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Enzyme-free DNA amplifiers can amplify the signal of nucleic acid molecules. They can be applied to DNA molecular operation and nucleic acid detection. The reaction speed is the core index to evaluate DNA amplifiers. In this study, we designed a DNA amplifier based on an enzyme-free chain reaction. This DNA amplifier can release one more signal molecule in each round of reaction and trigger the next round, which significantly improved reaction speed. Moreover, because the amplifier used a stable DNA structure, the reaction can occur at room temperature. To integrate the amplifier into other DNA molecular operations, we performed the amplification reaction in a microfluidic chip module. The results showed that the amplifier can realize real-time signal feedback at a proper input molecule concentration and reach the endpoint in 40 s, even at a low relative concentration. To apply the amplifier for nucleic acid detection, we also used a conventional fluorescent polymerase chain reaction instrument for the reaction. The results showed that the amplifier specifically detected trace DNA single-stranded molecules. To solve the leakage problem of existing amplifiers, we designed a DNA molecule as the chain reaction's inhibitor, which was crucial in controlling the reaction speed and preventing leakage. STATEMENT OF SIGNIFICANCE: Traditional amplifier strategies of enzyme-free DNA amplifiers relied on a constant number of cycling molecules to catalyze the amplifier molecules' changing structure and release fluorescent signals, which lead low reaction speed. Based on an enzyme-free chain reaction, we designed a DNA amplifier which can release one more cycling molecule in each loop and trigger the next loop and significantly improve reaction speed in this study. Our analysis on microfluidic chip module and PCR instrument verifies high sensitivity and selectivity. And this strategy of DNA amplifier realizes the control of reaction and prevents leakage. We believe that this automated amplification strategy could have great applications in vivo signal detection, imaging, and signal molecule translation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known computing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The underlying mechanism(s) by which the PML::RARA fusion protein initiates acute promyelocytic leukemia is not yet clear. We defined the genomic binding sites of PML::RARA in primary mouse and human hematopoietic progenitor cells with V5- tagged PML::RARA, using anti- V5- PML::RARA chromatin immunoprecipitation sequencing and CUT&RUN approaches. Most genomic PML::RARA binding sites were found in regions that were already chromatin- accessible (defined by ATAC- seq) in unmanipulated, wild- type promyelocytes, suggesting that these regions are -open- prior to PML::RARA expression. We found that GATA binding motifs, and the direct binding of the chromatin -pioneering factor- GATA2, were significantly enriched near PML::RARA binding sites. Proximity labeling studies revealed that PML::RARA interacts with -250 proteins in primary mouse hematopoietic cells; GATA2 and 33 others require PML::RARA binding to DNA for the interaction to occur, suggesting that binding to their cognate DNA target motifs may stabilize their interactions. In the absence of PML::RARA, Gata2 overexpression induces many of the same epigenetic and transcriptional changes as PML::RARA. These findings suggested that PML::RARA may indirectly initiate its transcriptional program by activating Gata2 expression: Indeed, we demonstrated that inactivation of Gata2 prior to PML::RARA expression prevented its ability to induce self- renewal. These data suggested that GATA2 binding creates accessible chromatin regions enriched for both GATA and Retinoic Acid Receptor Element motifs, where GATA2 and PML::RARA can potentially bind and interact with each other. In turn, PML::RARA binding to DNA promotes a feed- forward transcriptional program by positively regulating Gata2 expression. Gata2 may therefore be required for PML::RARA to establish its transcriptional program. [ABSTRACT FROM AUTHOR]