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1.
Eur J Investig Health Psychol Educ ; 14(6): 1647-1665, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38921075

RESUMO

Today, many individuals read the daily news from social media platforms. Research has shown that news with negative valence might influence the well-being of individuals. Existing research that examined the impact of headlines on individuals' well-being has primarily focused on examining the positive or negative polarity of words used in the headlines. In the present study, we adopt a different approach and ask participants to categorize the headlines themselves based on the emotions they experienced while reading them and how their choice impacts their well-being. A total of 306 participants were presented with 40 headlines from main news sites that were considered popular based on the number of public reactions. Participants had to rate their emotional experience of the headlines following five emotional states (i.e., happiness, anger, sadness, fear, and interest). Emotion regulation strategies and resilience were also measured. In line with our hypotheses, we found that participants reported experiencing negative emotions more intensively while reading the headlines. Emotion regulation was not found to influence the emotional states of individuals, whereas resilience did. These findings highlight that individuals can experience heightened emotions without reading the entire news story. This effect was observed regardless of the headline's emotional valence (i.e., positive, negative, or neutral). Furthermore, our study highlights the critical role of interest as a factor in news consumption. Interest significantly affects individuals' engagement and reactions to headlines, regardless of valence. The findings underscore the complex interplay between headline content and reader engagement and stress the need for further research into how headlines are presented to protect individuals from potential emotional costs.

2.
Front Psychol ; 14: 1223222, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37928576

RESUMO

Introduction: This research was conducted to examine the extent to which teachers' self-efficacy affects their well-being following the COVID-19 pandemic. The originality of the research lies in the fact that there are not enough studies that simultaneously examine the relationship between well-being and self-efficacy in primary school teachers in Greece and Cyprus. Methods: A total of 258 primary school teacher participants took part in this study, aged 23-62. The Teachers' Sense of Efficacy Scale and the PERMA Profiler questionnaire were used to study the relationship between teachers' well-being and self-efficacy. Results: Results show that after the COVID-19 pandemic, teachers' well-being is moderate to high. Moreover, teachers' self- efficacy is also high and related to their well-being. Discussion: An important finding from the current research is that teachers' self-efficacy in promoting student engagement was the most important predictor for teachers' well-being. The implications of the results are discussed, and recommendations are made.

3.
J Biol Chem ; 299(10): 105203, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37660911

RESUMO

Transcription/processing of the ribosomal RNA (rRNA) precursor, as part of ribosome biosynthesis, is intensively studied and characterized in eukaryotic cells. Here, we constructed shRNA-based mouse cell lines partially silenced for the Upstream Binding Factor UBF, the master regulator of rRNA transcription and organizer of open rDNA chromatin. Full Ubf silencing in vivo is not viable, and these new tools allow further characterization of rRNA transcription and its coordination with cellular signaling. shUBF cells display cell cycle G1 delay and reduced 47S rRNA precursor and 28S rRNA at baseline and serum-challenged conditions. Growth-related mTOR signaling is downregulated with the fractions of active phospho-S6 Kinase and pEIF4E translation initiation factor reduced, similar to phosphorylated cell cycle regulator retinoblastoma, pRB, positive regulator of UBF availability/rRNA transcription. Additionally, we find transcription-competent pUBF (Ser484) severely restricted and its interacting initiation factor RRN3 reduced and responsive to extracellular cues. Furthermore, fractional UBF occupancy on the rDNA unit is decreased in shUBF, and expression of major factors involved in different aspects of rRNA transcription is severely downregulated by UBF depletion. Finally, we observe reduced RNA Pol1 occupancy over rDNA promoter sequences and identified unexpected regulation of RNA Pol1 expression, relative to serum availability and under UBF silencing, suggesting that regulation of rRNA transcription may not be restricted to modulation of Pol1 promoter binding/elongation rate. Overall, this work reveals that UBF depletion has a critical downstream and upstream impact on the whole network orchestrating rRNA transcription in mammalian cells.

