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1.
Res Lang Soc Interact ; 57(1): 73-90, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38741749

RESUMO

We provide a state-of-the-art review of research on conversation analysis and telehealth. We conducted a systematic review of the literature, focusing on studies that investigate how technology is procedurally consequential for the interaction. We discerned three key topics: the interactional organization, the therapeutic relationship, and the clinical activities of the encounter. The literature on telehealth is highly heterogeneous, with significant differences between text-based care (e.g., via chat or e-mail) and audio(visual) care (e.g., via telephone or video). We discuss the extent to which remote care can be regarded as a demarcated field for study or whether the medium is merely part of the "context," particularly when investigating hybrid and polymedia forms of care involving multiple technological media.

2.
Patient Educ Couns ; 112: 107721, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37012192

RESUMO

Uncertainty is increasingly recognized as a crucial phenomenon throughout medical practice. Research on uncertainty so far has been scattered across disciplines, leading to a lack of consensus about what uncertainty represents and minimal integration of knowledge obtained within isolated disciplines. Currently, a comprehensive view of uncertainty which does justice to normatively or interactionally challenging healthcare settings is lacking. This impedes research teasing apart when and how uncertainty manifests, how all stakeholders experience and value it, and how it affects medical communication and decision-making. In this paper, we argue that we need a more integrated understanding of uncertainty. We illustrate our argument using the context of adolescent transgender care, in which uncertainty occurs in myriad ways. We first sketch how theories of uncertainty have emerged from isolated disciplines, leading to a lack of conceptual integration. Subsequently, we emphasize why it is problematic that no comprehensive approach to uncertainty has yet been developed, using examples from adolescent transgender care. Finally, we advocate an integrated approach of uncertainty to further advance empirical research and to ultimately benefit clinical practice.


Assuntos
Atenção à Saúde , Humanos , Adolescente , Incerteza
3.
J Med Internet Res ; 22(5): e17791, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32310816

RESUMO

BACKGROUND: Research on the use of video-mediated technology for medical consultations is increasing rapidly. Most research in this area is based on questionnaires and focuses on long-term conditions. The few studies that have focused on physical examinations in video consultations indicated that it poses challenges for the participants. The specific activity of wound assessment through video in postsurgery consultations has not yet been studied. Furthermore, a comparative analysis of face-to-face and video settings on the moment-to-moment organization of such an activity is original. OBJECTIVE: The aim of this study was to examine the impact of video technology on the procedure of postsurgery wound assessment and its limits. METHODS: We recorded 22 postoperative video consultations and 17 postoperative face-to-face consultations. The primary purpose of the consultation was to inform the patient about the final pathology results of the resected specimen, and the secondary purpose was to check on the patient's recovery, including an assessment of the closed wound. The recordings were transcribed in detail and analyzed using methods of conversation analysis. RESULTS: The way that an assessment of the wound is established in video consultations differs from the procedure in face-to-face consultations. In the consultation room, wound assessments overwhelmingly (n=15/17) involve wound showings in the context of surgeons reporting their observations formatted with evidentials ("looks neat") and subsequently assessing what these observations imply or what could be concluded from them. In contrast, wound assessments in video consultations do not tend to involve showing the wound (n=3/22) and, given the technological restrictions, do not involve palpation. Rather, the surgeon invites the patient to assess the wound, which opens up a sequence of patient and physician assessments where diagnostic criteria such as redness or swollenness are made explicit. In contrast to observations in regular consultations, these assessments are characterized by epistemic markers of uncertainty ("I think," "sounds...good") and evidentials are absent. Even in cases of a potential wound problem, the surgeon may rely on questioning the patient rather than requesting a showing. CONCLUSIONS: The impact of video technology on postoperative consultations is that a conclusive wound assessment is arrived at in a different way when compared to face-to-face consultations. In video consultations, physicians enquire and patients provide their own observations, which serve as the basis for the assessment. This means that, in video consultations, patients have a fundamentally different role. These talking-based assessments are effective unless, in cases of a potential problem, patient answers seem insufficient and a showing might be beneficial.


