RESUMO
Fertility preservation is an urgent challenge in the transplant setting. A panel of transplanters and fertility specialists within the Pediatric Diseases Working Party of the European Society for Blood and Marrow Transplantation (EBMT) and the International BFM Study Group provides specific guidelines. Patients and families should be informed of possible gender- and age-specific cryopreservation strategies that should be tailored according to the underlying disease, clinical condition and previous exposure to chemotherapy. Semen collection should be routinely offered to all postpubertal boys at the diagnosis of any disease requiring therapy that could potentially impair fertility. Testicular tissue collection might be offered to postpubertal boys; nevertheless, its use has been unsuccessful to date. Oocyte collection after hormonal hyperstimulation should be offered to postpubertal girls facing gonadotoxic therapies that could be delayed for the 2 weeks required for the procedure. Ovarian tissue collection could be offered to pre-/post-pubertal girls. Pregnancies have been reported after postpubertal ovarian tissue reimplantation; however, to date, no pregnancy has been reported after the reimplantation of prepubertal ovarian tissue or in vitro maturation of pre-/post-pubertal ovarian tissue. Possible future advances in reproductive medicine could change this scenario. Health authorities should prioritize fertility preservation projects in pediatric transplantation to improve patient care and quality of life.
Assuntos
Antineoplásicos/efeitos adversos , Consenso , Criopreservação/métodos , Preservação da Fertilidade/métodos , Transplante de Células-Tronco Hematopoéticas , Ovário , Testículo , Adolescente , Aloenxertos , Antineoplásicos/uso terapêutico , Criança , Feminino , Humanos , Masculino , Guias de Prática Clínica como AssuntoRESUMO
Nowadays, allogeneic haematopoietic stem cell transplantation (allo-HSCT) is a well-established treatment procedure and often the only cure for many patients with malignant and non-malignant diseases. Decrease in short-term complications has substantially contributed to increased survival. Therefore long-term sequelae are reaching the focus of patient care. One of the most important risks of stem cell transplant survivors is infertility. As well as in the field of allo-HSCT also the field of reproductive medicine has achieved substantial advances to offer potential options for fertility preservation in both boys and girls. Access to these procedures as well as their financing differs significantly throughout Europe. As all European children and adolescents should have the same possibility, the Paediatric Diseases Working Party of the European Society for Blood and Marrow Transplantation organised an expert meeting in September 2015. This manuscript describes the recommendations for the diagnosis and pre-emptive procedures that should be offered to all children and adolescents in Europe who have to undergo an allo-HSCT.
Assuntos
Fertilidade , Transplante de Células-Tronco Hematopoéticas , Infertilidade Feminina/prevenção & controle , Infertilidade Masculina/prevenção & controle , Adolescente , Áustria , Criança , Congressos como Assunto , Europa (Continente) , Feminino , Humanos , Masculino , Sociedades MédicasRESUMO
We report outcomes for 44 children who underwent stem cell transplantation (SCT) for refractory AML in the UK between 2000 and 2012. Median age at SCT was 11.5 years. Twenty-three patients had primary refractory and 21 relapsed refractory AML. Refractory disease was confirmed by cytogenetics/molecular genetics in 24 cases. Median follow-up of the whole cohort is 6.8 years (2.1-14.9 years). Thirty patients (68%) achieved a CR following SCT. Transplant-related mortality at 1 year was 18%. Acute GVHD incidence was 52% (grade ⩾III 19%), chronic 7%. Relapse was the major cause of treatment failure and occurred in 32% of patients at a median of 61 days post SCT. Five-year overall survival and leukemia-free survival (LFS) were 43% (95% CI 31-61%). All patients with favorable cytogenetics (n=6) are alive in CR. Outcomes in patients with primary refractory disease were equivalent to those with relapsed refractory AML. Blast percentage ⩽30% in the BM pre-SCT, myeloablative conditioning and acute GVHD proved to be favorable prognostic features. We could stratify patients according to age ⩾10 years and >30% blasts in BM pre-SCT. Patients with none/one of these risk factors were highly salvageable (5 years LFS 53%) whereas those with both factors had a very poor prognosis (5 years LFS 10%). This may facilitate decision making on whether it is appropriate to consider transplant in such patients.
