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Journal of Cell Science Jun 2020Podosomes play crucial roles in macrophage adhesion and migration. Wiskott-Aldrich syndrome protein (WASP; also known as WAS)-mediated actin polymerization is one of the...
Podosomes play crucial roles in macrophage adhesion and migration. Wiskott-Aldrich syndrome protein (WASP; also known as WAS)-mediated actin polymerization is one of the key events initiating podosome formation. Nevertheless, membrane signals to trigger WASP activation at macrophage podosomes remain unclear. Here, we show that phosphatidylinositol (3,4,5)-trisphosphate [PI(3,4,5)P3] lipids are enriched at the podosome and stably recruit WASP rather than the WASP-5KE mutant. Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit β (PIK3CB) is spatially located at the podosome core. Inhibition of PIK3CB and overexpression of phosphatase and tensin homolog (PTEN) impede F-actin polymerization of the podosome. PIK3CB activation is regulated by Abl1 and Src family kinases. At the podosome core, Src and Hck promote the phosphorylation of Tyr488 in the consensus Y-x-x-M motif of Abl1, which enables the association of phosphoinositide 3-kinase (PI3K) regulatory subunits. Knockdown of Abl1 rather than Abl2 suppresses the PI3K/Akt pathway, regardless of Src and Hck activities. Reintroduction of wild-type Abl1 rather than the Abl1-Y488F mutant rescues PI3KR1 recruitment and PI3K activation. When PIK3CB, Abl1 or Src/Hck is suppressed, macrophage podosome formation, matrix degradation and chemotactic migration are inhibited. Thus, Src/Hck-mediated phosphorylation of Abl1 Tyr488 triggers PIK3CB-dependent PI(3,4,5)P3 production and orchestrates the assembly and function of macrophage podosomes.
Topics: Actins; Macrophages; Phosphatidylinositol 3-Kinase; Phosphatidylinositol 3-Kinases; Phosphorylation; Podosomes
PubMed: 32393599
DOI: 10.1242/jcs.234385 -
European Journal of Cell Biology Oct 2014Podosomes are micrometer-sized, circular adhesions formed by cells such as osteoclasts, macrophages, dendritic cells, and endothelial cells. Because of their small size... (Review)
Review
Podosomes are micrometer-sized, circular adhesions formed by cells such as osteoclasts, macrophages, dendritic cells, and endothelial cells. Because of their small size and the lack of methods to visualize individual proteins and protein complexes, podosomes have long been considered a simple two-module structure with a protrusive actin core and a surrounding adhesive ring composed of integrins and cytoskeletal adaptor proteins such as vinculin and talin. In the past decade, the applications of fluorescence based techniques that circumvent the diffraction limit of conventional light microscopy took a major leap forward. Podosomes have been imaged by a variety of these super-resolution methods, and in this concise review we discuss how these super-resolution data have increased our understanding of the podosome ultra-structure and function.
Topics: Animals; Cell Surface Extensions; Humans; Microscopy, Fluorescence; Molecular Imaging
PubMed: 25454791
DOI: 10.1016/j.ejcb.2014.09.002 -
International Review of Cell and... 2021Invadopodia are actin-rich membrane protrusions that facilitate cancer cell dissemination by focusing on proteolytic activity and clearing paths for migration through... (Review)
Review
Invadopodia are actin-rich membrane protrusions that facilitate cancer cell dissemination by focusing on proteolytic activity and clearing paths for migration through physical barriers, such as basement membranes, dense extracellular matrices, and endothelial cell junctions. Invadopodium formation and activity require spatially and temporally regulated changes in actin filament organization and dynamics. About three decades of research have led to a remarkable understanding of how these changes are orchestrated by sequential recruitment and coordinated activity of different sets of actin-binding proteins. In this chapter, we provide an update on the roles of the actin cytoskeleton during the main stages of invadopodium development with a particular focus on actin polymerization machineries and production of pushing forces driving extracellular matrix remodeling.