Assuntos
Gravação de Videoteipe/métodos , Ferimentos e Lesões/terapia , Comunicação , Feminino , Humanos , Masculino , Período Pós-Operatório , Encaminhamento e Consulta
4.
Oncogene ; 20(42): 5941-50, 2001 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-11593401

RESUMO

The tyrosine kinase oncoprotein v-Src can overcome the requirements for serum growth factors and anchorage which restrain normal cell growth. Here we investigated the biochemical mechanisms whereby v-Src induces quiescent cells to enter S phase in the absence of serum mitogens. Activating a temperature sensitive v-Src in quiescent cells sequentially induced cyclins D1, E and A and also down regulated p27. We addressed whether p27 down regulation was required to activate cyclin D1/CDK4/6 or cyclin E/CDK2 by engineering cells with inducible p27. Both S phase entry and activation of cyclin/CDKs were inhibited by over expression of p27. Using cells engineered with inducible p16 we showed that Cyclin D/CDK4/6 activity was required for v-Src to increase expression of cyclin A but not cyclin E. To determine which downstream kinases mediated these effects of v-Src we added pharmacological inhibitors of phosphatidylinositol 3-kinase (PI3-K), LY294002 or mitogen activated protein kinase kinase (MEK), U0126. PI3-K was required for v-Src to activate MEK and MEK was required for v-Src to increase expression of cyclins D1 and E. However, the MEK inhibitor prevented p27 protein down regulation whereas the PI3-K inhibitor did not. This was because reduced PI3-K activity lead to proteolytic degradation of p27.


Assuntos
Ciclo Celular , Proteínas Musculares , Proteína Oncogênica pp60(v-src)/fisiologia , Animais , Butadienos/farmacologia , Linhagem Celular , Ciclina A/metabolismo , Ciclina D1/metabolismo , Ciclina E/metabolismo , Quinases Ciclina-Dependentes/fisiologia , Regulação para Baixo , Inibidores Enzimáticos/farmacologia , Cinética , MAP Quinase Quinase 1 , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Quinases de Proteína Quinase Ativadas por Mitógeno/fisiologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Nitrilas/farmacologia , Proteína Oncogênica pp60(v-src)/antagonistas & inibidores , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/fisiologia , RNA Mensageiro/biossíntese , Ratos , Transfecção
6.
Cell Death Differ ; 7(8): 685-96, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10918442

RESUMO

A number of oncogenes alter the regulation of the cell cycle and cell death, contributing to the altered growth of tumours. Expression of the v-Src oncoprotein in Rat-1 fibroblasts prevented cell cycle exit in response to growth factor withdrawal. Here we investigated whether survival of v-Src transformed cells in low serum is dependent on v-Src activity. We used a temperature sensitive v-Src to study the effect inactivating v-Src on transformed cells growing under low serum conditions. We found when we switched off v-Src the cells died by apoptosis characterised by activation of caspases and the stress-activated kinases, JNK (Jun N-terminal kinase) and p38 MAP (mitogen activated protein) kinase. We were able to prevent cell death by addition of serum or overexpression of Bcl-2. Thus v-Src transformed Rat-1 cells can be protected from apoptosis by serum, v-Src, or Bcl-2. We investigated how v-Src protects from apoptosis under these conditions. Amongst other effects, v-Src activates two kinases which have been shown to protect cells from apoptosis, phosphatidylinositol 3-kinase (PI3-K) and extracellular signal-regulated kinase (ERK1/2). We found that switching off v-Src led to a decrease in the activity of both PI3-K and ERK1/2, however, we found that adding a specific inhibitor of PI3-K (LY294002) to v-Src transformed Rat-1 cells grown in low serum induced apoptosis while a specific ERK kinase (MEK1) inhibitor (PD98059) had no effect. This suggests that v-Src protects from apoptosis under low serum conditions by activating PI3-K.


