The rockefeller university

The germinal center (GC) reaction begins with a diverse and expanded group of B cell clones bearing a wide range of antibody affinities. During GC colonization, B cells engage in long-lasting interactions with T follicular helper (Tfh) cells, a process that depends on antigen uptake and antigen presentation to the Tfh cells. How long-lasting T-B interactions and B cell clonal expansion are regulated by antigen presentation remains unclear. Here, we use in vivo B cell competition models and intravital imaging to examine the adhesive mechanisms governing B cell selection for GC colonization. We find that intercellular adhesion molecule 1 (ICAM-1) and ICAM-2 on B cells are essential for long-lasting cognate Tfh-B cell interactions and efficient selection of low-affinity B cell clones for proliferative clonal expansion. Thus, B cell ICAMs promote efficient antibody immune response by enhancement of T cell help to cognate B cells.

The recent approval of oncolytic virus for therapy of melanoma patients has increased the need for precise evaluation of the mechanisms by which oncolytic viruses affect tumor growth. Here we show that the human NK cell-activating receptor NKp46 and the orthologous mouse protein NCR1 recognize the reovirus sigma1 protein in a sialic-acid-dependent manner. We identify sites of NKp46/NCR1 binding to sigma1 and show that sigma1 binding by NKp46/NCR1 leads to NK cell activation in vitro. Finally, we demonstrate that NCR1 activation is essential for reovirus-based therapy in vivo. Collectively, we have identified sigma1 as a novel ligand for NKp46/ NCR1 and demonstrated that NKp46/NCR1 is needed both for clearance of reovirus infection and for reovirus-based tumor therapy. IMPORTANCE Reovirus infects much of the population during childhood, causing mild disease, and hence is considered to be efficiently controlled by the immune system. Reovirus also specifically infects tumor cells, leading to tumor death, and is currently being tested in human clinical trials for cancer therapy. The mechanisms by which our immune system controls reovirus infection and tumor killing are not well understood. We report here that natural killer (NK) cells recognize a viral protein named sigma1 through the NK cell-activating receptor NKp46. Using several mouse tumor models, we demonstrate the importance of NK cells in protection from reovirus infection and in reovirus killing of tumors in vivo. Collectively, we identify a new ligand for the NKp46 receptor and provide evidence for the importance of NKp46 in the control of reovirus infections and in reovirus-based cancer therapy.

Numerous studies have employed repeated social defeat stress (RSDS) to study the neurobiological mechanisms of depression in rodents. An important limitation of RSDS studies to date is that they have been conducted exclusively in male mice due to the difficulty of initiating attack behavior directed toward female mice. Here, we establish a female mouse model of RSDS by inducing male aggression toward females through chemogenetic activation of the ventrolateral subdivision of the ventromedial hypothalamus (VMHvl). We demonstrate that females susceptible to RSDS display social avoidance, anxiety-like behavior, reduction of body weight, and elevated levels of circulating interleukin 6. In contrast, a subset of mice we term resilient only display anxiety-like behaviors after RSDS. This model allows for investigation of sex differences in the neurobiological mechanisms of defeat. induced depression. like behaviors. A robust female social defeat model is a critical first step in the identification and development of novel therapeutic compounds to treat depression and anxiety disorders in women.

Recent approval and marketization of novel treatments have widened the range of therapeutic opportunities for moderate-to-severe psoriasis. In the next years, this panorama will be further enlarged as many other agents, both oral small molecules and biologics, have passed phase III and are expected to be approved, and subsequently marketed, shortly. In spite of this array of therapeutic possibilities, there is still an unmet need for an appropriate treatment in a large number of cases. This review was aimed to describe general principles regarding the therapeutic approach to moderate-severe plaque psoriasis, providing an updated overview of the therapeutic armamentarium that is specifically available in Italy, drug prescriptibility, and some peculiar limitations for reimbursement defined by our National Health Care System.

