COP9 signalosome component JAB1/CSN5 is necessary for T cell signaling through LFA-1 and HIV-1 replication.

To determine critical host factors involved in HIV-1 replication, a dominant effector genetics approach was developed to reveal signaling pathways on which HIV-1 depends for replication. A large library of short peptide aptamers was expressed via retroviral delivery in T cells. Peptides that interfered with T cell activation-dependent processes that might support HIV-1 replication were identified. One of the selected peptides altered signaling, lead to a difference in T cell activation status, and inhibited HIV-1 replication. The target of the peptide was JAB1/CSN5, a component of the signalosome complex. JAB1 expression overcame the inhibition of HIV-1 replication in the presence of peptide and also promoted HIV-1 replication in activated primary CD4(+) T cells. This peptide blocked physiological release of JAB1 from the accessory T cell surface protein LFA-1, downstream AP-1 dependent events, NFAT activation, and HIV-1 replication. Thus, genetic selection for intracellular aptamer inhibitors of host cell processes proximal to signals at the immunological synapse of T cells can define unique mechanisms important to HIV-1 replication

Large, Negative Magnetoresistance in an Oleic Acid-Coated Fe3O4 Nanocrystal Self-Assembled Film

An oleic acid-coated Fe3O4 nanocrystal self-assembled film was fabricated via drop casting of colloidal particles on a SiO2/Si substrate. The film exhibited bifurcation of the zero-field-cooled and field-cooled magnetizations around 250 K. The nonlinear current-voltage (I–V) characteristics between the source and drain electrodes in both zero and non-zero magnetic fields (H) were observed above and below the bifurcation temperature. A large negative magnetoresistance (MR ≈ −60%) was achieved at 200 K and H = 1 T. Even at 295 K and 0.2 T, the negative MR (≈ −50%) persisted. A Fowler–Nordheim plot and power-law scaling of the I–V characteristics revealed that the current flows through two-dimensional (2D) percolated electron tunneling paths. The enlargement of MR can be attributed to spin-dependent electron tunneling between magnetically coupled Fe3O4 nanocrystals self-assembled in 2D ordered arrays

Magnetic and magnetoelectric properties of self-assembled Fe2.5Mn0.5O4 nanocrystals

We report magnetoresistance of 40%, corresponding to 80% spin polarization, at magnetic field of 0.5 T and 200 K for oleic acid-coated Fe2.5Mn0.5O4 nanocrystals (FMO NCs) self-assembled on a SiO2/Si substrate by drop casting fabrication. TheFMONCs exhibited spin glass transition around 150 K and nonlinear current voltage (I V) characteristics. Fowler Nordheim plot of the I V characteristics indicated that electrons tunnel directly barriers between the FMO NCs. Transmission electron microscopy revealed that the FMO NCs are elongated hexagon in shape with size of ∼15 20 nm. The FMO NCs self-assembled in two-dimension hexagonal networks of collinear ferromagnetic moments. The [111] easy magnetization axis of each FMO NC was parallel to each other in the hexagonal arrays. Geometrically frustrated lattice of collinear ferromagnetic moments supports both a low and a high intergranular tunneling conductance for the self-assembled FMO NCs without and with magnetic fields, respectively

Coordinated Cellular Neighborhoods Orchestrate Antitumoral Immunity at the Colorectal Cancer Invasive Front.

Antitumoral immunity requires organized, spatially nuanced interactions between components of the immune tumor microenvironment (iTME). Understanding this coordinated behavior in effective versus ineffective tumor control will advance immunotherapies. We re-engineered co-detection by indexing (CODEX) for paraffin-embedded tissue microarrays, enabling simultaneous profiling of 140 tissue regions from 35 advanced-stage colorectal cancer (CRC) patients with 56 protein markers. We identified nine conserved, distinct cellular neighborhoods (CNs)-a collection of components characteristic of the CRC iTME. Enrichment of PD-1+CD4+ T cells only within a granulocyte CN positively correlated with survival in a high-risk patient subset. Coupling of tumor and immune CNs, fragmentation of T cell and macrophage CNs, and disruption of inter-CN communication was associated with inferior outcomes. This study provides a framework for interrogating how complex biological processes, such as antitumoral immunity, occur through concerted actions of cells and spatial domains

Snapin, positive regulator of stimulation- induced Ca²⁺ release through RyR, is necessary for HIV-1 replication in T cells.

