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1.
Genes Dev ; 35(13-14): 1020-1034, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34168041

RESUMO

During mitosis, chromatin condensation is accompanied by a global arrest of transcription. Recent studies suggest transcriptional reactivation upon mitotic exit occurs in temporally coordinated waves, but the underlying regulatory principles have yet to be elucidated. In particular, the contribution of sequence-specific transcription factors (TFs) remains poorly understood. Here we report that Brn2, an important regulator of neural stem cell identity, associates with condensed chromatin throughout cell division, as assessed by live-cell imaging of proliferating neural stem cells. In contrast, the neuronal fate determinant Ascl1 dissociates from mitotic chromosomes. ChIP-seq analysis reveals that Brn2 mitotic chromosome binding does not result in sequence-specific interactions prior to mitotic exit, relying mostly on electrostatic forces. Nevertheless, surveying active transcription using single-molecule RNA-FISH against immature transcripts reveals differential reactivation kinetics for key targets of Brn2 and Ascl1, with transcription onset detected in early (anaphase) versus late (early G1) phases, respectively. Moreover, by using a mitotic-specific dominant-negative approach, we show that competing with Brn2 binding during mitotic exit reduces the transcription of its target gene Nestin Our study shows an important role for differential binding of TFs to mitotic chromosomes, governed by their electrostatic properties, in defining the temporal order of transcriptional reactivation during mitosis-to-G1 transition.


Assuntos
Mitose , Células-Tronco Neurais , Cromatina , Cromossomos/metabolismo , Mitose/genética , Células-Tronco Neurais/metabolismo , Fatores de Transcrição/metabolismo
3.
EMBO Rep ; 24(9): e56463, 2023 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-37462213

RESUMO

Mitotic chromatin is largely assumed incompatible with transcription due to changes in the transcription machinery and chromosome architecture. However, the mechanisms of mitotic transcriptional inactivation and their interplay with chromosome assembly remain largely unknown. By monitoring ongoing transcription in Drosophila early embryos, we reveal that eviction of nascent mRNAs from mitotic chromatin occurs after substantial chromosome compaction and is not promoted by condensin I. Instead, we show that the timely removal of transcripts from mitotic chromatin is driven by the SNF2 helicase-like protein Lodestar (Lds), identified here as a modulator of sister chromatid cohesion defects. In addition to the eviction of nascent transcripts, we uncover that Lds cooperates with Topoisomerase 2 to ensure efficient sister chromatid resolution and mitotic fidelity. We conclude that the removal of nascent transcripts upon mitotic entry is not a passive consequence of cell cycle progression and/or chromosome compaction but occurs via dedicated mechanisms with functional parallelisms to sister chromatid resolution.


Assuntos
Cromátides , Drosophila , Mitose , Animais , Proteínas de Ciclo Celular/metabolismo , Cromátides/metabolismo , Cromatina , DNA Topoisomerases Tipo II/genética , Drosophila/citologia , Drosophila/genética
4.
Int J Mol Sci ; 24(15)2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37569309

RESUMO

Human pluripotent stem cells (PSCs), which include both embryonic and induced pluripotent stem cells, are widely used in fundamental and applied biomedical research. They have been instrumental for better understanding development and cell differentiation processes, disease origin and progression and can aid in the discovery of new drugs. PSCs also hold great potential in regenerative medicine to treat or diminish the effects of certain debilitating diseases, such as degenerative disorders. However, some concerns have recently been raised over their safety for use in regenerative medicine. One of the major concerns is the fact that PSCs are prone to errors in passing the correct number of chromosomes to daughter cells, resulting in aneuploid cells. Aneuploidy, characterised by an imbalance in chromosome number, elicits the upregulation of different stress pathways that are deleterious to cell homeostasis, impair proper embryo development and potentiate cancer development. In this review, we will summarize known molecular mechanisms recently revealed to impair mitotic fidelity in human PSCs and the consequences of the decreased mitotic fidelity of these cells. We will finish with speculative views on how the physiological characteristics of PSCs can affect the mitotic machinery and how their suboptimal mitotic fidelity may be circumvented.