Assuntos
Doença Enxerto-Hospedeiro/mortalidade , Transplante de Células-Tronco Hematopoéticas , Leucemia Mieloide Aguda/mortalidade , Leucemia Mieloide Aguda/terapia , Doença Aguda , Adolescente , Aloenxertos , Criança , Pré-Escolar , Aberrações Cromossômicas , Intervalo Livre de Doença , Feminino , Seguimentos , Doença Enxerto-Hospedeiro/genética , Doença Enxerto-Hospedeiro/patologia , Humanos , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Masculino , Recidiva , Taxa de Sobrevida , Reino Unido/epidemiologiaRESUMO
BACKGROUND: As stapled hemorrhoidopexy (SH) becomes more widely used, we see more patients with chronic postoperative anal pain after this surgery. Its presentation is variable and difficult to treat. The aim of our study was to investigate the impact of chronic anal pain after SH and whether tailored therapy was likely to achieve a favorable outcome. METHODS: We retrospectively analyzed 31 consecutive patients with chronic anal pain who had undergone SH in other hospitals and were referred to our institutions. Depending on the type of pain, unrelated (at rest) or related to defecation, two groups of patients were identified. Moreover, the mean distance of the staple line from the anal verge was calculated in both groups. Treatments included: topical nifedipine, local anesthetic and steroid infiltration, removal of retained staples, anal dilation, and scar excision with mucosal suturing. A visual analog scale (VAS) was used to compare pain at baseline, postoperatively, and in the follow-up. This mean difference of the VAS score between stages was always used as the main outcome measure, depending on the type of presentation, type of pain, and type of treatment. Treatment response was defined as a 50 % decrease of VAS from baseline. RESULTS: There were 22 males and 9 females. The overall median age was 43 years (range 21-62 years). On digital examination and proctoscopy, 15 (48 %) patients had inflammatory changes, 19 (61 %) patients had staple retention, 8 (26 %) patients had anorectal stenosis, and 30 (97 %) patients had scar tissue. All patients had one or more of the following treatments listed from the least to most invasive: topical nifedipine in 12 (39 %) patients, anal dilation in 6 (19 %) patients, anesthetic and steroid infiltration in 18 (58 %) patients, removal of staples in 10 (32 %) patients, and scar excision in 18 (58 %) patients. The mean VAS score at baseline was 6.100, ± 1.953 SD, which dropped significantly after treatment to 1.733, ± 1.658 SD (p < 0.001) and remained low at follow-up (1.741 ± SD 1.251; p < 0.743). In patients with pain at rest (n = 20, 65 %), the symptoms improved in 19 (95 %) patients, while the VAS score decreased from 5.552 ± 2.115 SD to 1.457 ± 1.440 SD (95 % CI 3.217-4.964; p < 0.001). In patients with post-evacuation pain (n = 11, 35 %), the symptoms improved in 11 (100 %) patients, while the VAS score decreased from 6.429 ± 1.835 SD to 1.891 ± 1.792 SD (95 % CI 3.784-5.269; p < 0.001). Rating of response based on presentation was 90.0 % (0.9/10) after treatment of staple retention, which led to a significant decrease in the mean VAS score from 6.304 ± 1.845 SD to 1.782 ± 1.731 SD (95 % CI 3.859-5.185; p < 0.001). Anal stenosis was successfully treated in 100.0 % (n = 8/8) of cases with the mean VAS score dropping from 6.500 ± 1.309 SD to 2.125 ± 1.808 SD (95 % CI 2.831-5.919; p < 0.001). Anal inflammation improved in 60.0 % (n = 9/15) of patients and the mean VAS score dropped from 6.006 ± 2.138 SD to 1.542 ± 1.457 SD (95 % CI 3.217-4.964; p < 0.001). The response after scar tissue treatment was 94 % (n = 17/18) of patients with a mean VAS decreasing from 6.117 ± 2.006 SD to 1.712 ± 1.697 SD (95 % CI 3.812-4.974; p < 0.001). Success for topical nifedipine was between 13 and 25 % of patients depending on the clinical presentation. Anal dilation was successful in 75 % of patients, while Anesthetic and steroid infiltration in 23-54 % of patients depending on the clinical presentation. Staple removal was successful in 77 % of patients, and scar excision with mucosal suturing in 94 % of patients. CONCLUSIONS: Our retrospective study suggests that most patients with chronic anal pain after SH may be cured with treatment by applying a stepwise approach from the least to the most invasive treatment.
