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1.
bioRxiv ; 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39229235

RESUMO

Purpose: Cross-linked actin networks (CLANs) are prevalent in the glaucomatous trabecular meshwork (TM), yet their role in ocular hypertension remains unclear. We used a human TM cell line that spontaneously forms fluorescently-labeled CLANs (GTM3L) to explore the origin of CLANs, developed techniques to increase CLAN incidence in GMT3L cells, and computationally studied the biomechanical properties of CLAN-containing cells. Methods: GTM3L cells were fluorescently sorted for viral copy number analysis. CLAN incidence was increased by (i) differential sorting of cells by adhesion, (ii) cell deswelling, and (iii) cell selection based on cell stiffness. GTM3L cells were also cultured on glass or soft hydrogel to determine substrate stiffness effects on CLAN incidence. Computational models were constructed to mimic and study the biomechanical properties of CLANs. Results: All GTM3L cells had an average of 1 viral copy per cell. LifeAct-GFP expression level did not affect CLAN incidence rate, but CLAN rate was increased from ∼0.28% to ∼50% by a combination of adhesion selection, cell deswelling, and cell stiffness-based sorting. Further, GTM3L cells formed more CLANs on a stiff vs. a soft substrate. Computational modeling predicted that CLANs contribute to higher cell stiffness, including increased resistance of the nucleus to tensile stress when CLANs are physically linked to the nucleus. Conclusions: It is possible to greatly enhance CLAN incidence in GTM3L cells. CLANs are mechanosensitive structures that affect cell biomechanical properties. Further research is needed to determine the effect of CLANs on TM biomechanics and mechanobiology as well as the etiology of CLAN formation in the TM.

4.
J Hand Microsurg ; 16(4): 100124, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39234367

RESUMO

The treatment of phalangeal fractures is guided by fracture characteristics, patient factors and surgeon judgment. This study retrospectively compares characteristics of phalangeal fractures treated with closed reduction percutaneous pinning (CRPP) with those of fractures treated with open reduction internal fixation (ORIF) to identify risk factors associated with reoperation. A total of 901 phalangeal fractures were included and treated operatively by either CRPP (748 fractures, 83 â€‹%) or ORIF (153 fractures, 17 â€‹%). Demographics, surgical management, and complication data were collected. Statistical analyses were performed to stratify risk associations and identify potential predictors of reoperation. With multivariate analysis and bootstrapped LASSO regression, fractures addressed by means of ORIF (vs. CRPP), work-related fractures, and open fractures were found to be independently associated with reoperation. These findings can be used to guide patient selection, surgical planning and timing of fracture repair. Level of evidence: Level III, Therapeutic.

5.
Pain Pract ; 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39219017

RESUMO

INTRODUCTION: Chronic knee pain is defined as pain that persists or recurs over 3 months. The most common is degenerative osteoarthritis (OA). This review represents a comprehensive description of the pathology, diagnosis, and treatment of OA of the knee. METHODS: The literature on the diagnosis and treatment of chronic knee pain was retrieved and summarized. A modified Delphi approach was used to formulate recommendations on interventional treatments. RESULTS: Patients with knee OA commonly present with insidious, chronic knee pain that gradually worsens. Pain caused by knee OA is predominantly nociceptive pain, with occasional nociplastic and infrequent neuropathic characteristics occurring in a diseased knee. A standard musculoskeletal and neurological examination is required for the diagnosis of knee OA. Although typical clinical OA findings are sufficient for diagnosis, medical imaging may be performed to improve specificity. The differential diagnosis should exclude other causes of knee pain including bone and joint disorders such as rheumatoid arthritis, spondylo- and other arthropathies, and infections. When conservative treatment fails, intra-articular injections of corticosteroids and radiofrequency (conventional and cooled) of the genicular nerves have been shown to be effective. Hyaluronic acid infiltrations are conditionally recommended. Platelet-rich plasma infiltrations, chemical ablation of genicular nerves, and neurostimulation have, at the moment, not enough evidence and can be considered in a study setting. The decision to perform joint-preserving and joint-replacement options should be made multidisciplinary. CONCLUSIONS: When conservative measures fail to provide satisfactory pain relief, a multidisciplinary approach is recommended including psychological therapy, integrative treatments, and procedural options such as intra-articular injections, radiofrequency ablation, and surgery.

