TY - JOUR. T1 - An actin-based protrusion originating from a podosome-enriched region initiates macrophage fusion. AU - Faust, James J.. AU - Balabiyev, Arnat. AU - Heddleston, John M.. AU - Podolnikova, Nataly P.. AU - Baluch, D. Page. AU - Chew, Teng Leong. AU - Ugarova, Tatiana P.. PY - 2019/8/1. Y1 - 2019/8/1. N2 - Macrophage fusion resulting in the formation of multinucleated giant cells occurs in a variety of chronic inflammatory diseases, yet the mechanism responsible for initiating this process is unknown. Here, we used live cell imaging to show that actin-based protrusions at the leading edge initiate macrophage fusion. Phase-contrast video microscopy demonstrated that in the majority of events, short protrusions (∼3 µm) between two closely apposed cells initiated fusion, but occasionally we observed long protrusions (∼12 µm). Using macrophages isolated from LifeAct mice and imaging with lattice light sheet microscopy, we further found that fusion-competent protrusions formed at ...
The major observation of this study is that Myo10 is critically important in a filopodial sensor mechanism that mediates BMP6-guided endothelial cell migration and angiogenesis. Specifically, BMP6 potently induces Myo10 expression, and Myo10, in turn, is required for filopodial formation, cell alignment, directed migration, and tube formation induced by BMP6. Additionally, Myo10 associates with the BMP6 receptor ALK6 and modulates BMP6-dependent endothelial activation by regulating the phosphorylation of Smads, the direct downstream transcriptional targets of the BMP receptors. These experiments extend the previous observation that Myo10 induces nondirectional filopodial formation (Bohil et al., 2006) and indicate that Myo10 serves as a critical integration node in growth factor signaling to facilitate directional probing of the local cellular environment as well as further amplification of growth factor signaling that is relevant to the pathophysiologically critical process of ...
SrGAP3/MEGAP is a member of the Slit-Robo GAP (srGAP) family and is implicated in repulsive axon guidance and neuronal migration through Slit-Robo-mediated signal transduction. Here we describe an inhibitory role of srGAP3 on actin dynamics, specifically on lamellipodia formation. We show that the F-BAR domain localizes srGAP3 to the leading edge of cellular protrusions whereas the SH3 domain is important for focal adhesion targeting. We report on a novel srGAP3 interaction partner, lamellipodin, which localizes with srGAP3 at the leading edge. Live-cell analyses revealed that srGAP3 influences lamellipodin-evoked lamellipodial dynamics. Furthermore, we show that mouse embryonic fibroblasts derived from homozygous srGAP3-knockout embryos display an increased cell area and lamellipodia formation that can be blocked by shRNA-mediated knockdown of lamellipodin.. ...
Detergents and solvents intercalate into a membrane bilayer, alter the membranes stable composition, expand the membrane area and, consequently, decrease membrane tension. A similar approach to expand the membrane area and decrease membrane tension involves the use of fluorescent lipid analogues. Fluorescent lipid analogues can be readily integrated into the outer leaflet of the plasma membrane bilayer of intact cells by spontaneous monomeric lipid transfer. Thus, to further test whether the lamellipodial extension rate is dependent on membrane tension, we have also used fluorescent lipid analogues to expand the membrane area and decrease the membrane tension. When NIH 3T3 fibroblasts are incubated with 5 mM of a Bodipy-labeled sphingomyelin analogue, C5-DMB-SM, and washed, a continuous plasma membrane fluorescence was observed (Fig. 4 a). A similar plasma membrane staining pattern was observed after cells were incubated with an FITC-phosphatidylethanolamine analogue, FITC-PL (Fig. 4 b), or a ...
End capping of cytoskeletal filaments is a key mechanism for regulating filaments elongation and disassembly, as well as the organization of the cytoskeletal architecture. CP binds to the barbed ends of actin filaments to inhibit further elongation and is involved in the formation of branched actin networks in concert with Arp2/3 (Akin and Mullins, 2008). Here, we show that CP plays an essential role in the formation of dendritic spines. In particular, CP knockdown promoted the formation of thin filopodia-like protrusions and inhibited proper spine development. Dendritic spines initiate as filopodia-like protrusions from dendritic shafts, and then convert to mature spine structure with an expanded head (Ziv and Smith, 1996; Yoshihara et al., 2009; Hotulainen and Hoogenraad, 2010). Our data thus suggest that CP may function in the transition of filopodia to spines. CP is known to function in the formation of branched actin networks in lamellipodia in non-neuronal cells, and CP knockdown promotes ...
