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Male Fertility ◽  
Electron Tomography ◽  
Structural Basis ◽  
Cellular Functions ◽  
Flagellar Beat ◽  
Cryo Electron Tomography ◽  
Axonemal Dynein ◽  
Dynein Arms ◽  
Cilia And Flagella

Posttranslational modifications of the microtubule cytoskeleton have emerged as key regulators of cellular functions, and their perturbations have been linked to a growing number of human pathologies. Tubulin glycylation modifies microtubules specifically in cilia and flagella, but its functional and mechanistic roles remain unclear. In this study, we generated a mouse model entirely lacking tubulin glycylation. Male mice were subfertile owing to aberrant beat patterns of their sperm flagella, which impeded the straight swimming of sperm cells. Using cryo–electron tomography, we showed that lack of glycylation caused abnormal conformations of the dynein arms within sperm axonemes, providing the structural basis for the observed dysfunction. Our findings reveal the importance of microtubule glycylation for controlled flagellar beating, directional sperm swimming, and male fertility.

scholarly journals Distinct segregation patterns of yeast cell-peripheral proteins uncovered by a method for protein segregatome analysis

2019 ◽  
Vol 116 (18) ◽  
pp. 8909-8918 ◽  
Author(s):  
Shinju Sugiyama ◽  
Motomasa Tanaka
Keyword(s):  
Wall Stress ◽  
Cell Periphery ◽  
Cellular Functions ◽  
Cellular Processes ◽  
Binding Domains ◽  
Peripheral Proteins ◽  
Flow Through ◽  
Membrane Spanning ◽  
Mother Cells ◽  
Er Membrane

Protein segregation contributes to various cellular processes such as polarization, differentiation, and aging. However, the difficulty in global determination of protein segregation hampers our understanding of its mechanisms and physiological roles. Here, by developing a quantitative proteomics technique, we globally monitored segregation of preexisting and newly synthesized proteins during cell division of budding yeast, and identified crucial domains that determine the segregation of cell-peripheral proteins. Remarkably, the proteomic and subsequent microscopic analyses demonstrated that the flow through the bud neck of the proteins that harbor both endoplasmic reticulum (ER) membrane-spanning and plasma membrane (PM)-binding domains is not restricted by the previously suggested ER membrane or PM diffusion barriers but by septin-mediated partitioning of the PM-associated ER (pmaER). Furthermore, the proteomic analysis revealed that although the PM-spanning t-SNARE Sso2 was retained in mother cells, its paralog Sso1 unexpectedly showed symmetric localization. We found that the transport of Sso1 to buds was required for enhancement of polarized cell growth and resistance to cell-wall stress. Taken together, these data resolve long-standing questions about septin-mediated compartmentalization of the cell periphery, and provide new mechanistic insights into the segregation of cell-periphery proteins and their cellular functions.

scholarly journals Infection with Replication-deficient Adenovirus Induces Changes in the Dynamic Instability of Host Cell Microtubules

2006 ◽  
Vol 17 (8) ◽  
pp. 3557-3568 ◽  
Author(s):  
James C. Warren ◽  
Adam Rutkowski ◽  
Lynne Cassimeris
Keyword(s):  
Host Cell ◽  
Dynamic Instability ◽  
Infection Process ◽  
Microtubule Dynamics ◽  
Cell Periphery ◽  
Adenovirus Infection ◽  
Drug Induced ◽  
Infected Cells ◽  
The Stability ◽  
Induced Changes

Adenovirus translocation to the nucleus occurs through a well characterized minus end-directed transport along microtubules. Here, we show that the adenovirus infection process has a significant impact on the stability and dynamic behavior of host cell microtubules. Adenovirus-infected cells had elevated levels of acetylated and detyrosinated microtubules compared with uninfected cells. The accumulation of modified microtubules within adenovirus-infected cells required active RhoA. Adenovirus-induced changes in microtubule dynamics were characterized at the centrosome and at the cell periphery in living cells. Adenovirus infection resulted in a transient enhancement of centrosomal microtubule nucleation frequency. At the periphery of adenovirus-infected cells, the dynamic instability of microtubules plus ends shifted toward net growth, compared with the nearly balanced growth and shortening observed in uninfected cells. In infected cells, microtubules spent more time in growth, less time in shortening, and underwent catastrophes less frequently compared with those in uninfected cells. Drug-induced inhibition of Rac1 prevented most of these virus-induced shifts in microtubule dynamic instability. These results demonstrate that adenovirus infection induces a significant stabilizing effect on host cell microtubule dynamics, which involve, but are not limited to, the activation of the RhoGTPases RhoA and Rac1.