6.
Pain Pract ; 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39219023

RESUMO

INTRODUCTION: Cervicogenic headache (CEH) and occipital neuralgia (ON) are headaches originating in the occiput and that radiate to the vertex. Because of the intimate relationship between structures based in the occiput and those in the upper cervical region, there is significant overlap between the presentation of CEH and ON. Diagnosis starts with a headache history to assess for diagnostic criteria formulated by the International Headache Society. Physical examination evaluates range of motion of the neck and the presence of tender areas or pressure points. METHODS: The literature for the diagnosis and treatment of CEH and ON was searched from 2015 through August 2022, retrieved, and summarized. RESULTS: Conservative treatment includes pain education and self-care, analgesic medication, physical therapy (such as reducing secondary muscle tension and improving posture), the use of TENS (transcutaneous electrical nerve stimulation), or a combination of the aforementioned treatments. Injection at various anatomical locations with local anesthetic with or without corticosteroids can provide pain relief for a short period. Deep cervical plexus block can result in improved pain for less than 6 months. In both CEH and ON, an occipital nerve block can provide important diagnostic information and improve pain in some patients, with PRF providing greater long-term pain control. Radiofrequency ablation of the cervical facet joints can result in improvement for over 1 year. Occipital nerve stimulation (ONS) should be considered for the treatment of refractory ON. CONCLUSION: The treatment of CEH preferentially consists of radiofrequency treatment of the facet joints, while for ON, pulsed radiofrequency of the occipital nerves is indicated. For refractory cases, ONS may be considered.

7.
J Pediatr ; : 114271, 2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39218208

RESUMO

OBJECTIVE: To examine sex differences in neurodevelopmental outcomes and brain development from early life to 8 years in males and females born preterm. STUDY DESIGN: This was a prospective cohort study of infants born very preterm (24-32 weeks' gestation) and followed to 8 years with standardized measures of neurodevelopment. Brain magnetic resonance imaging (MRI) scans were performed soon after birth, term-equivalent age, and 8 years. The relationship between sex, severe brain injury, early pain exposure, fractional anisotropy (FA), and neurodevelopmental outcomes were assessed using multivariable generalized estimating equations. RESULTS: Males (N=78) and females (N=66) were similar in clinical risk factors. Male sex was associated with lower cognitive scores (ß=-3.8, P=0.02) and greater motor impairment (OR=1.8, P=0.04) across time. Male sex was associated with lower superior white matter FA across time (ß=-0.01, P=0.04). Sex moderated the association between severe brain injury, early pain, and neurodevelopmental outcomes. With severe brain injury, males had lower cognitive scores at 3 years (P<0.001). With increasing pain, females had lower cognitive scores at 8 years (P=0.008), and males had greater motor impairment at 4.5 years (P=0.001) and 8 years (P=0.05). CONCLUSIONS: Males born preterm had lower cognitive scores and greater motor impairment compared with females, which were associated with differences in white matter maturation. The association between severe brain injury, early pain exposure, and neurodevelopmental outcomes was moderated by sex, indicating a differential response to early-life adversity in males and females born preterm.

8.
Transl Androl Urol ; 13(7): 1093-1103, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39100847

RESUMO

Background: In 2012 the United States Preventative Services Task Force (USPSTF) changed its prostate-specific antigen (PSA) screening recommendation to a category "D". The purpose of this study is to examine racial, ethnic, and socioeconomic differences in risk of presentation with metastatic prostate cancer (mPCa) at time of diagnosis before and after the 2012 USPSTF category "D" recommendation. Methods: This is a population-based cohort study. We identified patients with mPCa at diagnosis within the National Cancer Database from 2004-2017. Logistic regression models were used to examine associations of mPCa with age, race, ethnicity, geographic location, education level, income, and insurance status. Linear regression models assuming underlying binomial distribution were fitted to annual percentage of mPCa at diagnosis for years 2012-2017 to evaluate the post category "D" recommendation era. Results: From 2004 to 2017, 88,987 patients presented with mPCa. A higher percentage of mPCa was noted post-USPSTF category "D" recommendation, with a disproportionately greater increase observed among Hispanics and non-Hispanic Blacks [Δslope/year: Hispanics (0.0092), non-Hispanic Blacks (0.0073) and non-Hispanic Whites (0.0070)]. Insurance status impacts race/ethnicity differently: uninsured Hispanics were 3.66 times more likely to present with mPCa than insured Hispanics, while uninsured non-Hispanic Blacks were 2.62 times more likely to present with mPCa than insured non-Hispanic Blacks. Household income appears to be associated with differences in mPCa, particularly among non-Hispanic Blacks. Those earning <$30,000 were more likely to present with mPCa compared to higher income brackets. Conclusions: Since the USPSTF grade "D" recommendation against PSA screening, the percentage of mPCa at diagnosis has increased, with a higher rate of increase among Hispanic and non-Hispanic Blacks compared to non-Hispanic Whites.