Intracellular membrane traffic is an essential component of the membrane remodeling that supports lamellipodium extension during cell adhesion. The membrane trafficking pathways that contribute to cell adhesion have not been fully elucidated, but recent studies have implicated SNARE proteins. Here, the functions of several SNAREs (SNAP23, VAMP3, VAMP4 and syntaxin13) are characterized during the processes of cell spreading and membrane ruffling. We report the first description of a SNARE complex, containing SNAP23, syntaxin13 and cellubrevin/VAMP3, that is induced by cell adhesion to an extracellular matrix. Impairing the function of the SNAREs in the complex using inhibitory SNARE domains disrupted the recycling endosome, impeded delivery of integrins to the cell surface, and reduced haptotactic cell migration and spreading. Blocking SNAP23 also inhibited the formation of PMA-stimulated, F-actin-rich membrane ruffles; however, membrane ruffle formation was not significantly altered by inhibition of
Filopodia are finger-like protrusions at the leading edge of migrating cells that play a crucial antennal function during cell motility. It is known that actin filaments are bundled hexagonally and provide rigidity to filopodia by virtue of fascin, which plays a central role in actin filament bundli …
The major finding of the present study was that MIES-mediated spinogenesis in the ARH was necessary for the induction of sexual receptivity. Using a well established cyclical administration of estradiol, once every 4 d to mimic changing estradiol levels during the estrous cycle, we observed that estradiol induced new spines every cycle, which is necessary for estradiol induction of lordosis behavior. The initial action of estradiol was to increase the percentage of spines with filopodial morphology. With increasing time after estradiol priming, the percentage of filopodial spines decreased and mushroom shaped spines increased. This shift in morphology suggested that a population of immature filopodial spines matured to mushroom shapes. This is the natural development of spines, which begin as a filopodial extension of a dendrite. If a synaptic partner is found, receptors will be recruited into the spine membrane as well as scaffold proteins that anchor these receptors at the postsynaptic ...
To obtain insight into the actual mechanism of filopodia initiation, we next analyzed the kinetics of proteins enriched in filopodia, i.e., fascin and VASP. In GFP-fascin-expressing cells, a majority of nascent filopodia (66%, n = 207) first appeared as a bright dot or short rod on a dark background (Fig. 3, B and C). In other cases (34%), a bright dot of GFP-fascin rather suddenly appeared at the tip of a very faint Λ-shaped density in lamellipodia (Fig. 3 C, inset in 16 s frame). Both kinds of nascent fascin dots subsequently elongated to form a filopodium. Fusion of mature fascin-containing filopodia was also frequently seen (Fig. 3 C). Because fascin is present in lamellipodia, albeit at much lower concentration than in filopodia, the faint Λ-shaped fascin densities might correspond to Λ-precursors, suggesting that in the course of filopodia initiation, fascin initially appears at the tips of the Λ-precursors (see next section). In GFP-VASP sequences, we followed the formation of ...
Ena/VASP proteins are actin-associated proteins involved in a range of processes dependent on cytoskeleton remodeling and cell polarity such as axon guidance and lamellipodial and filopodial dynamics in migrating cells. EVL enhances actin nucleation and polymerization.
Using the knowledge gained through the study of Ena/VASP proteins in neuronal migration, the Gertler lab has identified domains within Ena/VASP, called EVH1 and EVH2, important for regulating cell motility. EVH1 is important for binding of proteins containing a specific prolinerich motif and EVH2 is the actin-binding domain. Interaction with the EVH1 domain allows for intracellular targeting of Ena/VASPproteins to receptor/signaling complexes. In their search of the proteome for these domains, the Gertler lab has identified new members of the signal network including lammellipodin (Lpd) that localizes to the leading edge of the cell membrane. In collaboration with the Yaffe lab, the Gertler lab demonstarted that a PH domain within Lpd binds to PI(3,4)P2, a phosphoinisotide produced in response to chemotactic stimulation. In addition, overabundance of Lpd increases the velocity of lamellipodia protrusion. The loss-offunction phenotype observed with Lpd is more severe than the loss of any one of ...
The use of fluorescent probes is one of the most powerful techniques for gaining spatial and temporal knowledge of dynamic events within living cells. Localized increases in the signal from cytosolic fl uo rescent protein constructs, for example, are frequently used as evidence for translocation of proteins to specifi c sites within the cell. However, differences in optical and geometrical properties of cytoplasm can infl uence the recorded intensity of the probe signal. Pseudopodia are especially problematic because their cytoplasmic properties can cause abrupt increases in fl uorescent signal of both GFP and fl uorescein. Investigators should therefore be cautious when interpreting fl uorescence changes within a cell, as these can result from either translocation of the probe or changes in the optical properties of the milieu surrounding the probe.. ...
Serglycin (SRGN), a hematopoietic cell granule proteoglycan, has recently been shown to be overexpressed in several aggressive cancer types. In nasopharyngeal and hepatocellular carcinomas, elevated expression of SRGN was shown to correlate with poor prognosis. However, the molecular mechanisms underlying SRGN-mediated malignancies remain to be explored. In this study, we showed that SRGN is expressed at elevated levels in several lung cancer-derived cell lines. By gain-of-function and loss-of-function approaches, we showed that SRGN promoted NSCLC cell migration. SRGN modulated actin cytoskeleton reorganization and promoted lamellipodia and filopodia formation at the leading edge, facilitating a directional movement during wound closure in NSCLC cells. In consistence, increased levels of activated Rac1, which is required for lamellipodia formation, and CDC42, which is required for filopodia formation, were detected. Increased focal adhesion (FA) turnover, the process of continuous assembly and ...