Assuntos
Dor Crônica/terapia , Hemorroidectomia/efeitos adversos , Hemorroidas/cirurgia , Dor Pós-Operatória/terapia , Suturas/efeitos adversos , Adulto , Dor Crônica/etiologia , Feminino , Seguimentos , Hemorroidectomia/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Dor Pós-Operatória/etiologia , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Mesenchymal stromal cells (MSCs) are multipotent cells, which exhibit broad immunosuppressive activities. Moreover, they may be administered irrespectively of human leukocyte antigen (HLA) compatibility, without inducing life-threatening immunological reactions, as they express no HLA class II and limited HLA class I antigens under resting conditions. These characteristics have made MSC an appealing candidate for cell therapy after hematopoietic stem cell transplantation (HSCT), for example, for treatment of graft-versus-host disease (GvHD) or for graft rejection prevention/treatment in allogeneic HSCT recipients. Unfortunately, information regarding the effect of MSC infusion on the host response to infectious agents is scarce, and study results on infectious complications in patients receiving MSC are conflicting. The present review focuses on the available data from in vitro studies and animal models regarding the interaction of MSC with bacterial, viral and fungal pathogens. In a clinical part, we present the current information on infectious complications in allogeneic HSCT recipients who had received MSCs as prophylaxis or treatment of GvHD disease.
Assuntos
Doença Enxerto-Hospedeiro/imunologia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Células-Tronco Hematopoéticas/citologia , Células-Tronco Mesenquimais/citologia , Animais , Anti-Infecciosos/farmacologia , Infecções Bacterianas/complicações , Ensaios Clínicos como Assunto , Modelos Animais de Doenças , Antígenos HLA/metabolismo , Humanos , Imunossupressores/farmacologia , Micoses/complicações , Esteroides/farmacologia , Viroses/complicaçõesRESUMO
Background. The event-free survival for pediatric leukemia in low-income Countries is much lower than in high-income countries. Late diagnosis, which is regarded as a contributing factor, may be due to "parental" or "medical" delay. Procedures. The present study analyses determinants of lag time from first symptoms to diagnosis of leukemia, comparing pediatric (0-16 years old) patients in two referral centers, one in Nicaragua and one in Italy. An observational retrospective study was conducted to assess factors influencing the time to diagnosis. Results. 81 charts of children diagnosed with acute myeloid leukemia or lymphoblastic leukemia were analyzed from each centre. Median lag time to diagnosis was higher in Nicaragua than in Italy (29 versus 14 days, P < 0.001) and it was mainly due to "physician delay" (16.5 versus 7 days, P < 0.001), whereas "patient delay" from symptoms to first medical assessment was similar in the two centers (7 versus 5 days, P = 0.27). Moreover, median lag time from symptoms to diagnosis was decreased in Nicaraguan districts were a specific training program upon childhood oncological diseases was carried out (20.5 versus 40 days, P = 0.0019). Conclusions. Our study shows that delay in diagnosis of childhood leukemia is mainly associated with "physician delay" and it may be overcome by programs of continuous medical education.
Assuntos
Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/citologia , Monitorização Imunológica , Adolescente , Adulto , Medula Óssea/metabolismo , Criança , Pré-Escolar , Elafina/sangue , Ensaio de Imunoadsorção Enzimática , Feminino , Doença Enxerto-Hospedeiro/sangue , Humanos , Subunidade alfa de Receptor de Interleucina-2/sangue , Masculino , Prognóstico , Receptores Tipo I de Fatores de Necrose Tumoral/sangue , Adulto JovemRESUMO
Progressive multifocal leukoencephalopathy (PML) associated with polyomavirus JC (JCV) infection has been reported to be usually fatal in allogeneic hematopoietic SCT (HSCT) recipients. We present the case of a 19-year-old HSCT patient diagnosed with JCV-associated PML after prolonged immunosuppression for severe GVHD. No short-term neurological improvement was observed after antiviral treatment and discontinuation of immunosuppressive therapy. Donor-derived JCV Ag-specific CTLs were generated in vitro after stimulation with 15-mer peptides derived from VP1 and large T viral proteins. After adoptive CTL infusion, virus-specific cytotoxic cells were shown in the peripheral blood, JCV-DNA was cleared in the cerebrospinal fluid and the patient showed remarkable improvement. Adoptive T-lymphocyte therapy with JCV-specific CTLs was feasible and had no side effects. This case suggests that adoptive transfer of JCV-targeted CTLs may contribute to restore JCV-specific immune competence and control PML in transplanted patients.
