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1.
J Biol Chem ; 300(5): 107234, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38552737

RESUMO

Focal adhesions (FAs) form the junction between extracellular matrix (ECM)-bound integrins and the actin cytoskeleton and also transmit signals that regulate cell adhesion, cytoskeletal dynamics, and cell migration. While many of these signals are rooted in reversible tyrosine phosphorylation, phosphorylation of FA proteins on Ser/Thr residues is far more abundant yet its mechanisms and consequences are far less understood. The cAMP-dependent protein kinase (protein kinase A; PKA) has important roles in cell adhesion and cell migration and is both an effector and regulator of integrin-mediated adhesion to the ECM. Importantly, subcellular localization plays a critically important role in specifying PKA function. Here, we show that PKA is present in isolated FA-cytoskeleton complexes and active within FAs in live cells. Furthermore, using kinase-catalyzed biotinylation of isolated FA-cytoskeleton complexes, we identify 53 high-stringency candidate PKA substrates within FAs. From this list, we validate tensin-3 (Tns3)-a well-established molecular scaffold, regulator of cell migration, and a component of focal and fibrillar adhesions-as a novel direct substrate for PKA. These observations identify a new pathway for phospho-regulation of Tns3 and, importantly, establish a new and important niche for localized PKA signaling and thus provide a foundation for further investigation of the role of PKA in the regulation of FA dynamics and signaling.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico , Adesões Focais , Tensinas , Animais , Humanos , Adesão Celular , Movimento Celular , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Citoesqueleto/metabolismo , Adesões Focais/enzimologia , Fosforilação , Tensinas/metabolismo , Camundongos , Ratos , Linhagem Celular , Transdução de Sinais/genética
2.
Biomed Pharmacother ; 133: 111055, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33378961

RESUMO

The AKT kinase family is a high-profile target for cancer therapy. Despite their high degree of homology the three AKT isoforms (AKT1, AKT2 and AKT3) are non-redundant and can even have opposing functions. Small-molecule AKT inhibitors affect all three isoforms which severely limits their usefulness as research tool or therapeutic. Using AKT2-specific nanobodies we examined the function of endogenous AKT2 in breast cancer cells. Two AKT2 nanobodies (Nb8 and Nb9) modulate AKT2 and reduce MDA-MB-231 cell viability/proliferation. Nb8 binds the AKT2 hydrophobic motif and reduces IGF-1-induced phosphorylation of this site. This nanobody also affects the phosphorylation and/or expression levels of a wide range of proteins downstream of AKT, resulting in a G0/G1 cell cycle arrest, the induction of autophagy, a reduction in focal adhesion count and loss of stress fibers. While cell cycle progression is likely to be regulated by more than one isoform, our results indicate that both the effects on autophagy and the cytoskeleton are specific to AKT2. By using an isoform-specific nanobody we were able to map a part of the AKT2 pathway. Our results confirm AKT2 and the hydrophobic motif as targets for cancer therapy. Nb8 can be used as a research tool to study AKT2 signalling events and aid in the design of an AKT2-specific inhibitor.


Assuntos
Antineoplásicos Imunológicos/farmacologia , Autofagia/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Adesões Focais/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Anticorpos de Domínio Único/farmacologia , Motivos de Aminoácidos , Neoplasias da Mama/enzimologia , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Adesões Focais/enzimologia , Adesões Focais/imunologia , Adesões Focais/patologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Fator de Crescimento Insulin-Like I/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas c-akt/imunologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais
3.
Proc Natl Acad Sci U S A ; 116(14): 6766-6774, 2019 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-30877242

RESUMO

Focal adhesion kinase (FAK) is a key signaling molecule regulating cell adhesion, migration, and survival. FAK localizes into focal adhesion complexes formed at the cytoplasmic side of cell attachment to the ECM and is activated after force generation via actomyosin fibers attached to this complex. The mechanism of translating mechanical force into a biochemical signal is not understood, and it is not clear whether FAK is activated directly by force or downstream to the force signal. We use experimental and computational single-molecule force spectroscopy to probe the mechanical properties of FAK and examine whether force can trigger activation by inducing conformational changes in FAK. By comparison with an open and active mutant of FAK, we are able to assign mechanoactivation to an initial rupture event in the low-force range. This activation event occurs before FAK unfolding at forces within the native range in focal adhesions. We are also able to assign all subsequent peaks in the force landscape to partial unfolding of FAK modules. We show that binding of ATP stabilizes the kinase domain, thereby altering the unfolding hierarchy. Using all-atom molecular dynamics simulations, we identify intermediates along the unfolding pathway, which provide buffering to allow extension of FAK in focal adhesions without compromising functionality. Our findings strongly support that forces in focal adhesions applied to FAK via known interactions can induce conformational changes, which in turn, trigger focal adhesion signaling.


