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1.
Nat Commun ; 15(1): 4316, 2024 May 21.
Article in English | MEDLINE | ID: mdl-38773095

ABSTRACT

As signalling organelles, cilia regulate their G protein-coupled receptor content by ectocytosis, a process requiring localised actin dynamics to alter membrane shape. Photoreceptor outer segments comprise an expanse of folded membranes (discs) at the tip of highly-specialised connecting cilia, into which photosensitive GPCRs are concentrated. Discs are shed and remade daily. Defects in this process, due to mutations, cause retinitis pigmentosa (RP). Whilst fundamental for vision, the mechanism of photoreceptor disc generation is poorly understood. Here, we show membrane deformation required for disc genesis is driven by dynamic actin changes in a process akin to ectocytosis. We show RPGR, a leading RP gene, regulates actin-binding protein activity central to this process. Actin dynamics, required for disc formation, are perturbed in Rpgr mouse models, leading to aborted membrane shedding as ectosome-like vesicles, photoreceptor death and visual loss. Actin manipulation partially rescues this, suggesting the pathway could be targeted therapeutically. These findings help define how actin-mediated dynamics control outer segment turnover.


Subject(s)
Actins , Eye Proteins , Retinitis Pigmentosa , Animals , Actins/metabolism , Mice , Retinitis Pigmentosa/metabolism , Retinitis Pigmentosa/genetics , Eye Proteins/metabolism , Eye Proteins/genetics , Cilia/metabolism , Humans , Retinal Photoreceptor Cell Outer Segment/metabolism , Mice, Knockout , Mice, Inbred C57BL , Cell Membrane/metabolism
2.
Elife ; 132024 May 07.
Article in English | MEDLINE | ID: mdl-38712822

ABSTRACT

Pancreatic ductal adenocarcinoma carries a dismal prognosis, with high rates of metastasis and few treatment options. Hyperactivation of KRAS in almost all tumours drives RAC1 activation, conferring enhanced migratory and proliferative capacity as well as macropinocytosis. Macropinocytosis is well understood as a nutrient scavenging mechanism, but little is known about its functions in trafficking of signalling receptors. We find that CYRI-B is highly expressed in pancreatic tumours in a mouse model of KRAS and p53-driven pancreatic cancer. Deletion of Cyrib (the gene encoding CYRI-B protein) accelerates tumourigenesis, leading to enhanced ERK and JNK-induced proliferation in precancerous lesions, indicating a potential role as a buffer of RAC1 hyperactivation in early stages. However, as disease progresses, loss of CYRI-B inhibits metastasis. CYRI-B depleted tumour cells show reduced chemotactic responses to lysophosphatidic acid, a major driver of tumour spread, due to impaired macropinocytic uptake of the lysophosphatidic acid receptor 1. Overall, we implicate CYRI-B as a mediator of growth and signalling in pancreatic cancer, providing new insights into pathways controlling metastasis.


Pancreatic cancer is an aggressive disease with limited treatment options. It is also associated with high rates of metastasis ­ meaning it spreads to other areas of the body. Environmental pressures, such as a lack of the nutrients metastatic cancer cells need to grow and divide, can change how the cells behave. Understanding the changes that allow cancer cells to respond to these pressures could reveal new treatment options for pancreatic cancer. When nutrients are scarce, metastatic cancer cells can gather molecules and nutrients by capturing large amounts of the fluid that surrounds them using a mechanism called macropinocytosis. They can also migrate to areas of the body with higher nutrient levels, through a process called chemotaxis. This involves cells moving towards areas with higher levels of certain molecules. For example, cancer cells migrate towards high levels of a lipid called lysophosphatidic acid, which promotes their growth and survival. A newly discovered protein known as CYRI-B has recently been shown to regulate how cells migrate and take up nutrients. It also interacts with proteins known to be involved in pancreatic cancer progression. Therefore, Nikolaou et al. set out to investigate whether CYRI-B also plays a role in metastatic pancreatic cancer. Experiments in a mouse model of pancreatic cancer showed that CYRI-B levels were high in pancreatic tumour cells. And when the gene for CYRI-B was removed from the tumour cells, they did not metastasise. Further analysis revealed that CYRI-B controls uptake and processing of nutrients and other signalling molecules through macropinocytosis. In particular, it ensures uptake of the receptor for lysophosphatidic acid, allowing the metastatic cancer cells to migrate. The findings of Nikolaou et al. reveal that CYRI-B is involved in metastasis of cancer cells in a mouse model of pancreatic cancer. This new insight into how metastasis is controlled could help to identify future targets for treatments that aim to prevent pancreatic cancer cells spreading to distant sites.