Assuntos
Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Imunoterapia Adotiva/métodos , Vírus JC/imunologia , Leucoencefalopatia Multifocal Progressiva/terapia , Linfócitos T Citotóxicos/imunologia , Adolescente , Adulto , Humanos , Leucoencefalopatia Multifocal Progressiva/imunologia , Leucoencefalopatia Multifocal Progressiva/virologia , Masculino , Adulto JovemRESUMO
Nowadays, different treatment options are available for an extending list of lysosomal storage diseases (LSDs). Hematopoietic stem cell transplantation (HSCT) can benefit selected subsets of patients with some LSDs, but results have been poor in several other disorders, including metachromatic leukodystrophy (MLD), outlining the need for innovative therapeutic approaches in this field. Enzyme replacement therapy has been developed recently for MLD, and a Phase I/II trial is ongoing. However, the blood-brain barrier limits the access of the recombinant product to the nervous tissues. Autologous hematopoietic stem/progenitor cells can be genetically modified to constitutively express supra-physiological levels of arylsulfatase-A and may become a quantitatively more effective source of functional enzyme than normal donor cells when transplanted in patients with MLD, thus possibly overcoming the limits of HSCT. Moreover, autologous transplantation might be associated with a significantly reduced transplant-related morbidity and TRM avoiding the risk of GVHD. Therefore, such a gene therapy strategy could represent a significant advance in comparison to conventional allogeneic HSCT.
Assuntos
Cerebrosídeo Sulfatase/uso terapêutico , Terapia Genética , Transplante de Células-Tronco Hematopoéticas , Leucodistrofia Metacromática/terapia , Proteínas Recombinantes/uso terapêutico , Barreira Hematoencefálica/enzimologia , Ensaios Clínicos Fase I como Assunto , Ensaios Clínicos Fase II como Assunto , Terapia Genética/tendências , Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas/tendências , Humanos , Leucodistrofia Metacromática/enzimologia , Fatores de Risco , Transplante Autólogo , Transplante HomólogoRESUMO
Recent observations indicate that immunosenescence is not accompanied by an unavoidable and progressive deterioration of the immune function, but is rather the result of a remodeling where some functions are reduced, others remain unchanged or even increased. In addition, it appears that the ancestral/innate compartment of the immune system is relatively preserved during aging in comparison to the more recent and sophisticated adaptive compartment that exhibit more profound modifications. The T-cell branch displays an age-dependent decline of the absolute number of total T-cells (CD3+), involving both CD4+ and CD8+ subsets, accompanied by an increase of NK cells with well-preserved cytotoxic function and by a reduction of B-cells. One of the main characteristics of the immune system during aging is a progressive, age-dependent decline of the virgin T-cells (CD95-), which is particularly profound at the level of the CD8+ subpopulation of the oldest old subjects. The progressive exhaustion of this important T-cell subpopulation dedicated primarily to the defense against new antigenic challenges (viral, neoplastic, bacterial ones), could be a consequence of both the thymic involution and the lifelong chronic antigenic stimulation. The immune function of the elderly, is therefore weakened by the exhaustion of CD95- virgin cells that are replaced by large clonal expansions of CD28- T-cells. The origin of CD28- cells has not been completely clarified yet, but it is assumed that they represent cells in the phase of replicative senescence characterized by shortening telomers and reduced proliferative capacity. A major characteristic of the immune system during aging is the up-regulation of the inflammatory responses which appears to be detrimental for longevity. In this regard, we have recently observed a progressive age-dependent increase of type 1(IL-2, IFN-gamma, TNF-alpha) and type 2 (IL-4, IL-6, IL-10) positive CD8+ T-cells; in particular, type 1 cytokine-positive cells significantly increased, with age, in all CD8+ subsets particularly among effector/cytotoxic and memory cells. A major force able to drive a chronic pro-inflammatory state during aging may be represented by persistent viral infections by EBV and CMV. Therefore, we have determined the frequency and the absolute number of viral antigen-specific CD8+ T-cells in subjects older than 85 years, who were serologically positive for CMV or EBV. In the majority of these subjects we detected the presence of T lymphocytes positive for epitopes of CMV or EBV. In all subjects the absolute number of CMV-positive CD8+ cells outnumbered that of EBV-positive ones. In addition, the majority of CMV+ T cells were included within the CD28- subpopulation, while EBV+ T cells belonged mainly to the CD28+ subset. These data indicate that the chronic antigenic stimulation induced by persistent viral infections during aging bring about important modifications among CD8+ subsets, which are particularly evident in the presence of CMV persistence. The age-dependent expansions of CD8+CD28- T-cells, mostly positive for pro-inflammatory cytokines and including the majority of CMV-epitope-specific cells, underlines the importance of chronic antigenic stimulation in the pathogenesis of the main immunological alterations of aging and may favour the appearance of several pathologies (arteriosclerosis, dementia, osteoporosis, cancer) all of which share an inflammatory pathogenesis.
