Biology subjects

Goel, V. Y.

Publications and source records attributed to Goel, V. Y..

4 recordsLinked to original sources

bioRxiv2024

Dynamics of microcompartment formation at the mitosis-to-G1 transition

As cells exit mitosis and enter G1, mitotic chromosomes decompact and transcription is reestablished. Previously, Hi-C studies showed that essentially all interphase 3D genome features including A/B-compartments, TADs, and CTCF loops, are lost during mitosis. However, Hi-C remains insensitive to features such as microcompartments, nested focal interactions between cis-regulatory elements (CREs). We therefore applied Region Capture Micro-C to cells from mitosis to G1. Unexpectedly, we observe microcompartments in prometaphase, which further strengthen in ana/telophase before gradually weakening in G1. Loss of loop extrusion through condensin depletion differentially impacts microcompartments and large A/B-compartments, suggesting that they are partially distinct. Using polymer modeling, we show that microcompartment formation is favored by chromatin compaction and disfavored by loop extrusion activity, explaining why ana/telophase likely provides a particularly favorable environment. Our results suggest that CREs exhibit intrinsic homotypic affinity leading to microcompartment formation, which may explain transient transcriptional spiking observed upon mitotic exit.

biophysics↗

bioRxiv2024

LDB1 establishes multi-enhancer networks to regulate gene expression

How specific enhancer-promoter pairing is established is still mostly unclear. Besides the CTCF/cohesin machinery, only a few nuclear factors have been studied for a direct role in physically connecting regulatory elements. Here, we show via acute degradation experiments that LDB1 directly and broadly promotes enhancer-promoter loops. Most LDB1-mediated contacts, even those spanning hundreds of kb, can form in the absence of CTCF, cohesin, or YY1 as determined via the use of multiple degron systems. Moreover, an engineered LDB1-driven chromatin loop is cohesin independent. Cohesin-driven loop extrusion does not stall at LDB1 occupied sites but may aid the formation of a subset of LDB1 anchored loops. Leveraging the dynamic reorganization of nuclear architecture during the transition from mitosis to G1-phase, we establish a relationship between LDB1-dependent interactions in the context of TAD organization and gene activation. Lastly, Tri-C and Region Capture Micro-C reveal that LDB1 organizes multi-enhancer networks to activate transcription. This establishes LDB1 as a direct driver of regulatory network inter-connectivity.

molecular biology↗

bioRxiv2023

Integrative PTEN Enhancer Discovery Reveals a New Model of Enhancer Organization

Enhancers possess both structural elements mediating promoter looping and functional elements mediating gene expression. Traditional models of enhancer-mediated gene regulation imply genomic overlap or immediate adjacency of these elements. We test this model by combining densely-tiled CRISPRa screening with nucleosome-resolution Region Capture Micro-C topology analysis. Using this integrated approach, we comprehensively define the cis-regulatory landscape for the tumor suppressor PTEN, identifying and validating 10 distinct enhancers and defining their 3D spatial organization. Unexpectedly, we identify several long-range functional enhancers whose promoter proximity is facilitated by chromatin loop anchors several kilobases away, and demonstrate that accounting for this spatial separation improves the computational prediction of validated enhancers. Thus, we propose a new model of enhancer organization incorporating spatial separation of essential functional and structural components.

genomics↗

bioRxiv2022

Region Capture Micro-C reveals coalescence of enhancers and promoters into nested microcompartments

Although enhancers are central to the regulation of mammalian gene expression, the mechanisms underlying Enhancer-Promoter (E-P) interactions remain unclear. Chromosome conformation capture (3C) methods effectively capture large-scale 3D genome structure but struggle to achieve the depth necessary to resolve fine-scale E-P interactions. Here, we develop Region Capture Micro-C (RCMC) by combining MNase-based 3C with a tiling region-capture approach and generate the deepest 3D genome maps reported thus far with only modest sequencing. By applying RCMC in mouse embryonic stem cells and reaching the genome-wide equivalent of [~]200 billion unique contacts, RCMC reveals previously unresolvable patterns of highly nested and focal 3D interactions, which we term microcompartments. Microcompartments frequently connect enhancers and promoters and are largely robust to loss of loop extrusion and inhibition of transcription. We therefore propose that many E-P interactions form through a compartmentalization mechanism, which may explain why acute cohesin depletion only modestly affects global gene expression.

genomics↗