Project description:Despite the physiological and pathophysiological significance of microenvironmental gradients, tools for generating such gradients and analysing their impact on cellular phenotypes are lacking. Here we present an integrated microfluidics-based workflow for mimicking extracellular pH gradients characteristic of solid tumors, and studying their multifactorial impact on cancer cells. Our microfluidics device generates a pH gradient across cancer cell 3D cultures in an extracellular matrix. The gradient, validated using pH-sensitive fluorophores can be rapidly controlled to represent spatiotemporal microenvironmental changes, and the device allows high resolution live imaging of, e.g., cell motility and chemotaxis. The device can be reopened, allowing immunofluorescence analysis of phenotypes and spatially resolved analysis of gene expression changes across the pH gradient. The workflow is easily adaptable for other gradients and multiple cell types, making it broadly applicable for integrated analysis of roles of microenvironmental gradients in biology.
Project description:Cross-linking Mass Spectrometry (XL-MS) is a powerful tool for examining protein structures and interactions. Nevertheless, anal-ysis of low-abundance cross-linked peptides is often limited in data-dependent acquisition (DDA) mode due to its semistochastic nature. To address this issue, we introduced a workflow called 4D-diaXLMS, representing the first-ever application of four-dimensional data-independent acquisition for proteome-wide cross-linking analysis.
Project description:Despite considerable excitement over the potential functional significance of copy number variants (CNVs), we still lack knowledge of the fine-scale architecture of the large majority of CNV regions in the human genome. In this study, we used a high-resolution array-based comparative genomic hybridization (aCGH) platform that targeted known CNV regions of the human genome at ~1 kb resolution to interrogate the genomic DNAs of 30 individuals from four HapMap populations. Our results revealed that 1,020 of 1,153 CNV loci (88%) were actually smaller in size than what is recorded in the Database of Genomic Variants based on previously published studies. A reduction in size of more than 50% was observed for 876 CNV regions (76%). We conclude that the total genomic content of common human CNVs may be smaller than previously thought. In addition, approximately 8% of the CNV regions observed in multiple individuals exhibited genomic architectural complexity in the form of smaller CNVs within larger ones and CNVs with inter-individual variation in breakpoints. Future association studies that aim to capture the potential influences of CNVs on disease phenotypes will need to consider how to best ascertain this previously underappreciated complexity. The DNA samples are a panel of 30 Hapmap samples, and a female sample NA15510 of undetermined geographic origin, which has been well characterized by fosmid-end sequencing (Tuzun et al. 2005, Nature Genetics 10, p1038). The DNA for this set of 16 female and 15 male samples are all supplied by the Coriell Cell Repository, and is comprised of samples from four populations: 10 unrelated Yoruban, 10 unrelated European-American individuals from Utah (CEPH), 5 unrelated Chinese, and 5 unrelated Japanese. The reference sample, NA10851 is also a male CEPH also from the HapMap Sample set (Corriel Cell Repository). Each of these samples was hybridized in pairs with the reversed labeling polarities. Additionally, 3 self-self control hybridizations were carried out for the reference sample, NA10851, one on each hybridization date. In the Title for each of the samples, each hybridization session is indicated by the letters A, B or C.
Project description:We provide a cross-linking/MS workflow that can be applied to complex systems. The software tool MeroX 2.0 can be used to identify cross-linked peptide on a proteome-wide level. We applied the workflow to extracts of Drosophila embryos and identified 5,129 unique cross-linked residue pairs in biological triplicates.
Project description:Here we describe a cross-linking-aided MS workflow for isolation and identification of signal-dependent membrane protein interactomes using EGFR as an example. Employing formaldehyde as a cross-linking reagent, we performed immuno-precipitation of endogenous EGFR upon EGF treatment, facilitating the capture of weak and transient interactions in the proximity of the receptor, and analyzed the associated proteins by quantitative mass spectrometry.