scholarly journals Cell motility through plasma membrane blebbing

2008 ◽  
Vol 181 (6) ◽  
pp. 879-884 ◽  
Author(s):  
Oliver T. Fackler ◽  
Robert Grosse
Keyword(s):  
Plasma Membrane ◽  
Cell Motility ◽  
Molecular Mechanisms ◽  
Cell Movement ◽  
Core Component ◽  
Membrane Blebbing ◽  
Membrane Blebs ◽  
Bleb Formation ◽  
Guanosine Triphosphatase

Plasma membrane blebs are dynamic cytoskeleton-regulated cell protrusions that have been implicated in apoptosis, cytokinesis, and cell movement. Influencing Rho–guanosine triphosphatase activities and subsequent actomyosin dynamics appears to constitute a core component for bleb formation. In this paper, we discuss recent evidence in support of a central role of nonapoptotic membrane blebbing for cell migration and cancer cell invasion as well as advances in our understanding of the underlying molecular mechanisms. Based on these studies, we propose that in a physiological context, bleb-associated cell motility reflects a cell's response to reduced substratum adhesion. The importance of blebbing as a functional protrusion is underscored by the existence of multiple molecular mechanisms that govern actin-mediated bleb retraction.

scholarly journals A RhoA and Rnd3 cycle regulates actin reassembly during membrane blebbing

2016 ◽  
Vol 113 (13) ◽  
pp. E1863-E1871 ◽  
Author(s):  
Kana Aoki ◽  
Fumiyo Maeda ◽  
Tomoya Nagasako ◽  
Yuki Mochizuki ◽  
Seiichi Uchida ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Growth Factor Receptor ◽  
Kinase Substrate ◽  
Membrane Blebbing ◽  
Actin Cortex ◽  
Membrane Blebs ◽  
Epidermal Growth ◽  
Intracellular Pressure

The actin cytoskeleton usually lies beneath the plasma membrane. When the membrane-associated actin cytoskeleton is transiently disrupted or the intracellular pressure is increased, the plasma membrane detaches from the cortex and protrudes. Such protruded membrane regions are called blebs. However, the molecular mechanisms underlying membrane blebbing are poorly understood. This study revealed that epidermal growth factor receptor kinase substrate 8 (Eps8) and ezrin are important regulators of rapid actin reassembly for the initiation and retraction of protruded blebs. Live-cell imaging of membrane blebbing revealed that local reassembly of actin filaments occurred at Eps8- and activated ezrin-positive foci of membrane blebs. Furthermore, we found that a RhoA–ROCK–Rnd3 feedback loop determined the local reassembly sites of the actin cortex during membrane blebbing.

scholarly journals Genetic disruption of calpain correlates with loss of membrane blebbing and differential expression of RhoGDI-1, cofilin and tropomyosin

2008 ◽  
Vol 411 (3) ◽  
pp. 657-666 ◽  
Author(s):  
Anna K. Larsen ◽  
René Lametsch ◽  
John S. Elce ◽  
Jørgen K. Larsen ◽  
Bo Thomsen ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Proteome Analysis ◽  
Time Lapse ◽  
Wild Type ◽  
Genetic Rescue ◽  
Dynamic Regulation ◽  
Membrane Blebbing ◽  
Signalling Molecules ◽  
Membrane Blebs

Dynamic regulation of the actin cytoskeleton is important for cell motility, spreading and the formation of membrane surface extensions such as lamellipodia, ruffles and blebs. The ubiquitous calpains contribute to integrin-mediated cytoskeletal remodelling during cell migration and spreading, by cleavage of focal adhesion components and signalling molecules. In the present study, the live-cell morphology of calpain-knockout and wild-type cells was examined by time-lapse fluorescence microscopy, and a role of calpain in mediating the formation of sporadic membrane blebs was established. Membrane blebbing was significantly reduced in calpain-knockout cells, and genetic rescue fully restored the wild-type phenotype in knockout cells. Proteomic comparison of wild-type and knockout cells identified decreased levels of RhoGDI-1 (Rho GDP-dissociation inhibitor) and cofilin 1, and increased levels of tropomyosin in calpain-knockout cells, suggesting a role of calpain in regulating membrane extensions involving these proteins. RhoGDI, cofilin and tropomyosin are known regulators of actin filament dynamics and membrane extensions. The reduced levels of RhoGDI-1 in calpain-knockout cells observed by proteome analysis were confirmed by immunoblotting. Genetic rescue of the calpain-knockout cells enhanced RhoGDI-1-expression 2-fold above that normally present in wild-type cells. These results suggest a regulatory connection between calpain and RhoGDI-1 in promoting formation of membrane blebs.

