SummaryMicroRNA-1 (miR-1) is preferentially expressed in cardiac muscles, and the expression has been demonstrated to be involved in cardiac development and cardiovascular diseases. Here we report that miR-1 is closely related with ischemia/reperfusion injury in a rat model. The level of miR-1 is inversely correlated with Bcl-2 protein expression in cardiomyocytes of the I/R rat model. In vitro, the level of miR-1 was dramatically increased in response to H2O2. Overexpression of miR-1 facilitated H2O2-induced apoptosis in cardiomyocytes. Inhibition of miR-1 by antisense inhibitory oligonucleotides caused marked resistance to H2O2. Through bioinformatics, we identified the potential target sites for miR-1 on the 3' UTR of Bcl-2. miR-1 significantly reduced the expression of Bcl-2 in the levels of mRNA and protein. The post-transcriptional repression of Bcl-2 was further confirmed by luciferase reporter experiments. These data demonstrated that miR-1 plays an important role in the regulation of cardiomyocyte apoptosis, which is involved in posttranscriptional repression of

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The assembly of the preinitiation complex (PIC) occurs upstream of the +1 nucleosome which, in yeast, obstructs the transcription start site and is frequently assembled with the histone variant H2A.Z. To understand the contribution of the transcription machinery in the disassembly of the +1 H2A.Z nucleosome, conditional mutants were used to block PIC assembly. A quantitative ChIP-seq approach, which allows detection of global occupancy change, was employed to measure H2A.Z occupancy. Blocking PIC assembly resulted in promoter-specific H2A.Z accumulation, indicating that the PIC is required to evict H2A.Z. By contrast, H2A.Z eviction was unaffected upon depletion of INO80, a remodeler previously reported to displace nucleosomal H2A.Z. Robust PIC-dependent H2A.Z eviction was observed at active and infrequently transcribed genes, indicating that constitutive H2A.Z turnover is a general phenomenon. Finally, sites with strong H2A.Z turnover precisely mark transcript starts, providing a new metric for identifying cryptic and alternative sites of initiation.DOI: http://dx.doi.org/10.7554/eLife.14243.001