JAZF1: A metabolic actor subunit of the NuA4/TIP60 chromatin modifying complex.

The multisubunit NuA4/TIP60 complex is a lysine acetyltransferase, chromatin modifying factor and gene co-activator involved in diverse biological processes. The past decade has seen a growing appreciation for its role as a metabolic effector and modulator. However, molecular insights are scarce and often contradictory, underscoring the need for further mechanistic investigation. A particularly exciting route emerged with the recent identification of a novel subunit, JAZF1, which has been extensively linked to metabolic homeostasis. This review summarizes the major findings implicating NuA4/TIP60 in metabolism, especially in light of JAZF1 as part of the complex.

Recurrent chromosomal translocations in sarcomas create a megacomplex that mislocalizes NuA4/TIP60 to Polycomb target loci.

Chromosomal translocations frequently promote carcinogenesis by producing gain-of-function fusion proteins. Recent studies have identified highly recurrent chromosomal translocations in patients with endometrial stromal sarcomas (ESSs) and ossifying fibromyxoid tumors (OFMTs), leading to an in-frame fusion of PHF1 (PCL1) to six different subunits of the NuA4/TIP60 complex. While NuA4/TIP60 is a coactivator that acetylates chromatin and loads the H2A.Z histone variant, PHF1 is part of the Polycomb repressive complex 2 (PRC2) linked to transcriptional repression of key developmental genes through methylation of histone H3 on lysine 27. In this study, we characterize the fusion protein produced by the EPC1-PHF1 translocation. The chimeric protein assembles a megacomplex harboring both NuA4/TIP60 and PRC2 activities and leads to mislocalization of chromatin marks in the genome, in particular over an entire topologically associating domain including part of the HOXD cluster. This is linked to aberrant gene expression-most notably increased expression of PRC2 target genes. Furthermore, we show that JAZF1-implicated with a PRC2 component in the most frequent translocation in ESSs, JAZF1-SUZ12-is a potent transcription activator that physically associates with NuA4/TIP60, its fusion creating outcomes similar to those of EPC1-PHF1 Importantly, the specific increased expression of PRC2 targets/HOX genes was also confirmed with ESS patient samples. Altogether, these results indicate that most chromosomal translocations linked to these sarcomas use the same molecular oncogenic mechanism through a physical merge of NuA4/TIP60 and PRC2 complexes, leading to mislocalization of histone marks and aberrant Polycomb target gene expression.

Rap1 regulates TIP60 function during fate transition between two-cell-like and pluripotent states.

In mammals, the conserved telomere binding protein Rap1 serves a diverse set of nontelomeric functions, including activation of the NF-kB signaling pathway, maintenance of metabolic function in vivo, and transcriptional regulation. Here, we uncover the mechanism by which Rap1 modulates gene expression. Using a separation-of-function allele, we show that Rap1 transcriptional regulation is largely independent of TRF2-mediated binding to telomeres and does not involve direct binding to genomic loci. Instead, Rap1 interacts with the TIP60/p400 complex and modulates its histone acetyltransferase activity. Notably, we show that deletion of Rap1 in mouse embryonic stem cells increases the fraction of two-cell-like cells. Specifically, Rap1 enhances the repressive activity of Tip60/p400 across a subset of two-cell-stage genes, including Zscan4 and the endogenous retrovirus MERVL. Preferential up-regulation of genes proximal to MERVL elements in Rap1-deficient settings implicates these endogenous retroviral elements in the derepression of proximal genes. Altogether, our study reveals an unprecedented link between Rap1 and the TIP60/p400 complex in the regulation of pluripotency.

Antithrombotic Therapy for Patients With Left Ventricular Mural Thrombus.