5.
PLoS Biol ; 17(2): e3000016, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30794535

RESUMO

Studying aneuploidy during organism development has strong limitations because chronic mitotic perturbations used to generate aneuploidy usually result in lethality. We developed a genetic tool to induce aneuploidy in an acute and time-controlled manner during Drosophila development. This is achieved by reversible depletion of cohesin, a key molecule controlling mitotic fidelity. Larvae challenged with aneuploidy hatch into adults with severe motor defects shortening their life span. Neural stem cells, despite being aneuploid, display a delayed stress response and continue proliferating, resulting in the rapid appearance of chromosomal instability, a complex array of karyotypes, and cellular abnormalities. Notably, when other brain-cell lineages are forced to self-renew, aneuploidy-associated stress response is significantly delayed. Protecting only the developing brain from induced aneuploidy is sufficient to rescue motor defects and adult life span, suggesting that neural tissue is the most ill-equipped to deal with developmental aneuploidy.


Assuntos
Aneuploidia , Drosophila melanogaster/fisiologia , Longevidade/fisiologia , Células-Tronco Neurais/fisiologia , Estresse Fisiológico , Animais , Encéfalo/fisiologia , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Autorrenovação Celular , Instabilidade Cromossômica , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos de Insetos/metabolismo , Cariótipo , Cinética , Larva/fisiologia , Mitose , Células-Tronco Neurais/citologia , Fatores de Tempo , Asas de Animais/fisiologia , Coesinas
6.
BMC Nephrol ; 20(1): 314, 2019 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-31409321

RESUMO

BACKGROUND: In kidney transplantation, immunotherapy with thymoglobulin (rATG) has been used to down-regulate the patient immune system. rATG is a powerful immunobiologic drug used to deplete lymphocytes to prevent early acute rejection. The aim of this research was to evaluate the effects of immunotherapy by rATG on graft suvival during a 9-year period in kidney-transplanted patients with different immunological profiles. METHODS: A sample of 469 patients were allocated into four groups (G) based on immunological risk of rejection: G1, low risk, not sensitized recipients, solid-phase immunoassay with single antigen beads (SPI-SAB) < 10%; G2, medium risk I, sensitized recipients, SPI-SAB ≥ 10 < 50%; G3, medium risk II sensitized (SPI-SAB ≥50%); and G4, high risk, sensitized recipients, SPI-SAB- donor-specific antibody positive (DSA+). Only patients from G3 and G4 received immunotherapy. RESULTS: Of 255 patients who received a kidney from a living donor (LD), 42 (16.47%) from all groups (G) had T-cell-mediated rejection (TCMR) and four (G1) lost their grafts, 8 (3.14%) had antibody-mediated rejection (AMR), and two lost their graft in G1 and G4. Of 214 patients who received a kidney from deceased donors (DD), 37 (17.29%) had TCMR with one lost graft in G1. AMR was shown in 13 (6.07%) patients, with three losses observed in G2. Statistical differences between the groups in the 9-year graft survival rate were found only in the comparison of G1 versus G2 (P = 0.005) and G2 versus G4 (P = 0.047) for DD. For LD, no statistical differences were found. CONCLUSION: This clinical retrospective study shows that immunotherapy induction was associated with improvement of outcomes, graft function, and survival in patients treated with immunotherapy in comparison with patients who did not received induction therapy. These findings strongly suggest that immunotherapy should be used for all patients transplanted with kidneys from deceased donors.


Assuntos
Soro Antilinfocitário/uso terapêutico , Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto/imunologia , Imunossupressores/uso terapêutico , Imunoterapia/métodos , Transplante de Rim , Adulto , Fatores Etários , Cadáver , Ciclosporina/efeitos adversos , Ciclosporina/uso terapêutico , Feminino , Rejeição de Enxerto/imunologia , Humanos , Imunossupressores/efeitos adversos , Doadores Vivos/estatística & dados numéricos , Quimioterapia de Manutenção/métodos , Masculino , Metilprednisolona/efeitos adversos , Metilprednisolona/uso terapêutico , Ácido Micofenólico/uso terapêutico , Estudos Retrospectivos , Risco , Fatores Sexuais , Sirolimo/uso terapêutico , Taxa de Sobrevida , Linfócitos T , Tacrolimo/efeitos adversos , Tacrolimo/uso terapêutico , Fatores de Tempo , Resultado do Tratamento
7.
Immunogenetics ; 70(8): 511-522, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29696367

