Project description:DNA-Diffusion is a novel generative approach leveraging diffusion probabilistic models for the design of cell type-specific DNA regulatory sequences. To evaluate the capacity of DNA-Diffusion sequences to endogenously alter AXIN2 transcription, we employed a novel MPRA-like system that utilizes CRE-recombinase mediated cassette exchange and long-read sequencing to measure the gene’s transcriptional output in response to enhancer sequences several kilobases away. We evaluated a total of 100 sequences using the AXIN2 endogenous replacement experiment using the following sequence groups: GM12878 DNA-Diffusion, GM12878 Positive Controls, GM12878 Negative Controls, K562 DNA-Diffusion, HepG2 DNA-Diffusion, and shuffled GM12878 DNA-Diffusion. Our findings demonstrate the potential of DNA-Diffusion to design sequences with therapeutic potential, showing their effectiveness in an endogenous setting.
Project description:DNA-Diffusion is a novel generative approach leveraging diffusion probabilistic models for the design of cell type-specific DNA regulatory sequences. To evaluate the capacity of DNA-Diffusion sequences to endogenously alter AXIN2 transcription, we employed a novel MPRA-like system that utilizes CRE-recombinase mediated cassette exchange and long-read sequencing to measure the gene’s transcriptional output in response to enhancer sequences several kilobases away. We evaluated a total of 100 sequences using the AXIN2 endogenous replacement experiment using the following sequence groups: GM12878 DNA-Diffusion, GM12878 Positive Controls, GM12878 Negative Controls, K562 DNA-Diffusion, HepG2 DNA-Diffusion, and shuffled GM12878 DNA-Diffusion. Our findings demonstrate the potential of DNA-Diffusion to design sequences with therapeutic potential, showing their effectiveness in an endogenous setting.
Project description:DNA-Diffusion is a novel generative approach leveraging diffusion probabilistic models for the design of cell type-specific DNA regulatory sequences. To evaluate the capacity of DNA-Diffusion sequences to endogenously alter AXIN2 transcription, we employed a novel MPRA-like system that utilizes CRE-recombinase mediated cassette exchange and long-read sequencing to measure the gene’s transcriptional output in response to enhancer sequences several kilobases away. We evaluated a total of 100 sequences using the AXIN2 endogenous replacement experiment using the following sequence groups: GM12878 DNA-Diffusion, GM12878 Positive Controls, GM12878 Negative Controls, K562 DNA-Diffusion, HepG2 DNA-Diffusion, and shuffled GM12878 DNA-Diffusion. Our findings demonstrate the potential of DNA-Diffusion to design sequences with therapeutic potential, showing their effectiveness in an endogenous setting.
Project description:To test how DNA-Diffusion sequences can induce transcription, we select 2150 sequences, including DNA-Diffusion synthetic and natural occurring DHS sites for each cell type (K562, HepG2, and GM12878) and insert them into STARR-Seq plasmids (N= 6450 sequences). all synthetic and naturally occurring sequences were combined into a single library, and this same library was experimentally tested using STARR-Seq in different cell lines (K562, HepG2, GM12878).
Project description:RNA-Sequencing is a transformative method that captures the quantitative dynamics of a transcriptome with exquisite sensitivity and single-base resolution. There are, however, few computational pipelines for RNA-Seq with statistical tests that evince sufficient robustness and power as demanded by the difficult combination of small sample sizes and high variability in sequence read counts. To this end, we developed GENE-counter, a complete software pipeline for analyzing RNA-Seq data for genome-wide expression differences between replicated treatment groups. One important component of GENE-counter is a statistical test based on the NBP parameterization of the negative binomial distribution for identifying differentially expressed genome features. We used GENE-counter to analyze RNA-Seq data derived from Arabidopsis thaliana infected with a strain of defense-eliciting bacteria. We identified 308 genes that were differentially induced. Using alternative methods, we provided support for the induced expression and biological relevance of a substantial proportion of the genes. These results suggest the NBP parameterization of the negative binomial distribution is well suited for explaining RNA-Seq data and the statistical test makes GENE-counter a powerful pipeline for studying genome-wide expression changes. GENE-counter is freely available at http://changlab.cgrb.oregonstate.edu/. Our RNA-seq data is uploaded on the NCBI short read archive (SRA) under the SRA025952.
Project description:Microfluidic devices provide a low-input and efficient platform for single-cell RNA-seq (scRNA-Seq). Here we present microfluidic diffusion-based RNA-seq (MID-RNA-seq) for conducting scRNA-seq with a diffusion-based reagent swapping scheme. This device incorporates cell trapping, lysis, reverse transcription and PCR amplification all in one microfluidic chamber. MID-RNA-Seq provides high data quality that is comparable to existing scRNA-seq methods while implementing a simple device design that permits multiplexing. The robustness and scalability of MID-RNA-Seq device will be important for transcriptomic studies of scarce cell samples.
Project description:Dynamic genome folding is important for V(D)J recombination at the immunoglobulin kappa (Igk) locus, which recombines Jk and Vk gene segments across a 3.2 Mb region in both deletional and inversional orientations. Chromatin loop extrusion and diffusion are considered two key mechanisms underlying Igk folding, but how they coordinate remains unclear. Here we show that CTCF is a key regulator coupling loop extrusion and diffusion during Igk V-J rearrangement, promoting recombination in both orientations across long genomic distances. Mechanistically, the CTCF N-terminus promotes long-range loop extrusion that facilitates distal Vk usage by stabilizing cohesin against WAPL release, and also forms loop barriers enabling chromatin diffusion for inversional Vk joining. In CTCF N-terminal-deficient B cells, defects in inversional Vk joining are not restored by WAPL depletion but are instead largely rescued by a dCas9-blockade targeted to the Vk-Jk intergenic region, mimicking the CTCF barrier. Our findings thus highlight how CTCF coordinates distinct genome-folding mechanisms through its dual roles in cohesin stabilization and extrusion barrier formation to ensure the generation of a diverse Igk repertoire.
Project description:Here we reveal a biophysical basis for the spreading behavior of Xist RNA on the inactive X-chromosome (Xi). Xist and HNRNPK together drive a liquid-liquid phase separation (LLPS) that encapsulates the Xi. HNRNPK and Xist exert mutual pulling forces that lead to RNA internalization into the condensate. While HNRNPK is sufficient for condensate formation, Xist induces a further phase transition into a "soft" droplet by altering elasticity, adhesiveness, and wetting properties of the condensate in vitro. Once phase transition occurs, other Xist-interacting factors are internalized and concentrated within the condensate. We attribute LLPS to HNRNPK's RGG and Xist's Repeat B (RepB) motifs. Mutating these motifs causes Xist diffusion, disrupts Polycomb recruitment, and precludes the required mixing of Xi chromatin for establishing the Xi superstructure. Thus, phase transitions driven by RepB and HNRNPK create a membrane-less subnuclear compartment for the localization and limited diffusion of Xist ribonucleoprotein complexes on the Xi.