Subject(s)
Pancreatic Neoplasms , Pinocytosis , Receptors, Lysophosphatidic Acid , Animals , Humans , Mice , Carcinoma, Pancreatic Ductal/metabolism , Carcinoma, Pancreatic Ductal/pathology , Carcinoma, Pancreatic Ductal/genetics , Cell Line, Tumor , Cell Proliferation , Disease Models, Animal , Neoplasm Metastasis , Pancreatic Neoplasms/metabolism , Pancreatic Neoplasms/pathology , Pancreatic Neoplasms/genetics , Proto-Oncogene Proteins p21(ras)/metabolism , Proto-Oncogene Proteins p21(ras)/genetics , Receptors, Lysophosphatidic Acid/metabolism , Receptors, Lysophosphatidic Acid/genetics
3.
Open Biol ; 14(3): 230376, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38503329

ABSTRACT

Fascin-1-mediated actin-bundling activity is central to the generation of plasma membrane protrusions required for cell migration. Dysregulated formation of cellular protrusions is observed in metastatic cancers, where they are required for increased invasiveness, and is often correlated with increased Fascin-1 abundance. Therefore, there is interest in generating therapeutic Fascin-1 inhibitors. We present the identification of Nb 3E11, a nanobody inhibitor of Fascin-1 actin-bundling activity and filopodia formation. The crystal structure of the Fascin-1/Nb 3E11 complex reveals the structural mechanism of inhibition. Nb 3E11 occludes an actin-binding site on the third ß-trefoil domain of Fascin-1 that is currently not targeted by chemical inhibitors. Binding of Nb 3E11 to Fascin-1 induces a conformational change in the adjacent domains to stabilize Fascin-1 in an inhibitory state similar to that adopted in the presence of small-molecule inhibitors. Nb 3E11 could be used as a tool inhibitor molecule to aid in the development of Fascin-1 targeted therapeutics.


Subject(s)
Actins , Carrier Proteins , Microfilament Proteins , Pseudopodia , Actins/metabolism , Pseudopodia/metabolism , Protein Binding , Cell Movement
4.
Cells ; 13(4)2024 Feb 06.
Article in English | MEDLINE | ID: mdl-38391912

ABSTRACT

Platelet function at vascular injury sites is tightly regulated through the actin cytoskeleton. The Wiskott-Aldrich syndrome protein-family verprolin-homologous protein (WAVE)-regulatory complex (WRC) activates lamellipodia formation via ARP2/3, initiated by GTP-bound RAC1 interacting with the WRC subunit CYFIP1. The protein FAM49b (Family of Unknown Function 49b), also known as CYRI-B (CYFIP-Related RAC Interactor B), has been found to interact with activated RAC1, leading to the negative regulation of the WRC in mammalian cells. To investigate the role of FAM49b in platelet function, we studied platelet-specific Fam49b-/--, Cyfip1-/--, and Cyfip1/Fam49b-/--mice. Platelet counts and activation of Fam49b-/- mice were comparable to those of control mice. On fully fibrinogen-coated surfaces, Fam49b-/--platelets spread faster with an increased mean projected cell area than control platelets, whereas Cyfip1/Fam49b-/--platelets did not form lamellipodia, phenocopying the Cyfip1-/--platelets. However, Fam49b-/--platelets often assumed a polarized shape and were more prone to migrate on fibrinogen-coated surfaces. On 2D structured micropatterns, however, Fam49b-/--platelets displayed reduced spreading, whereas spreading of Cyfip1-/-- and Cyfip1/Fam49b-/--platelets was enhanced. In summary, FAM49b contributes to the regulation of morphology and migration of spread platelets, but to exert its inhibitory effect on actin polymerization, the functional WAVE complex must be present.