What is the molecular basis of cell matching? The data above are consistent with matching being based on just two sets of molecular interactions, one allowing A compartment cells to recognise one another and the other performing the same function for P compartment cells. An obvious possibility is that the molecules that mediate cell matching during DC are the same as those that maintain the integrity of these compartments throughout the epithelium. Alternatively, there could be a different set of recognition molecules present exclusively at the leading edge to mediate cell-cell matching. Filopodia are also observed during the healing of wounds in the ventral epithelium and we reasoned that these wound filopodia should exhibit matching behaviour if the molecules that mediate matching are present throughout the epithelium (Wood et al., 2002). Laser wounds were made to the ventral epithelium across en stripes such that the wound edge consisted of both en-RFP-Moesin and ptc-GFP-Moesin cells. On ...
Improved visualization of actin filament branching in lamellipodia. EM of keratocyte or fibroblast lamellipodial actin network after cytochalasin D tr...
The specific function of this gene has not yet been determined; however, the protein it encodes is known to be a major constituent of the ARP2/3 complex. This complex is located at the cell surface and is essential to cell shape and motility through lamellipodial actin assembly and protrusion. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008 ...
Buy Lamellipodial Growth Promoter (CAS 870086-86-5), a cell-permeable fast acting, selective lamellipodial growth promoter. Join researchers using high quality…
Sciences STKE explores the molecular mechanisms that allow cells to navigate and migrate in a particular direction. New models for forming cellular extensions called filopodia that initiate migration, along with methods for analysis of the proteomic differences between the cell body and cellular protrusions (pseudopodia), are highlighted. The processes by which groups of cells, as well as individual cells, navigate in a particular direction are also featured.. ...
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MDNFFTEGTRVWLRENGQHFPSTVNSCAEGIVVFRTDYGQVFTYKQSTITHQKVTAMHPTNEEGVDDMAS 1 - 70 LTELHGGSIMYNLFQRYKRNQIYTYIGSILASVNPYQPIAGLYEPATMEQYSRRHLGELPPHIFAIANEC 71 - 140 YRCLWKRHDNQCILISGESGAGKTESTKLILKFLSVISQQSLELSLKEKTSCVERAILESSPIMEAFGNA 141 - 210 KTVYNNNSSRFGKFVQLNICQKGNIQGGRIVDYLLEKNRVVRQNPGERNYHIFYALLAGLEHEEREEFYL 211 - 280 STPENYHYLNQSGCVEDKTISDQESFREVITAMDVMQFSKEEVREVSRLLAGILHLGNIEFITAGGAQVS 281 - 350 FKTALGRSAELLGLDPTQLTDALTQRSMFLRGEEILTPLNVQQAVDSRDSLAMALYACCFEWVIKKINSR 351 - 420 IKGNEDFKSIGILDIFGFENFEVNHFEQFNINYANEKLQEYFNKHIFSLEQLEYSREGLVWEDIDWIDNG 421 - 490 ECLDLIEKKLGLLALINEESHFPQATDSTLLEKLHSQHANNHFYVKPRVAVNNFGVKHYAGEVQYDVRGI 491 - 560 LEKNRDTFRDDLLNLLRESRFDFIYDLFEHVSSRNNQDTLKCGSKHRRPTVSSQFKDSLHSLMATLSSSN 561 - 630 PFFVRCIKPNMQKMPDQFDQAVVLNQLRYSGMLETVRIRKAGYAVRRPFQDFYKRYKVLMRNLALPEDVR 631 - 700 GKCTSLLQLYDASNSEWQLGKTKVFLRESLEQKLEKRREEEVSHAAMVIRAHVLGFLARKQYRKVLYCVV 701 - 770 IIQKNYRAFLLRRRFLHLKKAAIVFQKQLRGQIARRVYRQLLAEKREQEEKKKQEEEEKKKREEEERERE 771 - 840 ...
An attractive rhizopod with long raylike pseudopodia. This culture contains sufficient material for a class of 30 students. To simplify ordering we provide our protozoan and algae …
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When it comes to water, some materials have a split personality - and some of these materials could hold the key to new ways of harnessing solar energy.read more
Filopodial dynamics are thought to control growth cone guidance, but the types and roles of growth cone dynamics underlying neural circuit assembly in a living brain are largely unknown. To address this issue, we have developed long-term, continuous, fast and high-resolution imaging of growth cone dynamics from axon growth to synapse formation in cultured Drosophila brains. Using R7 photoreceptor neurons as a model we show that >90% of the growth cone filopodia exhibit fast, stochastic dynamics that persist despite ongoing stepwise layer formation. Correspondingly, R7 growth cones stabilize early and change their final position by passive dislocation. N-Cadherin controls both fast filopodial dynamics and growth cone stabilization. Surprisingly, loss of N-Cadherin causes no primary targeting defects, but destabilizes R7 growth cones to jump between correct and incorrect layers. Hence, growth cone dynamics can influence wiring specificity without a direct role in target recognition and implement ...