scholarly journals ESCRT-dependent targeting of plasma membrane localized KCa3.1 to the lysosomes

2010 ◽  
Vol 299 (5) ◽  
pp. C1015-C1027 ◽  
Author(s):  
Corina M. Balut ◽  
Yajuan Gao ◽  
Sandra A. Murray ◽  
Patrick H. Thibodeau ◽  
Daniel C. Devor
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Close Association ◽  
Significant Inhibition ◽  
Dominant Negative ◽  
Human Embryonic Kidney Cells ◽  
Endosomal Sorting ◽  
Escrt Machinery ◽  
Interfering Rna

The number of intermediate-conductance, Ca2+-activated K+ channels (KCa3.1) present at the plasma membrane is deterministic in any physiological response. However, the mechanisms by which KCa3.1 channels are removed from the plasma membrane and targeted for degradation are poorly understood. Recently, we demonstrated that KCa3.1 is rapidly internalized from the plasma membrane, having a short half-life in both human embryonic kidney cells (HEK293) and human microvascular endothelial cells (HMEC-1). In this study, we investigate the molecular mechanisms controlling the degradation of KCa3.1 heterologously expressed in HEK and HMEC-1 cells. Using immunofluorescence and electron microscopy, as well as quantitative biochemical analysis, we demonstrate that membrane KCa3.1 is targeted to the lysosomes for degradation. Furthermore, we demonstrate that either overexpressing a dominant negative Rab7 or short interfering RNA-mediated knockdown of Rab7 results in a significant inhibition of channel degradation rate. Coimmunoprecipitation confirmed a close association between Rab7 and KCa3.1. On the basis of these findings, we assessed the role of the ESCRT machinery in the degradation of heterologously expressed KCa3.1, including TSG101 [endosomal sorting complex required for transport (ESCRT)-I] and CHMP4 (ESCRT-III) as well as VPS4, a protein involved in the disassembly of the ESCRT machinery. We demonstrate that TSG101 is closely associated with KCa3.1 via coimmunoprecipitation and that a dominant negative TSG101 inhibits KCa3.1 degradation. In addition, both dominant negative CHMP4 and VPS4 significantly decrease the rate of membrane KCa3.1 degradation, compared with wild-type controls. These results are the first to demonstrate that plasma membrane-associated KCa3.1 is targeted for lysosomal degradation via a Rab7 and ESCRT-dependent pathway.

Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity

Blood ◽  
2004 ◽  
Vol 103 (5) ◽  
pp. 1912-1919 ◽  
Author(s):  
James C.-M. Lee ◽  
J. Aura Gimm ◽  
Annie J. Lo ◽  
Mark J. Koury ◽  
Sharon W. Krauss ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Molecular Mechanisms ◽  
Immunofluorescence Microscopy ◽  
Protein Sorting ◽  
Membrane Cytoskeleton ◽  
Skeletal Protein ◽  
Regulate Protein ◽  
Membrane Components ◽  
Cytoskeletal Elements

AbstractDuring erythroblast enucleation, nuclei surrounded by plasma membrane separate from erythroblast cytoplasm. A key aspect of this process is sorting of erythroblast plasma membrane components to reticulocytes and expelled nuclei. Although it is known that cytoskeletal elements actin and spectrin partition to reticulocytes, little is understood about molecular mechanisms governing plasma membrane protein sorting. We chose glycophorin A (GPA) as a model integral protein to begin investigating protein-sorting mechanisms. Using immunofluorescence microscopy and Western blotting we found that GPA sorted predominantly to reticulocytes. We hypothesized that the degree of skeletal linkage might control the sorting pattern of transmembrane proteins. To explore this hypothesis, we quantified the extent of GPA association to the cytoskeleton in erythroblasts, young reticulocytes, and mature erythrocytes using fluorescence imaged microdeformation (FIMD) and observed that GPA underwent dramatic reorganization during terminal differentiation. We discovered that GPA was more connected to the membrane cytoskeleton, either directly or indirectly, in erythroblasts and young reticulocytes than in mature cells. We conclude that skeletal protein association can regulate protein sorting during enucleation. Further, we suggest that the enhanced rigidity of reticulocyte membranes observed in earlier investigations results, at least in part, from increased connectivity of GPA with the spectrin-based skeleton.

