Randall Division of Cell and Molecular Biophysics

About: Randall Division of Cell and Molecular Biophysics is a based out in . It is known for research contribution in the topics: Actin cytoskeleton & Skeletal muscle. The organization has 576 authors who have published 1229 publications receiving 78279 citations.

Immunohistochemical expression of cortactin and focal adhesion kinase predicts recurrence risk and laryngeal cancer risk beyond histologic grading

Abstract: Background: Cortactin (CTTN) and the focal adhesion kinase (FAK) are two major candidate genes to, respectively, drive 11q13- and 8q24-associated aggressive behavior in various cancers. Recent evidence uncovered their clinical relevance in early stages of tumorigenesis as promising biomarkers for cancer risk assessment.Methods: Using a multicenter validation study, CTTN and FAK expression was evaluated by immunohistochemistry (IHC) in a cohort of 109 patients with laryngeal precancerous lesions, and correlated with clinicopathologic parameters and laryngeal cancer risk. The pathophysiologic role of CTTN and FAK was further investigated using functional studies in cellular models.Results: Positive CTTN and FAK expression (scores 2 and 3) was detected in 49 (41%) and 35 (32%) laryngeal dysplasias, respectively. Univariate Cox analysis showed that CTTN and FAK expression but not histologic grading was significantly associated with both recurrence risk and laryngeal cancer risk. Patients carrying strong CTTN- or FAK-expressing lesions (score 3) experienced the highest laryngeal cancer incidence (log-rank P < 0.001). In multivariate stepwise analysis, FAK expression [HR = 13.91; 95% CI, 4.82-40.15; P < 0.001] and alcohol consumption (HR = 2.22; 95% confidence interval, 1.17-4.20; P = 0.014) were significant independent predictors of laryngeal cancer development. Targeting FAK by either RNAi or pharmacologic inhibitors effectively blocked cell growth, colony formation, and invasion into 3D collagen matrices.Conclusions: CTTN and FAK emerge as powerful predictors of laryngeal cancer risk and recurrence risk beyond histologic grading.Impact: Our work supports the applicability of IHC CTTN and FAK as complementary markers for risk stratification in patients with laryngeal precancerous lesions. Cancer Epidemiol Biomarkers Prev; 27(7); 805-13. ©2018 AACR.

Rhinitis with negative skin tests and absent serum allergen-specific IgE: more evidence for local IgE?

Abstract: The phenomenon of local production of IgE in the nasal mucosa is well documented in subjects with allergic rhinitis who have raised serum specific IgE and positive skin prick tests to clinically relevant allergens. Local IgE has also been detected in high levels in nasal polyps in which Staphylococcus-derived enterotoxins are associated with elevated enterotoxin-specific IgE antibodies and likely act as superantigens, thereby promoting increases in polyclonal IgE. Nonallergic rhinitis in the absence of systemic allergen-specific IgE with/without associated eosinophilia affects approximately 25% of patients who experience symptoms of rhinitis. In a subset of this group of heterogeneous disorders, IgE is detectable within the nasal mucosa and/or nasal secretions, implying that an IgE-mediated allergic response may be localized exclusively to the target organ. Huggins and Brostoff originally demonstrated the presence of specific IgE in nasal secretions of patients with rhinitis with negative skin prick tests. A number of studies since have provided further evidence of local allergic rhinitis in such patients. Rondon et al previously reported elevations in allergen-specific IgE in nasal lavage in a proportion of subjects who responded positively to a nasal allergen challenge in the absence of positive skin tests or elevated allergen-specific IgE. In this issue of the Journal, Rondon et al describe the associated local inflammatory response in 30 such patients. The mean age of onset of local allergic rhinitis in the cohort was 31 years, with a female to male bias of 19:11. Nearly half (14/30) of the patients with local allergic rhinitis had asthma, and 57% (17/30) had conjunctivitis. Symptoms were assessed by using a visual analogue scale and nasal patency by acoustic rhinometry at intervals after nasal provocation with grass pollen extract. Tryptase, eosinophilic cationic protein, and grass pollen–specific IgE were measured in nasal lavage. Intranasal challenge resulted in immediate (15 minutes to 1 hour) responses in all subjects and additional late responses (6-24 hours) in 70% of those tested. The proportion of patients with an isolated immediate response was similar to previous studies by the authors. Although the significance of an absent late

Quantification of fibrous spatial point patterns from single-molecule localization microscopy (SMLM) data.