Subject(s)
Carrier Proteins , rac1 GTP-Binding Protein , Animals , Mice , Actin Cytoskeleton/metabolism , Adaptor Proteins, Signal Transducing/metabolism , Blood Platelets/metabolism , Carrier Proteins/metabolism , Fibrinogen/metabolism , Mammals/metabolism , rac1 GTP-Binding Protein/metabolism
5.
J Pathol ; 262(4): 454-466, 2024 04.
Article in English | MEDLINE | ID: mdl-38229581

ABSTRACT

MAP4K4 is a serine/threonine kinase of the STE20 family involved in the regulation of actin cytoskeleton dynamics and cell motility. It has been proposed as a target of angiogenesis and inhibitors show potential in cardioprotection. MAP4K4 also mediates cell invasion in vitro, is overexpressed in various types of cancer, and is associated with poor patient prognosis. Recently, MAP4K4 has been shown to be overexpressed in pancreatic cancer, but its role in tumour initiation, progression, and metastasis is unknown. Here, using the KrasG12D Trp53R172H Pdx1-Cre (KPC) mouse model of pancreatic ductal adenocarcinoma (PDAC), we show that deletion of Map4k4 drives tumour initiation and progression. Moreover, we report that the acceleration of tumour onset is also associated with an overactivation of ERK and AKT, two major downstream effectors of KRAS, in vitro and in vivo. In contrast to the accelerated tumour onset caused by loss of MAP4K4, we observed a reduction in metastatic burden with both the KPC model and in an intraperitoneal transplant assay indicating a major role of MAP4K4 in metastatic seeding. In summary, our study sheds light on the dichotomous role of MAP4K4 in the initiation of PDAC onset, progression, and metastatic dissemination. It also identifies MAP4K4 as a possible druggable target against pancreatic cancer spread, but with the caveat that targeting MAP4K4 might accelerate early tumorigenesis. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.


Subject(s)
Carcinoma, Pancreatic Ductal , Pancreatic Neoplasms , Animals , Mice , Humans , Proto-Oncogene Proteins c-akt/metabolism , Proto-Oncogene Proteins p21(ras)/genetics , Proto-Oncogene Proteins p21(ras)/metabolism , MAP Kinase Signaling System , Cell Line, Tumor , Pancreatic Neoplasms/pathology , Carcinoma, Pancreatic Ductal/pathology , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Serine , Intracellular Signaling Peptides and Proteins/metabolism
6.
Cell Rep ; 42(12): 113554, 2023 12 26.
Article in English | MEDLINE | ID: mdl-38100355

ABSTRACT

Cell invasion is a multi-step process, initiated by the acquisition of a migratory phenotype and the ability to move through complex 3D extracellular environments. We determine the composition of cell-matrix adhesion complexes of invasive breast cancer cells in 3D matrices and identify an interaction complex required for invasive migration. ßPix and myosin18A (Myo18A) drive polarized recruitment of non-muscle myosin 2A (NM2A) to adhesion complexes at the tips of protrusions. Actomyosin force engagement then displaces the Git1-ßPix complex from paxillin, establishing a feedback loop for adhesion maturation. We observe active force transmission to the nucleus during invasive migration that is needed to pull the nucleus forward. The recruitment of NM2A to adhesions creates a non-muscle myosin isoform gradient, which extends from the protrusion to the nucleus. We postulate that this gradient facilitates coupling of cell-matrix interactions at the protrusive cell front with nuclear movement, enabling effective invasive migration and front-rear cell polarity.


Subject(s)
Actin Cytoskeleton , Actomyosin , Feedback , Cell Movement/physiology , Actomyosin/metabolism , Actin Cytoskeleton/metabolism , Myosins/metabolism , Cell Adhesion/physiology , Extracellular Matrix/metabolism
7.
Pathol Res Pract ; 251: 154836, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37832352