4.
Artigo em Inglês | MEDLINE | ID: mdl-37681850

RESUMO

Conspiracy theories flourish during periods of crisis. One way to counteract the believability of conspiracy theories is trust in science and knowledge about the "perceived threat", such as the SARS-CoV-2 virus. A total of 363 adults from Cyprus were recruited via convenience and snowball sampling methods. The data were collected via an internet-based questionnaire that examined participants' belief in 17 conspiracy theory statements, trust in science and scientists, knowledge about the symptoms and the spread of the SARS-CoV-2 virus, phobic anxiety, hostility, somatization, and personality traits based on the Big Five. The results suggest (a) the overall belief in conspiracy theories in Cyprus is low, even though a notable percentage holds a neutral stance towards these theories; (b) trust in science and knowledge about the symptoms and the spread of the SARS-CoV-2 virus is negatively related to conspiracy theories, indicating the importance of trusting science and having knowledge as a means to counteract conspiracy theories; (c) young adults, those residing in rural areas, and those with a low education level are more likely to believe in conspiracy theories; (d) there are no significant associations between conspiracy theories and the psychological dimensions of phobic anxiety, hostility, and somatization; (e) there is difficulty in identifying specific traits related to conspiracy ideation. Public health officials could benefit from the findings when communicating information during periods of crisis.


Assuntos
COVID-19 , Conhecimentos, Atitudes e Prática em Saúde , Humanos , COVID-19/epidemiologia , Chipre/epidemiologia , Pandemias , SARS-CoV-2 , Confiança , Desinformação , Adulto
5.
Artigo em Inglês | MEDLINE | ID: mdl-36833595

RESUMO

COVID-19 reminded us of the importance of vaccinating for successfully overcoming health-related crises. Yet, vaccine hesitancy is still present. This study examined the impacts of conspiracy theories, perceived risk, and trust in science on COVID-19 vaccination decisiveness. The study was conducted at the end of the third wave of the pandemic, in July 2021, in Cyprus. Data were collected via an online self-administered anonymous survey using convenience and snowball sampling methods. Participants were 363 adults who completed a set of questionnaires that examined their believability in ten vaccine-related conspiracy theories, their perceived dangerousness of COVID-19, and their level of trust in science and scientists. The results suggest that (a) participants with a high conspiracy theory belief are less likely to be vaccinated, (b) participants who perceive COVID-19 as a dangerous disease are more likely to be vaccinated, and (c) participants with high trust in science are more likely to be vaccinated. The implications of the findings are discussed and can be used by public health officials in their campaigns.


Assuntos
COVID-19 , Confiança , Adulto , Humanos , Chipre , Vacinas contra COVID-19 , Vacinação
6.
Int J Mol Sci ; 22(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34638576

RESUMO

Nuclear envelope (NE) and endoplasmic reticulum (ER) collaborate to control a multitude of nuclear and cytoplasmic actions. In this context, the transmembrane protein TMEM147 localizes to both NE and ER, and through direct and indirect interactions regulates processes as varied as production and transport of multipass membrane proteins, neuronal signaling, nuclear-shape, lamina and chromatin dynamics and cholesterol synthesis. Aiming to delineate the emerging multifunctionality of TMEM147 more comprehensively, we set as objectives, first, to assess potentially more fundamental effects of TMEM147 on the ER and, second, to identify significantly TMEM147-associated cell-wide protein networks and pathways. Quantifying curved and flat ER markers RTN4 and CLIMP63/CKAP4, respectively, we found that TMEM147 silencing causes area and intensity increases for both RTN4 and CLIMP63, and the ER in general, with a profound shift toward flat areas, concurrent with reduction in DNA condensation. Protein network and pathway analyses based on comprehensive compilation of TMEM147 interactors, targets and co-factors then served to manifest novel and established roles for TMEM147. Thus, algorithmically simplified significant pathways reflect TMEM147 function in ribosome binding, oxidoreductase activity, G protein-coupled receptor activity and transmembrane transport, while analysis of protein factors and networks identifies hub proteins and corresponding pathways as potential targets of TMEM147 action and of future functional studies.


Assuntos
Retículo Endoplasmático/química , Retículo Endoplasmático/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Membrana Nuclear/química , Membrana Nuclear/metabolismo , Retículo Endoplasmático/ultraestrutura , Inativação Gênica , Células HeLa , Humanos , Proteínas de Membrana/metabolismo , Proteínas Nogo/metabolismo , Mapas de Interação de Proteínas , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais , Receptor de Lamina B
7.
Artigo em Inglês | MEDLINE | ID: mdl-33917065

