Differential TCR signaling dynamics tune graded gene expression in early-activating CD8+ T cells

The strength of peptide:MHC interactions with the T cell receptor (TCR) is correlated with the time to first cell division, the relative scale of the effector cell response, and the graded expression of activation-induced proteins. The TCR proximal tyrosine kinase ITK simultaneously influences many biochemically separate signaling cascades. T cells lacking ITK exhibit selective impairments in effector T cell responses after activation, but under the strongest signaling conditions ITK activity is dispensable. To gain insight into whether TCR signal strength and ITK activity tune observed graded gene expression through unequal activation of disparate signaling pathways, I examined NFAT, NF-κB and MAP kinase pathways during early activation of individual naïve OT-I CD8+ T cells using peptide-loaded antigen presenting cells. Utilizing both measurement of transcription factor translocation in single T cell nuclei and conventional phospho-flow cytometry, I observed digital activation of Erk-MAPK and NFAT1 at all peptide doses and avidities. However, NF-κB activation showed a graded response to variation in TCR signal strength and was more sensitive to treatment with an ITK inhibitor. Inhibitor-treated cells showed poor induction of AP-1 factors Fos and Fosb, NF-κB response gene transcripts, and survival factor Il2 transcripts. ATAC-seq analysis revealed genomic regions most sensitive to ITK inhibition are enriched for NF-κB and AP-1 motifs. Together, these data indicate a key role for ITK in orchestrating optimal activation of separate TCR downstream pathways, specifically aiding NF-κB activation. More broadly, I describe a mechanism by which variation in TCR signal strength can produce patterns of graded gene expression in activated T cells

Steady-state crystallization of Rydberg excitations in an optically driven lattice gas

We study resonant optical excitations of atoms in a one-dimensional lattice to the Rydberg states interacting via the van der Waals potential which suppresses simultaneous excitation of neighboring atoms. Considering two- and three-level excitation schemes, we analyze the dynamics and stationary state of the continuously-driven, dissipative many-body system employing time-dependent density-matrix renormalization group (t-DMRG) simulations. We show that two-level atoms can exhibit only nearest neighbor correlations, while three-level atoms under dark-state resonant driving can develop finite-range crystalline order of Rydberg excitations. We present an approximate rate equation model whose analytic solution yields qualitative understanding of the numerical results.Comment: 5 pages,3 figure

Quantum information processing with single photons and atomic ensembles in microwave coplanar waveguide resonators

We show that pairs of atoms optically excited to the Rydberg states can strongly interact with each other via effective long-range dipole-dipole or van der Waals interactions mediated by their non-resonant coupling to a common microwave field mode of a superconducting coplanar waveguide cavity. These cavity mediated interactions can be employed to generate single photons and to realize in a scalable configuration a universal phase gate between pairs of single photon pulses propagating or stored in atomic ensembles in the regime of electromagnetically induced transparency

Peptide Antigen Concentration Modulates Digital NFAT1 Activation in Primary Mouse Naive CD8(+) T Cells as Measured by Flow Cytometry of Isolated Cell Nuclei

Circulating naive T cells exist in a quiescent state. After TCR contact with the cognate peptide presented by APCs in secondary lymphoid structures, T cells undergo a period of rapid transcriptional changes that set the stage for fate-determining effector or memory programming. We describe a novel method to analyze TCR signaling pathway activation in nuclei isolated from primary mouse naive T cells after stimulation with natural peptide Ags. We prelabeled cells with cell tracking dye to easily distinguish CD8(+) T cell nuclei from APC nuclei by conventional flow cytometry. Using this approach, we observed clear digital activation of NFAT1 transcription factor in OT-I T cells stimulated with OVA peptide presented by bulk splenocytes. OVA concentration had discrete control over the fraction of the cells that translocated NFAT1, indicating that a distinct threshold amount of TCR signaling is required to switch on NFAT1 in naive T cells. This behavior was cell contact dependent and qualitatively more exact than the NFAT1 response in ionomycin-stimulated naive T cells. These data contribute to our understanding of the digital behavior of TCR signaling components documented in other studies and indicate how T cells might discriminate log-fold changes in Ag availability during an actual infection. Overall, these results highlight the potential of this coculture nuclei isolation protocol to address stimulation-dependent translocation of proteins in primary lymphocytes

Intramolecular N-H...O, intermolecular O-H...O, C-H...O and Csp³-H...πarene interactions in (2S)-2-{[(2R)-2-hydroxy-2-phenylethanoyl]amino}-4-methylpentanoic acid

The title compound, C₁₄H₁₉NO₄, forms a hydrogenbonded network in the solid state, consisting of one intramolecular N--H...O [N...O 2.569 (3)Å] and two intermolecular O--H...0=C [O...O 2.704(2) and 2.801 (2)Å] hydrogen bonds, with weaker C--H...O [C...O 3.344(3)Å] and Csp³--H...πarene [shortest C...C 3.873 (4)Å] interactions completing the three-dimensional network

Spontaneous Evolution of Rydberg Atoms into an Ultracold Plasma

We have observed the spontaneous evolution of a dense sample of Rydberg atoms into an ultracold plasma, in spite of the fact that each of the atoms may initially be bound by up to 100 cm21. When the atoms are initially bound by 70 cm21, this evolution occurs when most of the atoms are translationally cold, ,1 mK, but a small fraction, 1%, is at room temperature. Ionizing collisions between hot and cold Rydberg atoms and blackbody photoionization produce an essentially stationary cloud of cold ions, which traps electrons produced later. The trapped electrons rapidly collisionally ionize the remaining cold Rydberg atoms to form a cold plasma

Spontaneous Evolution of Rydberg Atoms into an Ultracold Plasma

We have observed the spontaneous evolution of a dense sample of Rydberg atoms into an ultracold plasma, in spite of the fact that each of the atoms may initially be bound by up to 100 cm21. When the atoms are initially bound by 70 cm21, this evolution occurs when most of the atoms are translationally cold, ,1 mK, but a small fraction, 1%, is at room temperature. Ionizing collisions between hot and cold Rydberg atoms and blackbody photoionization produce an essentially stationary cloud of cold ions, which traps electrons produced later. The trapped electrons rapidly collisionally ionize the remaining cold Rydberg atoms to form a cold plasma

Anatomy of Cirrus Clouds: Results from the Emerald Airborne Campaigns

2000 FLORIDA AVE NW, WASHINGTON, USA, DC, 2000