30 research outputs found
Macrophage Activation and Differentiation Signals Regulate Schlafen-4 Gene Expression: Evidence for Schlafen-4 as a Modulator of Myelopoiesis
Background: The ten mouse and six human members of the Schlafen (Slfn) gene family all contain an AAA domain. Little is known of their function, but previous studies suggest roles in immune cell development. In this report, we assessed Slfn regulation and function in macrophages, which are key cellular regulators of innate immunity
Establishing the situated features associated with perceived stress
We propose that the domain general process of categorization contributes to the perception
of stress. When a situation contains features associated with stressful experiences, it is
categorized as stressful. From the perspective of situated cognition, the features used to
categorize experiences as stressful are the features typically true of stressful situations. To
test this hypothesis, we asked participants to evaluate the perceived stress of 572 imagined
situations, and to also evaluate each situation for how much it possessed 19 features
potentially associated with stressful situations and their processing (e.g., self-threat,
familiarity, visual imagery, outcome certainty). Following variable reduction through
factor analysis, a core set of 8 features associated with stressful situations—expectation
violation, self-threat, coping efficacy, bodily experience, arousal, negative valence, positive
valence, and perseveration—all loaded on a single Core Stress Features factor. In a
multilevel model, this factor and an Imagery factor explained 88% of the variance in
judgments of perceived stress, with significant random effects reflecting differences in how
individual participants categorized stress. These results support the hypothesis that people
categorize situations as stressful to the extent that typical features of stressful situations are
present. To our knowledge, this is the first attempt to establish a comprehensive set of
features that predicts perceived stress
Direct Observation of Downhill Folding of λ-Repressor in a Microfluidic Mixer
The protein λ6-85 has been implicated in barrierless folding by observations of kinetic relaxation after nanosecond T-jump. In this work we observed folding of this protein after dilution of a high denaturant in an ultrarapid microfluidic mixer at temperatures far below the thermal midpoint. The observations of total intensity and spectral shift of tryptophan fluorescence yielded distinctly different kinetics and activation energies. These results may be explained as diffusion on a low-barrier, one-dimensional, free-energy surface, with different probes having different sensitivities along the reaction coordinate. Additionally, we observed an extremely fast phase within the mixing time that was not observed by T-jump, suggesting that the ensemble of unfolded states populated at high denaturant is distinct from those accessible at high temperature
Plasmacytoid dendritic cell heterogeneity is defined by CXCL10 expression following TLR7 stimulation
Plasmacytoid dendritic cells (pDCs) play a critical role in bridging the innate and adaptive immune systems. pDCs are specialized type I interferon (IFN) producers, which has implicated them as initiators of autoimmune pathogenesis. However, little is known about the downstream effectors of type I IFN signaling that amplify autoimmune responses. Here, we have used a chemokine reporter mouse to determine the CXCR3 ligand responses in DCs subsets. Following TLR7 stimulation, conventional type 1 and type 2 DCs (cDC1 and cDC2, respectively) uniformly upregulate CXCL10. By contrast, the proportion of chemokine positive pDCs was significantly less, and stable CXCL10(+) and CXCL10(-) populations could be distinguished. CXCL9 expression was induced in all cDC1s, in half of the cDC2 but not by pDCs. The requirement for IFNAR signaling for chemokine reporter expression was interrogated by receptor blocking and deficiency and shown to be critical for CXCR3 ligand expression in Flt3-ligand-derived DCs. Chemokine-producing potential was not concordant with the previously identified markers of pDC heterogeneity. Finally, we show that CXCL10(+) and CXCL10(-) populations are transcriptionally distinct, expressing unique transcriptional regulators, IFN signaling molecules, chemokines, cytokines, and cell surface markers. This work highlights CXCL10 as a downstream effector of type I IFN signaling and suggests a division of labor in pDCs subtypes that likely impacts their function as effectors of viral responses and as drivers of inflammation
Protein Hydrophobic Collapse and Early Folding Steps Observed in a Microfluidic Mixer
We demonstrate that the sub-millisecond protein folding process referred to as “collapse” actually consists of at least two separate processes. We observe the UV fluorescence spectrum from naturally occurring tryptophans in three well-studied proteins, cytochrome c, apomyoglobin, and lysozyme, as a function of time in a microfluidic mixer with a dead time of ∼20 μs. Single value decomposition of the time-dependent spectra reveal two separate processes: 1), a spectral shift which occurs within the mixing time; and 2), a fluorescence decay occurring between ∼100 and 300 μs. We attribute the first process to hydrophobic collapse and the second process to the formation of the first native tertiary contacts