9.
J Palliat Med ; 2024 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-39112021

RESUMO

Background: Despite physical and emotional distress in patients with gynecologic malignancies, palliative care (PC) is underutilized. Objectives: We characterize referral practices, symptom burden and functional status at the time of initial PC encounter for patients with gynecologic cancer. Design: Data were extracted from the standardized Quality Data Collection Tool for Palliative Care (QDACT-PC). We describe symptom burden and performance status. Results: At initial specialty PC encounter, patients with gynecologic cancers reported a mean of 3.3 moderate/severe symptoms. Outpatients experienced the most moderate/severe symptoms (mean 3.9) versus inpatient (mean 2.1) or home (mean 1.5). A total of 72.7% of patients had significantly impaired functional status (palliative performance scale [PPS] <70) at initial encounter. Inpatients had a more impaired functional status (mean PPS 48.8) than outpatients (mean PPS 67.0). Conclusions: The symptom burden for gynecologic cancer patients at initial PC encounter is high. Despite better functional status, patients referred in the outpatient setting had the highest symptom burden.

10.
Artigo em Inglês | MEDLINE | ID: mdl-39116913

RESUMO

OBJECTIVE: The hippocampus plays a critical role in cognitive networks. The anterior hippocampus is vulnerable to early-life stress and socioeconomic status (SES) with alterations persisting beyond childhood. How SES modifies the relationship between early hippocampal development and cognition remains poorly understood. This study examined associations between SES, structural and functional development of neonatal hippocampus, and 18-month cognition in very preterm neonates. METHODS: In total, 179 preterm neonates were followed prospectively. Structural and resting-state functional MRI were obtained early-in-life and at term-equivalent age (median 32.9 and 41.1 weeks post-menstrual age) to calculate anterior and posterior hippocampal volumes and hippocampal functional connectivity strength. Eighteen-month cognition was assessed via Bayley-III. Longitudinal statistical analysis using generalized estimating equations, accounting for birth gestational age, post-menstrual age at scan, sex, and motion, was performed. RESULTS: SES, measured as maternal education level, modified associations between anterior but not posterior hippocampal volumes and 18-month cognition (interaction term p = 0.005), and between hippocampal connectivity and cognition (interaction term p = 0.05). Greater anterior hippocampal volumes and hippocampal connectivity were associated with higher cognitive scores only in the lowest SES group. Maternal education alone did not predict neonatal hippocampal volume from early-in-life and term. INTERPRETATION: SES modified the relationship between neonatal hippocampal development and 18-month cognition in very preterm neonates. The lack of direct association between maternal education and neonatal hippocampal volumes indicates that socio-environmental factors beyond the neonatal period contribute to modifying the relationship between hippocampal development and cognition. These findings point toward opportunities to more equitably promote optimal neurodevelopmental outcomes in very preterm infants.