RESUMO

The aim of the current study was to examine mental health effects of the first wave of COVID-19 (Corona Virus Disease-19) in Cyprus. Accordingly, 388 individuals aged 18-65+ responded to the Components of Mental Health Questionnaire that was distributed via social media for two weeks assessing how emotional distress, support and interest in self and others, lifestyle changes, engagement in protective measures, and avoidant behaviors were related to participants' gender, age, and place of residency. Additionally, we measured the level of concern of individuals during and after the first wave outbreak of the pandemic. The results suggest that (a) females experience higher levels of anxiety, stress, fear, worry, and despair than males and are more likely to undertake protective measures, (b) older individuals and those who live in urban areas perceive greater social support and interest in the emotional experience of significant others, (c) emotional distress and support and interest in self and others are associated with all other variables, indicating the importance of these constructs to the experience of a pandemic, and (d) there was a decrease in participants' concern after the end of the first wave of the pandemic. Mental health professionals could find this information useful when developing and implementing prevention programs that aim to offer psychological support during this stressful period.


Assuntos
COVID-19 , Pandemias , Adolescente , Adulto , Idoso , Chipre/epidemiologia , Feminino , Humanos , Masculino , Saúde Mental , Pessoa de Meia-Idade , SARS-CoV-2 , Adulto Jovem
8.
Cell Commun Signal ; 19(1): 3, 2021 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-33413438

RESUMO

BACKGROUND: Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is overexpressed or activated in several advanced-stage solid cancers. It is known to play both kinase-dependent and -independent roles in promoting tumor progression and metastasis. Numerous inhibitors, targeting either the enzymatic or scaffolding activities of FAK have been generated, with varying degree of success. Here, we describe a novel approach to site-specifically target both kinase-dependent and -independent FAK functions at focal adhesions (FAs), the primary sites at which the kinase exerts its activity. METHODS: We took advantage of the well-characterized interactions between the paxillin LD motifs and the FAK FAT domain and generated a polypeptide (LD2-LD3-LD4) expected to compete with interactions with paxillin. Co-immunoprecipitation experiments were performed to examine the interaction between the LD2-LD3-LD4 polypeptide and FAK. The effects of LD2-LD3-LD4 in the localization and functions of FAK, as well as FA composition, were evaluated using quantitative immunofluorescence, cell fractionation, FA isolation and Western Blot analysis. Live cell imaging, as well as 2-D migration and cell invasion assays were used to examine the effects on FA turnover and tumor cell migration and invasion. RESULTS: Expression of the LD2-LD3-LD4 polypeptide prevents FAK localization at FAs, in a controlled and dose-dependent manner, by competing with endogenous paxillin for FAK binding. Importantly, the LD2-LD3-LD4 peptide did not otherwise affect FA composition or integrin activation. LD2-LD3-LD4 inhibited FAK-dependent downstream integrin signaling and, unlike existing inhibitors, also blocked FAK's scaffolding functions. We further show that LD2-LD3-LD4 expression markedly reduces FA turnover and inhibits tumor cell migration and invasion. Finally, we show that dimers of a single motif, linked through a flexible linker of the proper size, are sufficient for the displacement of FAK from FAs and for inhibition of tumor cell migration. This work raises the possibility of using a synthetic peptide as an antimetastatic agent, given that effective displacement of FAK from FAs only requires dimers of a single LD motif linked by a short flexible linker. CONCLUSION: In conclusion, these results suggest that FAK displacement from FAs is a promising new strategy to target critical processes implicated in cancer progression and metastasis. Video abstract.


Assuntos
Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Adesões Focais/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Paxilina/metabolismo , Linhagem Celular , Movimento Celular , Progressão da Doença , Humanos , Paxilina/genética , Domínios Proteicos
9.
J Cell Sci ; 133(16)2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32694168

RESUMO

The structurally and functionally complex endoplasmic reticulum (ER) hosts critical processes including lipid synthesis. Here, we focus on the functional characterization of transmembrane protein TMEM147, and report that it localizes at the ER and nuclear envelope in HeLa cells. Silencing of TMEM147 drastically reduces the level of lamin B receptor (LBR) at the inner nuclear membrane and results in mistargeting of LBR to the ER. LBR possesses a modular structure and corresponding bifunctionality, acting in heterochromatin organization via its N-terminus and in cholesterol biosynthesis via its sterol-reductase C-terminal domain. We show that TMEM147 physically interacts with LBR, and that the C-terminus of LBR is essential for their functional interaction. We find that TMEM147 also physically interacts with the key sterol reductase DHCR7, which is involved in cholesterol biosynthesis. Similar to what was seen for LBR, TMEM147 downregulation results in a sharp decline of DHCR protein levels and co-ordinate transcriptional decreases of LBR and DHCR7 expression. Consistent with this, lipidomic analysis upon TMEM147 silencing identified changes in cellular cholesterol levels, cholesteryl ester levels and profile, and in cellular cholesterol uptake, raising the possibility that TMEM147 is an important new regulator of cholesterol homeostasis in cells.This article has an associated First Person interview with the first author of the paper.