ABSTRACT

BACKGROUND: The actin regulatory protein fascin (FSCN1) and epithelial mesenchymal transition (EMT) transcription factor (TF) SLUG/SNAI2 have been shown to be expressed in PDAC and its precursor lesions (pancreatic intraepithelial neoplasia (PanIN), graded 1-3) in in vitro and murine in vivo studies. Our aim was to investigate the expression of FSCN1 and EMT-TFs and their association with survival in human PanIN and PDAC. METHODS: Expression was investigated in silico using TCGA PanCancer Atlas data (177 PDAC samples with mRNA data) and immunohistochemical staining of a tissue microarray (TMA) (59 PDAC patients). RESULTS: High FSCN1 expression was associated with poorer overall survival (p = 0.02) in the TCGA data. EMT-TF expression was not associated with survival, however FSCN1 expression correlated with that of the EMT-TFs SLUG/SNAI2 (rho = 0.49, p < 0.001) and TWIST1 (rho = 0.52, p < 0.001). TMA IHC showed low expression of SNAI2 and TWIST1 in normal ductal epithelium, while FSCN1 was not expressed. SNAI2 increased slightly in PanIN1-2, then decreased in higher grade lesions. TWIST1 increased in PanIN2-3 and was retained in PDAC. FSCN1 was increasingly expressed from PanIN2 onwards. SNAI2 and TWIST1 expression positively correlated in all grades of PanIN and PDAC (rho = 0.52, p < 0.001). FSCN1 correlated positively with SNAI2 in PanIN1 (rho = 0.56, p < 0.01). CONCLUSIONS: Increased expression of EMT-TFs in low-grade PanIN followed by FSCN1 in PanIN3 and PDAC suggests EMT-TFs may trigger FSCN1 expression and are potential early diagnostic markers. FSCN1 expression correlated with overall survival in PDAC and may have value as a prognostic marker.


Subject(s)
Carcinoma in Situ , Carcinoma, Pancreatic Ductal , Pancreatic Neoplasms , Humans , Carcinoma in Situ/pathology , Carcinoma, Pancreatic Ductal/pathology , Carrier Proteins , Epithelial-Mesenchymal Transition/genetics , Microfilament Proteins/metabolism , Pancreatic Neoplasms/pathology , Transcription Factors/metabolism
8.
Sci Rep ; 13(1): 9526, 2023 06 12.
Article in English | MEDLINE | ID: mdl-37308549

ABSTRACT

The platelet specific integrin αIIbß3 mediates platelet adhesion, aggregation and plays a central role in thrombosis and hemostasis. In resting platelets, αIIbß3 is expressed on the membrane surface and in intracellular compartments. Upon activation, the number of surface-expressed αIIbß3 is increased by the translocation of internal granule pools to the plasma membrane. The WASH complex is the major endosomal actin polymerization-promoting complex and has been implicated in the generation of actin networks involved in endocytic trafficking of integrins in other cell types. The role of the WASH complex and its subunit Strumpellin in platelet function is still unknown. Here, we report that Strumpellin-deficient murine platelets display an approximately 20% reduction in integrin αIIbß3 surface expression. While exposure of the internal αIIbß3 pool after platelet activation was unaffected, the uptake of the αIIbß3 ligand fibrinogen was delayed. The number of platelet α-granules was slightly but significantly increased in Strumpellin-deficient platelets. Quantitative proteome analysis of isolated αIIbß3-positive vesicular structures revealed an enrichment of protein markers, which are associated with the endoplasmic reticulum, Golgi complex and early endosomes in Strumpellin-deficient platelets. These results point to a so far unidentified role of the WASH complex subunit Strumpellin in integrin αIIbß3 trafficking in murine platelets.


Subject(s)
Integrin alpha2 , Integrin beta3 , Intracellular Signaling Peptides and Proteins , Animals , Mice , Blood Platelets/metabolism , Integrin alpha2/metabolism , Integrin beta3/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Megakaryocytes/metabolism , Mice, Knockout
9.
Methods Mol Biol ; 2645: 189-209, 2023.
Article in English | MEDLINE | ID: mdl-37202620

ABSTRACT

Renewable and scalable human liver tissue platforms are a powerful tool to study organ physiology and model diseases, such as cancer. Stem cell-derived models provide an alternative to cell lines, which can display limited relevance to primary cells and tissue. Historically, two-dimensional (2D) cultures have been used to model liver biology as they are easy to scale and deploy. However, 2D liver models lack functional diversity and phenotypic stability in long-term culture. To address those issues, protocols for generating the three-dimensional (3D) tissue aggregates have been developed. Here, we describe a methodology to generate 3D liver spheres from pluripotent stem cells. Liver spheres are composed of three key liver cell types (hepatic progenitor cells, endothelial cells, and hepatic stellate cells) and have been used to study human cancer cell metastasis.