Transient receptor potential mucolipin 1 (TRPML1) is a Ca2+-releasing cation channel that mediates the calcium signalling and homeostasis of lysosomes. Mutations in TRPML1 lead to mucolipidosis type IV, a severe lysosomal storage disorder. Here we report two electron cryo-microscopy structures of full-length human TRPML1: a 3.72-A apo structure at pH 7.0 in the closed state, and a 3.49-A agonist-bound structure at pH 6.0 in an open state. Several aromatic and hydrophobic residues in pore helix 1, helices S5 and S6, and helix S6 of a neighbouring subunit, form a hydrophobic cavity to house the agonist, suggesting a distinct agonist-binding site from that found in TRPV1, a TRP channel from a different subfamily. The opening of TRPML1 is associated with distinct dilations of its lower gate together with a slight structural movement of pore helix 1. Our work reveals the regulatory mechanism of TRPML channels, facilitates better understanding of TRP channel activation, and provides insights into the molecular basis of mucolipidosis type IV pathogenesis.

The replisome, the multiprotein system responsible for genome duplication, is a highly dynamic complex displaying a large number of different enzyme activities. Recently, the Saccharomyces cerevisiae minimal replication reaction has been successfully reconstituted in vitro. This provided an opportunity to uncover the enzymatic activities of many of the components in a eukaryotic system. Their dynamic behavior and interactions in the context of the replisome, however, remain unclear. We use a tethered-bead assay to provide real-time visualization of leading-strand synthesis by the S. cerevisiae replisome at the single-molecule level. The minimal reconstituted leading-strand replisome requires 24 proteins, forming the CMG helicase, the Pol epsilon DNA polymerase, the RFC clamp loader, the PCNA sliding clamp, and the RPA single-stranded DNA binding protein. We observe rates and product lengths similar to those obtained from ensemble biochemical experiments. At the single-molecule level, we probe the behavior of two components of the replication progression complex and characterize their interaction with active leading-strand replisomes. The Minichromosome maintenance protein 10 (Mcm10), an important player in CMG activation, increases the number of productive replication events in our assay. Furthermore, we show that the fork protection complex Mrc1-Tof1-Csm3 (MTC) enhances the rate of the leading-strand replisome threefold. The introduction of periods of fast replication by MTC leads to an average rate enhancement of a factor of 2, similar to observations in cellular studies. We observe that the MTC complex acts in a dynamic fashion with the moving replisome, leading to alternating phases of slow and fast replication.

We demonstrate that stress differentially regulates glutamate homeostasis in the dorsal and ventral hippocampus and identify a role for the astroglial xCT in ventral dentate gyrus (vDG) in stress and antidepressant responses. Weprovide an RNA-seq roadmap for the stress-sensitive vDG. The transcription factor REST binds to xCT promoter in co-occupancy with the epigenetic marker H3K27ac to regulate expression of xCT, which is also reduced in a genetic mouse model of inherent susceptibility to depressive-like behavior. Pharmacologically, modulating histone acetylation with acetyl-L-carnitine (LAC) or acetylN- cysteine (NAC) rapidly increases xCT and activates a network with mGlu2 receptors to prime an enhanced glutamate homeostasis that promotes both pro-resilient and antidepressant-like responses. Pharmacological xCT blockage counteracts NAC prophylactic effects. GFAP(+)-Cre-dependent overexpression of xCT in vDG mimics pharmacological actions in promoting resilience. This work establishes a mechanismby which vDGprotection leads to stress resilience and antidepressant responses via epigenetic programming of an xCT-mGlu2 network.