Assuntos
Membrana Nuclear , Receptores Citoplasmáticos e Nucleares , Colesterol , Células HeLa , Homeostase , Humanos , Proteínas de Membrana , Proteínas do Tecido Nervoso , Membrana Nuclear/genética , Receptores Citoplasmáticos e Nucleares/genética , Receptor de Lamina B
10.
J Cell Sci ; 129(8): 1552-65, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26906412

RESUMO

The mechanism of endoplasmic reticulum (ER) morphogenesis is incompletely understood. ER tubules are shaped by the reticulons (RTNs) and DP1/Yop1p family members, but the mechanism of ER sheet formation is much less clear. Here, we characterize TMEM170A, a human transmembrane protein, which localizes in ER and nuclear envelope membranes. Silencing or overexpressing TMEM170A in HeLa K cells alters ER shape and morphology. Ultrastructural analysis reveals that downregulation of TMEM170A specifically induces tubular ER formation, whereas overexpression of TMEM170A induces ER sheet formation, indicating that TMEM170A is a newly discovered ER-sheet-promoting protein. Additionally, downregulation of TMEM170A alters nuclear shape and size, decreases the density of nuclear pore complexes (NPCs) in the nuclear envelope and causes either a reduction in inner nuclear membrane (INM) proteins or their relocalization to the ER. TMEM170A interacts with RTN4, a member of the reticulon family; simultaneous co-silencing of TMEM170A and RTN4 rescues ER, NPC and nuclear-envelope-related phenotypes, implying that the two proteins have antagonistic effects on ER membrane organization, and nuclear envelope and NPC formation.


Assuntos
Retículo Endoplasmático/fisiologia , Proteínas de Membrana/metabolismo , Proteínas Nogo/metabolismo , Membrana Nuclear/metabolismo , Células HeLa , Humanos , Proteínas de Membrana/genética , Proteínas Nogo/genética , Poro Nuclear/metabolismo , Transporte Proteico/genética , RNA Interferente Pequeno/genética , Transgenes
11.
Cell Mol Life Sci ; 73(1): 163-84, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26153462

RESUMO

Katanins are microtubule (MT)-severing AAA proteins with high phylogenetic conservation throughout the eukaryotes. They have been functionally implicated in processes requiring MT remodeling, such as spindle assembly in mitosis and meiosis, assembly/disassembly of flagella and cilia and neuronal morphogenesis. Here, we uncover a novel family of katanin-like 2 proteins (KATNAL2) in mouse, consisting of five alternatively spliced isoforms encoded by the Katnal2 genomic locus. We further demonstrate that in vivo these isoforms are able to interact with themselves, with each other and moreover directly and independently with MRP/MinD-type P-loop NTPases Nubp1 and Nubp2, which are integral components of centrioles, negative regulators of ciliogenesis and implicated in centriole duplication in mammalian cells. We find KATNAL2 localized on interphase MTs, centrioles, mitotic spindle, midbody and the axoneme and basal body of sensory cilia in cultured murine cells. shRNAi of Katnal2 results in inefficient cytokinesis and severe phenotypes of enlarged cells and nuclei, increased numbers of centrioles and the manifestation of aberrant multipolar mitotic spindles, mitotic defects, chromosome bridges, multinuclearity, increased MT acetylation and an altered cell cycle pattern. Silencing or stable overexpression of KATNAL2 isoforms drastically reduces ciliogenesis. In conclusion, KATNAL2s are multitasking enzymes involved in the same cell type in critically important processes affecting cytokinesis, MT dynamics, and ciliogenesis and are also implicated in cell cycle progression.