11.
Br J Cancer ; 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39117800

RESUMO

BACKGROUND: Cyclin-dependent kinase 9 (CDK9) stimulates oncogenic transcriptional pathways in cancer and CDK9 inhibitors have emerged as promising therapeutic candidates. METHODS: The activity of an orally bioavailable CDK9 inhibitor, CDKI-73, was evaluated in prostate cancer cell lines, a xenograft mouse model, and patient-derived tumor explants and organoids. Expression of CDK9 was evaluated in clinical specimens by mining public datasets and immunohistochemistry. Effects of CDKI-73 on prostate cancer cells were determined by cell-based assays, molecular profiling and transcriptomic/epigenomic approaches. RESULTS: CDKI-73 inhibited proliferation and enhanced cell death in diverse in vitro and in vivo models of androgen receptor (AR)-driven and AR-independent models. Mechanistically, CDKI-73-mediated inhibition of RNA polymerase II serine 2 phosphorylation resulted in reduced expression of BCL-2 anti-apoptotic factors and transcriptional defects. Transcriptomic and epigenomic approaches revealed that CDKI-73 suppressed signaling pathways regulated by AR, MYC, and BRD4, key drivers of dysregulated transcription in prostate cancer, and reprogrammed cancer-associated super-enhancers. These latter findings prompted the evaluation of CDKI-73 with the BRD4 inhibitor AZD5153, a combination that was synergistic in patient-derived organoids and in vivo. CONCLUSION: Our work demonstrates that CDK9 inhibition disrupts multiple oncogenic pathways and positions CDKI-73 as a promising therapeutic agent for prostate cancer, particularly aggressive, therapy-resistant subtypes.

12.
Adv Sci (Weinh) ; : e2401502, 2024 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-39120068

RESUMO

Multifaceted interrogation of the proteome deepens the system-wide understanding of biological systems; however, mapping the redox changes in the proteome has so far been significantly more challenging than expression and solubility/stability analyses. Here, the first high-throughput redox proteomics approach integrated with expression analysis (REX) is devised and combined with the Proteome Integral Solubility Alteration (PISA) assay. The whole PISA-REX experiment with up to four biological replicates can be multiplexed into a single tandem mass tag TMTpro set. For benchmarking this compact tool, HCT116 cells treated with auranofin are analyzed, showing great improvement compared with previous studies. PISA-REX is then applied to study proteome remodeling upon stimulation of human monocytes by interferon α (IFN-α). Applying this tool to study the proteome changes in plasmacytoid dendritic cells (pDCs) isolated from wild-type versus Ncf1-mutant mice treated with interferon α, shows that NCF1 deficiency enhances the STAT1 pathway and modulates the expression, solubility, and redox state of interferon-induced proteins. Providing comprehensive multifaceted information on the proteome, the compact PISA-REX has the potential to become an industry standard in proteomics and to open new windows into the biology of health and disease.

13.
Nat Aging ; 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39117982

RESUMO

Although cancer is an age-related disease, how the processes of aging contribute to cancer progression is not well understood. In this study, we uncovered how mouse B cell lymphoma develops as a consequence of a naturally aged system. We show here that this malignancy is associated with an age-associated clonal B cell (ACBC) population that likely originates from age-associated B cells. Driven by c-Myc activation, promoter hypermethylation and somatic mutations, IgM+ ACBCs clonally expand independently of germinal centers and show increased biological age. ACBCs become self-sufficient and support malignancy when transferred into young recipients. Inhibition of mTOR or c-Myc in old mice attenuates pre-malignant changes in B cells during aging. Although the etiology of mouse and human B cell lymphomas is considered distinct, epigenetic changes in transformed mouse B cells are enriched for changes observed in human B cell lymphomas. Together, our findings characterize the spontaneous progression of cancer during aging through both cell-intrinsic and microenvironmental changes and suggest interventions for its prevention.

