A5021229789- Cellular Mechanics and Interactions
- Cell Adhesion Molecules Research
- RNA Interference and Gene Delivery
- Force Microscopy Techniques and Applications
- MicroRNA in disease regulation
- Advanced biosensing and bioanalysis techniques
- RNA modifications and cancer
- RNA Research and Splicing
- DNA and Nucleic Acid Chemistry
- Genomics and Chromatin Dynamics
- DNA Repair Mechanisms
- RNA regulation and disease
- Advanced Fluorescence Microscopy Techniques
- Genetics and Neurodevelopmental Disorders
- Cytomegalovirus and herpesvirus research
- Virus-based gene therapy research
- Semantic Web and Ontologies
- Immunotherapy and Immune Responses
- Integrated Circuits and Semiconductor Failure Analysis
- Cognitive Computing and Networks
- Protein Tyrosine Phosphatases
- VLSI and Analog Circuit Testing
- Molecular Junctions and Nanostructures
- S100 Proteins and Annexins
- Neonatal Respiratory Health Research
Johns Hopkins University
2018-2024
Seoul National University
2012-2024
Boston Children's Hospital
2024
Harvard University
2024
Johns Hopkins Medicine
2020-2021
University of Baltimore
2019
Astronomy and Space
2015
Creative Research
2015
Initiatives (Denmark)
2015
Cells connect with their environment through surface receptors and use physical tension in receptor-ligand bonds for various cellular processes. Single-molecule techniques have revealed bond strength by measuring "rupture force," but it has long been recognized that rupture force is dependent on loading rate-how quickly ramped up. Thus, the physiological rate needs to be measured reveal mechanical of individual functional context. We developed an overstretching sensor (OTS) allow more...
The viral sensor MDA5 distinguishes between cellular and dsRNAs by length-dependent recognition in the range of ∼0.5–7 kb. ability to discriminate dsRNA length at this scale sets apart from other receptors immune system. We have shown previously that forms filaments along disassemble upon ATP hydrolysis. Here, we demonstrate filament formation alone is insufficient explain its specificity, because intrinsic affinity for depends only moderately on length. Instead, uses a combination end...
Integrins link the extracellular environment to actin cytoskeleton in cell migration and adhesiveness. Rapid coordination between events outside inside is essential. Single-molecule fluorescence dynamics show that ligand binding bent-closed integrin conformation, which predominates on surfaces, followed within milliseconds by two concerted changes, leg extension headpiece opening, give high-affinity conformation. The extended-closed conformation not an intermediate but can be directly...
Nucleosomal histone H2A is exchanged for its variant H2A.Z by the SWR1 chromatin remodeler, but mechanism and timing of exchange remain unclear. Here, we quantify DNA dynamics during in real time using a three-color single-molecule FRET assay. We show that operates with timed precision to unwrap large displacement from one face nucleosome, remove H2A-H2B same face, rewrap DNA, all within 2.3 s. This productive unwrapping requires full activation differs unproductive, smaller-scale caused...
Although Argonaute (AGO) proteins have been the focus of microRNA (miRNA) studies, we observed AGO-free mature miRNAs directly interacting with RNA-binding proteins, implying sophisticated nature fine-tuning gene regulation by miRNAs. To investigate microRNA-binding (miRBPs) globally, analyzed PAR-CLIP data sets to identify RBP quaking (QKI) as a novel miRBP for let-7b. Potential existence were further verified measuring miRNA levels in genetically engineered AGO-depleted human and mouse...
Abstract Although integrins are known to be mechanosensitive and possess many subtypes that have distinct physiological roles, single molecule studies of force exertion thus far been limited RGD-binding integrins. Here, we show integrin α4β1 (αVβ1 α5β1) require markedly different tension thresholds support cell spreading. Furthermore, actin assembled downstream forms cross-linked networks in circularly spread cells, is rapid retrograde flow, exerts low forces from polymerization. In...
