Biology subjects

Schadt, E.

Publications and source records attributed to Schadt, E..

5 recordsLinked to original sources

bioRxiv2018

Biology and Bias in Cell Type-Specific RNAseq of Nucleus Accumbens Medium Spiny Neurons

Isolation of cell populations is untangling complex biological interactions, but studies comparing methodologies lack in vivo complexity and draw limited conclusions about the types of transcripts identified by each technique. Furthermore, few studies compare FACS-based techniques to ribosomal affinity purification, and none do so genome-wide. We addressed this gap by systematically comparing nuclear-FACS, whole cell-FACS, and RiboTag affinity purification in the context of D1 or D2 dopamine receptor-expressing medium spiny neuron (MSN) subtypes of the nucleus accumbens (NAc), a key brain reward region. We find that nuclear-FACS-seq generates a substantially longer list of differentially expressed genes between these cell types, and a significantly larger number of neuropsychiatric GWAS hits than the other two methods. RiboTag-seq has much lower coverage of the transcriptome than the other methods, but very efficiently distinguishes D1- and D2-MSNs. We also demonstrate differences between D1- and D2-MSNs with respect to RNA localization, suggesting fundamental cell type differences in mechanisms of transcriptional regulation and subcellular transport of RNAs. Together, these findings guide the field in selecting the RNAseq method that best suits the scientific questions under investigation.

neuroscience↗

bioRxiv2018

A novel approach of human geroprotector discovery by targeting the converging subnetworks of aging and age-related diseases

A key goal of geroscience research is to discover effective interventions to extend human healthspan, the years of healthy life. Currently, majority of the geroprotectors are found by testing compounds in model organisms; whether these compounds will be effective in humans is largely unknown. Here we present a novel strategy called ANDRU (aging network based drug discovery) to help the discovery of human geroprotectors. Instead of relying on model organisms, this approach is driven by human genomic and pharmacogenomic data. It first identifies human aging subnetworks that putatively function at the interface between aging and age-related diseases; it then screens for pharmacological or genetic interventions that may \"reverse\" the age-associated transcriptional changes seen in these subnetworks. We applied ANDRU to human adipose and artery tissues. In adipose tissue, PTPN1, a target for diabetes treatment and APOE, a known genetic factor for human longevity and diseases like Alzheimers disease, were ranked at the top. For small molecules, conjugated linoleic acid and metformin, a drug commonly used to treat type 2 diabetes, were ranked among the top compounds. In artery tissue, N-methyl-D-aspartate antagonists and curcumin were ranked at the top. In summary, ANDRU represents a promising human data-driven strategy that may speed up the discovery of interventions to extend human healthspan.

systems biology↗

bioRxiv2018

B cell defects observed in Nod2 knockout mice are a consequence of a Dock2 mutation frequently found in inbred strains

Phenotypic differences among substrains of laboratory mice due to spontaneous mutations or pre-existing genetic variation confound the interpretation of targeted mutagenesis experiments, and contribute to challenges with reproducibility across institutions. Notably, C57BL/6NHsd mice and gene-targeted mice that have been backcrossed to this substrain have been reported to harbor a duplication in exons 28 and 29 of Dock2. Here, we demonstrate the presence of this Dock2 variant in the widely used Nod2-/- mice. NOD2 is a cytosolic innate immune receptor that has been the subject of intense investigation due to its association with inflammatory bowel disease (IBD) susceptibility. Consistent with a role of NOD2 in an immunological disorder, Nod2-/- mice bred at our institution displayed multiple B cell defects including deficiencies in recirculating B cells, marginal zone B cells and B1a cells. However, we found that these effects are due to the Dock2 variant and are independent of Nod2 deletion. Despite originating from the same gene-targeted founder mice, Nod2-/- mice from another source did not harbor the Dock2 variant or B cell defects. Finally, we show that Dock2-/- mice display the same B cell defects as mice harboring the Dock2 variant, confirming that the variant is a loss-of-function mutation and is sufficient to explain the alterations to the B cell compartment observed in Nod2-/- mice. Our findings highlight the effects of confounding mutations from widely-used inbred strains on gene-targeted mice and reveal new functions of DOCK2 in B cells.

immunology↗

bioRxiv2017

STAR Chimeric Post For Rapid Detection Of Circular RNA And Fusion Transcripts

MotivationThe biological relevance of chimeric RNA alignments is now well established. Chimera arising as chromosomal fusions are often drivers of cancer, and recently discovered circular RNA are only now being characterized. While software already exists for fusion discovery and quantitation, high false positive rates and high run-times hamper scalable fusion discovery on large datasets. Furthermore, very little software is available for circular RNA detection and quantification.\n\nResultsHere we present STAR Chimeric Post (STARChip), a novel software package that processes chimeric alignments from the STAR aligner and produces annotated circular RNA and high precision fusions in a rapid, efficient, and scalable manner that is appropriate for high dimensional medical omics datasets.\n\nAvailability and ImplementationSTARChip is available at https://github.com/LosicLab/STARChip\n\nContactsbojan.losic@mssm.edu or nicholas.kipp.akers@gmail.com\n\nSupplementary InformationSupplementary figures and tables are available online.

bioinformatics↗

bioRxiv2016

Human pancreatic β cell lncRNAs control cell-specific regulatory networks

Recent studies have uncovered thousands of long non-coding RNAs (IncRNAs) in human pancreatic {beta} cells. {beta} cell lncRNAs are often cell type-specific, and exhibit dynamic regulation during differentiation or upon changing glucose concentrations. Although these features hint at a role of lncRNAs in {beta} cell gene regulation and diabetes, the function of {beta} cell lncRNAs remains largely unknown. In this study, we investigated the function of {beta} cell-specific lncRNAs and transcription factors using transcript knockdowns and co-expression network analysis. This revealed lncRNAs that function in concert with transcription factors to regulate {beta} cell-specific transcriptional networks. We further demonstrate that lncRNA PLUTO affects local three-dimensional chromatin structure and transcription of PDX1, encoding a key {beta} cell transcription factor, and that both PLUTO and PDX1 are downregulated in islets from donors with type 2 diabetes or impaired glucose tolerance. These results implicate lncRNAs in the regulation of {beta} cell-specific transcription factor networks.

genomics↗