Project description:Histone variant H2A.Z is a critical player in setting up the chromatin environment that mediates transcription and other activities on chromatin. However, how H2A.Z is incorporated to specific chromatin regions is not clear. To examine the potential role of sequence-specific transcription factors in targeting H2A.Z, we screened for genome-wide H2A.Z-interacting proteins in vivo using a novel technique called bait Protein-Protein Interaction-sequencing (bPPI-seq). Among the hundreds of H2A.Z-interacting proteins identified by bPPI-seq, we show that a zinc-finger transcription factor, Osr1 interacts with H2A.Z both in vitro and in vivo and co-localizes with H2A.Z on chromatin. Knockdown of Osr1 compromised H2A.Z deposition to hundreds of chromatin sites enriched with Osr1 binding motifs. Furthermore, Osr1 and H2A.Z co-regulate the expression of numerous target genes. These results indicate that Osr1 directly interacts with H2A.Z, mediates its incorporation to a large number of target sites and regulates gene expression. Our data indicate that bPPI-seq can be widely applied to identify unbiasedly interacting proteins under physiologic conditions.
Project description:In this study, pull down assays combined with mass spectrometry analysis were performed in AC16 cardiomyocytes transfected with control plasmid (OE-Vector) or LOC107984012-overexpression plasmid to identify the repertoire of LOC107984012 interacting proteins. Pierce™ Magnetic RNA-Protein Pull-Down Kit (Thermo Fisher) provides reagents to efficiently enrich RNA Binding Proteins. Sense or antisense of LOC107984012 were in vitro transcription using the T7 RNA transcription system (Large Scale RNA ProductionSystem-T7, Promega) and biotin-labeled with the Pierce™ RNA 3’ End Desthiobiotinylation Kit (Thermo Scientific). RNA was then purified with QIAquick PCR Purification Kit (Qiagen). 30 μg of whole-cell protein lysates were incubated with purified biotinylated transcripts for 1 h at 4°C with rotation, then they were eluted for mass spectrometry identification.
Project description:In this study, pull down assays combined with mass spectrometry analysis were performed in HL-1 cardiomyocytes transfected with control plasmid (OE-Vector) or LOC107984012-overexpression plasmid to identify the repertoire of LOC107984012 interacting proteins.
Project description:Mutations or decreased expression of RNA-binding proteins (RBPs) can lead to cardiomyopathies in humans. Here we defined RBPs in healthy and diseased primary cardiomyocytes at a system-wide level by RNA Interactome Capture. This identified 67 novel cardiomyocyte specific RBPs including several contractile proteins. Furthermore, we identified Cytoplasmic polyadenylation element binding protein 4 (Cpeb4) as a dynamic RBP in diseased cardiomyocytes, regulating cardiac growth both in vitro and in vivo. To study Cpeb4 in cardiomyocytes, we identified mRNAs bound to and regulated by Cpeb4. Cpeb4 regulates cardiac remodeling by differential expression of transcription factors. Among Cpeb4 target mRNAs, two Zinc finger transcription factors (Zeb1 and Zbtb20) were identified. We show that Cpeb4 regulates the translation of these mRNAs and that Cpeb4 depletion increases their expression. Thus, Cpeb4 emerges as critical regulator of cardiomyocyte function by differential binding of specific mRNAs in response to pathological growth stimulation.