Topics: Actins; Animals; Humans; Microfilament Proteins; Models, Biological; Morphogenesis; Podosomes; Polymerization
PubMed: 33962752
DOI: 10.1016/bs.ircmb.2021.03.004 -
Journal of Cell Science Dec 2019Podosomes are dynamic adhesion structures formed constitutively by macrophages, dendritic cells and osteoclasts and transiently in a wide variety of cells, such as... (Review)
Review
Podosomes are dynamic adhesion structures formed constitutively by macrophages, dendritic cells and osteoclasts and transiently in a wide variety of cells, such as endothelial cells and megakaryocytes. They mediate numerous functions, including cell-matrix adhesion, extracellular matrix degradation, mechanosensing and cell migration. Podosomes present as micron-sized F-actin cores surrounded by an adhesive ring of integrins and integrin-actin linkers, such as talin and vinculin. In this Review, we highlight recent research that has considerably advanced our understanding of the complex architecture-function relationship of podosomes by demonstrating that the podosome ring actually consists of discontinuous nano-clusters and that the actin network in between podosomes comprises two subsets of unbranched actin filaments, lateral and dorsal podosome-connecting filaments. These lateral and dorsal podosome-connecting filaments connect the core and ring of individual podosomes and adjacent podosomes, respectively. We also highlight recent insights into the podosome cap as a novel regulatory module of actomyosin-based contractility. We propose that these newly identified features are instrumental for the ability of podosomes to generate protrusion forces and to mechanically probe their environment. Furthermore, these new results point to an increasing complexity of podosome architecture and have led to our current view of podosomes as autonomous force generators that drive cell migration.
Topics: Animals; Cell Movement; Endothelial Cells; Humans; Megakaryocytes; Myosin Type II; Podosomes
PubMed: 31836688
DOI: 10.1242/jcs.236828 -
European Journal of Cell Biology Apr 2022Podosomes are highly dynamic actin-rich structures in a variety of cell types, especially monocytic cells. They fulfill multiple functions such as adhesion,... (Review)
Review
Podosomes are highly dynamic actin-rich structures in a variety of cell types, especially monocytic cells. They fulfill multiple functions such as adhesion, mechanosensing, or extracellular matrix degradation, thus allowing cells to detect and respond to a changing environment. These abilities are based on an intricate architecture that enables podosomes to sense mechanical properties of their substratum and to transduce them intracellularly in order to generate an appropriate cellular response. These processes are enabled through the tightly orchestrated interplay of more than 300 different components that are dynamically recruited during podosome formation and turnover. In this review, we discuss the different phases of the podosome life cycle and the current knowledge on regulatory factors that impact on the genesis, activity, dissolution and reemergence of podosomes. We also highlight mechanoregulatory processes that become important during these different stages, on the level of individual podosomes, and also at podosome sub- and superstructures.
Topics: Actins; Podosomes
PubMed: 35334303
DOI: 10.1016/j.ejcb.2022.151218 -
Journal of Cell Science May 2023Rac (herein referring to the Rac family) and Cdc42 are Rho GTPases that regulate the formation of lamellipoda and filopodia, and are therefore crucial in processes such...
Rac (herein referring to the Rac family) and Cdc42 are Rho GTPases that regulate the formation of lamellipoda and filopodia, and are therefore crucial in processes such as cell migration. Relocation-based biosensors for Rac and Cdc42 have not been characterized well in terms of their specificity or affinity. In this study, we identify relocation sensor candidates for both Rac and Cdc42. We compared their (1) ability to bind the constitutively active Rho GTPases, (2) specificity for Rac and Cdc42, and (3) relocation efficiency in cell-based assays. Subsequently, the relocation efficiency was improved by a multi-domain approach. For Rac1, we found a sensor candidate with low relocation efficiency. For Cdc42, we found several sensors with sufficient relocation efficiency and specificity. These optimized sensors enable the wider application of Rho GTPase relocation sensors, which was showcased by the detection of local endogenous Cdc42 activity at assembling invadopodia. Moreover, we tested several fluorescent proteins and HaloTag for their influence on the recruitment efficiency of the Rho location sensor, to find optimal conditions for a multiplexing experiment. This characterization and optimization of relocation sensors will broaden their application and acceptance.
Topics: rho GTP-Binding Proteins; Cell Movement; Podosomes; Pseudopodia
PubMed: 37226883
DOI: 10.1242/jcs.260802 -
Biochimica Et Biophysica Acta.... Apr 2019Extensive in vitro studies have described podosomes as actin-based structures at the plasma membrane, connecting the cell with its extracellular matrix and endowed with... (Review)
Review
Extensive in vitro studies have described podosomes as actin-based structures at the plasma membrane, connecting the cell with its extracellular matrix and endowed with multiple capabilities. Contractile actin-myosin cables assemble them into a network that constitutes a multifaceted cellular superstructure taking different forms - with common characteristics - but manifesting different properties depending on the context of study. Their morphology and their role in cell functioning and behavior are therefore now apprehended in in vivo or in vitro situations relevant to physiological processes. We focus here on three of them, namely: macrophage migration, antigen presentation by dendritic cells and endothelial cell sprouting during angiogenesis to highlight the characteristics of podosomes and their functioning shaped by the microenvironment.