scholarly journals Silencing of Plasma Membrane Ca2+-ATPase Isoforms 2 and 3 Impairs Energy Metabolism in Differentiating PC12 Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Tomasz Boczek ◽  
Malwina Lisek ◽  
Bozena Ferenc ◽  
Antoni Kowalski ◽  
Magdalena Wiktorska ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Pc12 Cells ◽  
Molecular Mechanisms ◽  
Atp Synthesis ◽  
Mitochondrial Activity ◽  
Excitable Cells ◽  
Close Link ◽  
Atp Level ◽  
Atp Generation

A close link between Ca2+, ATP level, and neurogenesis is apparent; however, the molecular mechanisms of this relationship have not been completely elucidated. Transient elevations of cytosolic Ca2+may boost ATP synthesis, but ATP is also consumed by ion pumps to maintain a low Ca2+in cytosol. In differentiation process plasma membrane Ca2+ATPase (PMCA) is considered as one of the major players for Ca2+homeostasis. From four PMCA isoforms, the fastest PMCA2 and PMCA3 are expressed predominantly in excitable cells. In the present study we assessed whether PMCA isoform composition may affect energy balance in differentiating PC12 cells. We found that PMCA2-downregulated cells showed higher basal O2consumption, lower NAD(P)H level, and increased activity of ETC. These changes associated with higher[Ca2+]cresulted in elevated ATP level. Since PMCA2-reduced cells demonstrated greatest sensitivity to ETC inhibition, we suppose that the main source of energy for PMCA isoforms 1, 3, and 4 was oxidative phosphorylation. Contrary, cells with unchanged PMCA2 expression exhibited prevalence of glycolysis in ATP generation. Our results with PMCA2- or PMCA3-downregulated lines provide an evidence of a novel role of PMCA isoforms in regulation of bioenergetic pathways, and mitochondrial activity and maintenance of ATP level during PC12 cells differentiation.

scholarly journals Competitive binding of Rab21 and p120RasGAP to integrins regulates receptor traffic and migration

2011 ◽  
Vol 194 (2) ◽  
pp. 291-306 ◽  
Author(s):  
Anja Mai ◽  
Stefan Veltel ◽  
Teijo Pellinen ◽  
Artur Padzik ◽  
Eleanor Coffey ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Motility ◽  
Molecular Mechanisms ◽  
Regulatory Mechanism ◽  
Competitive Binding ◽  
Small Gtpase ◽  
Rab Gtpases ◽  
Endocytic Machinery ◽  
And Migration ◽  
Α Subunits

Integrin trafficking from and to the plasma membrane controls many aspects of cell behavior including cell motility, invasion, and cytokinesis. Recruitment of integrin cargo to the endocytic machinery is regulated by the small GTPase Rab21, but the detailed molecular mechanisms underlying integrin cargo recruitment are yet unknown. Here we identify an important role for p120RasGAP (RASA1) in the recycling of endocytosed α/β1-integrin heterodimers to the plasma membrane. Silencing of p120RasGAP attenuated integrin recycling and augmented cell motility. Mechanistically, p120RasGAP interacted with the cytoplasmic domain of integrin α-subunits via its GAP domain and competed with Rab21 for binding to endocytosed integrins. This in turn facilitated exit of the integrin from Rab21- and EEA1-positive endosomes to drive recycling. Our results assign an unexpected role for p120RasGAP in the regulation of integrin traffic in cancer cells and reveal a new concept of competitive binding of Rab GTPases and GAP proteins to receptors as a regulatory mechanism in trafficking.

scholarly journals MICROFILAMENTS AND CELL LOCOMOTION

1971 ◽  
Vol 49 (3) ◽  
pp. 595-613 ◽  
Author(s):  
Brian S. Spooner ◽  
Kenneth M. Yamada ◽  
Norman K. Wessells
Keyword(s):  
Protein Synthesis ◽  
Plasma Membrane ◽  
Cytochalasin B ◽  
Cell Movement ◽  
Leading Edge ◽  
Complete Recovery ◽  
Cell Locomotion ◽  
Cell Processes

The role of microfilaments in generating cell locomotion has been investigated in glial cells migrating in vitro. Such cells are found to contain two types of microfilament systems: First, a sheath of 50–70-A in diameter filaments is present in the cytoplasm at the base of the cells, just inside the plasma membrane, and in cell processes. Second, a network of 50-A in diameter filaments is found just beneath the plasma membrane at the leading edge (undulating membrane locomotory organelle) and along the sides of the cell. The drug, cytochalasin B, causes a rapid cessation of migration and a disruption of the microfilament network. Other organelles, including the microfilament sheath and microtubules, are unaltered by the drug, and protein synthesis is not inhibited. Removal of cytochalasin results in complete recovery of migratory capabilities, even in the absence of virtually all protein synthesis. Colchicine, at levels sufficient to disrupt all microtubules, has no effect on undulating membrane activity, on net cell movement, or on microfilament integrity. The microfilament network is, therefore, indispensable for locomotion.