scholarly journals Bistability in the synchronization of actuated microfilaments

2017 ◽  
Vol 836 ◽  
pp. 304-323 ◽  
Author(s):  
Hanliang Guo ◽  
Lisa Fauci ◽  
Michael Shelley ◽  
Eva Kanso
Keyword(s):  
Fluid Transport ◽  
Phase Synchronization ◽  
Biological Fluid ◽  
Building Blocks ◽  
Hydrodynamic Interactions ◽  
Cell Type ◽  
Hydrodynamic Coupling ◽  
Cilia And Flagella ◽  
Driving Torque

Cilia and flagella are essential building blocks for biological fluid transport and locomotion at the micrometre scale. They often beat in synchrony and may transition between different synchronization modes in the same cell type. Here, we investigate the behaviour of elastic microfilaments, protruding from a surface and driven at their base by a configuration-dependent torque. We consider full hydrodynamic interactions among and within filaments and no slip at the surface. Isolated filaments exhibit periodic deformations, with increasing waviness and frequency as the magnitude of the driving torque increases. Two nearby but independently driven filaments synchronize their beating in-phase or anti-phase. This synchrony arises autonomously via the interplay between hydrodynamic coupling and filament elasticity. Importantly, in-phase and anti-phase synchronization modes are bistable and coexist for a range of driving torques and separation distances. These findings are consistent with experimental observations of in-phase and anti-phase synchronization in pairs of cilia and flagella and could have important implications on understanding the biophysical mechanisms underlying transitions between multiple synchronization modes.

scholarly journals The microtubule lattice and plus-end association of Drosophila Mini spindles is spatially regulated to fine-tune microtubule dynamics

2011 ◽  
Vol 22 (22) ◽  
pp. 4343-4361 ◽  
Author(s):  
Joshua D. Currie ◽  
Shannon Stewman ◽  
Gregory Schimizzi ◽  
Kevin C. Slep ◽  
Ao Ma ◽  
...  
Keyword(s):  
Dynamic Instability ◽  
Function Analysis ◽  
Microtubule Dynamics ◽  
Cell Periphery ◽  
Cell Interior ◽  
Microtubule Associated Proteins ◽  
Contact Sites ◽  
Associated Proteins ◽  
Fine Tune

Individual microtubules (MTs) exhibit dynamic instability, a behavior in which they cycle between phases of growth and shrinkage while the total amount of MT polymer remains constant. Dynamic instability is promoted by the conserved XMAP215/Dis1 family of microtubule-associated proteins (MAPs). In this study, we conducted an in vivo structure–function analysis of the Drosophila homologue Mini spindles (Msps). Msps exhibits EB1-dependent and spatially regulated MT localization, targeting to microtubule plus ends in the cell interior and decorating the lattice of growing and shrinking microtubules in the cell periphery. RNA interference rescue experiments revealed that the NH2-terminal four TOG domains of Msps function as paired units and were sufficient to promote microtubule dynamics and EB1 comet formation. We also identified TOG5 and novel inter-TOG linker motifs that are required for targeting Msps to the microtubule lattice. These novel microtubule contact sites are necessary for the interplay between the conserved TOG domains and inter-TOG MT binding that underlies the ability of Msps to promote MT dynamic instability.

scholarly journals Podocyte bioenergetics in the development of diabetic nephropathy: the role of mitochondria

Endocrinology ◽  
2021 ◽  
Author(s):  
Irena Audzeyenka ◽  
Agnieszka Bierżyńska ◽  
Abigail C Lay
Keyword(s):  
Diabetic Nephropathy ◽  
Mitochondrial Function ◽  
Mitochondrial Dynamics ◽  
Signalling Pathways ◽  
Cell Type ◽  
Cellular Functions ◽  
Podocyte Injury ◽  
Underlying Pathogenesis ◽  
Novel Therapeutic