Topics: Antigen Presentation; Cell Membrane; Cell Movement; Dendritic Cells; Endothelium, Vascular; Gene Expression; Macrophages; Neovascularization, Physiologic; Podosomes; Signal Transduction
PubMed: 30594495
DOI: 10.1016/j.bbamcr.2018.12.009 -
Ageing Research Reviews Mar 2023With increasing age, bone tissue undergoes significant alterations in composition, architecture, and metabolic functions, probably causing senile osteoporosis.... (Review)
Review
With increasing age, bone tissue undergoes significant alterations in composition, architecture, and metabolic functions, probably causing senile osteoporosis. Osteoporosis possess the vast majority of bone disease and associates with a reduction in bone mass and increased fracture risk. Bone loss is on account of the disorder in osteoblast-induced bone formation and osteoclast-induced bone resorption. As a unique bone resorptive cell type, mature bone-resorbing osteoclasts exhibit dynamic actin-based cytoskeletal structures called podosomes that participate in cell-matrix adhesions specialized in the degradation of mineralized bone matrix. Podosomes share many of the same molecular constitutions as focal adhesions, but they have a unique structural organization, with a central core abundant in F-actin and encircled by scaffolding proteins, kinases and integrins. Here, we conclude recent advancements in our knowledge of the architecture and the functions of podosomes. We also discuss the regulatory pathways in osteoclast podosomes, providing a reference for future research on the podosomes of osteoclasts and considering podosomes as a therapeutic target for inhibiting bone resorption.
Topics: Humans; Actin Cytoskeleton; Actins; Bone Resorption; Osteoclasts; Podosomes
PubMed: 36621647
DOI: 10.1016/j.arr.2023.101842 -
Cancer Letters Feb 2024Growing evidence has suggested that increased matrix stiffness can significantly strengthen the malignant characteristics of hepatocellular carcinoma (HCC) cells....
Growing evidence has suggested that increased matrix stiffness can significantly strengthen the malignant characteristics of hepatocellular carcinoma (HCC) cells. However, whether and how increased matrix stiffness regulates the formation of invadopodia in HCC cells remain largely unknown. In the study, we developed different experimental systems in vitro and in vivo to explore the effects of matrix stiffness on the formation of invadopodia and its relevant molecular mechanism. Our results demonstrated that increased matrix stiffness remarkably augmented the migration and invasion abilities of HCC cells, upregulated the expressions of invadopodia-associated genes and enhanced the number of invadopodia. Two regulatory pathways contribute to matrix stiffness-driven invadopodia formation together in HCC cells, including direct triggering invadopodia formation through activating integrin β1 or Piezo1/ FAK/Src/Arg/cortactin pathway, and indirect stimulating invadopodia formation through improving EGF production to activate EGFR/Src/Arg/cortactin pathway. Src was identified as the common hub molecule of two synergistic regulatory pathways. Simultaneously, activation of integrin β1/RhoA/ROCK1/MLC2 and Piezo1/Ca/MLCK/MLC2 pathways mediate matrix stiffness-reinforced cell migration. This study uncovers a new mechanism by which mechanosensory pathway and biochemical signal pathway synergistically regulate the formation of invadopodia in HCC cells.
Topics: Humans; Carcinoma, Hepatocellular; Cortactin; Podosomes; Liver Neoplasms; Integrin beta1; Extracellular Matrix; Cell Line, Tumor; Neoplasm Invasiveness; rho-Associated Kinases
PubMed: 38145655
DOI: 10.1016/j.canlet.2023.216597 -
Journal of Cell Science Oct 2020Integrin adhesions are a structurally and functionally diverse family of transmembrane, multi-protein complexes that link the intracellular cytoskeleton to the... (Review)
Review
Integrin adhesions are a structurally and functionally diverse family of transmembrane, multi-protein complexes that link the intracellular cytoskeleton to the extracellular matrix (ECM). The different members of this family, including focal adhesions (FAs), focal complexes, fibrillar adhesions, podosomes and invadopodia, contain many shared scaffolding and signaling 'adhesome' components, as well as distinct molecules that perform specific functions, unique to each adhesion form. In this Hypothesis, we address the pivotal roles of mechanical forces, generated by local actin polymerization or actomyosin-based contractility, in the formation, maturation and functionality of two members of the integrin adhesions family, namely FAs and invadopodia, which display distinct structures and functional properties. FAs are robust and stable ECM contacts, associated with contractile stress fibers, while invadopodia are invasive adhesions that degrade the underlying matrix and penetrate into it. We discuss here the mechanisms, whereby these two types of adhesion utilize a similar molecular machinery to drive very different - often opposing cellular activities, and hypothesize that early stages of FAs and invadopodia assembly use similar biomechanical principles, whereas maturation of the two structures, and their 'adhesive' and 'invasive' functionalities require distinct sources of biomechanical reinforcement.
Topics: Cell Adhesion; Extracellular Matrix; Focal Adhesions; Integrins; Podosomes
PubMed: 33093229
DOI: 10.1242/jcs.244848