Assuntos
Trifosfato de Adenosina/química , Proteínas Aviárias/química , Proteína-Tirosina Quinases de Adesão Focal/química , Simulação de Dinâmica Molecular , Desdobramento de Proteína , Trifosfato de Adenosina/metabolismo , Animais , Proteínas Aviárias/genética , Proteínas Aviárias/metabolismo , Galinhas , Ativação Enzimática , Proteína-Tirosina Quinases de Adesão Focal/genética , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Adesões Focais/enzimologia , Adesões Focais/genética , Mecanotransdução Celular/genética , Domínios Proteicos , Relação Estrutura-Atividade
4.
J Cell Physiol ; 232(9): 2447-2460, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27591737

RESUMO

Glaucoma, a leading cause of irreversible blindness, is commonly associated with elevated intraocular pressure (IOP) due to impaired aqueous humor (AH) drainage through the trabecular meshwork (TM). Although dysregulated production and organization of extracellular matrix (ECM) is presumed to increase resistance to AH outflow and elevate IOP by altering TM cell contractile and adhesive properties, it is not known whether regulation of ECM protein phosphorylation via the secretory vertebrate lonesome kinase (VLK) influences TM cellular characteristics. Here, we tested this possibility. Experiments carried out in this study reveal that the 32 kDa protein is a prominent VLK isoform detectable in lysates and conditioned media (CM) of human TM cells. Increased levels of VLK were observed in CM of TM cells subjected to cyclic mechanical stretch, or treated with dexamethasone, TGF-ß2, and TM cells expressing constitutively active RhoA GTPase. Downregulation of VLK expression in TM cells using siRNA decreased tyrosine phosphorylation (TyrP) of ECM proteins and focal adhesions, and induced changes in cell shape in association with reduced levels of actin stress fibers and phospho-paxillin. VLK was also demonstrated to regulate TGF-ß2-induced TyrP of ECM proteins. Taken together, these results suggest that VLK secretion can be regulated by external cues, intracellular signal proteins, and mechanical stretch, and VLK can in turn regulate TyrP of ECM proteins secreted by TM cells and control cell shape, actin stress fibers, and focal adhesions. These observations indicate a potential role for VLK in homeostasis of AH outflow and IOP, and in the pathobiology of glaucoma. J. Cell. Physiol. 232: 2447-2460, 2017. © 2016 Wiley Periodicals, Inc.


Assuntos
Adesão Celular , Forma Celular , Proteínas da Matriz Extracelular/metabolismo , Proteínas Tirosina Quinases/metabolismo , Malha Trabecular/enzimologia , Adulto , Idoso , Humor Aquoso/metabolismo , Adesão Celular/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Células Cultivadas , Meios de Cultivo Condicionados/metabolismo , Dexametasona/farmacologia , Adesões Focais/enzimologia , Glaucoma/enzimologia , Glaucoma/patologia , Glaucoma/fisiopatologia , Humanos , Pressão Intraocular , Mecanotransdução Celular , Pessoa de Meia-Idade , Mutação , Paxilina/metabolismo , Fosforilação , Proteínas Tirosina Quinases/genética , Interferência de RNA , Fibras de Estresse/enzimologia , Fatores de Tempo , Malha Trabecular/efeitos dos fármacos , Transfecção , Fator de Crescimento Transformador beta2/farmacologia , Tirosina , Adulto Jovem , Proteína rhoA de Ligação ao GTP/genética , Proteína rhoA de Ligação ao GTP/metabolismo
5.
Cancer Lett ; 386: 151-160, 2017 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-27894956

RESUMO

Triple-negative breast cancers (TNBC) often exhibit an aggressive phenotype. Disulfiram (DSF) is an approved drug for the treatment of alcohol dependence, but has also been shown to kill TNBC cells in a copper (Cu)-dependent manner. Exactly how this occurs has not been clearly elucidated. We sought to investigate the mechanisms responsible for DSF/Cu-dependent induction of apoptosis and suppression of lung colonization by TNBC cells. DSF/Cu induced anoikis and significantly suppressed cell migration and invasion with negative effects on focal adhesions, coinciding with vimentin breakdown and calpain activation in TNBC cells. In a xenograft tumor model, DSF suppressed tumor growth and lung nodule growth, which was also associated with calpain activation. These findings warrant further investigation of disulfiram as a potential treatment for metastatic TNBC.