16.
JAMA Netw Open ; 7(8): e2427163, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39133487

RESUMO

Importance: Studies using human postmortem tissue and imaging with positron emission tomography (PET) support a low hippocampal availability of the α7 nicotinic acetylcholine receptor (α7-nAChR) in psychotic conditions, particularly in schizophrenia or schizoaffective disorder (nonaffective psychosis). If validated further, the finding may have implications for clinical diagnosis and treatment. Objective: To test for lower availability of the α7-nAChR in the hippocampus of individuals with recent-onset psychosis compared with healthy control individuals and its association with lower cognitive performance or higher psychotic symptom burden within recent-onset psychosis. Design, Setting, and Participants: In this cross-sectional study, healthy individuals without history of psychosis and patients within 10 years of a first onset of psychotic disorder were recruited from the greater Baltimore, Maryland, and Washington, DC, area. Fluorine 18-labeled ASEM ([18F] ASEM) PET data were acquired from participants enrolled between March 1, 2014, and July 31, 2023, from an academic research institution. Data acquired between March 1, 2014, and January 31, 2018 (n = 26), were published as a pilot study and were combined with new data acquired between January 1, 2019, and July 31, 2023 (n = 33). Main Outcome and Measures: Regional [18F]ASEM total distribution volume (VT) that measures α7-nAChR availability, global cognition composite score, and total scores on the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. Results: A total of 59 participants (30 women [51%]; mean [SD] age, 25.5 [5.2] years), including 35 with recent-onset psychosis and 24 healthy controls, completed the study. In age-adjusted analyses, lower hippocampal [18F]ASEM VT was found in individuals with recent-onset psychosis (mean [SE], 17.87 [0.60]) compared with healthy controls (mean [SE], 19.82 [0.73]) (P = .04). In addition, [18F]ASEM VT was lower in individuals with nonaffective psychosis (mean [SE], 16.30 [0.83]) compared with healthy controls (P = .006) or those with affective psychosis (mean [SE], 19.34 [0.80]) (P = .03). Across recent-onset psychosis and after controlling for age, lower hippocampal [18F]ASEM VT was associated with more positive (r = -0.44; P = .009) but not negative symptoms, and higher hippocampal VT was associated with better global cognition composite score (r = 0.38; P = .03). Conclusions and Relevance: In this cross-sectional study of individuals with recent-onset psychosis compared with healthy controls, a lower hippocampal α7-nAChR availability was found in recent-onset psychosis, and its availability was lower in those with nonaffective vs affective psychosis. Further study of the association between low availability of the α7-nAChR and recent-onset psychosis is warranted toward informing diagnostic or therapeutic strategies related to these findings.


Assuntos
Hipocampo , Tomografia por Emissão de Pósitrons , Transtornos Psicóticos , Receptor Nicotínico de Acetilcolina alfa7 , Humanos , Receptor Nicotínico de Acetilcolina alfa7/metabolismo , Hipocampo/metabolismo , Hipocampo/diagnóstico por imagem , Masculino , Transtornos Psicóticos/metabolismo , Transtornos Psicóticos/diagnóstico por imagem , Feminino , Estudos Transversais , Tomografia por Emissão de Pósitrons/métodos , Adulto , Adulto Jovem , Estudos de Casos e Controles
17.
Am J Sports Med ; 52(9): 2372-2383, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39101733

RESUMO

BACKGROUND: Early medical attention after concussion may minimize symptom duration and burden; however, many concussions are undiagnosed or have a delay in diagnosis after injury. Many concussion symptoms (eg, headache, dizziness) are not visible, meaning that early identification is often contingent on individuals reporting their injury to medical staff. A fundamental understanding of the types and levels of factors that explain when concussions are reported can help identify promising directions for intervention. PURPOSE: To identify individual and institutional factors that predict immediate (vs delayed) injury reporting. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: This study was a secondary analysis of data from the Concussion Assessment, Research and Education (CARE) Consortium study. The sample included 3213 collegiate athletes and military service academy cadets who were diagnosed with a concussion during the study period. Participants were from 27 civilian institutions and 3 military institutions in the United States. Machine learning techniques were used to build models predicting who would report an injury immediately after a concussive event (measured by an athletic trainer denoting the injury as being reported "immediately" or "at a delay"), including both individual athlete/cadet and institutional characteristics. RESULTS: In the sample as a whole, combining individual factors enabled prediction of reporting immediacy, with mean accuracies between 55.8% and 62.6%, depending on classifier type and sample subset; adding institutional factors improved reporting prediction accuracies by 1 to 6 percentage points. At the individual level, injury-related altered mental status and loss of consciousness were most predictive of immediate reporting, which may be the result of observable signs leading to the injury report being externally mediated. At the institutional level, important attributes included athletic department annual revenue and ratio of athletes to athletic trainers. CONCLUSION: Further study is needed on the pathways through which institutional decisions about resource allocation, including decisions about sports medicine staffing, may contribute to reporting immediacy. More broadly, the relatively low accuracy of the machine learning models tested suggests the importance of continued expansion in how reporting is understood and facilitated.