RESUMO

The Registries of Bone Marrow Donors around the world include more than 30 million volunteer donors from 57 different countries, and were responsible for over 17,000 hematopoietic stem cell transplants in 2016. The Brazilian Bone Marrow Volunteer Donor Registry (REDOME) was established in 1993 and is the third largest registry in the world with more than 4.3 million donors. We characterized HLA allele and haplotypes frequencies from REDOME comparing them with the donor self-reported race group classification. Five-locus haplotype frequencies (A~C~B~DRB1~DQB1) were estimated for each of the six race groups, resolving phase and allelic ambiguity using the expectation-maximization (EM) algorithm. The top 100 haplotypes in the race groups were separated into eight clusters of haplotypes, based on haplotype similarity, using CLUTO. We present HLA allele and haplotype frequency data from six race groups from 2,938,259 individuals from REDOME. The most frequent haplotype was the same for all groups: A*01:01g~C*07:01g~B*08:01g~DRB1*03:01g~DQB1*02:01g. Some frequent haplotypes such as A*02:01g~C*16:01g~B*44:03~DRB1*07:01g~DQB1*02:01g was not found in people with Preta (Sub-Saharan African descent). A cluster including Branca (European) and Parda or non-informed (admixed) could be distinguished from both Preta (SubSaharan) and Indígena (Amerindian) groups, and from the Amarela (Asian) ones, which clustered with their original population. These results have implications on cross-population matching and can help in donor searches and population-based recruitment strategies.


Assuntos
Medula Óssea/imunologia , Antígenos HLA/genética , Antígenos HLA/imunologia , Alelos , Brasil , Etnicidade/genética , Frequência do Gene/imunologia , Variação Genética/genética , Haplótipos/imunologia , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Humanos , Sistema de Registros , Doadores de Tecidos , Voluntários
8.
Prog Mol Subcell Biol ; 56: 485-513, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28840250

RESUMO

Sister chromatid cohesion, mediated by the cohesin complex, is a prerequisite for faithful chromosome segregation during mitosis. Premature release of sister chromatid cohesion leads to random segregation of the genetic material and consequent aneuploidy. Multiple regulatory mechanisms ensure proper timing for cohesion establishment, concomitant with DNA replication, and cohesion release during the subsequent mitosis. Here we summarize the most important phases of the cohesin cycle and the coordination of cohesion release with the progression through mitosis. We further discuss recent evidence that has revealed additional functions for centromeric localization of cohesin in the fidelity of mitosis in metazoans. Beyond its well-established role as "molecular glue", centromeric cohesin complexes are now emerging as a scaffold for multiple fundamental processes during mitosis, including the formation of correct chromosome and kinetochore architecture, force balance with the mitotic spindle, and the association with key molecules that regulate mitotic fidelity, particularly at the chromosomal inner centromere. Centromeric chromatin may be thus seen as a dynamic place where cohesin ensures mitotic fidelity by multiple means.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Centrômero/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Segregação de Cromossomos , Mitose , Coesinas
9.
EMBO J ; 32(5): 656-65, 2013 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-23340528