Assuntos
Anoikis/efeitos dos fármacos , Antineoplásicos/farmacologia , Calpaína/metabolismo , Movimento Celular/efeitos dos fármacos , Dissulfiram/farmacologia , Neoplasias Pulmonares/prevenção & controle , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cobre/farmacologia , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/enzimologia , Citoesqueleto/patologia , Relação Dose-Resposta a Droga , Ativação Enzimática , Feminino , Adesões Focais/efeitos dos fármacos , Adesões Focais/enzimologia , Adesões Focais/patologia , Humanos , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/secundário , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica , Proteólise , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Neoplasias de Mama Triplo Negativas/enzimologia , Neoplasias de Mama Triplo Negativas/patologia , Carga Tumoral/efeitos dos fármacos , Vimentina/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
6.
Cancer Lett ; 380(2): 505-512, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27452906

RESUMO

Triple-negative breast cancers (TNBCs) are among the most aggressive cancers characterized by a high propensity to invade, metastasize and relapse. We previously reported that the TNBC-specific inhibitor, AMPI-109, significantly impairs the ability of TNBC cells to migrate and invade by reducing levels of the metastasis-promoting phosphatase, PRL-3. Here, we examined the mechanisms by which AMPI-109 and loss of PRL-3 impede cell migration and invasion. AMPI-109 treatment or knock down of PRL-3 expression were associated with deactivation of Src and ERK signaling and concomitant downregulation of RhoA and Rac1/2/3 GTPase protein levels. These cellular changes led to rearranged filamentous actin networks necessary for cell migration and invasion. Conversely, overexpression of PRL-3 promoted TNBC cell invasion by upregulating matrix metalloproteinase 10, which resulted in increased TNBC cell adherence to, and degradation of, the major basement membrane component laminin. Our data demonstrate that PRL-3 engages the focal adhesion pathway in TNBC cells as a key mechanism for promoting TNBC cell migration and invasion. Collectively, these data suggest that blocking PRL-3 activity may be an effective method for reducing the metastatic potential of TNBC cells.


Assuntos
Citoesqueleto de Actina/enzimologia , Adesão Celular , Movimento Celular , Adesões Focais/enzimologia , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Fosfatases/metabolismo , Neoplasias de Mama Triplo Negativas/enzimologia , Citoesqueleto de Actina/efeitos dos fármacos , Citoesqueleto de Actina/patologia , Antineoplásicos/farmacologia , Calcitriol/análogos & derivados , Calcitriol/farmacologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Adesões Focais/efeitos dos fármacos , Adesões Focais/patologia , Humanos , Laminina/metabolismo , Metaloproteinase 10 da Matriz/metabolismo , Invasividade Neoplásica , Metástase Neoplásica , Proteínas de Neoplasias/genética , Proteínas Tirosina Fosfatases/genética , Interferência de RNA , Transdução de Sinais , Fatores de Tempo , Transfecção , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/patologia , Proteínas rac de Ligação ao GTP/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Quinases da Família src/metabolismo
7.
J Cell Biol ; 212(3): 349-64, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26833789

RESUMO

Integrin adhesion complexes (IACs) form mechanochemical connections between the extracellular matrix and actin cytoskeleton and mediate phenotypic responses via posttranslational modifications. Here, we investigate the modularity and robustness of the IAC network to pharmacological perturbation of the key IAC signaling components focal adhesion kinase (FAK) and Src. FAK inhibition using AZ13256675 blocked FAK(Y397) phosphorylation but did not alter IAC composition, as reported by mass spectrometry. IAC composition was also insensitive to Src inhibition using AZD0530 alone or in combination with FAK inhibition. In contrast, kinase inhibition substantially reduced phosphorylation within IACs, cell migration and proliferation. Furthermore using fluorescence recovery after photobleaching, we found that FAK inhibition increased the exchange rate of a phosphotyrosine (pY) reporter (dSH2) at IACs. These data demonstrate that kinase-dependent signal propagation through IACs is independent of gross changes in IAC composition. Together, these findings demonstrate a general separation between the composition of IACs and their ability to relay pY-dependent signals.


Assuntos
Adesão Celular/efeitos dos fármacos , Fibroblastos/enzimologia , Quinase 1 de Adesão Focal/metabolismo , Adesões Focais/enzimologia , Transdução de Sinais/efeitos dos fármacos , Quinases da Família src/metabolismo , Animais , Movimento Celular , Proliferação de Células , Relação Dose-Resposta a Droga , Fibroblastos/efeitos dos fármacos , Quinase 1 de Adesão Focal/antagonistas & inibidores , Quinase 1 de Adesão Focal/genética , Adesões Focais/efeitos dos fármacos , Adesões Focais/genética , Células HEK293 , Humanos , Camundongos , Células NIH 3T3 , Fosforilação , Fosfotirosina/metabolismo , Ligação Proteica , Inibidores de Proteínas Quinases/farmacologia , Fatores de Tempo , Transfecção , Domínios de Homologia de src , Quinases da Família src/antagonistas & inibidores
8.
Oncotarget ; 6(31): 30516-31, 2015 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-26483365