Eukaryotic gene expression is tightly regulated post-transcriptionally by RNA-binding proteins (RBPs) and microRNAs. The RBP AU-rich-binding factor 1 (AUF1) isoform p37 was found to have high affinity for the microRNA let-7b in vitro ( K d = ∼6 nM) cells. Ribonucleoprotein immunoprecipitation, association, single-molecule-binding analyses revealed that AUF1 promoted loading onto Argonaute 2 (AGO2), catalytic component of RNA-induced silencing complex (RISC). In turn, AGO2–let-7 triggered...
Eukaryotic mRNA decay is tightly modulated by RNA-binding proteins (RBPs) and microRNAs (miRNAs). RBP AU-binding factor 1 (AUF1) has four isoforms resulting from alternative splicing critical for miRNA-mediated gene silencing with a distinct preference of target miRNAs. Previously, we have shown that AUF1 facilitates miRNA loading to Argonaute 2 (AGO2), the catalytic component RNA-induced complex. Here, further demonstrate depletion abolishes global interaction miRNAs AGO2. Single-molecule...
Cells must respond specifically and dynamically to mechanical cues from the extracellular environment dysregulation of force sensing leads a variety diseases. Therefore, it is important deconvolve many inputs that transduce signals understand how these are interpreted responded to. DNA peptide-based molecular sensors have been previously developed measure forces applied through single membrane receptors including integrins Notch receptors. The tension gauge tether (TGT) exploits physical...
Significance Cas9 complexed with a programmable guide RNA has been repurposed for genome-engineering applications. Mechanistic understanding of Cas9-mediated DNA cleavage provides opportunities rational engineering to improve its efficiency and specificity. Domain movements have well studied before but not after. In this study, we observed the HNH nuclease domain motions from binding post-DNA in real time using single-molecule fluorescence techniques. The coupling between activity...
Mechanical response to external stimuli is a conserved feature of many cell types. For example, neurotransmitters (e.g., histamine) trigger calcium signals that induce actomyosin-regulated contraction airway smooth muscle (ASM); the resulting shortening causes narrowing, excess which can cause asthma. Despite intensive studies, however, it remains unclear how physical forces are propagated through focal adhesion (FA)—the major force-transmission machinery cell—during ASM shortening. We...
In eukaryotes, small RNAs play important roles in both gene regulation and resistance to viral infection. Argonaute proteins have been identified as a key component of the effector complexes various RNA-silencing pathways, but mechanistic these pathways are not clearly understood. To address this question, we performed single-molecule fluorescence experiments using an RNA-induced silencing complex (core-RISC) composed RNA human 2. We found that target binding core-RISC starts at seed region...
Abstract A library of Trp‐containing amphiphilic peptides was synthesized and screened for the ability to bind pre‐miRNA targets. Two members this family, Ac‐WKKLLKWLKKLLKLAG‐NH 2 ( b ) Ac‐WKKLLKWLKKLLDabLAG‐NH 4 were found have nanomolar binding affinities pre‐let7a‐1. Peptides caused an increase in vitro Dicer cleavage This observation confirmed by a cell‐based assay, results which show up 50 % activity. Enhanced expression let7a‐1 promoted specific reductions target mRNAs. The microarray...
On arrested neutrophils a focal adhesive cluster of ~200 high affinity (HA) β2-integrin bonds under tension is sufficient to trigger Ca2+ flux that signals an increase in activation direct proportion increments shear stress. We reasoned threshold acting on individual provides mechanical means transducing the magnitude fluid drag force into enhance efficiency neutrophil recruitment and effector function. Tension gauge tethers (TGT) are duplex DNA nucleotides rupture at precise force, which...
Abstract Nucleosomal histone H2A is exchanged for its variant H2A.Z by the SWR1 chromatin remodeler, but mechanism and timing of exchange remain unclear. Here, we quantify DNA dynamics during in real-time using a three-color single-molecule FRET assay. We show that operates with timed precision to unwrap large displacement from one face nucleosome, remove H2A-H2B same face, rewrap DNA, all within 2.3 seconds. Such productive unwrapping requires full activation differs unproductive,...
Abstract Review: 48 refs.