Assuntos
Apoptose , Proteína Oncogênica pp60(v-src)/metabolismo , Animais , Inibidores de Caspase , Caspases/fisiologia , Linhagem Celular , Linhagem Celular Transformada , Sobrevivência Celular , Meios de Cultura , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/fisiologia , Proteína Oncogênica pp60(v-src)/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Soroalbumina Bovina , Proteínas Quinases p38 Ativadas por Mitógeno
7.
Oncogene ; 16(15): 2017-28, 1998 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-9591786

RESUMO

To determine how an oncogenic tyrosine kinase disturbs cell cycle control we examined expression of cell cycle proteins and growth of fibroblasts reversibly transformed by a temperature sensitive mutant of v-Src (ts LA 29). ts LA 29 Rat-1 cells and normal Rat-1 cells had similar growth rates but the transformed cells traversed the G1 phase of the cell cycle more rapidly and failed to exit cycle efficiently in response to serum starvation and cell confluence. Cyclin D1 and cyclin E levels were not elevated in growing ts LA 29 Rat-1 cells and the abbreviated G1 was further accelerated by overexpression of cyclin E. A fall in cyclin E and cyclin A dependent kinase activities in Rat-1 cells in response to inhibitory growth conditions was abrogated in ts LA 29 Rat-1 cells and correlated with lack of p27 accumulation or cyclin A down regulation, the latter due to sustained cyclin A promoter activity. The expression of p27 mRNA was lower in ts LA 29 Rat-1 cells than Rat-1 cells and was elevated following v-Src inactivation concurrent with an increase in p27 promoter activity and temporary cell cycle exit. The suppression of mRNA or transcription is a novel way an oncoprotein can induce down regulation of p27 and contributes to the G1 shortening and perturbed cell cycle regulation of the v-Src transformed cells.


Assuntos
Proteínas de Ciclo Celular , Transformação Celular Neoplásica , Quinases Ciclina-Dependentes/antagonistas & inibidores , Inibidores Enzimáticos , Proteínas Associadas aos Microtúbulos/fisiologia , Proteínas Supressoras de Tumor , Animais , Células Cultivadas , Inibidor de Quinase Dependente de Ciclina p27 , Ciclinas/fisiologia , Fase G1 , Proteína Oncogênica pp60(v-src)/fisiologia , Ratos , Transcrição Gênica
8.
J Med Genet ; 35(1): 42-4, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9475093

RESUMO

A locus for Peutz-Jeghers syndrome (PJS) was recently mapped to chromosome 19p13.3. Each of 12 families studied was compatible with linkage to the marker D19S886. We have analysed 20 further families and found that the majority of these are consistent with a PJS gene on 19p13.3. Three families were, however, unlinked to 19p13.3 and none of the available PJS polyps from these families showed allele loss at D19S886. There were no obvious clinicopathological or ethnic differences between the 19p13.3 linked and unlinked families. There appears, therefore, to be a major PJS locus on chromosome 19p13.3 and the possibility exists of a minor locus (or loci) elsewhere.


Assuntos
Cromossomos Humanos Par 19/genética , Ligação Genética , Síndrome de Peutz-Jeghers/genética , Feminino , Heterogeneidade Genética , Marcadores Genéticos , Humanos , Masculino , Linhagem
9.
J Cell Biol ; 135(6 Pt 1): 1551-64, 1996 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8978822

RESUMO

We have isolated Swiss 3T3 subclones that are resistant to the mitogenic and morphological transforming effects of v-Src as a consequence of aberrant translocation of the oncoprotein under low serum conditions. In chicken embryo and NIH 3T3 fibroblasts under similar conditions, v-Src rapidly translocates from the perinuclear region to the focal adhesions upon activation of the tyrosine kinase, resulting in downstream activation of activator protein-1 and mitogen-activated protein kinase, which are required for the mitogenic and transforming activity of the oncoprotein. Since serum deprivation induces cytoskeletal disorganization in Swiss 3T3, we examined whether regulators of the cytoskeleton play a role in the translocation of v-Src, and also c-Src, in response to biological stimuli. Actin stress fibers and translocation of active v-Src to focal adhesions in quiescent Swiss 3T3 cells were restored by microinjection of activated Rho A and by serum. Double labeling with anti-Src and phalloidin demonstrated that v-Src localized along the reformed actin filaments in a pattern that would be consistent with trafficking in complexes along the stress fibers to focal adhesions. Furthermore, treatment with the actin-disrupting drug cytochalasin D, but not the microtubule-disrupting drug nocodazole, prevented v-Src translocation. In addition to v-Src, we observed that PDGF-induced, Rac-mediated membrane ruffling was accompanied by translocation of c-Src from the cytoplasm to the plasma membrane, an effect that was also blocked by cytochalasin D. Thus, we conclude that translocation of Src from its site of synthesis to its site of action at the cell membrane requires an intact cytoskeletal network and that the small G proteins of the Rho family may specify the peripheral localization in focal adhesions or along the membrane, mediated by their effects on the cytoskeleton.