RESUMO

Cells induced into senescence exhibit a marked increase in the secretion of pro-inflammatory cytokines termed senescence-associated secretory phenotype (SASP). Here we report that SASP from senescent stromal fibroblasts promote spontaneous morphological changes accompanied by an aggressive migratory behavior in originally non-motile human breast cancer cells. This phenotypic switch is coordinated, in space and time, by a dramatic reorganization of the actin and microtubule filament networks, a discrete polarization of EB1 comets, and an unconventional front-to-back inversion of nucleus-MTOC polarity. SASP-induced morphological/migratory changes are critically dependent on microtubule integrity and dynamics, and are coordinated by the inhibition of RhoA and cell contractility. RhoA/ROCK inhibition reduces focal adhesions and traction forces, while promoting a novel gliding mode of migration.


Assuntos
Neoplasias da Mama/enzimologia , Movimento Celular , Senescência Celular , Fibroblastos/metabolismo , Miosinas/metabolismo , Comunicação Parácrina , Quinases Associadas a rho/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Actinas/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Movimento Celular/efeitos dos fármacos , Polaridade Celular , Forma Celular , Feminino , Adesões Focais/enzimologia , Humanos , Células MCF-7 , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/enzimologia , Mutação , Fenótipo , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais , Fatores de Tempo , Transfecção , Quinases Associadas a rho/antagonistas & inibidores , Proteína rhoA de Ligação ao GTP/antagonistas & inibidores , Proteína rhoA de Ligação ao GTP/genética
9.
Biochem Biophys Res Commun ; 464(1): 275-80, 2015 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-26116771

RESUMO

Cancer cell invasion is a critical phenomenon in cancer pathogenesis. Glycogen synthase kinase-3ß (GSK-3ß) has been reported to regulate cancer cell invasion both negatively and positively. Thus, the net effect of GSK-3ß on invasion is unclear. In this report, we showed that GSK-3ß inhibitors induced dysregulation of the actin cytoskeleton and functional insufficiency of focal adhesion, which resulted in suppressed invasion. In addition, WAVE2, an essential molecule for actin fibre branching, was down-regulated after GSK-3ß inhibition. Collectively, we propose that the WAVE2-actin cytoskeleton axis is an important target of GSK-3ß inhibitors in cancer cell invasion.


Assuntos
Citoesqueleto de Actina/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Tiazóis/farmacologia , Ureia/análogos & derivados , Família de Proteínas da Síndrome de Wiskott-Aldrich/antagonistas & inibidores , Citoesqueleto de Actina/enzimologia , Citoesqueleto de Actina/ultraestrutura , Actinas/química , Actinas/genética , Actinas/metabolismo , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Colágeno/química , Combinação de Medicamentos , Adesões Focais/efeitos dos fármacos , Adesões Focais/enzimologia , Adesões Focais/ultraestrutura , Expressão Gênica , Quinase 3 da Glicogênio Sintase/genética , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Humanos , Laminina/química , Proteoglicanas/química , Ureia/farmacologia , Família de Proteínas da Síndrome de Wiskott-Aldrich/genética , Família de Proteínas da Síndrome de Wiskott-Aldrich/metabolismo
11.
EMBO J ; 34(4): 448-65, 2015 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-25471072

RESUMO

Paradoxically, the thymidine kinase (TK) encoded by Kaposi sarcoma-associated herpesvirus (KSHV) is an extremely inefficient nucleoside kinase, when compared to TKs from related herpesviruses. We now show that KSHV-TK, in contrast to HSV1-TK, associates with the actin cytoskeleton and induces extensive cell contraction followed by membrane blebbing. These dramatic changes in cell morphology depend on the auto-phosphorylation of tyrosines 65, 85 and 120 in the N-terminus of KSHV-TK. Phosphorylation of tyrosines 65/85 and 120 results in an interaction with Crk family proteins and the p85 regulatory subunit of PI3-Kinase, respectively. The interaction of Crk with KSHV-TK leads to tyrosine phoshorylation of this cellular adaptor. Auto-phosphorylation of KSHV-TK also induces a loss of FAK and paxillin from focal adhesions, resulting in activation of RhoA-ROCK signalling to myosin II and cell contraction. In the absence of FAK or paxillin, KSHV-TK has no effect on focal adhesion integrity or cell morphology. Our observations demonstrate that by acting as a tyrosine kinase, KSHV-TK modulates signalling and cell morphology.