Assuntos
Sistema Imunitário/fisiologia , Longevidade/imunologia , Idoso de 80 Anos ou mais , Linfócitos T CD8-Positivos/imunologia , Citocinas/fisiologia , Feminino , Humanos , Memória Imunológica , Inflamação , Ativação Linfocitária , MasculinoRESUMO
Group B streptococci (GBS) are an important cause of neonatal sepsis and meningitis. New rapid, sensitive and specific methods for detection of GBS in pregnant women are needed in order to provide timely treatment of neonates. The sensitivity, specificity and cost of a LightCycler PCR method was compared with selective culture for the detection of GBS from 400 vaginal swabs. In addition, two DNA extraction methods (simple boiling and automated DNA extraction by Roche MagNA Pure LC) were compared for a subgroup of 100 clinical samples. The sensitivity of the LightCycler PCR assay for the detection of GBS from vaginal swabs was significantly higher than that of culture. There were no culture-positive, LightCycler PCR-negative cases. The efficiencies of the two DNA extraction procedures were not significantly different. The detection of GBS from vaginal swabs by the molecular method (including simple boiling extraction) required the same hands-on time, but the procedure was completed in 1.5 h, compared with c. 48 h for the culture-based approach. Disadvantages of the molecular method are the increased costs (45%) and the absence of antibiogram data. The LightCycler PCR is a promising tool for sensitive, specific and rapid detection of GBS directly from clinical specimens of pregnant women.
Assuntos
DNA Bacteriano/análise , Reação em Cadeia da Polimerase/métodos , Streptococcus agalactiae/isolamento & purificação , Técnicas de Tipagem Bacteriana , Técnicas de Cultura de Células , Meios de Cultura , Feminino , Humanos , Reação em Cadeia da Polimerase/economia , Gravidez , Streptococcus agalactiae/classificação , Streptococcus agalactiae/genética , Vagina/microbiologia , Esfregaço VaginalRESUMO
The evolutionarily conserved yeast Mec1 and Tel1 protein kinases, as well as the Mec1-interacting protein Ddc2, are involved in the DNA damage checkpoint response. We show that regulation of Tel1 and Ddc2-Mec1 activities is important to modulate both activation and termination of checkpoint-mediated cell cycle arrest. In fact, overproduction of either Tel1 or Ddc2 causes a prolonged cell cycle arrest and cell death in response to DNA damage, impairing the ability of cells to recover from checkpoint activation. This cell cycle arrest is independent of Mec1 in UV-irradiated Tel1-overproducing cells, while it is strictly Mec1 dependent in similarly treated DDC2-overexpressing cells. The Rad53 checkpoint kinase is instead required in both cases for cell cycle arrest, which correlates with its enhanced and persistent phosphorylation, suggesting that unscheduled Rad53 phosphorylation might prevent cells from re-entering the cell cycle after checkpoint activation. In addition, Tel1 overproduction results in transient nuclear division arrest and concomitant Rad53 phosphorylation in the absence of exogenous DNA damage independently of Mec1 and Ddc1.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Dano ao DNA , Proteínas Fúngicas/metabolismo , Fosfoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae , Proteínas Adaptadoras de Transdução de Sinal , Antineoplásicos/farmacologia , Ciclo Celular , Morte Celular , Núcleo Celular/metabolismo , Separação Celular , Quinase do Ponto de Checagem 2 , Reparo do DNA , Relação Dose-Resposta a Droga , Relação Dose-Resposta à Radiação , Citometria de Fluxo , Fase G2 , Galactose/metabolismo , Genótipo , Hidroxiureia/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular , Cinética , Metanossulfonato de Metila/farmacologia , Mitose , Mutagênicos/farmacologia , Nocodazol/farmacologia , Inibidores da Síntese de Ácido Nucleico/farmacologia , Fosforilação , Plasmídeos/metabolismo , Ligação Proteica , Proteínas Serina-Treonina Quinases/metabolismo , Fatores de Tempo , Raios UltravioletaRESUMO
