Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Akt2 regulates expression of the actin-bundling protein palladin.

ABSTRACT: The phosphatidylinositol 3-kinase/Akt pathway is responsible for key aspects of tumor progression, and is frequently hyperactivated in cancer. We have recently identified palladin, an actin-bundling protein that functions to control the actin cytoskeleton, as an Akt1-specific substrate that inhibits breast cancer cell migration. Here we have identified a role for Akt isoforms in the regulation of palladin expression. Akt2, but not Akt1, enhances palladin expression by maintaining protein stability and upregulating transcription. These data reveal that Akt signaling regulates the stability of palladin, and further supports the notion that Akt isoforms have distinct and specific roles in tumorigenesis.

SUBMITTER: Chin YR

PROVIDER: S-EPMC2997733 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Akt2 regulates expression of the actin-bundling protein palladin.

Chin Y Rebecca YR Toker Alex A

FEBS letters 20101102 23

The phosphatidylinositol 3-kinase/Akt pathway is responsible for key aspects of tumor progression, and is frequently hyperactivated in cancer. We have recently identified palladin, an actin-bundling protein that functions to control the actin cytoskeleton, as an Akt1-specific substrate that inhibits breast cancer cell migration. Here we have identified a role for Akt isoforms in the regulation of palladin expression. Akt2, but not Akt1, enhances palladin expression by maintaining protein stabili ...[more]

PMID: 21050850

Similar Datasets

Actin-induced dimerization of palladin promotes actin-bundling.

Project description:A subset of actin binding proteins is able to form crosslinks between two or more actin filaments, thus producing structures of parallel or networked bundles. These actin crosslinking proteins interact with actin through either bivalent binding or dimerization. We recently identified two binding sites within the actin binding domain of palladin, an actin crosslinking protein that plays an important role in normal cell adhesion and motility during wound healing and embryonic development. In this study, we show that actin induces dimerization of palladin. Furthermore, the extent of dimerization reflects earlier comparisons of actin binding and bundling between different domains of palladin. On the basis of these results we hypothesized that actin binding may promote a conformational change that results in dimerization of palladin, which in turn may drive the crosslinking of actin filaments. The proximal distance between two actin binding sites on crosslinking proteins determines the ultrastructural properties of the filament network, therefore we also explored interdomain interactions using a combination of chemical crosslinking experiments and actin cosedimentation assays. Limited proteolysis data reveals that palladin is less susceptible to enzyme digestion after actin binding. Our results suggest that domain movements in palladin are necessary for interactions with actin and are induced by interactions with actin filaments. Accordingly, we put forth a model linking the structural changes to functional dynamics.

| S-EPMC4282413 | biostudies-literature

The actin-bundling protein palladin is an Akt1-specific substrate that regulates breast cancer cell migration.

Project description:The phosphatidylinositol 3-kinase (PI3K) signaling pathway is frequently deregulated in cancer. Downstream of PI3K, Akt1 and Akt2 have opposing roles in breast cancer invasive migration, leading to metastatic dissemination. Here, we identify palladin, an actin-associated protein, as an Akt1-specific substrate that modulates breast cancer cell invasive migration. Akt1, but not Akt2, phosphorylates palladin at Ser507 in a domain that is critical for F-actin bundling. Downregulation of palladin enhances migration and invasion of breast cancer cells and induces abnormal branching morphogenesis in 3D cultures. Palladin phosphorylation at Ser507 is required for Akt1-mediated inhibition of breast cancer cell migration and also for F-actin bundling, leading to the maintenance of an organized actin cytoskeleton. These findings identify palladin as an Akt1-specific substrate that regulates cell motility and provide a molecular mechanism that accounts for the functional distinction between Akt isoforms in breast cancer cell signaling to cell migration.

| S-EPMC2872630 | biostudies-literature

Cysteine-rich protein 1 (CRP1) regulates actin filament bundling.

Project description:BackgroundCysteine-rich protein 1 (CRP1) is a LIM domain containing protein localized to the nucleus and the actin cytoskeleton. CRP1 has been demonstrated to bind the actin-bundling protein alpha-actinin and proposed to modulate the actin cytoskeleton; however, specific regulatory mechanisms have not been identified.ResultsCRP1 expression increased actin bundling in rat embryonic fibroblasts. Although CRP1 did not affect the bundling activity of alpha-actinin, CRP1 was found to stabilize the interaction of alpha-actinin with actin bundles and to directly bundle actin microfilaments. Using confocal and photobleaching fluorescence resonance energy transfer (FRET) microscopy, we demonstrate that there are two populations of CRP1 localized along actin stress fibers, one associated through interaction with alpha-actinin and one that appears to bind the actin filaments directly. Consistent with a role in regulating actin filament cross-linking, CRP1 also localized to the membrane ruffles of spreading and PDGF treated fibroblasts.ConclusionCRP1 regulates actin filament bundling by directly cross-linking actin filaments and stabilizing the interaction of alpha-actinin with actin filament bundles.

| S-EPMC1318456 | biostudies-literature

Dynamin regulates the dynamics and mechanical strength of the actin cytoskeleton as a multifilament actin-bundling protein.