Abstract Diabetic Nephropathy (DN) is the leading cause of kidney failure, with an increasing incidence worldwide. Mitochondrial dysfunction is known to occur in DN and has been implicated in the underlying pathogenesis of disease. These complex organelles have an array of important cellular functions and involvement in signalling pathways; and understanding the intricacies of these responses in health, as well as how they are damaged in disease, is likely to highlight novel therapeutic avenues. A key cell type damaged early in DN is the podocyte and increasing studies have focused on investigating the role of mitochondria in podocyte injury. This review will summarise what is known about podocyte mitochondrial dynamics in DN, with a particular focus on bioenergetic pathways, highlighting key studies in this field and potential opportunities to target, enhance or protect podocyte mitochondrial function in the treatment of DN.

Immunolocalization of cytoplasmic dynein and dynactin subunits in cultured macrophages: enrichment on early endocytic organelles

2001 ◽  
Vol 114 (1) ◽  
pp. 229-240 ◽  
Author(s):  
A. Habermann ◽  
T.A. Schroer ◽  
G. Griffiths ◽  
J.K. Burkhardt
Keyword(s):  
Cytoplasmic Dynein ◽  
Mitochondrial Outer Membrane ◽  
Cell Periphery ◽  
Cell Type ◽  
Double Labeling ◽  
Dynein Intermediate Chain ◽  
Golgi Region ◽  
Early Endosomes ◽  
Single Cell Type ◽  
Specific Membrane

Cytoplasmic dyneins and their cofactor, dynactin, work together to mediate the movement of numerous cargo organelles toward the minus-ends of microtubules. In many cases, there is compelling evidence that dynactin functions in part to attach dyneins to cargo organelles, but this may not always be the case. We have localized three dynactin subunits (Arp1, p62 and p150(Glued)) and two subunits of conventional cytoplasmic dynein (dynein intermediate chain and dynein heavy chain 1) in murine macrophages using immunogold labeling of thawed cryosections. Using stereological techniques, we have quantified the relative distributions of each of these subunits on specific membrane organelles to generate a comprehensive analysis of the distribution of these proteins in a single cell type. Our results show that each of the subunits tested exhibits the same distribution with respect to different membrane organelles, with highest levels present on early endosomes, and lower levels present on later endocytic organelles, the mitochondrial outer membrane, the plasma membrane and vesicles in the Golgi region. An additional pool of punctate dynactin labeling was detected in the cell periphery, in the absence of dynein labeling. Even when examined closely, membrane organelles could not be detected in association with these dynactin-positive sites; however, double labeling with anti-tubulin antibody revealed that at least some of these sites represent the ends of microtubules. The similarities among the labeling profiles with respect to membrane organelles suggest that dynein and dynactin bind to membrane organelles as an obligate unit. In contrast, our results show that dynactin can associate with microtubule ends in the absence of dynein, perhaps providing sites for subsequent organelle and dynein association to form a functional motility complex.

scholarly journals Microtubule structure by cryo-EM: snapshots of dynamic instability

2018 ◽  
Vol 62 (6) ◽  
pp. 737-751 ◽  
Author(s):  
Szymon W. Manka ◽  
Carolyn A. Moores
Keyword(s):  
Conformational Changes ◽  
Structural Model ◽  
Dynamic Instability ◽  
Electron Tomography ◽  
3D Structure ◽  
Cellular Functions ◽  
Microtubule Binding ◽  
Binding Domains ◽  
Binding Partners ◽  
Gtpase Cycle

The development of cryo-electron microscopy (cryo-EM) allowed microtubules to be captured in their solution-like state, enabling decades of insight into their dynamic mechanisms and interactions with binding partners. Cryo-EM micrographs provide 2D visualization of microtubules, and these 2D images can also be used to reconstruct the 3D structure of the polymer and any associated binding partners. In this way, the binding sites for numerous components of the microtubule cytoskeleton—including motor domains from many kinesin motors, and the microtubule-binding domains of dynein motors and an expanding collection of microtubule associated proteins—have been determined. The effects of various microtubule-binding drugs have also been studied. High-resolution cryo-EM structures have also been used to probe the molecular basis of microtubule dynamic instability, driven by the GTPase activity of β-tubulin. These studies have shown the conformational changes in lattice-confined tubulin dimers in response to steps in the tubulin GTPase cycle, most notably lattice compaction at the longitudinal inter-dimer interface. Although work is ongoing to define a complete structural model of dynamic instability, attention has focused on the role of gradual destabilization of lateral contacts between tubulin protofilaments, particularly at the microtubule seam. Furthermore, lower resolution cryo-electron tomography 3D structures are shedding light on the heterogeneity of microtubule ends and how their 3D organization contributes to dynamic instability. The snapshots of these polymers captured using cryo-EM will continue to provide critical insights into their dynamics, interactions with cellular components, and the way microtubules contribute to cellular functions in diverse physiological contexts.