Assuntos
Actinas/fisiologia , Proteínas de Ligação ao GTP/metabolismo , Proteína Oncogênica pp60(v-src)/metabolismo , Células 3T3 , Animais , Transporte Biológico , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Divisão Celular , Membrana Celular/metabolismo , Embrião de Galinha , Citoesqueleto/fisiologia , Camundongos , Microtúbulos/fisiologia , Fator de Transcrição AP-1/metabolismo , Proteínas rho de Ligação ao GTP
10.
Cell Growth Differ ; 6(10): 1225-34, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8845299

RESUMO

Activation of the tyrosine kinase of a temperature-sensitive mutant v-Src oncoprotein in quiescent Rat-1 cells leads to passage through the cell cycle. Temperature shift experiments show that v-Src is needed to leave G0, to pass a relatively stable G1 "pause" point, and to pass a later G1 point committing cells to S phase. Classic immediate early responses that activate both AP-1 DNA binding and mitogen-activated protein (MAP) kinase are induced at G0 exit, but unexpectedly they rise again in mid-G1 and before the onset of S phase, fluctuations that parallel the need for v-Src. An estrogen-inducible mutant c-Raf-1 renders these cells susceptible to mitogenic stimulation by beta-estradiol, without v-Src activity, but greatly inhibits the ability of v-Src to induce DNA synthesis and MAP kinase, probably because v-Src physically associates with inactive c-Raf-1 at permissive but not restrictive temperature. This implicates c-Raf-1 association with enzymically active v-Src and consequent activation of the MAP kinase pathway in v-Src mitogenesis. Furthermore, temperature shift experiments indicate that the mid-G1 peak of MAP kinase activity is associated with cells reaching the G1 pause point, while the pre-S phase peak is needed for DNA synthesis. In contrast, cell transformation by v-Src does not require enhanced MAP kinase activity at any stage of the cell cycle.


Assuntos
Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Fase G1 , Mitógenos/fisiologia , Proteína Oncogênica pp60(v-src)/fisiologia , Fator de Transcrição AP-1/metabolismo , Animais , Vírus do Sarcoma Aviário , Linhagem Celular , Transformação Celular Neoplásica , DNA/biossíntese , DNA/metabolismo , Ativação Enzimática , Estradiol/farmacologia , Mutação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-fos/biossíntese , Proteínas Proto-Oncogênicas c-jun/biossíntese , Proteínas Proto-Oncogênicas c-raf , RNA Mensageiro/biossíntese , Ratos , Transdução de Sinais/fisiologia , Temperatura
11.
Oncogene ; 10(11): 2247-52, 1995 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-7784071

RESUMO

Morphological transformation of cells by the v-Src tyrosine kinase is incompletely understood. However, it is independent of nuclear functions and probably involves phosphorylation of targets associated with the cytoskeleton and focal adhesions, structures which tether the cytoskeleton to the points of cell attachment. v-Src activity both stimulates tyrosine phosphorylation of a tyrosine kinase present in focal adhesions (focal adhesion kinase or pp125FAK) and disrupts focal adhesions, leading to cell rounding and detachment. However, pp125FAK is also phosphorylated on tyrosine as a result of integrin stimulation which induces quite different biological consequences including the organisation of focal adhesions when cells spread on fibronectin (reviewed in Schaller and Parsons, 1993). To address this paradox, we examined changes in pp125FAK during activation and shut-off of temperature sensitive mutant v-Src proteins that induce varying degrees of transformation in chick embryo fibroblasts. An efficiently transforming v-Src mutant initially stimulated pp125FAK tyrosine phosphorylation, but induced subsequent pp125FAK degradation prior to the onset of cell rounding and detachment. v-Src mutants which are impaired in their ability to induce morphological transformation were much less efficient at inducing degradation of pp125FAK. Moreover, cell spreading during restitution of normal morphology did not require detectable tyrosine phosphorylation of pp125FAK, or its potential substrate paxillin, suggesting that pp125FAK may function more in the turnover of focal adhesions than in their assembly.


