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Hair cells, the mechanosensory receptors of the inner ear, are responsible for hearing and balance. Hair cell death and consequent hearing loss are common results of treatment with ototoxic drugs, including the widely used aminoglycoside antibiotics. Induction of heat shock proteins (HSPs) confers protection against aminoglycoside-induced hair cell death via paracrine signaling that requires extracellular heat shock 70-kDa protein (HSP70). We investigated the mechanisms underlying this non-cell-autonomous protective signaling in the inner ear. In response to heat stress, inner ear tissue releases exosomes that carry HSP70 in addition to canonical exosome markers and other proteins. Isolated exosomes from heat-shocked utricles were sufficient to improve survival of hair cells exposed to the aminoglycoside antibiotic neomycin, whereas inhibition or depletion of exosomes from the extracellular environment abolished the protective effect of heat shock. Hair cell-specific expression of the known HSP70 receptor TLR4 was required for the protective effect of exosomes, and exosomal HSP70 interacted with TLR4 on hair cells. Our results indicate that exosomes are a previously undescribed mechanism of intercellular communication in the inner ear that can mediate nonautonomous hair cell survival. Exosomes may hold potential as nanocarriers for delivery of therapeutics against hearing loss., Introduction Disabling hearing loss affects approximately 6.1% of the global population (1). Most hearing loss is due to death of sensory hair cells of the inner ear. These mechanosensitive receptor [...]

Hepatitis B virus (HBV) remains a major public health threat with nearly 300 million people chronically infected worldwide who are at a high risk of developing hepatocellular carcinoma. Current therapies are effective in suppressing HBV replication but rarely lead to cure. Current therapies do not affect the HBV covalently closed circular DNA (cccDNA), which serves as the template for viral transcription and replication and is highly stable in infected cells to ensure viral persistence. In this study, we aim to identify and elucidate the functional role of cccDNA-associated host factors using affinity purification and protein mass spectrometry in HBV-infected cells. Nucleolin was identified as a key cccDNA-binding protein and shown to play an important role in HBV cccDNA transcription, likely via epigenetic regulation. Targeting nucleolin to silence cccDNA transcription in infected hepatocytes may be a promising therapeutic strategy for a functional cure of HBV. [ABSTRACT FROM AUTHOR]

The transcription factor NF-κB is required for lymphocyte activation and proliferation as well as the survival of certain lymphoma types (1,2). Antigen receptor stimulation assembles an NF-κB activating platform containing the scaffold protein CARMA1 (also called CARD11), the adaptor BCL10 and the paracaspase MALT1 (the CBM complex), linked to the inhibitor of NF-κB kinase complex (3-12), but signal transduction is not fully understood (1). We conducted parallel screens involving a mass spectrometry analysis of CARMA1 binding partners and an RNA interference screen for growth inhibition of the CBM-dependent 'activated B-cell-like' (ABC) subtype of diffuse large B-cell lymphoma (DLBCL)(12). Here we report that both screens identified casein kinase lα (CK1α) as a bifunctional regulator of NF-κB. CK1 α dynamically associates with the CBM complex on T-cell-receptor (TCR) engagement to participate in cytokine production and lymphocyte proliferation. However, CK1α kinase activity has a contrasting role by subsequently promoting the phosphorylation and inactivation of CARMA1. CK1α has thus a dual 'gating' function which first promotes and then terminates receptor-induced NF--κB. ABC DLBCL cells required CK1α for constitutive NF-κB activity, indicating that CK1α functions as a conditionally essential malignancy gene--a member of a new class of potential cancer therapeutic targets., For a better understanding of signal regulation by the CBM complex, we performed a mass spectrometry proteomic screen after CARMA1 immunoprecipitation. Sixteen peptides covering 54% of the length of CK1α [...]

The effects of the uniform incorporation of the unnatural amino acid 2-fluorohistidine (2-FHis) on the structure of anthrax protective antigen (PA) moiety to form a heptameric pore in the endosomal membrane is reported.

One member of each of 52 pairs of friends told true and fabricated stories to a partner (the judge) who guessed whether each story was true. This procedure was followed when the friends had known each other for 1 month and again 5 months later. Across all of the pairs, accuracy at detecting deception did not improve over time. However, judges from the emotionally closer pairs did become more accurate at 6 months than they had been at 1 month. The judges from the less-close pairs instead became less inclined to regard the stories as truthful, especially when they actually were truthful. Results of a second study ruled out the alternative interpretation that the closer friends told stories that were more obviously truthful or deceptive at 6 months than they had at 1 month. On indirect measures of deception detection, all of the groups of judges could distinguish the truths from the lies.

Many novel signal transduction domains are being identified in the wake of genome sequencing projects and improved sensitivity in homology-detection techniques. The functions of these domains are being discovered by hypothesis-driven experiments and structural genomics approaches. This article reviews the recent highlights of research on modular signaling domains, and the relative contributions and limitations of the various approaches being used.