Project description:The dynamin GTPase is known to bundle actin filaments, but the underlying molecular mechanism and physiological relevance remain unclear. Our genetic analyses revealed a function of dynamin in propelling invasive membrane protrusions during myoblast fusion in vivo. Using biochemistry, total internal reflection fluorescence microscopy, electron microscopy and cryo-electron tomography, we show that dynamin bundles actin while forming a helical structure. At its full capacity, each dynamin helix captures 12-16 actin filaments on the outer rim of the helix. GTP hydrolysis by dynamin triggers disassembly of fully assembled dynamin helices, releasing free dynamin dimers/tetramers and facilitating Arp2/3-mediated branched actin polymerization. The assembly/disassembly cycles of dynamin promote continuous actin bundling to generate mechanically stiff actin super-bundles. Super-resolution and immunogold platinum replica electron microscopy revealed dynamin along actin bundles at the fusogenic synapse. These findings implicate dynamin as a unique multifilament actin-bundling protein that regulates the dynamics and mechanical strength of the actin cytoskeletal network.

| S-EPMC7953826 | biostudies-literature

Mst1 Kinase Regulates the Actin-Bundling Protein L-Plastin To Promote T Cell Migration.

Project description:Exploring the mechanisms controlling lymphocyte trafficking is essential for understanding the function of the immune system and the pathophysiology of immunodeficiencies. The mammalian Ste20-like kinase 1 (Mst1) has been identified as a critical signaling mediator of T cell migration, and loss of Mst1 results in immunodeficiency disease. Although Mst1 is known to support T cell migration through induction of cell polarization and lamellipodial formation, the downstream effectors of Mst1 are incompletely defined. Mice deficient for the actin-bundling protein L-plastin (LPL) have phenotypes similar to mice lacking Mst1, including decreased T cell polarization, lamellipodial formation, and cell migration. We therefore asked whether LPL functions downstream of Mst1. The regulatory N-terminal domain of LPL contains a consensus Mst1 phosphorylation site at Thr(89) We found that Mst1 can phosphorylate LPL in vitro and that Mst1 can interact with LPL in cells. Removal of the Mst1 phosphorylation site by mutating Thr(89) to Ala impaired localization of LPL to the actin-rich lamellipodia of T cells. Expression of the T89A LPL mutant failed to restore migration of LPL-deficient T cells in vitro. Furthermore, expression of T89A LPL in LPL-deficient hematopoietic cells, using bone marrow chimeras, failed to rescue the phenotype of decreased thymic egress. These results identify LPL as a key effector of Mst1 and establish a novel mechanism linking a signaling intermediate to an actin-binding protein critical to T cell migration.

| S-EPMC4992580 | biostudies-literature

miR-125a-5p regulates megakaryocyte proplatelet formation via the actin-bundling protein L-plastin.

Project description:There is heritability to interindividual variation in platelet count, and better understanding of the regulating genetic factors may provide insights for thrombopoiesis. MicroRNAs (miRs) regulate gene expression in health and disease, and megakaryocytes (MKs) deficient in miRs have lower platelet counts, but information about the role of miRs in normal human MK and platelet production is limited. Using genome-wide miR profiling, we observed strong correlations among human bone marrow MKs, platelets, and differentiating cord blood-derived MK cultures, and identified MK miR-125a-5p as associated with human platelet number but not leukocyte or hemoglobin levels. Overexpression and knockdown studies showed that miR-125a-5p positively regulated human MK proplatelet (PP) formation in vitro. Inhibition of miR-125a-5p in vivo lowered murine platelet counts. Analyses of MK and platelet transcriptomes identified LCP1 as a miR-125a-5p target. LCP1 encodes the actin-bundling protein, L-plastin, not previously studied in MKs. We show that miR-125a-5p directly targets and reduces expression of MK L-plastin. Overexpression and knockdown studies show that L-plastin promotes MK progenitor migration, but negatively correlates with human platelet count and inhibits MK PP formation (PPF). This work provides the first evidence for the actin-bundling protein, L-plastin, as a regulator of human MK PPF via inhibition of the late-stage MK invagination system, podosome and PPF, and PP branching. We also provide resources of primary and differentiating MK transcriptomes and miRs associated with platelet counts. miR-125a-5p and L-plastin may be relevant targets for increasing in vitro platelet manufacturing and for managing quantitative platelet disorders.

| S-EPMC7544541 | biostudies-literature

Swiprosin-1 is a novel actin bundling protein that regulates cell spreading and migration.