Subject(s)
Neoplasms , Pluripotent Stem Cells , Humans , Endothelial Cells , Cell Culture Techniques/methods , Liver , Hepatocytes/metabolism , Cell Differentiation , Neoplasms/metabolism
10.
Nat Cell Biol ; 25(3): 375-376, 2023 03.
Article in English | MEDLINE | ID: mdl-36918690

Subject(s)
Actins , Cytoskeleton
11.
Biochem Soc Trans ; 51(2): 579-585, 2023 04 26.
Article in English | MEDLINE | ID: mdl-36892409

ABSTRACT

Cells use actin-based protrusions not only to migrate, but also to sample their environment and take up liquids and particles, including nutrients, antigens and pathogens. Lamellipodia are sheet-like actin-based protrusions involved in sensing the substratum and directing cell migration. Related structures, macropinocytic cups, arise from lamellipodia ruffles and can take in large gulps of the surrounding medium. How cells regulate the balance between using lamellipodia for migration and macropinocytosis is not yet well understood. We recently identified CYRI proteins as RAC1-binding regulators of the dynamics of lamellipodia and macropinocytic events. This review discusses recent advances in our understanding of how cells regulate the balance between eating and walking by repurposing their actin cytoskeletons in response to environmental cues.


Subject(s)
Actin Cytoskeleton , Actins , Actins/metabolism , Cell Movement , Actin Cytoskeleton/metabolism , Cell Membrane Structures/metabolism , Pseudopodia/metabolism , Walking
12.
Pigment Cell Melanoma Res ; 36(1): 71-77, 2023 01.
Article in English | MEDLINE | ID: mdl-36412082

ABSTRACT

Genetic approaches that allow lineage tracing are essential to our future understanding of melanocytes and melanoma. To date, the approaches used to label melanocytes in mice have relied on random integration of transgenes driven by the promoters of the Tyrosinase and Dopachrome tautomerase genes, knock-in to the Dopachrome tautomerase locus or knock-in to the Mlana locus in a bacterial artificial chromosome. These strategies result in expression in other tissues such as telencephalon and other cell types such as nerves. Here we used homologous recombination in mouse embryonic stem cells to generate a targeted multicistronic allele of the Pmel locus that drives melanocyte-specific expression of CreERT2, nuclear localised H2B-Cerulean and membrane localised marcks-mKate2 allowing live imaging of melanocytes and activation of other conditional alleles. We combined this allele with R26R-EYFP mice allowing induction of EYFP expression on administration of tamoxifen or its metabolite 4-OHT. The fluorescent proteins H2B-Cerulean and marcks-mKate2 label the cell nucleus and plasma membrane respectively allowing live imaging and FACS isolation of melanoblasts and melanocytes as well as serving to provide an internal control allowing estimation of recombination efficiency after administration of tamoxifen. We demonstrate the utility of the transgene in embryonic and adult tissues.


Subject(s)
Melanocytes , Melanoma , Mice , Animals , Mice, Transgenic , Alleles , Melanocytes/metabolism , Melanoma/metabolism , Tamoxifen/metabolism , Tamoxifen/pharmacology
13.
J Cell Sci ; 135(24)2022 12 15.
Article in English | MEDLINE | ID: mdl-36546396

ABSTRACT

Pancreatic cancer is a deadly and highly metastatic disease, although how metastatic lesions establish is not fully understood. A key feature of pancreatic tumours is extensive fibrosis and deposition of extracellular matrix (ECM). While pancreatic cancer cells are programmed by stimuli derived from a stiff ECM, metastasis requires loss of attachment and adaptation to a softer microenvironment at distant sites. Growing evidence suggests that stiff ECM influences pancreatic cancer cell behaviour. Here, we argue that this influence is reversible and that pancreatic cancer cells can be reprogrammed upon sensing soft substrates. Using engineered polyacrylamide hydrogels with tuneable mechanical properties, we show that collagen VI is specifically upregulated in pancreatic cancer cells on soft substrates, due to a lack of integrin engagement. Furthermore, the expression of collagen VI is inversely correlated with mechanosensing and activity of YAP (also known as YAP1), which might be due to a direct or indirect effect on transcription of genes encoding collagen VI. Collagen VI supports migration in vitro and metastasis formation in vivo. Metastatic nodules formed by pancreatic cancer cells lacking Col6a1 display stromal cell-derived collagen VI deposition, suggesting that collagen VI derived from either cancer cells or the stroma is an essential component of the metastatic niche. This article has an associated First Person interview with Vasileios Papalazarou, joint first author of the paper.