The endocytic protein dynamin participates in the formation of actin-based membrane protrusions such as podosomes, pseudopodia, and invadopodia, which facilitate cancer cell migration, invasion, and metastasis. However, the role of dynamin in the formation of actin-based membrane protrusions at the leading edge of cancer cells is unclear. In this study, we demonstrate that the ubiquitously expressed dynamin 2 isoform facilitates cell migration by stabilizing F-actin bundles in filopodia of the lung cancer cell line H1299. Pharmacological inhibition of dynamin 2 decreased cell migration and filopodial formation. Furthermore, dynamin 2 and cortactin mostly colocalized along F-actin bundles in filopodia of serum-stimulated H1299 cells by immunofluorescent and immunoelectron microscopy. Knockdown of dynamin 2 or cortactin inhibited the formation of filopodia in serum-stimulated H1299 cells, concomitant with a loss of F-actin bundles. Expression of wild-type cortactin rescued the punctate-like ...
The second messenger cyclic adenosine monophosphate (cAMP) plays a pivotal role in axonal growth and guidance, but its downstream mechanisms remain elusive. In this study, we report that type II protein kinase A (PKA) is highly enriched in growth cone filopodia, and this spatial localization enables the coupling of cAMP signaling to its specific effectors to regulate guidance responses. Disrupting the localization of PKA to filopodia impairs cAMP-mediated growth cone attraction and prevents the switching of repulsive responses to attraction by elevated cAMP. Our data further show that PKA targets protein phosphatase-1 (PP1) through the phosphorylation of a regulatory protein inhibitor-1 (I-1) to promote growth cone attraction. Finally, we find that I-1 and PP1 mediate growth cone repulsion induced by myelin-associated glycoprotein. These findings demonstrate that the spatial localization of type II PKA to growth cone filopodia plays an important role in the regulation of growth cone motility and ...
Filopodia are active tubular structures protruding from the cell surface which allow the cell to sense and interact with the surrounding environment through repetitive elongation-retraction cycles. The mechanical behavior of filopodia has been studied by measuring the traction forces exerted on external substrates.(1) These studies have revealed that internal actin flow can transduce a force across the cell surface through transmembrane linkers like integrins. In addition to the elongation-retraction behavior filopodia also exhibit a buckling and rotational behavior. Filopodial buckling in conjunction with rotation enables the cell to explore a much larger 3-dimensional space and allows for more complex, and possibly stronger, interactions with the external environment.(2) Here we focus on how bending of the filopodial actin dynamically correlates with pulling on an optically trapped microsphere which acts like an external substrate attached to the filopodial tip. There is a clear correlation ...
Not all lamellipodia are created equal: some contain a highly branched actin network, protrude slowly, and are persistent, whereas those with longer, less branched actin filaments are more dynamic. But behind every lamellipodium lies polymerized actin, actin-binding proteins and their regulators, and a protein called lamellipodin (Lpd), and Law et al. now provide new insight into how Lpd controls lamellipodium formation and cell migration.. The Scar/WAVE complex recruits the Arp2/3 complex to the leading edge to regulate actin branching, whereas filament elongation is mediated by Lpd engaging Ena/VASP. But the absence of Ena/VASP has a much less profound effect on lamellipodia than does depleting Lpd, which severely impairs lamellipodia formation, implying that Lpd might regulate additional actin cytoskeleton effectors. Law et al. postulated that the Scar/WAVE complex could be one such candidate, and set about testing their hypothesis.. After showing that Lpd colocalized with the Scar/WAVE ...
Marian Blanca Ramírez from the CSIC in Spain has been studying the effects of LRRK2, a protein associated with Parkinsons disease, on cell motility. A Travelling Fellowship from Journal of Cell Science allowed her to spend time in Prof Maddy Parsons lab at Kings College London, learning new cell migration assays and analysing fibroblasts cultured from individuals with Parkinsons. Read more on her story here. Where could your research take you? The deadline to apply for the current round of Travelling Fellowships is 23rd Feburary 2018. Apply now!. ...
After trauma, regeneration of adult CNS axons is abortive, causing devastating neurologic deficits. Despite progress in rehabilitative care, there is no effective treatment that stimulates axonal growth following injury. Using models with different regenerative capacities, followed by gain- and loss-of-function analysis, we identified profilin 1 (Pfn1) as a coordinator of actin and microtubules (MTs), powering axonal growth and regeneration. In growth cones, Pfn1 increased actin retrograde flow, MT growth speed, and invasion of filopodia by MTs, orchestrating cytoskeletal dynamics toward axonal growth. In vitro, active Pfn1 promoted MT growth in a formin-dependent manner, whereas localization of MTs to growth cone filopodia was facilitated by direct MT binding and interaction with formins. In vivo, Pfn1 ablation limited regeneration of growth-competent axons after sciatic nerve and spinal cord injury. Adeno-associated viral (AAV) delivery of constitutively active Pfn1 to rodents promoted axonal ...