Checkpoints prevent DNA replication or nuclear division when chromosomes are damaged. The Saccharomyces cerevisiae DDC1 gene belongs to the RAD17, MEC3 and RAD24 epistasis group which, together with RAD9, is proposed to act at the beginning of the DNA damage checkpoint pathway. Ddc1p is periodically phosphorylated during unperturbed cell cycle and hyperphosphorylated in response to DNA damage. We demonstrate that Ddc1p interacts physically in vivo with Mec3p, and this interaction requires Rad17p. We also show that phosphorylation of Ddc1p depends on the key checkpoint protein Mec1p and also on Rad24p, Rad17p and Mec3p. This suggests that Mec1p might act together with the Rad24 group of proteins at an early step of the DNA damage checkpoint response. On the other hand, Ddc1p phosphorylation is independent of Rad53p and Rad9p. Moreover, while Ddc1p is required for Rad53p phosphorylation, it does not play any major role in the phosphorylation of the anaphase inhibitor Pds1p, which requires RAD9 and MEC1. We suggest that Rad9p and Ddc1p might function in separated branches of the DNA damage checkpoint pathway, playing different roles in determining Mec1p activity and/or substrate specificity.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Dano ao DNA/fisiologia , Proteínas Fúngicas/metabolismo , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Ciclo Celular/fisiologia , Proteínas de Ciclo Celular/genética , DNA Fúngico/genética , Proteínas Fúngicas/genética , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Nucleares/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases , Saccharomyces cerevisiae/metabolismo , SecurinaRESUMO
In the framework of the EU programme for systematic sequencing of the Saccharomyces cervisiae genome we determined the sequence of a 9359 bp fragment of the right arm of chromosome VII. Five open reading frames (ORFs) of at least 300 nucleotides were found in this region. YGR267c encodes a protein with significant similarity to the enzyme GTP-cyclohydrolase I, that controls the first step in the biosynthetic pathway leading to various pterins and shows a high degree of sequence conservation from bacteria to mammals. We have recently demonstrated (Nardese et al., 1996) that YGR267c corresponds to the FOL2 gene, previously localized in the same chromosomal region by genetic mapping. The protein deduced from YGR270w belongs to the superfamily of putative ATPases associated with diverse cellular activities. It corresponds to the YTA7 gene, a member of a set of yeast genes coding for putative ATPases with high similarity to constituents of the 26S protease. The three ORFs YGR266w, YGR268c and YGR269w encode putative products of unknown function, with neither significant similarity to proteins in databases nor recognizable domains. YGR268c and YGR269w are partially overlapping ORFs: YGR268c seems to correspond to a real gene. whereas YGR269w is probably a fortuitous ORF.
Assuntos
Adenosina Trifosfatases/genética , Cromossomos Fúngicos/genética , GTP Cicloidrolase/genética , Fases de Leitura Aberta , Saccharomyces cerevisiae/genética , Sequência de Aminoácidos , Cosmídeos/genética , Genes Fúngicos , Dados de Sequência Molecular , Saccharomyces cerevisiae/enzimologia , Análise de Sequência de DNARESUMO
The B subunit of the DNA polymerase (pol) alpha-primase complex executes an essential role at the initial stage of DNA replication in Saccharomyces cerevisiae and is phosphorylated in a cell cycle-dependent manner. In this report, we show that the four subunits of the yeast DNA polymerase alpha-primase complex are assembled throughout the cell cycle, and physical association between newly synthesized pol alpha (p180) and unphosphorylated B subunit (p86) occurs very rapidly. Therefore, B subunit phosphorylation does not appear to modulate p180.p86 interaction. Conversely, by depletion experiments and by using a yeast mutant strain, which produces a low and constitutive level of the p180 polypeptide, we found that formation of the p180.p86 subcomplex is required for B subunit phosphorylation.