scholarly journals The role of post-Golgi transport pathways and sorting motifs in the plasmodesmal targeting of the movement protein (MP) of Ourmia melon virus (OuMV)

2019 ◽  
Author(s):  
Natali Ozber ◽  
Paolo Margaria ◽  
Charles T. Anderson ◽  
Massimo Turina ◽  
Cristina Rosa
Keyword(s):  
Plasma Membrane ◽  
Movement Protein ◽  
Cell Movement ◽  
Systemic Infection ◽  
Multivesicular Body ◽  
Plant Viruses ◽  
Transport Pathways ◽  
Intracellular Targeting ◽  
Golgi Network

SummaryPlants have a highly sophisticated endomembrane system that is targeted by plant viruses for cell-to-cell movement. The movement protein (MP) of Ourmia melon virus (OuMV) is targeted to plasmodesmata (PD) and forms tubules to facilitate cell-to-cell movement. Despite a number of functionally important regions for correct subcellular localization of OuMV MP has been identified, little is known about the pathways OuMV MP hijacks to reach PD. Here, we demonstrate that OuMV MP localizes to the trans-Golgi network (TGN), but not to the multivesicular body/prevacuolar compartment or Golgi, and carries two putative sorting motifs, a tyrosine (Y) and a dileucine (LL) motif, near its N-terminus. Introducing glycine substitutions in these motifs results in loss of OuMV infectivity in Nicotiana benthamiana and Arabidopsis (Arabidopsis thaliana). Live cell imaging of GFP-labeled sorting motif mutants shows that Y motif mutants fail to localize to the TGN, plasma membrane, and PD. Mutations in the LL motif do not impair plasma membrane targeting of MP, but affect its ability to associate with callose deposits at PD. Taken together, these data suggest that both Y and LL motifs are indispensable for targeting of OuMV MP to PD and for efficient systemic infection, but show differences in functionality. This study provides new insights into the role of sorting motifs in intracellular targeting of MPs and vesicle trafficking pathways that plant viruses hijack for cell-to-cell movement.

Mobility and invasiveness of metastatic esophageal cancer are potentiated by shear stress in a ROCK- and Ras-dependent manner

2006 ◽  
Vol 291 (4) ◽  
pp. C668-C677 ◽  
Author(s):  
Karen Lawler ◽  
Eilis Foran ◽  
Gerald O'Sullivan ◽  
Aideen Long ◽  
Dermot Kenny
Keyword(s):  
Shear Stress ◽  
Leading Edge ◽  
Basement Membranes ◽  
Dependent Manner ◽  
Shear Forces ◽  
Membrane Blebbing ◽  
Metastatic Cells ◽  
Bleb Formation ◽  
Static Conditions

To metastasize, tumor cells must adopt different morphological responses to resist shear forces encountered in circulating blood and invade through basement membranes. The Rho and Ras GTPases play a critical role in regulating this dynamic behavior. Recently, we demonstrated shear-induced activation of adherent esophageal metastatic cells, characterized by formation of dynamic membrane blebs. Although membrane blebbing has only recently been characterized as a rounded mode of cellular invasion promoted through Rho kinase (ROCK), the role of shear forces in modulating membrane blebbing activity is unknown. To further characterize membrane blebbing in esophageal metastatic cells (OC-1 cell line), we investigated the role of shear in cytoskeletal remodeling and signaling through ROCK and Ras. Our results show that actin and tubulin colocalize to the cortical ring of the OC-1 cell under static conditions. However, under shear, actin acquires a punctuate distribution and tubulin localizes to the leading edge of the OC-1 cell. We show for the first time that dynamic bleb formation is induced by shear alone independent of integrin-mediated adhesion ( P < 0.001, compared with OC-1 cells). Y-27632, a specific inhibitor of ROCK, causes a significant reduction in shear-induced bleb formation and inhibits integrin αvβ3-Ras colocalization at the leading edge of the cell. Direct measurement of Ras activation shows that the level of GTP-bound Ras is elevated in sheared OC-1 cells and that the shear-induced increase in Ras activity is inhibited by Y-27632. Finally, we show that shear stress significantly increases OC-1 cell invasion ( P < 0.007), an effect negated by the presence of Y-27632. Together our findings suggest a novel physiological role for ROCK and Ras in metastatic cell behavior.

Sign in / Sign up

Export Citation Format

Share Document