@article {717, title = {Developmental heterogeneity in DNA packaging patterns influences T-cell activation and transmigration.}, journal = {PLoS One}, volume = {7}, year = {2012}, month = {2012}, pages = {e43718}, abstract = {

Cellular differentiation programs are accompanied by large-scale changes in nuclear organization and gene expression. In this context, accompanying transitions in chromatin assembly that facilitates changes in gene expression and cell behavior in a developmental system are poorly understood. Here, we address this gap and map structural changes in chromatin organization during murine T-cell development, to describe an unusual heterogeneity in chromatin organization and associated functional correlates in T-cell lineage. Confocal imaging of DNA assembly in cells isolated from bone marrow, thymus and spleen reveal the emergence of heterogeneous patterns in DNA organization in mature T-cells following their exit from the thymus. The central DNA pattern dominated in immature precursor cells in the thymus whereas both central and peripheral DNA patterns were observed in na{\"\i}ve and memory cells in circulation. Na{\"\i}ve T-cells with central DNA patterns exhibited higher mechanical pliability in response to compressive loads in vitro and transmigration assays in vivo, and demonstrated accelerated expression of activation-induced marker CD69. T-cell activation was characterized by marked redistribution of DNA assembly to a central DNA pattern and increased nuclear size. Notably, heterogeneity in DNA patterns recovered in cells induced into quiescence in culture, suggesting an internal regulatory mechanism for chromatin reorganization. Taken together, our results uncover an important component of plasticity in nuclear organization, reflected in chromatin assembly, during T-cell development, differentiation and transmigration.

}, keywords = {Animals, Antigens, CD, Antigens, Differentiation, T-Lymphocyte, Bone Marrow Cells, Cell Lineage, Cell Movement, Cell Nucleus, Chromatin, DNA, Hematopoietic Stem Cells, Lectins, C-Type, Lymphocyte Activation, Mice, Microscopy, Confocal, Models, Biological, Models, Statistical, Sequence Analysis, DNA, Spleen, T-Lymphocytes}, issn = {1932-6203}, doi = {10.1371/journal.pone.0043718}, author = {Gupta, Soumya and Marcel, Nimi and Talwar, Shefali and Garg, Megha and R, Indulaxmi and Perumalsamy, Lakshmi R and Sarin, Apurva and Shivashankar, G V} } @article {715, title = {Dynamic imaging of homo-FRET in live cells by fluorescence anisotropy microscopy.}, journal = {Methods Enzymol}, volume = {505}, year = {2012}, month = {2012}, pages = {291-327}, abstract = {

Multiple lipid and protein components of the plasma membrane of a living cell are organized, both compositionally and functionally, at different spatial and temporal scales. For instance, Rab protein domains in membranes the clathrin-coated pit, or the immunological synapse are exquisite examples of functional compartmentalization in cell membranes. These assemblies consist in part of nanoscale complexes of lipids and proteins and are necessary to facilitate some specific sorting and signaling functions. It is evident that cellular functions require a regulated spatiotemporal organization of components at the nanoscale, often comprising of countable number of molecular species. Here, we describe multiple homo-FRET-based imaging methods that provide information about nanoscale interactions between fluorescently tagged molecules in live cells, at optically resolved spatial resolution.

}, keywords = {Animals, Cell Membrane, Cell Tracking, Drosophila, Fluorescence Polarization, Fluorescence Resonance Energy Transfer, Green Fluorescent Proteins, Image Processing, Computer-Assisted, Lipid Metabolism, Microscopy, Confocal, Microscopy, Fluorescence}, issn = {1557-7988}, doi = {10.1016/B978-0-12-388448-0.00024-3}, author = {Ghosh, Subhasri and Saha, Suvrajit and Goswami, Debanjan and Bilgrami, Sameera and Mayor, Satyajit} }