Subject(s)
Collagen , Pancreatic Neoplasms , Humans , Collagen/metabolism , Extracellular Matrix/metabolism , Pancreatic Neoplasms/genetics , Pancreatic Neoplasms/pathology , Integrins/metabolism , Tumor Microenvironment , Pancreatic Neoplasms
14.
Bio Protoc ; 12(7): e4367, 2022 Apr 05.
Article in English | MEDLINE | ID: mdl-35530513

ABSTRACT

Macropinocytosis is an evolutionarily conserved process, which is characterized by the formation of membrane ruffles and the uptake of extracellular fluid. We recently demonstrated a role for CYFIP-related Rac1 Interactor (CYRI) proteins in macropinocytosis. High-molecular weight dextran (70kDa or higher) has generally been used as a marker for macropinocytosis because it is too large to fit in smaller endocytic vesicles, such as those of clathrin or caveolin-mediated endocytosis. Through the use of an image-based dextran uptake assay, we showed that cells lacking CYRI proteins internalise less dextran compared to their wild-type counterparts. Here, we will describe a step-by-step experimentation procedure to detect internalised dextran in cultured cells, and an image pipeline to analyse the acquired images, using the open-access software ImageJ/Fiji. This protocol is detailed yet simple and easily adaptable to different treatment conditions, and the analysis can also be automated for improved processing speed.

15.
Nat Cell Biol ; 23(11): 1111-1112, 2021 11.
Article in English | MEDLINE | ID: mdl-34737441
16.
Cell Rep ; 36(11): 109689, 2021 09 14.
Article in English | MEDLINE | ID: mdl-34525350

ABSTRACT

Assessing drug response within live native tissue provides increased fidelity with regards to optimizing efficacy while minimizing off-target effects. Here, using longitudinal intravital imaging of a Rac1-Förster resonance energy transfer (FRET) biosensor mouse coupled with in vivo photoswitching to track intratumoral movement, we help guide treatment scheduling in a live breast cancer setting to impair metastatic progression. We uncover altered Rac1 activity at the center versus invasive border of tumors and demonstrate enhanced Rac1 activity of cells in close proximity to live tumor vasculature using optical window imaging. We further reveal that Rac1 inhibition can enhance tumor cell vulnerability to fluid-flow-induced shear stress and therefore improves overall anti-metastatic response to therapy during transit to secondary sites such as the lung. Collectively, this study demonstrates the utility of single-cell intravital imaging in vivo to demonstrate that Rac1 inhibition can reduce tumor progression and metastases in an autochthonous setting to improve overall survival.


Subject(s)
Biosensing Techniques/methods , Breast Neoplasms/pathology , rac1 GTP-Binding Protein/metabolism , Aminoquinolines/pharmacology , Animals , Breast Neoplasms/diagnostic imaging , Cell Line, Tumor , Cell Movement/drug effects , Cell Survival/drug effects , Female , Fluorescence Resonance Energy Transfer , Humans , Lung Neoplasms/diagnostic imaging , Lung Neoplasms/pathology , Lung Neoplasms/secondary , Mice , Mice, Inbred BALB C , Pyrimidines/pharmacology , Shear Strength , Signal Transduction , rac1 GTP-Binding Protein/antagonists & inhibitors
17.
J Cell Biol ; 220(8)2021 08 02.
Article in English | MEDLINE | ID: mdl-34264264

ABSTRACT

The ARP2/3 complex promotes branched actin networks, but the importance of specific subunit isoforms is unclear. In this issue, Galloni, Carra, et al. (2021. J. Cell Biol. https://doi.org/10.1083/jcb.202102043) show that MICAL2 mediates methionine oxidation of ARP3B, thus destabilizing ARP2/3 complexes and leading to disassembly of branched actin filaments.


Subject(s)
Actin-Related Protein 2-3 Complex , Actins , Actin Cytoskeleton , Actin-Related Protein 2-3 Complex/genetics
18.
J Cell Biol ; 220(9)2021 09 06.
Article in English | MEDLINE | ID: mdl-34165494

ABSTRACT

The Scar/WAVE complex drives actin nucleation during cell migration. Interestingly, the same complex is important in forming membrane ruffles during macropinocytosis, a process mediating nutrient uptake and membrane receptor trafficking. Mammalian CYRI-B is a recently described negative regulator of the Scar/WAVE complex by RAC1 sequestration, but its other paralogue, CYRI-A, has not been characterized. Here, we implicate CYRI-A as a key regulator of macropinosome formation and integrin internalization. We find that CYRI-A is transiently recruited to nascent macropinosomes, dependent on PI3K and RAC1 activity. CYRI-A recruitment precedes RAB5A recruitment but follows sharply after RAC1 and actin signaling, consistent with it being a local inhibitor of actin polymerization. Depletion of both CYRI-A and -B results in enhanced surface expression of the α5ß1 integrin via reduced internalization. CYRI depletion enhanced migration, invasion, and anchorage-independent growth in 3D. Thus, CYRI-A is a dynamic regulator of macropinocytosis, functioning together with CYRI-B to regulate integrin trafficking.