scholarly journals The Spectraplakin Short Stop Is an Actin–Microtubule Cross-Linker That Contributes to Organization of the Microtubule Network

2010 ◽  
Vol 21 (10) ◽  
pp. 1714-1724 ◽  
Author(s):  
Derek A. Applewhite ◽  
Kyle D. Grode ◽  
Darby Keller ◽  
Alireza Dehghani Zadeh ◽  
Kevin C. Slep ◽  
...  
Keyword(s):  
Cross Talk ◽  
Function Analysis ◽  
Cytoskeletal Proteins ◽  
Actin Binding ◽  
Cross Linking ◽  
Cell Periphery ◽  
Cellular Functions ◽  
Microtubule Organization ◽  
Microtubule Network ◽  
Cross Linker

The dynamics of actin and microtubules are coordinated in a variety of cellular and morphogenetic processes; however, little is known about the molecules mediating this cytoskeletal cross-talk. We are studying Short stop (Shot), the sole Drosophila spectraplakin, as a model actin–microtubule cross-linking protein. Spectraplakins are an ancient family of giant cytoskeletal proteins that are essential for a diverse set of cellular functions; yet, we know little about the dynamics of spectraplakins and how they bridge actin filaments and microtubules. In this study we describe the intracellular dynamics of Shot and a structure–function analysis of its role as a cytoskeletal cross-linker. We find that Shot interacts with microtubules using two different mechanisms. In the cell interior, Shot binds growing plus ends through an interaction with EB1. In the cell periphery, Shot associates with the microtubule lattice via its GAS2 domain, and this pool of Shot is actively engaged as a cross-linker via its NH2-terminal actin-binding calponin homology domains. This cross-linking maintains microtubule organization by resisting forces that produce lateral microtubule movements in the cytoplasm. Our results provide the first description of the dynamics of these important proteins and provide key insight about how they function during cytoskeletal cross-talk.

scholarly journals Proteomic and Transcriptomic Profiling Identifies Early Developmentally Regulated Proteins in Dictyostelium Discoideum

Cells ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1187 ◽  
Author(s):  
González-Velasco ◽  
De Las Rivas ◽  
Lacal
Keyword(s):  
Dictyostelium Discoideum ◽  
Proteome Analysis ◽  
Wild Type ◽  
Cellular Functions ◽  
Developmentally Regulated ◽  
Transcriptomic Profiling ◽  
Novel Proteins ◽  
Proteomic Data ◽  
Secondary Messenger ◽  
Substrate Adhesion

Cyclic AMP acts as a secondary messenger involving different cellular functions in eukaryotes. Here, proteomic and transcriptomic profiling has been combined to identify novel early developmentally regulated proteins in eukaryote cells. These proteomic and transcriptomic experiments were performed in Dictyostelium discoideum given the unique advantages that this organism offers as a eukaryotic model for cell motility and as a nonmammalian model of human disease. By comparing whole-cell proteome analysis of developed (cAMP-pulsed) wild-type AX2 cells and an independent transcriptomic analysis of developed wild-type AX4 cells, our results show that up to 70% of the identified proteins overlap in the two independent studies. Among them, we have found 26 proteins previously related to cAMP signaling and identified 110 novel proteins involved in calcium signaling, adhesion, actin cytoskeleton, the ubiquitin-proteasome pathway, metabolism, and proteins that previously lacked any annotation. Our study validates previous findings, mostly for the canonical cAMP-pathway, and also generates further insight into the complexity of the transcriptomic changes during early development. This article also compares proteomic data between parental and cells lacking glkA, a GSK-3 kinase implicated in substrate adhesion and chemotaxis in Dictyostelium. This analysis reveals a set of proteins that show differences in expression in the two strains as well as overlapping protein level changes independent of GlkA.

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