The planar cell polarity (PCP) pathway is a cell-contact mediated mechanism for transmitting polarity information between neighboring cells. PCP core components (Vangl, Fz, Pk, Dsh, and Celsr) are essential for a number of cell migratory events including the posterior migration of facial branchiomotor neurons (FBMNs) in the plane of the hindbrain neuroepithelium in zebrafish and mice. While the mechanism by which PCP signaling polarizes static epithelial cells is well understood, how PCP signaling controls highly dynamic processes like neuronal migration remains an important outstanding question given that PCP components have been implicated in a range of directed cell movements, particularly during vertebrate development. Here, by systematically disrupting PCP signaling in a rhombomere-restricted manner we show that PCP signaling is required both within FBMNs and the hindbrain rhombomere 4 environment at the time when they initiate their migration. Correspondingly, we demonstrate planar ...
Actin polymerization-driven protrusion of the leading edge is a key element of cell motility. The important actin nucleators formins and the Arp2/3 complex are believed to have nonoverlapping functions in inducing actin filament bundles in filopodia and dendritic networks in lamellipodia, respective …
The reggie protein family consists of two proteins, reggie-1 and -2, also called flotillins, which are highly ubiquitous and evolutionarily conserved. Both reggies have been shown to be associated with membrane rafts and are involved in various cellular processes such as T-cell activation, phagocytosis and insulin signalling. However, the exact molecular function of these proteins remains to be determined. In addition, the mechanism of membrane association of reggie-1, which does not contain any transmembrane domain, is not known. In this study, we have produced a fusion protein of reggie-1 with enhanced green fluorescent protein and generated targeted substitutions for the inactivation of putative palmitoylation and myristoylation sites. We were able to show that reggie-1 is myristoylated and multiply palmitoylated and that lipid modifications are necessary for membrane association of reggie-1. Overexpression of reggie-1 resulted in the induction of numerous filopodia-like protrusions in ...
RESULTS Glucose stimulation of β-cells in monolayer significantly increased phosphorylation of FAK and paxillin as well as cell surface area. This coincided with the appearance at the basal membrane of numerous shorter actin filopodial extensions, containing not only phosphorylated paxillin, FAK, and extracellular signal-related kinase 1/2 but also two SNARE proteins, S-nitroso-N-acetylpenicillamine-25 and syntaxin 1, indicating involvement in exocytosis. SR7037 completely inhibited this sequence of events, indicating the requirement of increased cytosolic Ca2+. Furthermore, knockdown of paxillin significantly decreased GSIS, as did inhibition of glucose-induced FAK phosphorylation by compound Y15. Key findings were confirmed in β-cells within the natural setting of islets. ...
Our results provide important insight into the activity of the delta cell in health and pre-diabetes and a possible mechanism for how somatostatin so effectively can exert its potent suppressive effects within the islet of Langerhans, comments senior study-author Professor Per-Olof Berggren of the Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet in Sweden, who is also a visiting professor at Lee Kong Chian School of Medicine, Singapore.. Most delta cells are elongated and have a well-defined cell soma and a filopodia-like structure. Using in vivo optogenetics and high-speed Ca2+ imaging, Per-Olof Berggren and his colleagues show that these filopodia are dynamic structures that contain a secretory machinery, enabling the delta cell to reach large numbers of beta cells within the islet.. This provides for efficient regulation of beta cell activity and is modulated by endogenous IGF-1/VEGF-A signaling. In pre-diabetes, delta cells undergo morphological changes that ...
Prerequisites for all modes of cell migration are cell-substratum interactions that require a sophisticated interplay of membrane dynamics and cytoskeletal rearrangement. Generally, a migrating cell is polarized with a distinct rear and front, from which it extends a wide and thin membrane protrusion- lamellipodium, small fingerlike projections- filopodia, and membrane blisters- blebs. The development of these structures is primarily driven by cytoskeletal contractions and actin polymerization, which are under regulation of several actin-binding proteins and the small GTPases Cdc42, Rac and Rho. Lamellipodia and filopodia are assumed to arise from polymerizing actin, pushing the membrane forward through a Brownian-ratchet mechanism. However, other models based on shifts in the local hydrostatic pressure have also been suggested since blebs are initially void of actin. Recently, fluxes of water through membrane-anchored water channels, aquaporins (AQPs), have been implicated in cell motility, ...