Subject(s)
Endosomes/metabolism , Integrin alpha5beta1/genetics , Intracellular Signaling Peptides and Proteins/genetics , Mitochondrial Proteins/genetics , Pinocytosis/genetics , Wiskott-Aldrich Syndrome Protein Family/genetics , Actins/genetics , Actins/metabolism , Animals , COS Cells , Cell Line, Tumor , Cell Movement , Cell Proliferation , Chlorocebus aethiops , Endosomes/pathology , Endosomes/ultrastructure , Gene Expression Regulation , HEK293 Cells , Humans , Integrin alpha5beta1/metabolism , Intracellular Signaling Peptides and Proteins/metabolism , Mitochondrial Proteins/metabolism , Osteoblasts/metabolism , Osteoblasts/pathology , Phosphatidylinositol 3-Kinase/genetics , Phosphatidylinositol 3-Kinase/metabolism , Polymerization , Protein Transport , Signal Transduction , Wiskott-Aldrich Syndrome Protein Family/metabolism , rab5 GTP-Binding Proteins/genetics , rab5 GTP-Binding Proteins/metabolism , rac1 GTP-Binding Protein/genetics , rac1 GTP-Binding Protein/metabolism
19.
Dis Model Mech ; 14(4)2021 04 01.
Article in English | MEDLINE | ID: mdl-33973625

ABSTRACT

Dissemination of malignant cells from primary tumours to metastatic sites is a key step in cancer progression. Disseminated tumour cells preferentially settle in specific target organs, and the success of such metastases depends on dynamic interactions between cancer cells and the microenvironments they encounter at secondary sites. Two emerging concepts concerning the biology of metastasis are that organ-specific microenvironments influence the fate of disseminated cancer cells, and that cancer cell-extracellular matrix interactions have important roles at all stages of the metastatic cascade. The extracellular matrix is the complex and dynamic non-cellular component of tissues that provides a physical scaffold and conveys essential adhesive and paracrine signals for a tissue's function. Here, we focus on how extracellular matrix dynamics contribute to liver metastases - a common and deadly event. We discuss how matrix components of the healthy and premetastatic liver support early seeding of disseminated cancer cells, and how the matrix derived from both cancer and liver contributes to the changes in niche composition as metastasis progresses. We also highlight the technical developments that are providing new insights into the stochastic, dynamic and multifaceted roles of the liver extracellular matrix in permitting and sustaining metastasis. An understanding of the contribution of the extracellular matrix to different stages of metastasis may well pave the way to targeted and effective therapies against metastatic disease.


Subject(s)
Extracellular Matrix/metabolism , Liver Neoplasms/pathology , Models, Biological , Animals , Epithelial-Mesenchymal Transition , Humans , Neoplasm Metastasis , Neoplastic Cells, Circulating/pathology
20.
Curr Opin Cell Biol ; 68: 37-44, 2021 02.
Article in English | MEDLINE | ID: mdl-32977244

ABSTRACT

The Arp2/3 complex orchestrates the formation of branched actin networks at the interface between the cytoplasm and membranes. Although it is widely appreciated that these networks are useful for scaffolding, creating pushing forces and delineating zones at the membrane interface, it has only recently come to light that branched actin networks are mechanosensitive, giving them special properties. Here, we discuss recent advances in our understanding of how Arp2/3-generated actin networks respond to load forces and thus allow cells to create pushing forces in responsive and tuneable ways to effect cellular processes such as migration, invasion, phagocytosis, adhesion and even nuclear and DNA damage repair.


Subject(s)
Actin-Related Protein 2-3 Complex/physiology , Actin Cytoskeleton/metabolism , Animals , Cell Movement , Cell Nucleus/metabolism , Extracellular Matrix/metabolism , Humans , Intercellular Junctions , Mechanotransduction, Cellular , Yeasts
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