To identify critical host factors necessary for human immunodeficiency virus 1 (HIV-1) replication, large libraries of short-peptide-aptamers were expressed retrovirally. The target of one inhibitor peptide, Pep80, identified in this screen was determined to be Snapin, a protein associated with the soluble N-ethyl maleimide sensitive factor adaptor protein receptor (SNARE) complex that is critical for calcium-dependent exocytosis during neurotransmission. Pep80 inhibited Ca²⁺ release from intracellular stores and blocked downstream signaling by direct interruption of the association between Snapin and an intracellular calcium release channel, the ryanodine receptor (RyR). NFAT signaling was preferentially abolished by Pep80. Expression of Snapin overcame Pep80-mediated inhibition of Ca²⁺/NFAT signaling and HIV-1 replication. Furthermore, Snapin induced HIV-1 replication in primary CD4⁺ T cells. Thus, through its interaction with RyR, Snapin is a critical regulator of Ca²⁺ signaling and T cell activation. Use of the genetically selected intracellular aptamer inhibitors allowed us to define unique mechanisms important to HIV-1 replication and T cell biology

JAB1 overcomes the inhibition of HIV-1 replication in cognate peptide expressing SupT1 cells.

<p>(A) pBMN-control IRES-Lyt2α’ or pBMN-JAB1 IRES-Lyt2α’ retrovirus vectors were transduced into SupT1 cells that expressed either C-Pep1 or Pep24. (B) pBMN-control IRES-Lyt2α’ or pBMN-JAB1 IRES-Lyt2α’ retrovirus vectors were transduced into SupT1 cells. These cells were challenged with HIV-1 (NL4-3) at a dose 400 TCID₅₀ per 5×10⁴ cells. p24^gag levels in culture supernatants were assayed from four wells on the indicated days after infection. p24^gag levels were normalized to cell number determined using an XTT assay. Data are presented as the average ± SE per 10⁶ cells. Similar results were observed in three independent experiments. * indicates <i>p</i><0.05, Control C-Pep-1 SupT1 versus Control Pep24 SupT1, and # indicates <i>p</i><0.05, Control Pep24 SupT1 versus JAB1 Pep24 SupT1 by <i>t</i> test. (C) JNK inhibitor (SP600125) inhibits HIV-1 replication. SupT1 cells were treated JNK inhibitor (SP600125) for 30 min before HIV-1 challenge. These cells were challenged with HIV-1 (NL4-3) at a dose 400 TCID₅₀ per 5×10⁴ cells. p24^gag levels in culture supernatants were assayed from five wells on the indicated days after infection. p24^gag levels were normalized for cell number using XTT assay. Data are presented as the average ± SE per 10⁶ cells. Similar results were observed in three independent experiments. *indicates <i>p</i><0.05, No treatment versus 10 µM SP600125, and # indicates <i>p</i><0.05, No treatment versus 30 µM SP600125 by <i>t</i> test.</p

JNK is one of kinases on which HIV-1 depends.

<p>Jurkat cells expressing C-Pep1 or Pep24 were treated with indicated stimuli. Cells were stained with pERK-Alexa 647 or pJNK-Alexa 647 phosphospecific antibodies and analyzed by flow cytometry. (A) Histograms are colored according to the different stimuli. (B) Fold change was approximated by calculating the log2 ratio of mean fluorescence intensity of stimulated versus unstimulated cells.</p

Proposed model for the inhibition of signalling pathway by Pep24.

<p>(A) After LFA-1 activation, JAB1 relocalizes into cytoplasm and nucleus, activates AP-1 and induces gene activation, and finally activates HIV-1 replication. (B) When Pep24 binds to JAB-1, JAB1 relocalization is blocked inhibiting downstream signals and HIV-1 replication.</p