RESUMO

Cohesin's Smc1, Smc3, and kleisin subunits create a tripartite ring within which sister DNAs are entrapped. Evidence suggests that DNA enters through a gate created by transient dissociation of the Smc1/3 interface. Release at the onset of anaphase is triggered by proteolytic cleavage of kleisin. Less well understood is the mechanism of release at other stages of the cell cycle, in particular during prophase when most cohesin dissociates from chromosome arms in a process dependent on the regulatory subunit Wapl. We show here that Wapl-dependent release from salivary gland polytene chromosomes during interphase and from neuroblast chromosome arms during prophase is blocked by translational fusion of Smc3's C-terminus to kleisin's N-terminus. Our findings imply that proteolysis-independent release of cohesin from chromatin is mediated by Wapl-dependent escape of DNAs through a gate created by transient dissociation of the Smc3/kleisin interface. Thus, cohesin's DNA entry and exit gates are distinct.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Drosophila/metabolismo , Interfase/fisiologia , Mitose/fisiologia , Cromossomos Politênicos/genética , Animais , Animais Geneticamente Modificados , Western Blotting , Proteínas de Ciclo Celular/genética , Cromatina/genética , Proteínas Cromossômicas não Histona/genética , DNA/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Feminino , Técnicas Imunoenzimáticas , Masculino , Neurônios/citologia , Neurônios/metabolismo , Cromossomos Politênicos/metabolismo , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Glândulas Salivares/citologia , Glândulas Salivares/metabolismo
10.
PLoS Biol ; 12(10): e1001962, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25290697

RESUMO

Pericentric heterochromatin, while often considered as "junk" DNA, plays important functions in chromosome biology. It contributes to sister chromatid cohesion, a process mediated by the cohesin complex that ensures proper genome segregation during nuclear division. Long stretches of heterochromatin are almost exclusively placed at centromere-proximal regions but it remains unclear if there is functional (or mechanistic) importance in linking the sites of sister chromatid cohesion to the chromosomal regions that mediate spindle attachment (the centromere). Using engineered chromosomes in Drosophila melanogaster, we demonstrate that cohesin enrichment is dictated by the presence of heterochromatin rather than centromere proximity. This preferential accumulation is caused by an enrichment of the cohesin-loading factor (Nipped-B/NIPBL/Scc2) at dense heterochromatic regions. As a result, chromosome translocations containing ectopic pericentric heterochromatin embedded in euchromatin display additional cohesin-dependent constrictions. These ectopic cohesion sites, placed away from the centromere, disjoin abnormally during anaphase and chromosomes exhibit a significant increase in length during anaphase (termed chromatin stretching). These results provide evidence that long stretches of heterochromatin distant from the centromere, as often found in many cancers, are sufficient to induce abnormal accumulation of cohesin at these sites and thereby compromise the fidelity of chromosome segregation.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos de Insetos/fisiologia , Heterocromatina/metabolismo , Anáfase , Animais , Animais Geneticamente Modificados , Centrômero , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Masculino , Coesinas
11.
Int J Mol Sci ; 18(12)2017 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-29258269

RESUMO

Mitotic chromosomes are long-known structures, but their internal organization and the exact process by which they are assembled are still a great mystery in biology. Topoisomerase II is crucial for various aspects of mitotic chromosome organization. The unique ability of this enzyme to untangle topologically intertwined DNA molecules (catenations) is of utmost importance for the resolution of sister chromatid intertwines. Although still controversial, topoisomerase II has also been proposed to directly contribute to chromosome compaction, possibly by promoting chromosome self-entanglements. These two functions raise a strong directionality issue towards topoisomerase II reactions that are able to disentangle sister DNA molecules (in trans) while compacting the same DNA molecule (in cis). Here, we review the current knowledge on topoisomerase II role specifically during mitosis, and the mechanisms that directly or indirectly regulate its activity to ensure faithful chromosome segregation. In particular, we discuss how the activity or directionality of this enzyme could be regulated by the SMC (structural maintenance of chromosomes) complexes, predominantly cohesin and condensin, throughout mitosis.


Assuntos
Cromossomos/metabolismo , Mitose/fisiologia , Adenosina Trifosfatases/metabolismo , Animais , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Segregação de Cromossomos/fisiologia , Cromossomos/genética , DNA Topoisomerases Tipo II/metabolismo , Proteínas de Ligação a DNA/metabolismo , Humanos , Mitose/genética , Complexos Multiproteicos/metabolismo , Coesinas
12.
Proc Natl Acad Sci U S A ; 108(24): 10016-21, 2011 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-21617094

