Spleen Swabs for Sensitive and High-Throughput Detection of African Swine Fever Virus by Real-Time PCR.

African swine fever (ASF) continues to spread in Africa, Europe, Asia and the island of Hispaniola, increasing the need to develop more streamlined and highly efficient surveillance and diagnostic capabilities. One way to achieve this is by further optimization of already established standard operating procedures to remove bottlenecks for high-throughput screening. Real-time polymerase chain reaction (real-time PCR) is the most sensitive and specific assay available for the early detection of the ASF virus (ASFV) genome, but it requires high-quality nucleic acid extracted from the samples. Whole blood from live pigs and spleen tissue from dead pigs are the preferred samples for real-time PCR. Whole blood can be used as is in nucleic acid extractions, but spleen tissues require an additional homogenization step. In this study, we compared the homogenates and swabs prepared from 52 spleen samples collected from pigs experimentally inoculated with highly and moderately virulent ASF virus strains. The results show that not only are the spleen swabs more sensitive when executed with a low-cell-count nucleic acid extraction procedure followed by real-time PCR assays but they also increase the ability to isolate ASFV from positive spleen samples. Swabbing is a convenient, simpler and less time-consuming alternative to tissue homogenization. Hence, we recommend spleen swabs over tissue homogenates for high-throughput detection of ASFV by real-time PCR.

Mtf2-PRC2 control of canonical Wnt signaling is required for definitive erythropoiesis.

Polycomb repressive complex 2 (PRC2) accessory proteins play substoichiometric, tissue-specific roles to recruit PRC2 to specific genomic loci or increase enzymatic activity, while PRC2 core proteins are required for complex stability and global levels of trimethylation of histone 3 at lysine 27 (H3K27me3). Here, we demonstrate a role for the classical PRC2 accessory protein Mtf2/Pcl2 in the hematopoietic system that is more akin to that of a core PRC2 protein. Mtf2-/- erythroid progenitors demonstrate markedly decreased core PRC2 protein levels and a global loss of H3K27me3 at promoter-proximal regions. The resulting de-repression of transcriptional and signaling networks blocks definitive erythroid development, culminating in Mtf2-/- embryos dying by e15.5 due to severe anemia. Gene regulatory network (GRN) analysis demonstrated Mtf2 directly regulates Wnt signaling in erythroblasts, leading to activated canonical Wnt signaling in Mtf2-deficient erythroblasts, while chemical inhibition of canonical Wnt signaling rescued Mtf2-deficient erythroblast differentiation in vitro. Using a combination of in vitro, in vivo and systems analyses, we demonstrate that Mtf2 is a critical epigenetic regulator of Wnt signaling during erythropoiesis and recast the role of polycomb accessory proteins in a tissue-specific context.

Targeting the MTF2-MDM2 Axis Sensitizes Refractory Acute Myeloid Leukemia to Chemotherapy.

Deep sequencing has revealed that epigenetic modifiers are the most mutated genes in acute myeloid leukemia (AML). Thus, elucidating epigenetic dysregulation in AML is crucial to understand disease mechanisms. Here, we demonstrate that metal response element binding transcription factor 2/polycomblike 2 (MTF2/PCL2) plays a fundamental role in the polycomb repressive complex 2 (PRC2) and that its loss elicits an altered epigenetic state underlying refractory AML. Unbiased systems analyses identified the loss of MTF2-PRC2 repression of MDM2 as central to, and therefore a biomarker for, refractory AML. Thus, immature MTF2-deficient CD34+CD38- cells overexpress MDM2, thereby inhibiting p53 that leads to chemoresistance due to defects in cell-cycle regulation and apoptosis. Targeting this dysregulated signaling pathway by MTF2 overexpression or MDM2 inhibitors sensitized refractory patient leukemic cells to induction chemotherapeutics and prevented relapse in AML patient-derived xenograft mice. Therefore, we have uncovered a direct epigenetic mechanism by which MTF2 functions as a tumor suppressor required for AML chemotherapeutic sensitivity and identified a potential therapeutic strategy to treat refractory AML.Significance: MTF2 deficiency predicts refractory AML at diagnosis. MTF2 represses MDM2 in hematopoietic cells and its loss in AML results in chemoresistance. Inhibiting p53 degradation by overexpressing MTF2 in vitro or by using MDM2 inhibitors in vivo sensitizes MTF2-deficient refractory AML cells to a standard induction-chemotherapy regimen. Cancer Discov; 8(11); 1376-89. ©2018 AACR. See related commentary by Duy and Melnick, p. 1348 This article is highlighted in the In This Issue feature, p. 1333.