Assuntos
DNA Polimerase II/metabolismo , Replicação do DNA , RNA Nucleotidiltransferases/metabolismo , Ciclo Celular , DNA Primase , Substâncias Macromoleculares , Peso Molecular , Fosforilação , Ligação Proteica , Saccharomyces cerevisiae/enzimologiaRESUMO
The yeast DNA polymerase alpha-primase B subunit functions in initiation of DNA replication. This protein is present in two forms, of 86 and 91 kDa, and the p91 polypeptide results from cell cycle-regulated phosphorylation of p86. The B subunit present in G1 arises by dephosphorylation of p91 while cells are exiting from mitosis, becomes phosphorylated in early S phase, and is competent and sufficient to initiate DNA replication. The B subunit transiently synthesized as a consequence of periodic transcription of the POL12 gene is phosphorylated no earlier than G2. Phosphorylation of the B subunit does not require execution of the CDC7-dependent step and ongoing DNA synthesis. We suggest that posttranslational modifications of the B subunit might modulate the role of DNA polymerase alpha-primase in DNA replication.
Assuntos
Ciclo Celular/fisiologia , RNA Nucleotidiltransferases/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/enzimologia , Fosfatase Ácida , Western Blotting , DNA Primase , Replicação do DNA , Fase G1 , Expressão Gênica , Genótipo , Cinética , Substâncias Macromoleculares , Mutagênese , Fosforilação , Plasmídeos , Regiões Promotoras Genéticas , Saccharomyces cerevisiae/genética , Solanum tuberosum/enzimologia , Fatores de TempoRESUMO
A new DNA polymerase activity was identified and purified to near homogeneity from extracts of mitotic and meiotic cells of the yeast Saccharomyces cerevisiae. This activity increased at least 5-fold during meiosis, and it was shown to be associated with a 68-kDa polypeptide as determined by SDS-polyacrylamide gel electrophoresis. This new DNA polymerase did not have any detectable 3'-->5' exonuclease activity and preferred small gapped DNA as a template-primer. The activity was inhibited by dideoxyribonucleoside 5'-triphosphates and N-ethylmaleimide but not by concentrations of aphidicolin which completely inhibit either DNA polymerases I (alpha), II (epsilon), or III (delta). Since no polypeptide(s) in the extensively purified DNA polymerase fractions cross-reacted with antibodies raised against yeast DNA polymerases I, II, and III, we called this enzyme DNA polymerase IV. The DNA polymerase IV activity increased at least 10-fold in a yeast strain overexpressing the gene product predicted from the YCR14C open-reading frame (identified on S. cerevisiae chromosome III and provisionally called POLX), while no activity was detected in a strain where POLX was deleted. These results strongly suggest that DNA polymerase IV is encoded by the POLX gene and is a probable homolog of mammalian DNA polymerase beta.
Assuntos
DNA Polimerase Dirigida por DNA/isolamento & purificação , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/enzimologia , Animais , Sequência de Bases , DNA Polimerase I/genética , DNA Polimerase beta , Primers do DNA , DNA Polimerase Dirigida por DNA/genética , DNA Polimerase Dirigida por DNA/metabolismo , Eletroforese em Gel de Poliacrilamida , Escherichia coli/genética , Humanos , Cinética , Magnésio , Dados de Sequência Molecular , Inibidores da Síntese de Ácido Nucleico , Cloreto de Potássio , Homologia de Sequência do Ácido Nucleico , Especificidade por SubstratoRESUMO
The POL1 gene, encoding DNA polymerase alpha (pol alpha) in Saccharomyces cerevisiae, is transiently transcribed during the cell cycle at the G1/S phase boundary. Here we show that yeast pol alpha is present at every stage of the cell cycle, and its level only slightly increases following the peak of POL1 transcription. POL1 mRNA synthesis driven by a GAL1 promoter can be completely abolished without affecting the growth rate of logarithmically growing yeast cultures for several cell divisions, although the amount of the pol alpha polypeptide drops below the physiological level. Moreover, alpha-factor-arrested cells can enter S phase and divide synchronously even if POL1 transcription is abolished. These results indicate that the level of yeast pol alpha is not rate limiting and de novo synthesis of the enzyme is not required for entrance into S phase.