Cytoskeletal motor proteins generate mechanical forces, which drive numerous cellular processes that are essential for life.  Research in the Tyska laboratory is focused on elucidating the function of the actin cytoskeleton and its associated myosin motor proteins.  The context for our studies is the ‘brush border’: an array of actin-based protrusions known as microvilli, which extend from the surface of polarized epithelial cells.  In the gut, the brush border serves as the sole site of nutrient absorption and a barrier to micro-organisms that reside in the lumenal space.  Using an approach that combines biophysics, biochemistry, and cell biology, we are currently studying mechanisms that control microvillar dynamics, morphology, and function. We have also begun to dissect the mechanism of microvillar assembly, which was jumpstarted by our recent elucidation of the entire brush border proteome.  A broad long-term goal is to develop our understanding of molecules and
Cytoskeletal motor proteins generate mechanical forces, which drive numerous cellular processes that are essential for life.  Research in our laboratory is focused on elucidating the function of the actin cytoskeleton and its associated myosin motor proteins.  The context for our studies is the ‘brush border’: an array of actin-based protrusions known as microvilli, which extend from the surface of polarized epithelial cells.  In the gut, the brush border serves as the sole site of nutrient absorption and a barrier to micro-organisms that reside in the lumenal space.  Using an approach that combines biophysics, biochemistry, and cell biology, we are currently studying mechanisms that control microvillar dynamics, morphology, and function. We have also begun to dissect the mechanism of microvillar assembly, which was jump started by our recent elucidation of the entire brush border proteome.  A broad long-term goal is to develop our understanding of molecules and
The extracellular cue signal must be relayed to the cell by Rho family of GTPases, like in the case of filopodia and lammelipodia. This causes local actin polymerization leading to extension of pseudopodium. For a casual reference you can check the wikipedia page on Rho family of GTPases. Cell biology books like MBOTC also have information on mechanism of cytoskeletal dynamics. ...
Electron micrograph of keratocyte or fibroblast lamellipodial actin network after unprotected extraction. All examples demonstrate frequent branching...
The main function of the algorithm is to distribute nascent FAs and determine which of these (and their associated actin filaments) should be selected for maturation/reinforcement. The algorithm currently considers three mechanisms for FA maturation: (i) lamellipodia retraction occurs that would otherwise leave a nascent adhesion outside the cell body (Zaidel-Bar et al. 2003), (ii) membrane tension spanning two FAs exceeds a certain force threshold (Balaban et al. 2001; Bischofs et al. 2009), and (iii) the cell leading edge advances until it encompasses a nascent FA at the protruding tip of an existing filopodium (Schäfer et al. 2009).. FA maturation induced by lamellipodial retraction has been described as a force independent process (Zaidel-Bar et al. 2003). While experimentally well characterized, it is to date not well understood. In contrast, the separate mechanism of tension induced adhesion maturation is clearly force regulated, inherently involving actin SFs that are recruited to the ...
Axonal growth and pathfinding is fundamental to the development and regeneration of the nervous system. Src tyrosine kinase has been implicated in this process; however, the detailed molecula
This protein is associated with nerve growth. It is a major component of the motile growth cones that form the tips of elongating axons. Plays a role in axonal and dendritic filopodia induction ...
00) have been made use of. Secondary antibodies conjugated with Alexa 488, Alexa 568, Alexa 647 and Phalloidin conjugated with Alexa 647 had been from Molecular
One of us predicted previously that the cytoplasmic conclude of CHL1 protein may interact with the cytoskeleton and might induce/control filopodia formation driving tumor cell migration and invasion. CHL1 behavior in CYT387 cancer is as a result strikingly equivalent to L1 and LOX which both perform by way of the actin network. This examine suggested that CHL1 may possibly add to cancer invasive growth and metastasis. It might act possibly as a tumorsuppressor or oncogene. CHL1 consequently could belong to the new rapidly developing category of most cancers genes that could operate possibly as TSGs or oncogenes. For the duration of initial progress CHL1 is not expressed in tumor cells to aid in situ tumor expansion. Re-expression of CHL1 on the edge of the tumor mass and all around tumor vessels could encourage migration and nearby invasive expansion and furthermore enable initiating the metastatic approach. As a result, our final results along with the results that CHL1 was a mutated applicant ...
May help orchestrate cytoskeletal arrangement. Contribute to lamellipodia formation. Overexpression of pleckstrin 2 causes large lamellipodia and peripheral ruffle formation.
A. Growth cone motility and neurite branch formation are activated (+) by Rac1 and Cdc42 and negatively regulated (-) by RhoA. Reelin participates in the regulation of growth cone motility and branching by regulating Rho GTPase activity (B). Filopodia formation and the formation of neuronal transport vesicles, both known to be mediated by Cdc42, are triggered by Reelin. B. Binding of the extracellular matrix protein Reelin to its transmembrane receptors Apoer2 and Vldlr triggers Dab1 tyrosine phosphorylation by Src-family-kinases (SFK). This leads to the activation of several downstream signals, including phosphatidylinositol-3-kinase (PI3K), which activates Cdc42 via an unknown intermediate effector. There is evidence that Reelin also might locally activate Rac1. N-WASP and WAVE link Cdc42 and Rac1 activity to changes of the actin cytoskeleton, leading to increased growth cone motility, filopodia and vesicle formation, and dendritic branching (A). Cdc42 and Rac1 also contribute to activation of ...