BACKGROUND: Contemporary data are lacking regarding the prognosis and management of left ventricular thrombus (LVT). OBJECTIVES: The purpose of this study was to quantify the effect of anticoagulation therapy on LVT evolution using sequential imaging and to determine the impact of LVT regression on the incidence of thromboembolism, bleeding, and mortality. METHODS: From January 2011 to January 2018, a comprehensive computerized search of LVT was conducted using 90,065 consecutive echocardiogram reports. Only patients with a confirmed LVT were included after imaging review by 2 independent experts. Major adverse cardiovascular events (MACE), which included death, stroke, myocardial infarction, or acute peripheral artery emboli, were determined as well as major bleeding events (BARC ≥3) and all-cause mortality rates. RESULTS: There were 159 patients with a confirmed LVT. Patients were treated with vitamin K antagonists (48.4%), parenteral heparins (27.7%), and direct oral anticoagulants (22.6%). Antiplatelet therapy was used in 67.9% of the population. A reduction of the LVT area from baseline was observed in 121 patients (76.1%), and total LVT regression occurred in 99 patients (62.3%) within a median time of 103 days (interquartile range: 32 to 392 days). The independent correlates of LVT regression were a nonischemic cardiomyopathy (hazard ratio [HR]: 2.74; 95% confidence interval [CI]: 1.43 to 5.26; p = 0.002) and a smaller baseline thrombus area (HR: 0.66; 95% CI: 0.45 to 0.96; p = 0.031). The frequency of MACE was 37.1%; mortality 18.9%; stroke 13.3%; and major bleeding 13.2% during a median follow-up of 632 days (interquartile range: 187 to 1,126 days). MACE occurred in 35.4% and 40.0% of patients with total LVT regression and those with persistent LVT (p = 0.203). A reduced risk of mortality was observed among patients with total LVT regression (HR: 0.48; 95% CI: 0.23 to 0.98; p = 0.039), whereas an increased major bleeding risk was observed among patients with persistent LVT (9.1% vs. 12%; HR 0.34; 95% CI: 0.14 to 0.82; p = 0.011). A left ventricular ejection fraction ≥35% (HR: 0.46; 95% CI: 0.23 to 0.93; p = 0.029) and anticoagulation therapy >3 months (HR: 0.42; 95% CI: 0.20 to 0.88; p = 0.021) were independently associated with less MACE. CONCLUSIONS: The presence of LVT was associated with a very high risk of MACE and mortality. Total LVT regression, obtained with different anticoagulant regimens, was associated with reduced mortality.

Impact of negative inotropic drugs on accuracy of diastolic stress echocardiography for evaluation of left ventricular filling pressure.

The ratio of early diastolic trans-mitral flow velocity to tissue-Doppler mitral annular early diastolic velocity (E/e'), and left ventricular end-diastolic pressure(LVEDP) have been shown to be correlated at rest, provided that patients are not on positive inotropic drugs. Data concerning the latter correlation during exercise stress are conflicting. Therefore, we investigated if use of negative inotropic drugs (NID), impacts the accuracy of E/e' as a surrogate for LVEDP during low-level exercise. An exercise(50 watts) during cardiac invasive hemodynamic monitoring and an exercise echocardiography were performed prospectively within 24 hours in 54 patients (81%male, 62 ± 9years) with preserved LV Ejection-Fraction. Before exercise, the patients had scattered LVEDP (13.8 ± 5.8 mmHg) and septal E/e' (8.7 ± 2.7). Half of them were on NID, mainly betablockers(n = 26). The correlation between septal-E/e' and LVEDP was low for examinations performed at rest (r = 0.35,p = 0.01) with no significant impact of NID. For measurements performed at 50 Watts, NID had a significant impact on the association between septal-E/e'50 watts and LVEDP50 watts (ß = -0.28,p = 0.03). Correlation between septal-E/e'50 watts and LVEDP50 watts persisted in patients on NID (r = 0.61,p = 0.001) while it disappeared in the group of patients with no NID (r = 0.15,p = 0.47). NID use is an important confounding factor to take into consideration when assessing exercise LVFP using stress E/e' in patients with preserved LVEF.