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Biomedical subjects

Oksana Sirenko

Publications and source records attributed to Oksana Sirenko.

4 recordsLinked to original sources

Cell membrane array fabrication and assay technology.

BACKGROUND: Microarray technology has been used extensively over the past 10 years for assessing gene expression, and has facilitated precise genetic profiling of everything from tumors to small molecule drugs. By contrast, arraying cell membranes in a manner which preserves their ability to mediate biochemical processes has been considerably more difficult. RESULTS: In this article, we describe a novel technology for generating cell membrane microarrays for performing high throughput biology. Our robotically-arrayed supported membranes are physiologically fluid, a critical property which differentiates this technology from other previous membrane systems and makes it useful for studying cellular processes on an industrialized scale. Membrane array elements consist of a solid substrate, above which resides a fluid supported lipid bilayer containing biologically-active molecules of interest. Incorporation of transmembrane proteins into the arrayed membranes enables the study of ligand/receptor binding, as well as interactions with live intact cells. The fluidity of these molecules in the planar lipid bilayer facilitates dimerization and other higher order interactions necessary for biological signaling events. In order to demonstrate the utility of our fluid membrane array technology to ligand/receptor studies, we investigated the multivalent binding of the cholera toxin B-subunit (CTB) to the membrane ganglioside GM1. We have also displayed a number of bona fide drug targets, including bacterial endotoxin (also referred to as lipopolysaccharide (LPS)) and membrane proteins important in T cell activation. CONCLUSION: We have demonstrated the applicability of our fluid cell membrane array technology to both academic research applications and industrial drug discovery. Our technology facilitates the study of ligand/receptor interactions and cell-cell signaling, providing rich qualitative and quantitative information.

Animals↗

Lipid mobility and molecular binding in fluid lipid membranes.

The lateral mobility of dilute concentrations of fluorescently labeled lipids doped into supported membranes is found to change upon receptor ligand binding at the membrane surface, even when the lipid is not directly involved in the binding event. Experiments using membrane microarrays are performed that illustrate the use of lipid mobility measurements as an effectively label-free strategy of detecting binding on membrane surfaces.

Animals↗

Method for analyzing signaling networks in complex cellular systems.

Now that the human genome has been sequenced, the challenge of assigning function to human genes has become acute. Existing approaches using microarrays or proteomics frequently generate very large volumes of data not directly related to biological function, making interpretation difficult. Here, we describe a technique for integrative systems biology in which: (i) primary cells are cultured under biologically meaningful conditions; (ii) a limited number of biologically meaningful readouts are measured; and (iii) the results obtained under several different conditions are combined for analysis. Studies of human endothelial cells overexpressing different signaling molecules under multiple inflammatory conditions show that this system can capture a remarkable range of functions by a relatively small number of simple measurements. In particular, measurement of seven different protein levels by ELISA under four different conditions is capable of reconstructing pathway associations of 25 different proteins representing four known signaling pathways, implicating additional participants in the NF-kappaBorRAS/mitogen-activated protein kinase pathways and defining additional interactions between these pathways.

Cells, Cultured↗

IL-1 beta transcript stability in monocytes is linked to cytoskeletal reorganization and the availability of mRNA degradation factors.

Monocyte extravasation initiates reorganization of the cytoskeleton (CSK) and adhesion-dependent cytokine gene transcription. The actin CSK is thought to be crucial for compartmentalization and translation of mRNA, many of which contain AU-rich (ARE) instability motifs in the 3' untranslated region. We investigated regulation of adhesion-induced IL-1 beta expression by the monocyte CSK. In serum-free adherent monocytes, the induced IL-1 beta mRNA was stable and did not coextract with actin filaments. In contrast, in cells adherent in autologous serum, IL-1 beta transcripts were unstable, coextracted with actin filaments and were associated with only transient activation of the mitogen-activated protein kinases (MAPK). Under both conditions of adherence, the ARE-binding protein AUF1/hnRNP D was readily extracted in the cytosolic fraction. Electro-injection with AUF1/hnRNP D modified the actin CSK and, surprisingly, stabilized IL-1 beta transcripts. These data suggest that the control of mRNA degradation is linked with changes in the CSK. Mitogen-activated protein kinase activation or alterations in the availability of mRNA degradation factors may mediate these effects.

Actin Cytoskeleton↗