Prerequisites for all modes of cell migration are cell-substratum interactions that require a sophisticated interplay of membrane dynamics and cytoskeletal rearrangement. Generally, a migrating cell is polarized with a distinct rear and front, from which it extends a wide and thin membrane protrusion- lamellipodium, small fingerlike projections- filopodia, and membrane blisters- blebs. The development of these structures is primarily driven by cytoskeletal contractions and actin polymerization, which are under regulation of several actin-binding proteins and the small GTPases Cdc42, Rac and Rho. Lamellipodia and filopodia are assumed to arise from polymerizing actin, pushing the membrane forward through a Brownian-ratchet mechanism. However, other models based on shifts in the local hydrostatic pressure have also been suggested since blebs are initially void of actin. Recently, fluxes of water through membrane-anchored water channels, aquaporins (AQPs), have been implicated in cell motility, ...
GbpD, a Dictyostelium discoideum guanine exchange factor specific for Rap1, has been implicated in adhesion, cell polarity, and chemotaxis. Cells overexpressing GbpD are flat, exhibit strongly increased cell-substrate attachment, and extend many bifurcated and lateral pseudopodia. Phg2, a serine/threonine-specific kinase, mediates Rap1-regulated cell-substrate adhesion, but not cell polarity or chemotaxis. In this study we demonstrate that overexpression of GbpD in pi3k1/2-null cells does not induce the adhesion and cell morphology phenotype. Furthermore we show that Rap1 directly binds to the Ras binding domain of PI3K, and overexpression of GbpD leads to strongly enhanced PIP3 levels. Consistently, upon overexpression of the PIP3-degradating enzyme PTEN in GbpD-overexpressing cells, the strong adhesion and cell morphology phenotype is largely lost. These results indicate that a GbpD/Rap/PI3K pathway helps control pseudopod formation and cell polarity. As in Rap-regulated pseudopod formation in ...
Cyclase-associated protein 2 (CAP2) is a conserved protein that is found up-regulated in hepatocellular carcinoma (HCC). By using zebrafish, combined with HCC cell lines, we further investigated the role of CAP2. The zebrafish CAP2 sequence was 60% identical to human CAP2 with 77% homology in the C-terminal actin-binding domain, and 58% in the N-terminal cyclase-binding domain. CAP2 expression was observed during zebrafish development and was preferentially expressed in the skeletal muscle and heart. Knockdown using two different morpholinos against CAP2 resulted in a short-body morphant zebrafish phenotype with pericardial edema. CAP2 was observed co-localized with actin in zebrafish skeletal muscle, and in the leading edge of lamellipodium in HCC cell lines. CAP2 silencing resulted in a defect in lamellipodium formation and decreased cell motility in HCC cell lines. Strongly positive expression of CAP2 was observed in 10 of 16 (63%) poorly, 30 of 68 (44%) moderately, and 2 of 21 (10%) well ...
View Notes - Protists from BSC BSC1005 at Broward College. • locomotor organelles - provides movt o mainly through flagella (single or cilia) or pseudopodial (false foot) movt o lobopodia -
The main function of the algorithm is to distribute nascent FAs and determine which of these (and their associated actin filaments) should be selected for maturation/reinforcement. The algorithm currently considers three mechanisms for FA maturation: (i) lamellipodia retraction occurs that would otherwise leave a nascent adhesion outside the cell body (Zaidel-Bar et al. 2003), (ii) membrane tension spanning two FAs exceeds a certain force threshold (Balaban et al. 2001; Bischofs et al. 2009), and (iii) the cell leading edge advances until it encompasses a nascent FA at the protruding tip of an existing filopodium (Schäfer et al. 2009).. FA maturation induced by lamellipodial retraction has been described as a force independent process (Zaidel-Bar et al. 2003). While experimentally well characterized, it is to date not well understood. In contrast, the separate mechanism of tension induced adhesion maturation is clearly force regulated, inherently involving actin SFs that are recruited to the ...
Amoeboid motion: In the event of amoeboid movement, pseudopodia are included rather then cilia or flagella. In such cases, two cytoskeletal proteins termed actin and myosin receives polymerized. This generates vacancy and thats why cytoplasmic substance stream to address the vacancy that is established as a result of polymerization reaction. When amoeba moves, cytoplasm moves to the arm like extension referred to as pseudopodium ...
What is Amoeba? An amoeba is a simple eukaryotic organism that moves around through Pseudopodia (cytoplasm pushing the cell membrane); the word pseudopodia means false feet. They are commonly found on freshwater surfaces such as ponds and rivers. The ability to change its body shape as required is the key feature to amoebae (plural). The […]
Rear-polarized Wnt5a-receptor-actin-myosin-polarity (WRAMP) structures promote the speed and persistence of directional cell migration Journal Article ...