Assuntos
Adenosina Trifosfatases/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Microtúbulos/metabolismo , Mapas de Interação de Proteínas , Adenosina Trifosfatases/análise , Adenosina Trifosfatases/genética , Animais , Ciclo Celular , Centrossomo/metabolismo , Centrossomo/ultraestrutura , Cílios/metabolismo , Cílios/ultraestrutura , Citocinese , Proteínas de Ligação ao GTP/análise , Inativação Gênica , Interfase , Peptídeos e Proteínas de Sinalização Intracelular , Katanina , Camundongos , Microtúbulos/ultraestrutura , Células NIH 3T3 , Isoformas de Proteínas/análise , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Fuso Acromático/metabolismo , Fuso Acromático/ultraestrutura , Regulação para Cima
12.
Trials ; 16: 372, 2015 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-26292675

RESUMO

BACKGROUND: Lifestyle and health behaviours are strongly linked to non-communicable disease risk, but modifying them is challenging. There is an increasing recognition that adolescence is an important time for lifestyle and health behaviours to become embedded. Improving these behaviours in adolescents is important not only for their own health but also for that of their future children. LifeLab Southampton has been developed as a purpose-built classroom and laboratory in University Hospital Southampton. Secondary school students visit LifeLab to learn how childhood, adolescent and parental nutrition influences health, understand the impact of their lifestyle on their cardiovascular and metabolic health, and to inspire them with the excitement of research and future career possibilities in science. The LifeLab visit is part of a programme of work linked to the English National Curriculum. Pilot work has indicated that attitudes towards health can be changed by such LifeLab sessions. METHODS/DESIGN: A cluster randomised controlled trial is being conducted to evaluate the effectiveness of the LifeLab intervention, the primary outcome being a measurement of the change in nutrition, health and lifestyle literacy from before to after the LifeLab intervention. The LifeLab intervention comprises professional development for the teachers involved; preparatory lessons for the school students, delivered in school; a hands-on practical day at LifeLab, including a 'Meet the Scientist' session; post-visit lessons delivered in school; and the opportunity to participate in the annual LifeLab Schools' Conference. This study aims to recruit approximately 2,500 secondary school students aged 13 to 14 years from 32 schools (the clusters) from Southampton and neighbouring areas. Participating schools will be randomised to control or intervention groups. The intervention will be run over two academic school years, with baseline questionnaire data collected from students at participating schools at the start of the academic year and follow- up questionnaire data collected approximately 12 months later. TRIAL REGISTRATION: Evaluation of LifeLab is a cluster randomised controlled trial ( ISRCTN71951436 , registered 25 March 2015), funded by the British Heart Foundation (PG/14/33/30827).


Assuntos
Comportamento do Adolescente , Comportamentos Relacionados com a Saúde , Conhecimentos, Atitudes e Prática em Saúde , Estilo de Vida , Ciência/educação , Adolescente , Fatores Etários , Pesquisa Biomédica , Escolha da Profissão , Currículo , Inglaterra , Feminino , Letramento em Saúde , Promoção da Saúde , Nível de Saúde , Humanos , Masculino , Estado Nutricional , Avaliação de Programas e Projetos de Saúde , Projetos de Pesquisa , Comportamento de Redução do Risco , Inquéritos e Questionários
13.
Small GTPases ; 6(1): 20-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25862163

RESUMO

The GTP bound form of the Ran GTPase (RanGTP) in the nucleus promotes nuclear import of the proteins bearing nuclear localization signals (NLS). When nuclear envelopes break down during mitosis, RanGTP is locally produced around chromosomes and drives the assembly of the spindle early in mitosis and the nuclear envelope (NE) later. RanGTP binds to the heterodimeric nuclear transport receptor importin α/ß and releases NLS proteins from the receptor. Liberated NLS proteins around chromosomes have been shown to play distinct, essential roles in spindle and NE assembly. Here we provide a highly specific protocol to purify NLS proteins from crude cell lysates. The pure NLS fraction is an excellent resource to investigate the NLS protein function and identify new mitotic regulators, uncovering fundamental mechanisms of the cell division cycle. It takes 2-3 days to obtain the NLS fraction.


Assuntos
Proteínas de Ciclo Celular/isolamento & purificação , Fracionamento Celular/métodos , Núcleo Celular/química , Mitose , Sinais de Localização Nuclear , Proteínas Nucleares/isolamento & purificação , Óvulo/química , Animais , Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Células HeLa , Humanos , Proteínas Nucleares/metabolismo , Óvulo/metabolismo , Transporte Proteico , Xenopus , Proteína ran de Ligação ao GTP/metabolismo
14.
Cell Mol Life Sci ; 71(3): 517-38, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23807208