Assuntos
Adesões Focais/enzimologia , Adesões Focais/metabolismo , Herpesvirus Humano 8/enzimologia , Proteínas Tirosina Quinases/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Animais , Células COS , Chlorocebus aethiops , Células HeLa , Humanos , Immunoblotting , Imunoprecipitação , Paxilina/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas c-crk/metabolismo
12.
Am J Pathol ; 184(10): 2742-56, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25239564

RESUMO

Aberrant focal adhesion turnover is centrally involved in podocyte actin cytoskeleton disorganization and foot process effacement. The structural and dynamic integrity of focal adhesions is orchestrated by multiple cell signaling molecules, including glycogen synthase kinase 3ß (GSK3ß), a multitasking kinase lately identified as a mediator of kidney injury. However, the role of GSK3ß in podocytopathy remains obscure. In doxorubicin (Adriamycin)-injured podocytes, lithium, a GSK3ß inhibitor and neuroprotective mood stabilizer, obliterated the accelerated focal adhesion turnover, rectified podocyte hypermotility, and restored actin cytoskeleton integrity. Mechanistically, lithium counteracted the doxorubicin-elicited GSK3ß overactivity and the hyperphosphorylation and overactivation of paxillin, a focal adhesion-associated adaptor protein. Moreover, forced expression of a dominant negative kinase dead mutant of GSK3ß highly mimicked, whereas ectopic expression of a constitutively active GSK3ß mutant abolished, the effect of lithium in doxorubicin-injured podocytes, suggesting that the effect of lithium is mediated, at least in part, through inhibition of GSK3ß. Furthermore, paxillin interacted with GSK3ß and served as its substrate. In mice with doxorubicin nephropathy, a single low dose of lithium ameliorated proteinuria and glomerulosclerosis. Consistently, lithium therapy abrogated GSK3ß overactivity, blunted paxillin hyperphosphorylation, and reinstated actin cytoskeleton integrity in glomeruli associated with an early attenuation of podocyte foot process effacement. Thus, GSK3ß-modulated focal adhesion dynamics might serve as a novel therapeutic target for podocytopathy.


Assuntos
Adesões Focais/enzimologia , Quinase 3 da Glicogênio Sintase/metabolismo , Glomérulos Renais/enzimologia , Lítio/farmacologia , Paxilina/metabolismo , Podócitos/fisiologia , Citoesqueleto de Actina/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Antibióticos Antineoplásicos/farmacologia , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Doxorrubicina/farmacologia , Adesões Focais/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Glicogênio Sintase Quinase 3 beta , Humanos , Glomérulos Renais/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Fosforilação/efeitos dos fármacos , Podócitos/efeitos dos fármacos , Podócitos/enzimologia , Podócitos/patologia , Transdução de Sinais/efeitos dos fármacos
13.
Sci Rep ; 4: 5756, 2014 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-25056908

RESUMO

Focal adhesions (FAs) are dynamic subcellular structures crucial for cell adhesion, migration and differentiation. It remains an enigma how enzymatic activities in these local complexes regulate their structural remodeling in live cells. Utilizing biosensors based on fluorescence resonance energy transfer (FRET), we developed a correlative FRET imaging microscopy (CFIM) approach to quantitatively analyze the subcellular coordination between the enzymatic Src activation and the structural FA disassembly. CFIM reveals that the Src kinase activity only within the microdomain of lipid rafts at the plasma membrane is coupled with FA dynamics. FA disassembly at cell periphery was linearly dependent on this raft-localized Src activity, although cells displayed heterogeneous levels of response to stimulation. Within lipid rafts, the time delay between Src activation and FA disassembly was 1.2 min in cells seeded on low fibronectin concentration ([FN]) and 4.3 min in cells on high [FN]. CFIM further showed that the level of Src-FA coupling, as well as the time delay, was regulated by cell-matrix interactions, as a tight enzyme-structure coupling occurred in FA populations mediated by integrin αvß3, but not in those by integrin α5ß1. Therefore, different FA subpopulations have distinctive regulation mechanisms between their local kinase activity and structural FA dynamics.