RESUMO

The mitotic checkpoint prevents a eukaryotic cell from commencing to separate its replicated genome into two daughter cells (anaphase) until all of its chromosomes are properly aligned on the metaphase plate, with the two copies of each chromosome attached to opposite poles of the mitotic spindle. The mitotic checkpoint is exquisitely sensitive in that a single unaligned chromosome, 1 of a total of ~50, is sufficient to delay progression into anaphase; however, when the last chromosome comes into alignment on the metaphase plate, the mitotic checkpoint is quickly satisfied, and the replicated chromosomes are rapidly partitioned to opposite poles of the dividing cell. The mitotic checkpoint is also curious in the sense that, before metaphase alignment, chromosomes that are not being pulled in opposite directions by the mitotic spindle activate the checkpoint, but during anaphase, these same tensionless chromosomes can no longer activate the checkpoint. These and other puzzles associated with the mitotic checkpoint are addressed by a proposed molecular mechanism, which involves two positive feedback loops that create a bistable response of the checkpoint to chromosomal tension.


Assuntos
Algoritmos , Anáfase/genética , Retroalimentação Fisiológica , Modelos Genéticos , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromátides/genética , Segregação de Cromossomos/genética , Ciclina B , Humanos , Mitose/genética , Fuso Acromático/genética , Fuso Acromático/metabolismo
13.
Transpl Immunol ; 82: 101989, 2024 02.
Artigo em Inglês | MEDLINE | ID: mdl-38199270

RESUMO

INTRODUCTION: Hematopoietic stem cell transplantation (HSCT) remains a critical treatment for advanced or high-risk hematological malignancies, posing challenges such as finding suitable donors and managing of graft-versus-host disease (GvHD). This study estimates 3-year overall survival in patients who underwent HSCT at our referral service in the state of Minas Gerais, Brazil. MATERIAL AND METHODS: This retrospective observational cohort study involved 41 patients who received HSCT between 2017 and 2021 at the Felício Rocho Hospital. Recipients received HSCT from either haploidentical donor (Haplo), matched unrelated donor (MUD), or HLA-matched sibling donor (MSD). The study evaluated parameters that included 3-year overall survival (OS), treatment-related mortality (TRM), GvHD incidence, post-transplant relapse rate, and engraftment. ANOVA, Kruskal-Wallis, and chi-square tests were used for statistical analysis. Survival curves were calculated using the Kaplan-Meier method and the Log-rank test compared the curves. RESULTS: Our study found that the engraftment time differed among groups: Haplo recipients engrafted earlier within a median of 16 days (ranging between 10 and 20 days) than MSD recipients with 18 days (ranging between 11 and 28 days), and MUD recipients with 19 days (ranging between 11 and 24 days; p = 0.019). Mild acute GvHD (grade I-II) was observed in 13 patients, progressing to chronic GvHD in 5 patients. Three-year OS rates were as follows: MSD group - 67.7%, Haplo group - 42.2%, and MUD group - 44.4% (MSD vs Haplo, p = 0.039). Three-year cumulative treatment-related mortality (TRM) rates were 17.8% for MSD group, 22.9% for Haplo group, and 22.1% for MUD group (pairwise comparisons p > 0.05). Infection-related mortality was reported in eight patients, while relapse rates at 3 years were similar across MSD, Haplo, and MUD groups (p = 0.891). Donor age influenced OS rates, showing better outcomes with donors under 45 years old, and significant differences were found in pairwise comparisons (p = 0.015). CONCLUSION: Donor type and donor age significantly impacted HSCT outcomes in our analysis, thus emphasizing the importance of rigorous donor selection in risk stratification and suggesting potential benefits for younger donors.


Assuntos
Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Humanos , Pessoa de Meia-Idade , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Transplante de Células-Tronco Hematopoéticas/métodos , Recidiva Local de Neoplasia/complicações , Recidiva , Estudos Retrospectivos , Irmãos , Doadores não Relacionados , Adulto
14.
Transpl Immunol ; 85: 102057, 2024 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-38797338