Abstract: Motivation Unlike conventional microscopy which produces pixelated images, SMLM produces data in the form of a list of localization coordinates-a spatial point pattern (SPP). Often, such SPPs are analyzed using cluster analysis algorithms to quantify molecular clustering within, for example, the plasma membrane. While SMLM cluster analysis is now well developed, techniques for analyzing fibrous structures remain poorly explored. Results Here, we demonstrate a statistical methodology, based on Ripley's K-function to quantitatively assess fibrous structures in 2D SMLM datasets. Using simulated data, we present the underlying theory to describe fiber spatial arrangements and show how these descriptions can be quantitatively derived from pointillist datasets. We also demonstrate the techniques on experimental data acquired using the image reconstruction by integrating exchangeable single-molecule localization (IRIS) approach to SMLM, in the context of the fibrous actin meshwork at the T cell immunological synapse, whose structure has been shown to be important for T cell activation. Availability and implementation Freely available on the web at https://github.com/RubyPeters/Angular-Ripleys-K . Implemented in MatLab. Contact dylan.owen@kcl.ac.uk. Supplementary information Supplementary data are available at Bioinformatics online.

Conformation and dynamics of a rhodamine probe attached at two sites on a protein: implications for molecular structure determination in situ.

Abstract: Replica exchange molecular dynamics (REMD) calculations were used to determine the conformation and dynamics of bifunctional rhodamine probes attached to pairs of cysteines in three model systems: (a) a polyalanine helix, (b) the isolated C helix (residues 53-66) of troponin C, and (c) the C helix of the N-terminal region (residues 1-90) of troponin C (sNTnC). In each case, and for both diastereoisomers of each probe-protein complex, the hydrophobic face of the probe is close to the protein surface, and its carboxylate group is highly solvated. The visible-range fluorescence dipole of the probe is approximately parallel to the line joining the two cysteine residues, as assumed in previous in situ fluorescence polarization studies. The independent rotational motion of the probe with respect to the protein on the nanosecond time scale is highly restricted, in agreement with data from fluorescence polarization and NMR relaxation studies. The detailed interaction of the probe with the protein surface depends on steric factors, electrostatic and hydrophobic interactions, hydrogen bonds, and hydration effects. The interaction is markedly different between diastereoisomers, and multiple preferred conformations exist for a single diasteroisomer. These results show that the combination of the hydrophobic xanthylium moiety of bifunctional rhodamine with the carboxylate substitution in its pendant phenyl ring causes the probe to be immobilized on the protein surface, while the two-site cysteine attachment defines the orientation of its fluorescence dipole. These features allow the orientation of protein components to be accurately determined in situ by polarized fluorescence measurements from bifunctional rhodamine probes.

The cryo-EM structure of the bacterial flagellum cap complex suggests a molecular mechanism for filament elongation

Abstract: The bacterial flagellum is a remarkable molecular motor, whose primary function in bacteria is to facilitate motility through the rotation of a filament protruding from the bacterial cell A cap complex, consisting of an oligomer of the protein FliD, is localized at the tip of the flagellum, and is essential for filament assembly, as well as adherence to surfaces in some bacteria However, the structure of the intact cap complex, and the molecular basis for its interaction with the filament, remains elusive Here we report the cryo-EM structure of the Campylobacter jejuni cap complex, which reveals that FliD is pentameric, with the N-terminal region of the protomer forming an extensive set of contacts across several subunits, that contribute to FliD oligomerization We also demonstrate that the native C jejuni flagellum filament is 11-stranded, contrary to a previously published cryo-EM structure, and propose a molecular model for the filament-cap interaction