Assuntos
Adesões Focais/enzimologia , Animais , Técnicas Biossensoriais , Adesão Celular , Células Cultivadas , Ativação Enzimática , Fibronectinas/metabolismo , Transferência Ressonante de Energia de Fluorescência , Adesões Focais/ultraestrutura , Proteínas Luminescentes/biossíntese , Camundongos , Microscopia de Fluorescência , Fator de Crescimento Derivado de Plaquetas/fisiologia , Quinases da Família src/metabolismo , Proteína Vermelha Fluorescente
14.
J Biol Chem ; 289(26): 18427-41, 2014 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-24821720

RESUMO

Interleukin-1 (IL-1) signaling in fibroblasts is mediated through focal adhesions, organelles that are enriched with adaptor and cytoskeletal proteins that regulate signal transduction. We examined interactions of the focal adhesion kinase (FAK) with protein-tyrosine phosphatase-α (PTP-α) in IL-1 signaling. In wild type and FAK knock-out mouse embryonic fibroblasts, we found by immunoblotting, immunoprecipitation, immunostaining, and gene silencing that FAK is required for IL-1-mediated sequestration of PTPα to focal adhesions. Immunoprecipitation and pulldown assays of purified proteins demonstrated a direct interaction between FAK and PTPα, which was dependent on the FAT domain of FAK and by an intact membrane-proximal phosphatase domain of PTPα. Recruitment of PTPα to focal adhesions, IL-1-induced Ca(2+) release from the endoplasmic reticulum, ERK activation, and IL-6, MMP-3, and MMP-9 expression were all blocked in FAK knock-out fibroblasts. These processes were restored in FAK knock-out cells transfected with wild type FAK, FAT domain, and FRNK. Our data indicate that IL-1-induced signaling through focal adhesions involves interactions between the FAT domain of FAK and PTPα.


Assuntos
Fibroblastos/enzimologia , Proteína-Tirosina Quinases de Adesão Focal/química , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Adesões Focais/enzimologia , Interleucina-1/metabolismo , Proteínas Tirosina Fosfatases Classe 4 Semelhantes a Receptores/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fibroblastos/metabolismo , Proteína-Tirosina Quinases de Adesão Focal/genética , Adesões Focais/metabolismo , Interleucina-1/genética , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Knockout , Células NIH 3T3 , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Tirosina Fosfatases Classe 4 Semelhantes a Receptores/genética , Transdução de Sinais
15.
Int J Biochem Cell Biol ; 51: 131-41, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24747131

RESUMO

Focal contacts, large macromolecular complexes that link the extracellular matrix and the internal cell cytoskeleton, are thought to govern cell locomotion. However, the maturation process through which focal contacts control the cellular migratory machinery by changes in size and molecular composition remain unclear. Here, we fabricated cell growth substrates that contained linear ECM strips of micron- or submicron-width in order to limit the enlargement of focal contacts. We found that NBT-II cells plated on the submicron substrate possessed smaller focal complexes that exhibited a highly dynamic turnover. These cells possessed various leading edges at multiple sites of the cell periphery, which prevented the cell from advancing. In contrast, cells grown on the micron-width substrate possessed large and stable focal adhesions. Most of these cells were elongated bipolar cells that were tethered at both ends and were immobile. Further, EGF and ROCK signaling pathways can modulate the cellular migratory responses according to the substrate guidance. On the submicron-width substrate, EGF treatment increased the focal contact size and the contractile force, causing these cells to develop one leading edge and migrate along the submicron-sized ECM paths. In contrast, inhibition of ROCK signaling decreased the focal contact size for cells plated on the micron substrate. These cells became less tethered and were able to migrate along or even across the micron-sized ECM paths. Our results indicate that formation and maturation of focal contacts is controlled by both ECM cues and intracellular signaling and they play a central role in directed cell motion.


Assuntos
Movimento Celular/fisiologia , Fator de Crescimento Epidérmico/metabolismo , Adesões Focais/fisiologia , Neoplasias da Bexiga Urinária/patologia , Quinases Associadas a rho/metabolismo , Animais , Linhagem Celular Tumoral , Adesões Focais/enzimologia , Ratos , Transdução de Sinais , Transfecção , Neoplasias da Bexiga Urinária/enzimologia , Neoplasias da Bexiga Urinária/metabolismo
16.
Eur J Pharm Sci ; 55: 46-57, 2014 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-24486483