RESUMO

INTRODUCTION: Despite significant progress over the last decades in the survival of kidney allografts, several risk factors remain contributing to worsening kidney function or even loss of transplants. We aimed to evaluate a new machine learning method to identify these variables which may predict the early graft loss in kidney transplant patients and to assess their usefulness for improving clinical decisions. MATERIAL AND METHODS: A retrospective cohort study was carried out with 627 kidney transplant patients followed at least three months. All these data were pre-processed, and their selected features were used to develop an automatically working a machine learning algorithm; this algorithm was then applied for training and parameterization of the model; and finally, the tested model was then used for the analysis of patients' features that were the most impactful for the prediction of clinical outcomes. Our models were evaluated using the Area Under the Curve (AUC), and the SHapley Additive exPlanations (SHAP) algorithm was used to interpret its predictions. RESULTS: The final selected model achieved a precision of 0.81, a sensitivity of 0.61, a specificity of 0.89, and an AUC value of 0.84. In our model, serum creatinine levels of kidney transplant patients, evaluated at the hospital discharge, proved to be the most important factor in the decision-making for the allograft loss. Patients with a weight equivalent to a BMI closer to the normal range prior to a kidney transplant are less likely to experience graft loss compared to patients with a BMI below the normal range. The age of patients at transplantation and Polyomavirus (BKPyV) infection had significant impact on clinical outcomes in our model. CONCLUSIONS: Our algorithm suggests that the main characteristics that impacted early allograft loss were serum creatinine levels at the hospital discharge, as well as the pre-transplant values such as body weight, age of patients, and their BKPyV infection. We propose that machine learning tools can be developed to effectively assist medical decision-making in kidney transplantation.

15.
Transpl Immunol ; 84: 102019, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38447737

RESUMO

INTRODUCTION: The global health crisis caused by the COVID-19 pandemic has resulted in severe mortality and morbidity. Immunosuppressed patients, such as kidney transplant recipients, are particularly susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. OBJECTIVE: The aim of this cohort study was to evaluate the impact of COVID-19 vaccination on clinical outcomes in patients with kidney transplants. MATERIALS AND METHODS: In this retrospective study, 254 patients with kidney transplants were vaccinated against SARS-CoV-2 and a fraction of these contracted COVID-19. The diagnosis of COVID-19 was carried out by reverse transcriptase-polymerase chain reaction testing, and the patients received treatment involving immunosuppressive and COVID-19-specific protocols. RESULTS: SARS-CoV-2 infection was diagnosed in 38 (14.96%) patients before the COVID-19 vaccine was administered. After vaccination, an additional 29 (11.42%) patients were diagnosed with COVID-19. Risk factors for hospitalization included age, body mass index (BMI), comorbidities, and time elapsed since renal transplantation (p = 0.025, 0.038, 0.012, and 0.046, respectively). COVID-19 vaccination resulted in a significant decrease in the rate of hospital-acquired SARS-CoV-2 infection from 63.16% to 34.48% (p = 0.020). The proportion of patients from this cohort placed in intensive care units decreased from 23.68% to zero. Allograft rejections exhibited a decreasing trend from 13.16% to 6.90% (p = 0.690). This patient cohort displayed 15.79% mortality prior to COVID-19 vaccination that was reduced to nil after immunization. CONCLUSION: COVID-19 vaccination significantly reduced COVID-19 severity and mortality in this cohort of patients with kidney transplants. The risk factors for hospitalization were determined to be age, BMI, comorbidities, and time since renal transplantation. COVID-19 vaccination resulted in a clinical outcome of reduced hospitalization and a decrease in clinical complications. The COVID-19 vaccination-derived adverse effects in this cohort were found to be comparable to those in the immunocompetent population.


Assuntos
Vacinas contra COVID-19 , COVID-19 , Transplante de Rim , SARS-CoV-2 , Vacinação , Humanos , COVID-19/prevenção & controle , COVID-19/epidemiologia , Masculino , Feminino , Pessoa de Meia-Idade , Estudos Retrospectivos , SARS-CoV-2/imunologia , Adulto , Idoso , Fatores de Risco , Hospedeiro Imunocomprometido , Hospitalização/estatística & dados numéricos , Resultado do Tratamento
16.
Biophys J ; 104(12): 2595-606, 2013 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-23790367

