Biology subjects

Parker, K. R.

Publications and source records attributed to Parker, K. R..

3 recordsLinked to original sources

bioRxiv2018

Atlas of Subcellular RNA Localization Revealed by APEX-seq

We introduce APEX-seq, a method for RNA sequencing based on spatial proximity to the peroxidase enzyme APEX2. APEX-seq in nine distinct subcellular locales produced a nanometer-resolution spatial map of the human transcriptome, revealing extensive and exquisite patterns of localization for diverse RNA classes and transcript isoforms. We uncover a radial organization of the nuclear transcriptome, which is gated at the inner surface of the nuclear pore for cytoplasmic export of processed transcripts. We identify two distinct pathways of messenger RNA localization to mitochondria, each associated with specific sets of transcripts for building complementary macromolecular machines within the organelle. APEX-seq should be widely applicable to many systems, enabling comprehensive investigations of the spatial transcriptome.

cell biology↗

bioRxiv2018

Coupled single-cell CRISPR screening and epigenomic profiling reveals causal gene regulatory networks

Here we present Perturb-ATAC, a method which combines multiplexed CRISPR interference or knockout with genome-wide chromatin accessibility profiling in single cells, based on the simultaneous detection of CRISPR guide RNAs and open chromatin sites by assay of transposase-accessible chromatin with sequencing (ATAC-seq). We applied Perturb-ATAC to transcription factors (TFs), chromatin-modifying factors, and noncoding RNAs (ncRNAs) in [~]4,300 single cells, encompassing more than 63 unique genotype-phenotype relationships. Perturb-ATAC in human B lymphocytes uncovered regulators of chromatin accessibility, TF occupancy, and nucleosome positioning, and identified a hierarchical organization of TFs that govern B cell state, variation, and disease-associated cis-regulatory elements. Perturb-ATAC in primary human epidermal cells revealed three sequential modules of cis-elements that specify keratinocyte fate, orchestrated by the TFs JUNB, KLF4, ZNF750, CEBPA, and EHF. Combinatorial deletion of all pairs of these TFs uncovered their epistatic relationships and highlighted genomic co-localization as a basis for synergistic interactions. Thus, Perturb-ATAC is a powerful and general strategy to dissect gene regulatory networks in development and disease.\n\nHighlightsO_LIA new method for simultaneous measurement of CRISPR perturbations and chromatin state in single cells.\nC_LIO_LIPerturb-ATAC reveals regulatory factors that control cis-element accessibility, trans-factor occupancy, and nucleosome positioning.\nC_LIO_LIPerturb-ATAC reveals regulatory modules of coordinated trans-factor activity in B lymphoblasts.\nC_LIO_LIKeratinocyte differentiation is orchestrated by synergistic activities of co-binding TFs on cis-elements.\nC_LI

genomics↗

bioRxiv2017

ciRS-7 exonic sequence is embedded in a long-noncoding RNA locus

ciRS-7 is an intensely studied, highly expressed and conserved circRNA. Essentially nothing is known about its biogenesis, including the location of its promoter. A prevailing assumption has been that ciRS-7 is an exceptional circRNA because it is transcribed from a locus lacking any mature linear RNA transcripts of the same sense. Our interest in the biogenesis of ciRS-7 led us to develop an algorithm to define its promoter. This approach predicted that the human ciRS-7 promoter coincides with that of the long non-coding RNA, LINC00632. We validated this prediction using multiple orthogonal experimental assays. We also used computational approaches and experimental validation to establish that ciRS-7 exonic sequence is embedded in linear transcripts that are flanked by cryptic exons in both human and mouse. Together, this experimental and computational evidence generate a new view of regulation in this locus: (a) ciRS-7 is like other circRNAs, as it is spliced into linear transcripts; (b) expression of ciRS-7 is primarily determined by the chromatin state of LINC00632 promoters; (c) transcription and splicing factors sufficient for ciRS-7 biogenesis are expressed in cells that lack detectable ciRS-7 expression. These findings have significant implications for the study of the regulation and function of ciRS-7, and the analytic framework we developed to jointly analyze RNA-seq and ChlP-seq data reveal the potential for genome-wide discovery of important biological regulation missed in current reference annotations.\n\nAuthor SummarycircRNAs were recently discovered to be a significant product of host gene expression programs but little is known about their transcriptional regulation. Here, we have studied the expression of a well-known circRNA named ciRS-7. ciRS-7 has an unusual function for a circRNA; it is believed to be a miRNA sponge. Previously, ciRS-7 was thought to be transcribed from a locus lacking any mature linear isoforms, unlike all other circular RNAs known to be expressed in human cells. However, we have found this to be false; using a combination of bioinformatic and experimental genetic approaches, in both human and mouse, we discovered that linear transcripts containing the ciRS-7 exonic sequence, linking it to upstream genes. This suggests the potential for additional functional roles of this important locus and provides critical information to begin study on the biogenesis of ciRS-7.

genetics↗