The TLK-ASF1 histone chaperone pathway plays a critical role in IL-1ß-mediated AML progression.

ABSTRACT: Identifying and targeting microenvironment-driven pathways that are active across acute myeloid leukemia (AML) genetic subtypes should allow the development of more broadly effective therapies. The proinflammatory cytokine interleukin-1ß (IL-1ß) is abundant in the AML microenvironment and promotes leukemic growth. Through RNA-sequencing analysis, we identify that IL-1ß-upregulated ASF1B (antisilencing function-1B), a histone chaperone, in AML progenitors compared with healthy progenitors. ASF1B, along with its paralogous protein ASF1A, recruits H3-H4 histones onto the replication fork during S-phase, a process regulated by Tousled-like kinase 1 and 2 (TLKs). Although ASF1s and TLKs are known to be overexpressed in multiple solid tumors and associated with poor prognosis, their functional roles in hematopoiesis and inflammation-driven leukemia remain unexplored. In this study, we identify that ASF1s and TLKs are overexpressed in multiple genetic subtypes of AML. We demonstrate that depletion of ASF1s significantly reduces leukemic cell growth in both in vitro and in vivo models using human cells. Using a murine model, we show that overexpression of ASF1B accelerates leukemia progression. Moreover, Asf1b or Tlk2 deletion delayed leukemia progression, whereas these proteins are dispensable for normal hematopoiesis. Through proteomics and phosphoproteomics analyses, we uncover that the TLK-ASF1 pathway promotes leukemogenesis by affecting the cell cycle and DNA damage pathways. Collectively, our findings identify the TLK1-ASF1 pathway as a novel mediator of inflammatory signaling and a promising therapeutic target for AML treatment across diverse genetic subtypes. Selective inhibition of this pathway offers potential opportunities to intervene effectively, address intratumoral heterogeneity, and ultimately improve clinical outcomes in AML.

RNAi Suppression of LEAFY Gives Stable Floral Sterility, and Reduced Growth Rate and Leaf Size, in Field-Grown Poplars.

The central floral development gene LEAFY (LFY), whose mutation leads to striking changes in flowering and often sterility, is commonly expressed in non-floral structures; however, its role in vegetative development is poorly understood. Sterility associated with suppression of LFY expression is an attractive means for mitigating gene flow by both seeds and pollen in vegetatively propagated forest trees, but the consequences of its suppression for tree form and wood production are unclear. To study the vegetative effects of RNAi suppression of LFY, we created a randomized, multiple-year field study with 30-40 trees (ramets) in each of two sterile gene insertion events, three transgenic control events, and a wild-type control population. We found that floral knock-down phenotypes were stable across years and propagation cycles, but that several leaf morphology and productivity traits were statistically and often substantially different in sterile vs. normal flowering RNAi-LFY trees. Though trees with suppressed LEAFY expression looked visibly normal, they appear to have reduced growth and altered leaf traits. LFY appears to have a significant role in vegetative meristem development, and evaluation of vegetative impacts from LFY suppression would be prudent prior to large-scale use for genetic containment.

Transient upregulation of PGC-1alpha diminishes cardiac ischemia tolerance via upregulation of ANT1.

Prolonged cardiac overexpression of the mitochondrial biogenesis regulatory transcriptional coactivator PGC-1alpha disrupts cardiac contractile function and its genetic ablation limits cardiac capacity to enhance workload. In contrast, transient induction of PGC-1alpha alleviates neuronal cell oxidative stress and enhances skeletal myotube anti-oxidant defenses. We explored whether transient upregulation of PGC-1alpha in the heart protects against ischemia-reperfusion injury. The transient induction of PGC-1alpha in the cardiac-restricted inducible PGC-1alpha transgenic mouse, increased PGC-1alpha protein levels 5-fold. Following 25 min of ischemia and 2h of reperfusion on a Langendorff perfusion apparatus, contractile recovery and the rate pressure product was significantly blunted in mice overexpressing PGC-1alpha vs. controls. Affymetrix gene array analysis showed a 3-fold PGC-1alpha-mediated upregulation of adenine nucleotide translocase 1 (ANT1). As ANT1 upregulation induces cardiomyocyte cell death we investigated whether the induction of ANT1 by PGC-1alpha contributes to this enhanced ischemia-stress susceptibility. Infection with adenovirus harboring PGC-1alpha into cardiac-derived H9c2 cells significantly upregulates ANT1 without changing basal cell viability. In response to anoxia-reoxygenation injury cell death is significantly increased following PGC-1alpha overexpression. This detrimental effect is abolished following siRNA knockdown of ANT1. Similarly, the attenuation of ANT-1 in the presence of PGC-1alpha overexpression preserves the mitochondrial membrane potential in response to hydrogen-peroxide stress. Interestingly, the isolated knockdown of ANT1 also protects H9c2 cells from anoxia-reoxygenation injury. Taken together these data suggest that transient induction of PGC-1alpha in the murine heart decreases ischemia-reperfusion contractile recovery and diminishes anoxia-reoxygenation tolerance in H9c2 cells. These adverse phenotypes appear to be mediated, in part, by PGC-1alpha induced upregulation of ANT1.

Conduction patterns of idiopathic arrhythmias from the endocardium and epicardium of outflow tracts: New insights with noninvasive electroanatomic mapping.

BACKGROUND: Idiopathic arrhythmias commonly arise from the septal right ventricular outflow tract (RVOT), sinuses of Valsalva (SoV), and great cardiac vein (GCV). Predicting the exact site of origin is important for preparation for catheter ablation. OBJECTIVE: The purpose of this study was to examine the diagnostic value of noninvasive electroanatomic mapping (NIEAM) to differentiate between septal RVOT, SoV, and GCV origin and compare it to that of 12-lead electrocardiography (ECG). METHODS: NIEAM maps (CardioInsight, Medtronic) were generated during spontaneous ventricular premature depolarizations (VPDs) and threshold pacing from septal RVOT, SoV, and GCV. Origin prediction using NIEAM was compared to algorithmic ECG criteria (maximal deflection index; V2 transition ratio) and subjective ECG evaluation. RESULTS: Sixty NIEAMs (18 spontaneous VPDs and 42 pace-maps) from 31 patients (age 56 ± 16 years) were analyzed. NIEAM showed distinct conduction patterns, best visualized at the base of the heart: septal RVOT VPDs propagate toward the tricuspid annulus, depolarizing the septum from inferior to superior; SoV VPDs engage the superior septum early; and GCV VPDs move laterally along the mitral annulus, depolarizing the heart from left to right. Activation of the lateral mitral annulus >60.50 ms and the superior basal septum <22.5 ms from onset predicts RVOT and SoV origin, respectively, in 100% of cases. NIEAM was superior to maximum deflection index in predicting GCV origin (100% vs 42.2% accuracy) and superior to V2 transition ratio in predicting SoV origin (100% vs 75.9% accuracy). CONCLUSION: Arrhythmias arising from the outflow tracts follow distinct propagation patterns depending on the origin. A 2-step algorithm using activation timing by NIEAM yields 100% diagnostic accuracy in predicting origin.