Project description:Protein functions are often revealed by their localization to specialized cellular sites. Recent reports demonstrated that swiprosin-1 is found together with actin and actin-binding proteins in the cytoskeleton fraction of human mast cells and NK-like cells. However, direct evidence of whether swiprosin-1 regulates actin dynamics is currently lacking. We found that swiprosin-1 localizes to microvilli-like membrane protrusions and lamellipodia and exhibits actin-binding activity. Overexpression of swiprosin-1 enhanced lamellipodia formation and cell spreading. In contrast, swiprosin-1 knockdown showed reduced cell spreading and migration. Swiprosin-1 induced actin bundling in the presence of Ca(2+), and deletion of the EF-hand motifs partially reduced bundling activity. Swiprosin-1 dimerized in the presence of Ca(2+) via its coiled-coil domain, and a lysine (Lys)-rich region in the coiled-coil domain was essential for regulation of actin bundling. Consistent with these observations, mutations of the EF-hand motifs and coiled-coil region significantly reduced cell spreading and lamellipodia formation. We provide new evidence of how swiprosin-1 influences cytoskeleton reorganization and cell spreading.

| S-EPMC3744483 | biostudies-literature

The actin-bundling protein, PLS3, is part of the mechanoresponsive machinery that regulates osteoblast mineralization.

Project description:Plastin-3 (PLS3) is a calcium-sensitive actin-bundling protein that has recently been linked to the development of childhood-onset osteoporosis. Clinical data suggest that PLS3 mutations lead to a defect in osteoblast function, however the underlying mechanism remains elusive. To investigate the role of PLS3 in bone mineralization, we generated MC3T3-E1 preosteoblast cells that are stably depleted of PLS3. Analysis of osteogenic differentiation of control and PLS3 knockdown (PLS3 KD) cells showed that depletion of PLS3 does not alter the first stage of osteoblast mineralization in which a collagen matrix is deposited, but severely affects the subsequent mineralization of that matrix. During this phase, osteoblasts heavily rely on mechanosensitive signaling pathways to sustain mineral deposition in response to increasing stiffness of the extracellular matrix (ECM). PLS3 prominently localizes to focal adhesions (FAs), which are intricately linked to mechanosensation. In line with this, we observed that depletion of PLS3 rendered osteoblasts unresponsive to changes in ECM stiffness and showed the same cell size, FA lengths and number of FAs when plated on soft (6 kPa) versus stiff (100 kPa) substrates in contrast to control cells, which showed an increased in each of these parameters when plated on 100 kPa substrates. Defective cell spreading of PLS3 KD cells on stiff substrates could be rescued by expression of wildtype PLS3, but not by expression of three PLS3 mutations that were identified in patients with early onset osteoporosis and that have aberrant actin-bundling activity. Altogether, our results show that actin-bundling by PLS3 is part of the mechanosensitive mechanism that promotes osteoblast mineralization and thus begins to elucidate how PLS3 contributes to the development of bone defects such as osteoporosis.

| S-EPMC10711096 | biostudies-literature

Vinculin-dependent actin bundling regulates cell migration and traction forces.

Project description:Vinculin binding to actin filaments is thought to be critical for force transduction within a cell, but direct experimental evidence to support this conclusion has been limited. In the present study, we found mutation (R1049E) of the vinculin tail impairs its ability to bind F-actin, stimulate actin polymerization, and bundle F-actin in vitro. Further, mutant (R1049E) vinculin expressing cells are altered in cell migration, which is accompanied by changes in cell adhesion, cell spreading and cell generation of traction forces, providing direct evidence for the critical role of vinculin in mechanotransduction at adhesion sites. Lastly, we discuss the viability of models detailing the F-actin-binding surface on vinculin in the context of our mutational analysis.

| S-EPMC4418518 | biostudies-literature

The Calcium-Dependent Switch Helix of L-Plastin Regulates Actin Bundling.

Project description:L-plastin is a calcium-regulated actin-bundling protein that is expressed in cells of hematopoietic origin and in most metastatic cancer cells. These cell types are mobile and require the constant remodeling of their actin cytoskeleton, where L-plastin bundles filamentous actin. The calcium-dependent regulation of the actin-bundling activity of L-plastin is not well understood. We have used NMR spectroscopy to determine the solution structure of the EF-hand calcium-sensor headpiece domain. Unexpectedly, this domain does not bind directly to the four CH-domains of L-plastin. A novel switch helix is present immediately after the calcium-binding region and it binds tightly to the EF-hand motifs in the presence of calcium. We demonstrate that this switch helix plays a major role during actin-bundling. Moreover a peptide that competitively inhibits the association between the EF-hand motifs and the switch helix was shown to deregulate the actin-bundling activity of L-plastin. Overall, these findings may help to develop new drugs that target the L-plastin headpiece and interfere in the metastatic activity of cancer cells.

| S-EPMC5286426 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data