RESUMO

Nucleotide-binding proteins Nubp1 and Nubp2 are MRP/MinD-type P-loop NTPases with sequence similarity to bacterial division site-determining proteins and are conserved, essential proteins throughout the Eukaryotes. They have been implicated, together with their interacting minus-end directed motor protein KIFC5A, in the regulation of centriole duplication in mammalian cells. Here we show that Nubp1 and Nubp2 are integral components of centrioles throughout the cell cycle, recruited independently of KIFC5A. We further demonstrate their localization at the basal body of the primary cilium in quiescent vertebrate cells or invertebrate sensory cilia, as well as in the motile cilia of mouse cells and in the flagella of Chlamydomonas. RNAi-mediated silencing of nubp-1 in C. elegans causes the formation of morphologically aberrant and additional cilia in sensory neurons. Correspondingly, downregulation of Nubp1 or Nubp2 in mouse quiescent NIH 3T3 cells markedly increases the number of ciliated cells, while knockdown of KIFC5A dramatically reduces ciliogenesis. Simultaneous double silencing of Nubp1 + KIFC5A restores the percentage of ciliated cells to control levels. We document the normal ciliary recruitment, during these silencing regimes, of basal body proteins critical for ciliogenesis, namely CP110, CEP290, cenexin, Chibby, AurA, Rab8, and BBS7. Interestingly, we uncover novel interactions of Nubp1 with several members of the CCT/TRiC molecular chaperone complex, which we find enriched at the basal body and recruited independently of the Nubps or KIFC5A. Our combined results for Nubp1, Nubp2, and KIFC5A and their striking effects on cilium formation suggest a central regulatory role for these proteins, likely involving CCT/TRiC chaperone activity, in ciliogenesis.


Assuntos
Ciclo Celular/fisiologia , Centríolos/metabolismo , Cílios/fisiologia , Proteínas de Ligação ao GTP/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Animais , Western Blotting , Chlamydomonas , Cromatografia Líquida , Imunofluorescência , Técnicas de Silenciamento de Genes , Imuno-Histoquímica , Imunoprecipitação , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Microscopia Eletrônica de Transmissão , Chaperonas Moleculares/metabolismo , Células NIH 3T3 , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Espectrometria de Massas em Tandem
15.
J Cell Sci ; 119(Pt 10): 2035-47, 2006 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-16638812

RESUMO

Inhibition of motor protein activity has been linked with defects in the formation of poles in the spindle of dividing cells. However, the molecular mechanisms underlying the functional relationship between motor activity and centrosome dynamics have remained uncharacterised. Here, we characterise KIFC5A, a mouse kinesin-like protein that is highly expressed in dividing cells and tissues, and is subject to developmental and cell-type-specific regulation. KIFC5A is a minus-end-directed, microtubule-dependent motor that produces velocities of up to 1.26 microm minute(-1) in gliding assays and possesses microtubule bundling activity. It is nuclear in interphase, localises to the centre of the two microtubule asters at the beginning of mitosis, and to spindle microtubules in later mitotic phases. Overexpression of KIFC5A in mouse cells causes the formation of aberrant, non-separated microtubule asters and mitotic arrest in a prometaphase-like state. KIFC5A knockdown partly rescues the phenotype caused by inhibition of plus-end-directed motor Eg5 by monastrol on the mitotic spindle, indicating that it is involved in the balance of forces determining bipolar spindle assembly and integrity. Silencing of KIFC5A also results in centrosome amplification detectable throughout the cell cycle. Supernumerary centrosomes arise primarily as a result of reduplication and partly as a result of cytokinesis defects. They contain duplicated centrioles and have the ability to organise microtubule asters, resulting in the formation of multipolar spindles. We show that KIFC5A interacts with nucleotide-binding proteins 1 and 2 (Nubp1 and Nubp2), which have extensive sequence similarity to prokaryotic division-site-determining protein MinD. Nubp1 and Nubp2 also interact with each other. Knockdown of Nubp1 or double knockdown of Nubp1 and Nubp2 (Nubp1&Nubp2) both phenocopy the KIFC5A silencing effect. These results implicate KIFC5A and the Nubp proteins in a common regulatory pathway involved in the control of centrosome duplication in mammalian cells.


Assuntos
Centrossomo/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Motores Moleculares/metabolismo , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Sequência de Aminoácidos , Animais , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Ligação ao GTP/genética , Hipocampo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Proteínas Associadas aos Microtúbulos/biossíntese , Proteínas Associadas aos Microtúbulos/genética , Proteínas Motores Moleculares/biossíntese , Proteínas Motores Moleculares/genética , Dados de Sequência Molecular , Células NIH 3T3 , Complexo de Inativação Induzido por RNA , Análise de Sequência , Fuso Acromático/metabolismo , Transfecção
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