Assuntos
Traumatismos em Atletas , Concussão Encefálica , Aprendizado de Máquina , Humanos , Concussão Encefálica/diagnóstico , Estudos de Casos e Controles , Masculino , Traumatismos em Atletas/diagnóstico , Feminino , Adulto Jovem , Militares , Adolescente , Estados Unidos , Aceitação pelo Paciente de Cuidados de Saúde , Atletas , Adulto
18.
J Vasc Surg ; 2024 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-39181338

RESUMO

OBJECTIVE: Current literature reports conflicting findings regarding the effect of diabetes mellitus (DM) on outcomes of AAA repair. In this study we examined the effect of DM and its management on outcomes following open (OAR) and endovascular (EVAR) AAA repair. METHODS: We identified all patients undergoing OAR or EVAR for infrarenal AAA between 2003-2018 in the Vascular Quality Initiative (VQI) registry data linked with Medicare claims. We excluded patients with missing DM status. Patients were stratified by their preoperative DM status, and then further stratified by DM management: dietary, non-insulin anti-diabetic medications (NIM), or insulin. Outcomes of interest included one-year aneurysm sac dynamics, 8-year aneurysm rupture, reintervention, and all-cause mortality. These outcomes were analyzed with chi-square, Kaplan-Meier methods, and multivariable cox regression analyses. RESULTS: We identified 34,021 EVAR patients and 4,127 OAR patients of which 20% and 16% had DM, respectively. Of all DM patients, 22% were managed by dietary management, 59% by NIM, and 19% by insulin. Following EVAR, DM patients were more likely to have stable sacs while non-DM patients were more likely to have sac regression at 1 year. Compared with non-DM, DM was associated with a significantly lower risk for 8-year rupture in EVAR (EVAR HR: 0.68 [0.51-0.92]). Compared with non-DM, NIM was associated with lower risk of rupture within 8-years for both EVAR and OAR (EVAR HR: 0.64 [0.44-0.94]; OAR HR: 0.29 [0.41-0.80]), while dietary and insulin had similar rupture risk compared with non-DM. However, compared with non-DM, DM was associated with higher risk of 8-year all-cause mortality following EVAR and OAR (DM vs. non-DM: EVAR HR: 1.17 [1.11-1.23]; OAR HR: 1.16 [1.00-1.36]). Following further DM management sub-stratification, compared with non-DM, management with NIM and insulin were associated with higher 8-year mortality in EVAR and OAR (EVAR: NIM HR: 1.12 [1.05-1.20] & insulin HR: 1.40 [1.26-1.55]; OAR: NIM HR: 1.27 [1.06-1.54] & insulin HR: 1.57 [1.15-2.13]). Finally, there was a similar risk of reintervention across the DM and non-DM populations in EVAR and OAR. CONCLUSION: DM was associated with lower adjusted risk of rupture following EVAR as well as OAR in patients managed with NIM. Nevertheless, just as in patients without AAA, preoperative DM was associated with a higher adjusted risk of all-cause mortality. Further study is needed to evaluate for differences in aneurysm-related mortality between DM and non-DM, and studies are planned to evaluate the independent effect of NIM on aneurysm-related outcomes.

19.
Cell ; 2024 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-39094570

RESUMO

Faithful transfer of parental histones to newly replicated daughter DNA strands is critical for inheritance of epigenetic states. Although replication proteins that facilitate parental histone transfer have been identified, how intact histone H3-H4 tetramers travel from the front to the back of the replication fork remains unknown. Here, we use AlphaFold-Multimer structural predictions combined with biochemical and genetic approaches to identify the Mrc1/CLASPIN subunit of the replisome as a histone chaperone. Mrc1 contains a conserved histone-binding domain that forms a brace around the H3-H4 tetramer mimicking nucleosomal DNA and H2A-H2B histones, is required for heterochromatin inheritance, and promotes parental histone recycling during replication. We further identify binding sites for the FACT histone chaperone in Swi1/TIMELESS and DNA polymerase α that are required for heterochromatin inheritance. We propose that Mrc1, in concert with FACT acting as a mobile co-chaperone, coordinates the distribution of parental histones to newly replicated DNA.

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