RESUMO

Diacylglycerol (DAG) is a central mediator of signaling pathways that regulate cell proliferation, survival and apoptosis. Therefore, C1 domain, the DAG binding site within protein kinase C (PKC) and other DAG effector proteins, is considered a potential cancer drug target. Derivatives of 5-(hydroxymethyl)isophthalic acid are a novel group of C1 domain ligands with antiproliferative and differentiation-inducing effects. Our previous work showed that these isophthalate derivatives exhibit antiproliferative and elongation-inducing effects in HeLa human cervical cancer cells. In this study we further characterized the effects of bis(3-trifluoromethylbenzyl) 5-(hydroxymethyl)isophthalate (HMI-1a3) on HeLa cell proliferation and morphology. HMI-1a3-induced cell elongation was accompanied with loss of focal adhesions and actin stress fibers, and exposure to HMI-1a3 induced a prominent relocation of cofilin-1 into the nucleus regardless of cell phenotype. The antiproliferative and morphological responses to HMI-1a3 were not modified by pharmacological inhibition or activation of PKC, or by RNAi knock-down of specific PKC isoforms, suggesting that the effects of HMI-1a3 were not mediated by PKC. Genome-wide gene expression microarray and gene set enrichment analysis suggested that, among others, HMI-1a3 induces changes in small GTPase-mediated signaling pathways. Our experiments revealed that the isophthalates bind also to the C1 domains of ß2-chimaerin, protein kinase D (PKD) and myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK), which are potential mediators of small GTPase signaling and cytoskeletal reorganization. Pharmacological inhibition of MRCK, but not that of PKD attenuated HMI-1a3-induced cell elongation, suggesting that MRCK participates in mediating the effects of HMI-1a3 on HeLa cell morphology.


Assuntos
Forma Celular/efeitos dos fármacos , Ácidos Ftálicos/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cofilina 1/metabolismo , Relação Dose-Resposta a Droga , Adesões Focais/efeitos dos fármacos , Adesões Focais/enzimologia , Células HeLa , Humanos , Miotonina Proteína Quinase , Fenótipo , Fosforilação , Proteína Quinase C/antagonistas & inibidores , Proteína Quinase C/genética , Proteína Quinase C/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Interferência de RNA , Fibras de Estresse/efeitos dos fármacos , Fibras de Estresse/enzimologia , Fatores de Tempo , Transfecção
17.
J Orthop Res ; 32(3): 448-54, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24249698

RESUMO

Focal adhesions are transmembrane protein complexes that attach chondrocytes to the pericellular cartilage matrix and in turn, are linked to intracellular organelles via cytoskeleton. We previously found that excessive compression of articular cartilage leads to cytoskeleton-dependent chondrocyte death. Here we tested the hypothesis that this process also requires integrin activation and signaling via focal adhesion kinase (FAK) and Src family kinase (SFK). Osteochondral explants were treated with FAK and SFK inhibitors (FAKi, SFKi, respectively) for 2 h and then subjected to a death-inducing impact load. Chondrocyte viability was assessed by confocal microscopy immediately and at 24 h post-impact. With no treatment immediate post-impact viability was 59%. Treatment with 10 µM SFKi, 10 µM, or 100 µM FAKi improved viability to 80%, 77%, and 82%, respectively (p < 0.05). After 24 h viability declined to 34% in controls, 48% with 10 µM SFKi, 45% with 10 µM FAKi, and 56% with 100 µM FAKi (p < 0.01) treatment. These results confirmed that most of the acute chondrocyte mortality was FAK- and SFK-dependent, which implicates integrin-cytoskeleton interactions in the death signaling pathway. Together with previous findings, these data support the hypothesis that the excessive tissue strains accompanying impact loading induce death via a pathway initiated by strain on cell adhesion receptors.


Assuntos
Cartilagem Articular/lesões , Morte Celular/fisiologia , Condrócitos/enzimologia , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Adesões Focais/enzimologia , Quinases da Família src/metabolismo , Animais , Cartilagem Articular/enzimologia , Bovinos , Proteína-Tirosina Quinases de Adesão Focal/antagonistas & inibidores , Adesões Focais/patologia , Distribuição Aleatória , Quinases da Família src/antagonistas & inibidores
18.
Mol Cells ; 36(1): 1-6, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23686429

RESUMO

Focal adhesion kinase (FAK) is a protein tyrosine kinase (PTK) crucial in regulation of cell migration and proliferation. In addition to its canonical roles as a cytoplasmic kinase downstream of integrin and growth factor receptor signaling, recent studies revealed new aspects of FAK action in the nucleus. Nuclear FAK promotes p53 and GATA4 degradation via ubiquitination, resulting in enhanced cell proliferation and reduced inflammatory responses. FAK can also serve as a co-transcriptional regulator that alters a gene transcriptional activity. These findings established a new paradigm of FAK signaling from cellular adhesions to the nucleus. Although physiological stimuli for controlling FAK nuclear localization have not been completely characterized, FAK shuttles from focal adhesions to the nucleus to directly convey extracellular signals. Interestingly, nuclear translocation of FAK becomes prominent in kinase-inhibited conditions such as in de-adhesion and pharmacological FAK inhibition, while a small fraction of nuclear FAK is observed a normal growth condition. In this review, roles of nuclear FAK in regulating transcription factors will be discussed. Furthermore, a potential use of a pharmacological FAK inhibitor to target nuclear FAK function in diseases such as inflammation will be emphasized.