Assuntos
Moléculas de Adesão Celular/metabolismo , Transformação Celular Neoplásica , Proteína Oncogênica pp60(v-src)/fisiologia , Proteínas Tirosina Quinases/metabolismo , Animais , Linhagem Celular Transformada , Células Cultivadas , Embrião de Galinha , Quinase 1 de Adesão Focal , Proteína-Tirosina Quinases de Adesão Focal , Hidrólise , Mutação , Proteína Oncogênica pp60(v-src)/genética , Fosforilação , Tirosina/metabolismo
12.
J Virol ; 68(7): 4392-9, 1994 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8207813

RESUMO

We have analyzed two functionally significant amino acid alterations encoded by the temperature-sensitive (ts) v-src mutant of Rous sarcoma virus, LA32. The G-to-V change at residue 300 in the catalytic domain nonconditionally impairs morphological transformation, in vitro kinase activity, in vivo tyrosine phosphorylation, and the cytoskeletal association of v-Src while rendering anchorage- and serum-independent growth ts. The R-to-P mutation in the SH3 domain subtly enhances morphological transformation but has no phenotype if the catalytic domain is inactivated. In the presence of the G-300-to-V mutation, this SH3 domain lesion does not affect v-Src in vitro kinase activity and cytoskeletal association, but it nonconditionally enhances cellular tyrosine phosphorylation and restores morphological transformation at the permissive temperature only. This ability to induce a ts transformed morphology, in concert with nonconditional elevations of cellular phosphotyrosine, suggest that a subset of v-Src targets that are crucial to transformation may be affected in ts fashion by the SH3 mutation. Consistent with this, we find that the R-107-to-P mutation confers ts activity and tyrosine phosphorylation on the SH3-binding enzyme phosphatidylinositol 3'-kinase. Thus, both the SH3 and catalytic domain mutations in LA32 have some ts attributes and they cooperate in determining the mutant's behavior. The ts SH3 mutation is unique and offers the potential for deeper understanding of the function of this domain.


Assuntos
Transformação Celular Viral/genética , Mutação , Proteína Oncogênica pp60(v-src)/genética , Tirosina/metabolismo , Animais , Vírus do Sarcoma Aviário/genética , Catálise , Células Cultivadas , Embrião de Galinha , Proteína Oncogênica pp60(v-src)/metabolismo , Fosfatidilinositol 3-Quinases , Fosforilação , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Temperatura
13.
Cell Biol Int ; 18(5): 337-44, 1994 May.
Artigo em Inglês | MEDLINE | ID: mdl-8049678

RESUMO

The peripheral non-receptor tyrosine kinase oncoprotein, v-Src, has pleiotropic effects. It is a mitogen for quiescent cells, substituting for both competence and progression factor-mediated signals but it also induces cellular morphological transformation. We are dissecting the activities of v-Src by studying mutant proteins, including those with temperature sensitive (ts) effects, in different cellular backgrounds. Activation of a ts v-Src kinase rapidly increases activity of both the transcription factor, AP-1, and MAP kinase, an enzyme that enhances AP-1 activity by both phosphorylation of c-Jun and increased c-fos transcription; the relative contribution of these two events depends on the cells in which v-Src is expressed. Transient early AP-1 activation requires proper location of v-Src at the cell periphery and it is essential for mitogenesis. It is not, however, sufficient for entry into S-phase, there being a second need for v-Src later in G1. Transformation by v-Src does not require AP-1 activation but seems linked to events at the cell periphery, notably phosphorylation of proteins that bind to the v-Src SH3 domain such as the p85 subunit of PI-3 kinase.