Research was conducted to examine the properties and folding pathway of the alpha-lytic protease (LP) precursor. A structural model for the precursor where the pro region is fully folded while the alpha-LP depends on folded pro region for its structure is proposed. Once it is folded, the protease region cleaves the precursor to create the significantly more stable Pro/alpha-LP complex.

The soil bacterium Lysobacter enzymogenes secrets the 198-residue chymotrypsin-like serine protease, alpha-lytic protease (alpha-LP), which is encoded with a 166-residue amino acid N-terminal pro region that is needed for the production of active protease. A new study investigates how alpha-LP is folded by its pro region and examines the different interactions between the pro region and the protease domain occurring during the folding reaction. It is shown that such pro region C-terminal/active site interactions are crucial in catalyzing protease folding.

Bacteroides fragilis toxin (BFT) is a protein secreted by enterotoxigenic (ETBF) strains of B. fragilis. BFT is synthesized as a proprotein (proBFT) that is predicted to be a lipoprotein and that is cleaved into two discrete fragments by a clostripain‐like protease called fragipain (Fpn). In this study, we obtained evidence that Fpn cleaves proBFT following its transport across the outer membrane. Remarkably, we also found that the disruption of the fpn gene led to a strong reduction in the level of >100 other proteins, many of which are predicted to be lipoproteins, in the culture medium of an ETBF strain. Experiments performed with purified Fpn provided direct evidence that the protease releases at least some of these proteins from the cell surface. The observation that wild‐type cells outcompeted an fpn‐ strain in co‐cultivation assays also supported the notion that Fpn plays an important role in cell physiology and is not simply dedicated to toxin biogenesis. Finally, we found that purified Fpn altered the adhesive properties of HT29 intestinal epithelial cells. Our results suggest that Fpn is a broad‐spectrum protease that not only catalyzes the protein secretion on a wide scale but that also potentially cleaves host cell proteins during colonization. [ABSTRACT FROM AUTHOR]

The solid-state nuclear magnetic resonance (NMR) measurements are employed to study the characterization and molecular structure of yeast prion fibrils with Ure2p protein. The [beta]-sheets present in these fibrils are shown to consist only of intermolecular hydrogen bonds.

Quantitative characterization of the in vitro interactions among 14-3-3, the Forkhead transcription factor FOXO4 and its target DNA, the insulin response element, are discussed. It is demonstrated that in the presence of 14-3-3, two phosphorylated 14-3-3 binding motifs are needed for the complete inhibition of FOXO4 binding to its target DNA.

EDTA-derivatized deoxythymidine is presented as a tool for rapid determination of protein binding polarity to DNA by intermolecular paramagnetic relaxation. The method is evaluated and it is found that it has widespread utility in structural and chemical studies of protein-DNA complexes.

Previous studies show that close friends improve at lie detection over time. However, is this improvement due to an increase in the ability to decode the feelings of close friends or a change in how close friends communicate their true and deceptive emotions? In a study of 45 pairs of friends, one friend from each pair (the "sender") was videotaped showing truthful and faked affect in response to pleasant and unpleasant movie clips. The other friend from each pair (the "judge") guessed the true emotions of both the friend and a stranger 1 month and 6 months into the friendship. Judges were better at guessing the true emotions of friends than strangers, and this advantage in judging friends increased among close friends over time. Surprisingly, improvement over time was due mostly to a change in the sender's communication, rather than an increase in judges' ability to decode their friends' feelings. [ABSTRACT FROM AUTHOR]

The transcription factor NF-κB is required for lymphocyte activation and proliferation as well as the survival of certain lymphoma types. Antigen receptor stimulation assembles an NF-κB activating platform containing the scaffold protein CARMA1 (also called CARD11), the adaptor BCL10 and the paracaspase MALT1 (the CBM complex), linked to the inhibitor of NF-κB kinase complex, but signal transduction is not fully understood. We conducted parallel screens involving a mass spectrometry analysis of CARMA1 binding partners and an RNA interference screen for growth inhibition of the CBM-dependent ‘activated B-cell-like’ (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). Here we report that both screens identified casein kinase 1α (CK1α) as a bifunctional regulator of NF-κB. CK1α dynamically associates with the CBM complex on T-cell-receptor (TCR) engagement to participate in cytokine production and lymphocyte proliferation. However, CK1α kinase activity has a contrasting role by subsequently promoting the phosphorylation and inactivation of CARMA1. CK1α has thus a dual ‘gating’ function which first promotes and then terminates receptor-induced NF-κB. ABC DLBCL cells required CK1α for constitutive NF-κB activity, indicating that CK1α functions as a conditionally essential malignancy gene—a member of a new class of potential cancer therapeutic targets. [ABSTRACT FROM AUTHOR]