RESUMO

Chromosome bi-orientation at the metaphase spindle is essential for precise segregation of the genetic material. The process is error-prone, and error-correction mechanisms exist to switch misaligned chromosomes to the correct, bi-oriented configuration. Here, we analyze several possible dynamical scenarios to explore how cells might achieve correct bi-orientation in an efficient and robust manner. We first illustrate that tension-mediated feedback between the sister kinetochores can give rise to a bistable switch, which allows robust distinction between a loose attachment with low tension and a strong attachment with high tension. However, this mechanism has difficulties in explaining how bi-orientation is initiated starting from unattached kinetochores. We propose four possible mechanisms to overcome this problem (exploiting molecular noise; allowing an efficient attachment of kinetochores already in the absence of tension; a trial-and-error oscillation; and a stochastic bistable switch), and assess their impact on the bi-orientation process. Based on our results and supported by experimental data, we put forward a trial-and-error oscillation and a stochastic bistable switch as two elegant mechanisms with the potential to promote bi-orientation both efficiently and robustly.


Assuntos
Posicionamento Cromossômico , Cromossomos/metabolismo , Modelos Genéticos , Animais , Segregação de Cromossomos , Humanos , Cinetocoros/metabolismo , Processos Estocásticos
17.
Dev Cell ; 14(2): 239-51, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18267092

RESUMO

Cohesin is a highly conserved multisubunit complex that holds sister chromatids together in mitotic cells. At the metaphase to anaphase transition, proteolytic cleavage of the alpha kleisin subunit (Rad21) by separase causes cohesin's dissociation from chromosomes and triggers sister-chromatid disjunction. To investigate cohesin's function in postmitotic cells, where it is widely expressed, we have created fruit flies whose Rad21 can be cleaved by TEV protease. Cleavage causes precocious separation of sister chromatids and massive chromosome missegregation in proliferating cells, but not disaggregation of polytene chromosomes in salivary glands. Crucially, cleavage in postmitotic neurons is lethal. In mushroom-body neurons, it causes defects in axon pruning, whereas in cholinergic neurons it causes highly abnormal larval locomotion. These data demonstrate essential roles for cohesin in nondividing cells and also introduce a powerful tool by which to investigate protein function in metazoa.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Endopeptidases/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Proteínas Nucleares/metabolismo , Animais , Axônios/metabolismo , Colina/metabolismo , Cromátides/metabolismo , Segregação de Cromossomos , Dendritos/metabolismo , Drosophila melanogaster/embriologia , Embrião não Mamífero/citologia , Embrião não Mamífero/metabolismo , Fertilidade , Larva , Locomoção , Mitose , Mutação/genética , Especificidade de Órgãos , Ligação Proteica , Coesinas
18.
Life Sci Alliance ; 6(1)2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36379670

RESUMO

Membrane organelle function, localization, and proper partitioning upon cell division depend on interactions with the cytoskeleton. Whether membrane organelles also impact the function of cytoskeletal elements remains less clear. Here, we show that acute disruption of the ER around spindle poles affects mitotic spindle size and function in Drosophila syncytial embryos. Acute ER disruption was achieved through the inhibition of ER membrane fusion by the dominant-negative cytoplasmic domain of atlastin. We reveal that when centrosome-proximal ER membranes are disrupted, specifically at metaphase, mitotic spindles become smaller, despite no significant changes in microtubule dynamics. These smaller spindles are still able to mediate sister chromatid separation, yet with decreased velocity. Furthermore, by inducing mitotic exit, we found that nuclear separation and distribution are affected by ER disruption. Our results suggest that ER integrity around spindle poles is crucial for the maintenance of mitotic spindle shape and pulling forces. In addition, ER integrity also ensures nuclear spacing during syncytial divisions.