Assuntos
Proteína Oncogênica pp60(v-src)/fisiologia , Animais , Linhagem Celular , Transformação Celular Neoplásica , Células Cultivadas , Ativação Enzimática , Proteína Quinase 1 Ativada por Mitógeno , Mitose , Modelos Biológicos , Mutação/fisiologia , Proteína Oncogênica pp60(v-src)/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-jun/metabolismo
15.
Virology ; 196(2): 564-75, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8396803

RESUMO

Previous reports have shown that Rous sarcoma virus (RSV) transcript levels in mammalian cells can be elevated by serum treatment and cellular transformation. To understand this, we have examined how the RSV long terminal repeat (LTR) enhancer is affected by cellular growth state in clonally related normal and RSV-infected Rat-1 cell lines. Functional assays with enhancer mutants have shown that two LTR CArG motifs and a CCAAT box have individual and combinatorial effects on basal LTR activity, but only the CArG elements contribute to serum responses in phenotypically normal cells. Augmented enhancer activity in transformed cells is mediated in part by these CArG motifs, which under these conditions are not further stimulable by serum. Protein binding to the CArG and CCAAT elements corresponds with functional variations, binding proteins being scarce in serum-deprived normal cells and enhanced by serum stimulation, cellular transformation and, in part, cellular density. These findings provide an explanation for physiologically dependent fluctuations in RSV expression, which may include the initiation of the proviral transcriptional repression that is frequently observed in mammalian hosts. However, we also show that transcript levels of some integrated proviruses are independent of variations in the cell's ability to support LTR activity, showing that the site of insertion can be of overriding importance in determining proviral expression.


Assuntos
Vírus do Sarcoma Aviário/genética , Elementos Facilitadores Genéticos/genética , Regulação Viral da Expressão Gênica , Sequências Repetitivas de Ácido Nucleico/genética , Animais , Vírus do Sarcoma Aviário/crescimento & desenvolvimento , Sequência de Bases , Transformação Celular Viral , Células Cultivadas , Cloranfenicol O-Acetiltransferase/biossíntese , Cloranfenicol O-Acetiltransferase/genética , Meios de Cultura Livres de Soro , Proteínas de Ligação a DNA/metabolismo , Dados de Sequência Molecular , Ratos , Proteínas Recombinantes de Fusão/biossíntese
16.
Cell Growth Differ ; 4(8): 671-8, 1993 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8398908

RESUMO

Activation of the tyrosine kinase of a temperature sensitive v-Src mutant of Rous sarcoma virus in quiescent Rat-1 cells leads to passage through the cell cycle. This is accompanied by a transient increase of the DNA binding activity of the transcription factor AP-1 which is not sufficient for the v-Src mediated cell cycle traverse. There is another need for v-Src later in the G1 phase of the cycle, and after completion of that event, cells are able to progress through DNA synthesis and division in the absence of either v-Src or other growth factors. When cells are exposed to v-Src activity for periods insufficient for it to behave as a complete mitogen, it can act as either a competence or progression factor in conjunction with appropriate purified growth factors.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Fase G1/genética , Mitose/genética , Oncogenes , Fase de Repouso do Ciclo Celular/genética , Animais , Linhagem Celular , Substâncias de Crescimento/fisiologia , Fase S/genética
17.
Oncogene ; 8(7): 1875-86, 1993 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8510932