Background: Atopic dermatitis (AD) presents a large unmet need for treatments with better safety and efficacy. To facilitate development of topical therapeutics, we need an efficient model for assessing different formulations and concentrations. The "plaque model'' has been successfully implemented in patients with psoriasis, another common inflammatory disease, to assess the efficacy of topical treatments. This model has not been validated for AD, which has higher placebo responses and less stable lesions than psoriasis. Objective: We aimed to assess changes in molecular signatures of intrapatient target lesions treated with topical therapeutics. Methods: We enrolled 30 patients with mild-to-moderate AD in a randomized, double-blind, intraindividual comparison of 3 approved agents applied blindly at the investigator site daily for 14 days: pimecrolimus, betamethasone dipropionate, clobetasol propionate, and a vehicle/emollient control. Changes in total sign scores (TSSs), transepidermal water loss, and tissue biomarkers (determined by using RT-PCR and immunohistochemistry) were evaluated. Results: TSSs showed improvements of 30%, 40%, 68%, and 76% at 2 weeks with vehicle, pimecrolimus, betamethasone, and clobetasol, respectively, with parallel changes in transepidermal water loss (P < .05). Significant differences versus vehicle values were limited to steroids (P < .0001). Steroids (particularly clobetasol) restored epidermal hyperplasia and terminal differentiation versus minimal changes with vehicle or pimecrolimus (P < .001). Levels of cellular infiltrates and cytokines (IL-13, IL-22, and S100As) were similarly reduced only by steroids (P < .001). TSS improvement correlated with changes in hyperplasia, infiltrates, and differentiation markers. Conclusion: We detected significant clinical and tissue differences between agents, providing a novel approach to study the differential effects of topical formulations using a limited sample size.

Noncoding RNAs (ncRNAs) regulate gene expression in all organisms. Bacterial 6S RNAs globally regulate transcription by binding RNA polymerase (RNAP) holoenzyme and competing with promoter DNA. Escherichia coli (Eco) 6S RNA interacts specifically with the housekeeping sigma(70)-holoenzyme (E sigma(70)) and plays a key role in the transcriptional reprogramming upon shifts between exponential and stationary phase. Inhibition is relieved upon 6S RNA-templated RNA synthesis. We report here the 3.8 A resolution structure of a complex between 6S RNA and E sigma(70) determined by single-particle cryo-electron microscopy and validation of the structure using footprinting and crosslinking approaches. Duplex RNA segments have A-form C3' endo sugar puckers but widened major groove widths, giving the RNA an overall architecture that mimics B-form promoter DNA. Our results help explain the specificity of Eco 6S RNA for E sigma (70) and show how an ncRNA can mimic B-form DNA to directly regulate transcription by the DNA-dependent RNAP.

The nosocomial prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Portugal is close to 50% and remains one of the highest in Europe. MRSA reservoirs in the animal setting in Portugal have been very poorly investigated, namely among animal husbandry. A total of 52 samples (nasal, inguinal region, and milk) were obtained from bovine animals and analyzed for the presence of S. aureus. The isolates were characterized by pulsed-field gel electrophoresis (PFGE), spa typing, SCCmec typing, and multilocus sequence typing and tested for antimicrobial susceptibility, presence of mecA and mecC genes, and virulence determinants. Overall, 54% of the screened animals were colonized with S. aureus in at least one body site. Notably, S. aureus nasal carriage followed an increasing trend with animal age (p = 0.0006). None of the isolates harbored the mecA or mecC genes. Resistance to penicillin, rifampicin, and tetracycline was observed in 24%, 18%, and 6% of the isolates, respectively. The isolates were distributed into three clonal lineages: PFGE type A, spa type t1166, ST1247-CC133 (43%), PFGE B-t267-ST352-CC97 (30%), and PFGE C-t091-ST7-CC7 (27%). CC133 was associated to older animals (p = 0.0025), whereas CC97 was isolated from calves (p = 0.0016). Virulence determinants commonly found in mastitis were widely detected in carriage isolates: lukDE and hlgv (100%), hlb (76%), and lukM (35%). Although healthy bovines do not represent a MRSA reservoir in Portugal, they are mainly colonized with S. aureus pathogenic lineages associated to mastitis in cattle (CC97 and CC133).