Assuntos
Proteínas de Drosophila , Fuso Acromático , Animais , Fuso Acromático/metabolismo , Centrossomo/metabolismo , Microtúbulos/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Retículo Endoplasmático/metabolismo , Drosophila/metabolismo
19.
Transpl Immunol ; 77: 101807, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36842568

RESUMO

INTRODUCTION: Anemia in chronic kidney disease is of great concern regarding blood transfusions and the possibility of allosensitization for future kidney transplants and the occurrence of rejection and allograft loss in the post-transplant period. The aim of this study was to evaluate the effect of early blood transfusion on the occurrence of rejections, allograft function and survival in the first year after transplantation. MATERIAL AND METHODS: This retrospective study was carried out with 445 patients submitted to kidney transplant allocated to two groups. The first group received early blood transfusions after transplant (n = 125, 28.09%), and the second group did not receive blood transfusions (n = 320, 71.91%). The patient outcomes were evaluated during a 1-year follow-up. RESULTS: 14 patients given blood transfusion (11.2%) lost their allograft in the first year in comparison with 8 (2.5%) without transfusion (p < 0.001). There were 9 deaths in each group, which corresponded to 7.2% of the patients who received blood transfusions and 2.81% of those who did not (p < 0.035). Patient hospitalization lasted 15 days in transfusion group and 8.5 days in non-transfusion group (p < 0.001). Creatinine levels were higher in the patients who received blood transfusion than in those without transfusion in the first and third months after transplantation (p = 0.012 and 0.038, respectively). During the first year, the patients who received blood products experienced more antibody-mediated rejection (ABMR) (13.60%) than patients who did not (4.38%) (p < 0.001). Those who received blood transfusions also developed de novo DSA in higher proportion than those without transfusion against both class I and class II HLA (p < 0.001). CONCLUSION: This study showed that blood transfusions in the first month after transplantation had a negative impact on kidney function, graft survival, and contributed to the development of de novo DSA, an increased risk of ABMR and infections.


Assuntos
Aloenxertos , Transfusão de Sangue , Sobrevivência de Enxerto , Transplante de Rim , Cuidados Pós-Operatórios , Resultado do Tratamento , Transfusão de Sangue/métodos , Cuidados Pós-Operatórios/métodos , Fatores de Tempo , Humanos , Masculino , Feminino , Adulto , Anemia/prevenção & controle , Anemia/terapia , Formação de Anticorpos , Rejeição de Enxerto , Estudos Retrospectivos , Segurança do Paciente
20.
Transpl Immunol ; 78: 101821, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36921732

RESUMO

BACKGROUND: The main goal of kidney allograft transplantation is to improve survival in patients with end-stage kidney failure. Herein, we report a 49-year long-term allograft survival with non-identical human leukocyte antigens (HLA). The purpose of this study was to report the successful clinical outcome of 49 years of transplant survival in a 79-year-old patient with a 107-year-old kidney undergoing continued immunosuppressive monotherapy. MATERIAL AND METHODS: The patient was evaluated clinically and immunologically with HLA typing and anti-HLA antibodies before transplantation. Post-transplant, the patient's clinical and immunological survival were monitored for 49 years. The state of the chimerism was assessed using the polymerase chain reaction to amplify 24 short tandem repeats using a DNA thermocycler and DNA analyzer. RESULTS: The patient and donor were haploidentical and the patient was treated with azathioprine monotherapy. Donor-specific antibodies were detected only for the HLA-DPB1* 03:01 mismatch. This patient developed multiple skin tumors 26 years after transplant, which were successfully treated with topical therapy or surgical removal. The patient developed an intestinal adenocarcinoma 43 years after kidney transplantation, which was surgically removal; six years later, adenocarcinoma was diagnosed in a finger, followed by axillar and hepatic metastases. After 49 years of graft survival of a kidney of 107 years old in a patient with 79 years of age, the patient's health worsened with severe dehydration, anemia, and bacterial infection. The patient was hospitalized with a serum creatinine level of 3.45 mg/dL, urea level of 188 mg/dL, and estimated glomerular filtration rate of 22 mL/1.72 m2; septicemia developed and was treated with antibiotics. The patient had poor clinical progress, was intubated, and later died due to septic shock. CONCLUSIONS: To the best of our knowledge, this is the first case of a 107-year-old kidney, transplanted into a recipient who was treated with azathioprine monotherapy for 49 years.


Assuntos
Azatioprina , Transplante de Rim , Humanos , Idoso de 80 Anos ou mais , Idoso , Azatioprina/uso terapêutico , Rejeição de Enxerto/tratamento farmacológico , Imunossupressores/uso terapêutico , Rim , Sobrevivência de Enxerto , Antígenos HLA
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