RESUMO

Activation of rapidly reversible temperature-sensitive (ts) v-Src in quiescent chicken embryo fibroblasts (CEFs) results in both morphological transformation and exit from G0 to G1, resulting in mitosis. This phenomenon permits examination of cellular responses very soon after activating the oncoprotein, and we have used this to study changes in endogenous AP-1, and the regulation of its major components, in the first few hours after activating v-Src. This approach contrasts with a number of studies that have demonstrated enhanced activity of exogenously added AP-1 components in cells transformed by v-Src. Reactivation of a membrane-associated tyrosine kinase (tsRCAN-29) results in a several-fold increase in AP-1 DNA binding and a similar increase in the activity of an AP-1-responsive reporter soon after temperature shift. c-Jun and c-Fos are regulated at a number of levels in response to both stimuli. In quiescent RCAN-29-infected CEFs stimulated into cycle by shift to permissive temperature, c-fos transcripts are elevated by 15 min and remain above basal level for at least 4 h. Serum induces much greater elevation of c-fos transcripts, although this response is transient. Despite the difference in magnitude of the transcript responses, the stimulation of nuclear c-Fos protein is similar in both serum and v-Src-stimulated cultures. No elevation in c-jun transcripts or nuclear c-Jun protein level is evident in v-Src-stimulated quiescent CEFs. However, there is an early change in the tryptic phosphopeptide map of p39 c-Jun in response to both v-Src and serum. Upon stimulation we observed a novel redistribution of phosphate in the carboxy-terminal tryptic phosphopeptide that may be responsible in part for the increase in AP-1 DNA binding. Phosphorylation of amino-terminal serines 63 and 73 on peptides Y and X, believed to be responsible for regulation of the transactivation function of c-Jun, is constitutively high in resting CEF cultures; stimulation with serum or v-Src results in only a modest increase in phosphorylation at these sites. Significantly, reactivation of a non-myristylated, transformation-defective version of the tsRCAN-29 v-Src protein (RCAN-29A2) is unable to induce resting CEFs to re-enter cycle. In addition, this mutant fails to induce early increases in AP-1 activity, implying that these nuclear changes require crucial signalling events at the cell periphery, and that these events correlate with the biological consequences of expression of v-Src.


Assuntos
Proteína Oncogênica pp60(v-src)/genética , Proteínas Proto-Oncogênicas c-jun/metabolismo , Animais , Sequência de Bases , Divisão Celular , Membrana Celular/metabolismo , Embrião de Galinha , DNA/metabolismo , Fibroblastos/fisiologia , Expressão Gênica , Genes fos , Genes jun , Dados de Sequência Molecular , Mutação , Fosforilação , Proteínas Tirosina Quinases/análise , Transcrição Gênica
18.
J Gen Virol ; 73 ( Pt 12): 3247-50, 1992 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1335025

RESUMO

We have previously shown that most Rous sarcoma proviruses in Rat-1 cells are simple insertions, at apparently random sites, and are not transcribed. A small minority of simple insertions are transcribed and these show a bias to insertion at sites closely 3' to presumptive cellular CG-rich islands. However, most transcribed proviruses are complex, typified by contiguous duplications of proviral DNA 5' to a complete proviral unit. The cellular sites of these complex insertions are unknown and their structure and significance incompletely documented. We report here more extensive analyses of proviral duplications, with the following findings. The 5' duplications predominantly involve proviral regions known to contain enhancer functions, substantiating earlier data. The cellular insertion sites are not biased to CG-rich loci at the level displayed by simple transcribed proviruses. The detailed structure of two duplications, and partial analysis of several others, strongly favours their genesis by illegitimate template transfer at reverse transcription, followed by self-recombination. These findings show that aberrant reverse transcription can generate duplications that dispense with the need for an expressed provirus to be integrated at a favourable cellular site.


Assuntos
Vírus do Sarcoma Aviário/genética , Provírus/genética , Animais , Sequência de Bases , Células Cultivadas , DNA Viral/ultraestrutura , Genes gag , Genes src , Ligação de Hidrogênio , Técnicas In Vitro , Dados de Sequência Molecular , Família Multigênica , Ratos , Recombinação Genética , Mapeamento por Restrição
19.
J Virol ; 65(1): 461-3, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1845901

RESUMO

Transcribed Rous sarcoma proviruses in Rat-1 DNA tend to integrate closely 3' to C-G-rich restriction enzyme sites, and 2 of 13 such proviruses were found to have inserted at the same locus. However, most integrated proviruses were transcriptionally silent insertions at sites indistinguishable from random. We conclude that Rous sarcoma proviruses in rat cells usually fail to integrate in a favorable site for transcription, in contrast to studies on proviral integration in permissive hosts.


Assuntos
Vírus do Sarcoma Aviário/genética , Transformação Celular Neoplásica , DNA Viral/genética , Provírus/genética , Transcrição Gênica , Animais , Linhagem Celular , Células Clonais , Enzimas de Restrição do DNA , Ratos , Mapeamento por Restrição
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