Cells are able to develop various types of membrane protrusions that modulate their adhesive, migratory, or functional properties. However, their ability to form basal protrusions, particularly in the context of epithelial sheets, is not widely characterized. The authors built hexagonal lattices to probe systematically the microtopography-induced formation of epithelial cell protrusions. Lattices of hexagons of various sizes (from 1.5 to 19 μm) and 5-10 μm height were generated by two-photon photopolymerization in NOA61 or poly(ethylene glycol) diacrylate derivatives. The authors found that cells generated numerous, extensive, and deep basal protrusions for hexagons inferior to cell size (3-10 μm) while maintaining a continuous epithelial layer above structures. They characterized the kinetics of protrusion formation depending on scaffold geometry and size. The reported formation of extensive protrusions in 3D microtopography could be beneficial to develop new biomaterials with increased ...
The mammalian verprolin, WIRE induces filopodia independent of N-WASP through IRSp53. Exp Cell Res. 2010 Oct 15; 316(17):2810-24 ...
Our research is aimed at understanding the cellular and molecular mechanisms that regulate cell migration, and how defects in cell migration contribute to human disease. We use both in vitro approaches including cell culture systems and human studies, and in vivo studies using zebrafish as a genetic model system.. Cell migration plays a central role in many different disease processes including cancer, heart disease, asthma and arthritis. Insight into the mechanisms that regulate cell migration will contribute to our understanding of basic cellular processes, but may also aid in the development of new therapeutic approaches for a wide variety of medical conditions. Despite extensive interest in the receptors and mechanisms that regulate cell migration, many fundamental questions remain unanswered. What are the mechanisms by which a cell initiates and then subsequently stops directional cell migration and how is this altered in disease? How are signaling events coordinated both temporally and ...
On the walk home, Nightlee is full on crying so that every damn person in town stares at me and thinks about what a terrible mother I am. I stick my knuckle in her mouth again, but when she sucks and comes up dry, she screams even louder.. As I pass Dells, theres a crash that sounds like train-on-train action from the lot behind the store. The old guys hit the deck and people come trotting out of every building on Main. Nightlee is startled into silence by the kind of booming vibration that you feel in your heart.. What the hell was that? asks Mama Tracey, picking herself up off the ground.. Im guessing people are just pretending they dont know, because weve all heard that noise before. Its the sound of one of the rocks smashing into a house.. I come around Dells and take a minute to figure out where the trailer used to be, because I can only see the basalt, standing on its small end like a skyscraper.. Its nestled in the new guys place. He was passing through last year and found our ...
Your students will enjoy learning about amoeba with this colorful model. The model covers all the main parts of these cells: contractile vacuole, pseudopodia, cell membrane, food vesicle, nucleus, chromosomes, mitochondria, rough ER and Golgi ...
On the other hand, the correlative functions, so long as they are exerted by a simple undifferentiated morphological unit or cell, are of the simplest character, consisting of those modifications of position which can be effected by mere changes in the form or arrangement of the parts of the protoplasm, or of those prolongations of the protoplasm which are called pseudopodia or cilia. But, in the higher animals and plants, the movements of the organism and of its parts are brought about by the change of the form of certain tissues, the property of which is to shorten in one direction when exposed to certain stimuli. Such tissues are termed contractile; and, in their most fully developed condition, muscular. The stimulus by which this contraction is naturally brought about is a molecular change, either in the substance of the contractile tissue itself, or in some other parts of the body; in which latter case, the motion which is set up in that part of the body must be propagated to the ...
What makes this drawing good. Accuracy; it actually looks like the specimen. Anyone can recognize it. all major parts of the organism are clearly and ccurately portrayed. The major parts of the cell are clearly labeled. Notice that not all of the detail is shown. The finer details are filled in in only part of the drawing. This is OK. There is enough to give the viewer a good idea of the appearance of the cell. As this was an observation on a living specimen, it is important that patterns of movement are noted. This could have been done a bit more clearly, for example, indicating the pattern of cytoplasm out of the uroid portion of the cell, as well as the patern of flow in the oldest of the pseudopodia. Notice the use of lables and marginal notes. These are important.. Why was the mark on this drawing 8.5 and not higher? The contractile vacuole was plainly visible in these specimens and was missed. It is usually located in the region between the nucleus and the uroid. As mentioned bove, the ...
Genus Discamoeba Jahn, Bovee & Griffith, 1979. Diagnosis: Length and width of locomotive form similar. Clear zone extends around the endoplasmic mass. No posterior uroid. Cytoplasm contains a spherical nucleus and frequently a contractile vacuole and crystals. Floating form without radiating pseudopodia ...
Providing Wage Parity benefits to your employees is a complex process.. Leading Edge manages one of the largest and most sought after Wage Parity Programs in New York State. Our experience and efficiency set us apart by giving our clients a distinct advantage in the marketplace. Among the many attributes of Leading Edge offerings is our dedicated multilingual member services team which includes availability of all materials and resources in a wide variety of languages.. ...
A white leading edge is placed on transparent carriers for copiers to prevent a dark leading edge which tends to create copy sheet paper wraps.
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