Assuntos
Núcleo Celular/enzimologia , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Regulação da Expressão Gênica , Animais , Adesão Celular/genética , Proteína-Tirosina Quinases de Adesão Focal/química , Adesões Focais/enzimologia , Humanos , Transdução de Sinais/genética
19.
Microcirculation ; 20(7): 637-49, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23600470

RESUMO

OBJECTIVE: To determine the role of FAK in the regulation of endothelial barrier function. METHODS: Stable FAK knockdown HLEC were generated by lentiviral infection of FAK shRNA. Measurements of isometric tension and transendothelial electrical resistance were performed. RESULTS: A FAK knockdown human pulmonary endothelial cell line was generated by lentiviral infection with FAK shRNA and resulted in greater than 90% reduction in FAK protein with no change in Pyk2 protein. Loss of FAK altered cell morphology and actin distribution in both pre- and post-confluent endothelial cells. Large, polygonal shaped endothelial cells with randomly organized stress fibers were identified in pre-confluent cultures, while in confluent monolayers, endothelial cells were irregularly shaped with actin bundles present at cell margins. An increase in the number and size of vinculin plaques was detected in FAK-depleted cells. FAK knockdown monolayers generated a greater transendothelial electrical resistance than controls. Thrombin treatment induced similar changes in TER in both FAK knockdown and control cell lines. FAK-depleted endothelial cells developed a higher stable basal isometric tension compared to control monolayers, but the increase in tension stimulated by thrombin does not differ between the cell lines. Basal myosin II regulatory light chain phosphorylation was unaltered in FAK-depleted cells. In addition, loss of FAK enhanced VE-cadherin localization to the cell membrane without altering VE-cadherin protein levels. CONCLUSIONS: The loss of FAK in endothelial cells enhanced cell attachment and strengthened cell-cell contacts resulting in greater basal tension leading to formation of a tighter endothelial monolayer.


Assuntos
Células Endoteliais/enzimologia , Endotélio Vascular/enzimologia , Quinase 1 de Adesão Focal/metabolismo , Adesões Focais/enzimologia , Pulmão/enzimologia , Animais , Linhagem Celular Transformada , Impedância Elétrica , Células Endoteliais/citologia , Endotélio Vascular/citologia , Quinase 1 de Adesão Focal/genética , Adesões Focais/genética , Técnicas de Silenciamento de Genes , Humanos , Pulmão/citologia , Camundongos , Camundongos Knockout
20.
Biol Psychiatry ; 74(6): 418-26, 2013 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-23482246

RESUMO

BACKGROUND: Evidence from genetic association studies implicate genes involved in neural migration associated with schizophrenia risk. Neural stem/progenitor cell cultures (neurosphere-derived cells) from olfactory mucosa of schizophrenia patients have significantly dysregulated expression of genes in focal adhesion kinase (FAK) signaling, a key pathway regulating cell adhesion and migration. The aim of this study was to investigate whether olfactory neurosphere-derived cells from schizophrenia patients have altered cell adhesion, cell motility, and focal adhesion dynamics. METHODS: Olfactory neurosphere-derived cells from nine male schizophrenia patients and nine male healthy control subjects were used. Cells were assayed for cell adhesion and cell motility and analyzed for integrins and FAK proteins. Focal adhesions were counted and measured in fixed cells, and time-lapse imaging was used to assess cell motility and focal adhesion dynamics. RESULTS: Patient-derived cells were less adhesive and more motile than cells derived from healthy control subjects, and their motility was reduced to control cell levels by integrin-blocking antibodies and by inhibition of FAK. Vinculin-stained focal adhesion complexes were significantly smaller and fewer in patient cells. Time-lapse imaging of cells expressing FAK tagged with green fluorescent protein revealed that the disassembly of focal adhesions was significantly faster in patient cells. CONCLUSIONS: The evidence for altered motility and focal adhesion dynamics in patient-derived cells is consistent with dysregulated gene expression in the FAK signaling pathway in these cells. Alterations in cell adhesion dynamics and cell motility could bias the trajectory of brain development in schizophrenia.


Assuntos
Adesões Focais/ultraestrutura , Células-Tronco Neurais/fisiologia , Esquizofrenia/fisiopatologia , Adolescente , Adulto , Movimento Celular , Proteína-Tirosina Quinases de Adesão Focal/fisiologia , Adesões Focais/enzimologia , Humanos , Masculino , Pessoa de Meia-Idade , Células-Tronco Neurais/enzimologia , Mucosa Olfatória/citologia , Mucosa Olfatória/fisiologia , Esquizofrenia/enzimologia , Esquizofrenia/patologia , Adulto Jovem
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