Interrogating Matrix Stiffness and Metabolomics in Pancreatic Ductal Carcinoma Using an Openable Microfluidic Tumor-on-a-Chip.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a dense fibrotic stroma that contributes to aggressive tumor biology and therapeutic resistance. Current in vitro PDAC models lack sufficient optical and physical access for fibrous network visualization, in situ mechanical stiffness measurement, and metabolomic profiling. Here, we describe an openable multilayer microfluidic PDAC-on-a-chip platform that consists of pancreatic tumor cells (PTCs) and pancreatic stellate cells (PSCs) embedded in a 3D collagen matrix that mimics the stroma.

Asymmetric drug binding in an ATP-loaded inward-facing state of an ABC transporter.

Substrate efflux by ATP-binding cassette (ABC) transporters, which play a major role in multidrug resistance, entails the ATP-powered interconversion between transporter intermediates. Despite recent progress in structure elucidation, a number of intermediates have yet to be visualized and mechanistically interpreted. Here, we combine cryogenic-electron microscopy (cryo-EM), double electron-electron resonance spectroscopy and molecular dynamics simulations to profile a previously unobserved intermediate of BmrCD, a heterodimeric multidrug ABC exporter from Bacillus subtilis.

TANDEM: biomicrofluidic systems with transverse and normal diffusional environments for multidirectional signaling.

Biomicrofluidic systems that can recapitulate complex biological processes with precisely controlled 3D geometries are a significant advancement from traditional 2D cultures. To this point, these systems have largely been limited to either laterally adjacent channels in a single plane or vertically stacked single-channel arrangements. As a result, lateral (or transverse) and vertical (or normal) diffusion have been isolated to their respective designs only, thus limiting potential access to nutrients and 3D communication that typifies microenvironments.

Interaction of yeast Rad51 and Rad52 relieves Rad52-mediated inhibition of de novo telomere addition.

DNA double-strand breaks (DSBs) are toxic forms of DNA damage that must be repaired to maintain genome integrity. Telomerase can act upon a DSB to create a de novo telomere, a process that interferes with normal repair and creates terminal deletions. We previously identified sequences in Saccharomyces cerevisiae (SiRTAs; Sites of Repair-associated Telomere Addition) that undergo unusually high frequencies of de novo telomere addition, even when the original chromosome break is several kilobases distal to the eventual site of telomerase action.

Integrated electrochemical measurement of endothelial permeability in a 3D hydrogel-based microfluidic vascular model.

Mimicking the physiological or pathophysiological barrier function of endothelial and epithelial cells is an essential consideration in organ-on-a-chip models of numerous tissues including the vascular system, lungs, gut and blood-brain barrier. Recent models have furthermore incorporated 3D extracellular matrix hydrogels to recapitulate the composition and cell-matrix interactions found in the native microenvironment. Assessment of barrier function in these 3D organ-on-a-chip models, however, is typically limited to diffusive permeability measurements that are exclusively fluorescence-based.

Amyloid-β(1-42) protofibrils stimulate a quantum of secreted IL-1β despite significant intracellular IL-1β accumulation in microglia.

Neuroinflammation is a characteristic feature of the Alzheimer's disease (AD) brain. Significant inflammatory markers such as activated microglia and cytokines can be found surrounding the extracellular senile plaques predominantly composed of amyloid-β protein (Aβ). Several innate immune pathways, including Toll-like receptors (TLRs) and the NLRP3 inflammasome, have been implicated in AD inflammation.

YycH and YycI interact to regulate the essential YycFG two-component system in Bacillus subtilis.

The YycFG two-component system is the only signal transduction system in Bacillus subtilis known to be essential for cell viability. This system is highly conserved in low-G+C gram-positive bacteria, regulating important processes such as cell wall homeostasis, cell membrane integrity, and cell division. Four other genes, yycHIJK, are organized within the same operon with yycF and yycG in B.

The crystal structure of Bacillus subtilis YycI reveals a common fold for two members of an unusual class of sensor histidine kinase regulatory proteins.

YycI and YycH are two membrane-anchored periplasmic proteins that regulate the essential Bacillus subtilis YycG histidine kinase through direct interaction. Here we present the crystal structure of YycI at a 2.9-A resolution.

The crystal structure of YycH involved in the regulation of the essential YycFG two-component system in Bacillus subtilis reveals a novel tertiary structure.

The Bacillus subtilis YycFG two-component signal transduction system is essential for cell viability, and the YycH protein is part of the regulatory circuit that controls its activity. The crystal structure of YycH was solved by two-wavelength selenium anomalous dispersion data, and was refined using 2.3 A data to an R-factor of 25.

Two-dimensional diversity: screening human cDNA phage display libraries with a random diversity probe for the display cloning of phosphotyrosine binding domains.

A random phosphopeptide probe (bio-pYZZZ) has been used for the isolation and identification of multiple SH2 domains from human cDNA-displaying phage libraries. In addition, on-phage analysis and quantification of binding affinities for these phage-displayed proteins has shown them to be functional domains, retaining the same characteristics as in their native state.