Monitoring and Control of an Adsorption System Using Electrical Properties of the Adsorbent for Organic Compound Abatement

Adsorption systems typically need gas and temperature sensors to monitor their adsorption/regeneration cycles to separate gases from gas streams. Activated carbon fiber cloth (ACFC)–electrothermal swing adsorption (ESA) is an adsorption system that has the potential to be controlled with the electrical properties of the adsorbent and is studied here to monitor and control the adsorption/regeneration cycles without the use of gas and temperature sensors and to <i>predict</i> breakthrough before it occurs. The ACFC’s electrical resistance was characterized on the basis of the amount of adsorbed organic gas/vapor and the adsorbent temperature. These relationships were then used to develop control logic to monitor and control ESA cycles on the basis of measured resistance and applied power values. Continuous sets of adsorption and regeneration cycles were performed sequentially entirely on the basis of remote electrical measurements and achieved ≥95% capture efficiency at inlet concentrations of 2000 and 4000 ppm_v for isobutane, acetone, and toluene in dry and elevated relative humidity gas streams, demonstrating a novel cyclic ESA system that does not require gas or temperature sensors. This contribution is important because it reduces the cost and simplifies the system, predicts breakthrough before its occurrence, and reduces emissions to the atmosphere

RNF26 Temporally Regulates Virus-Triggered Type I Interferon Induction by Two Distinct Mechanisms

<div><p>Viral infection triggers induction of type I interferons (IFNs), which are critical mediators of innate antiviral immune response. Mediator of IRF3 activation (MITA, also called STING) is an adapter essential for virus-triggered IFN induction pathways. How post-translational modifications regulate the activity of MITA is not fully elucidated. In expression screens, we identified RING finger protein 26 (RNF26), an E3 ubiquitin ligase, could mediate polyubiquitination of MITA. Interestingly, RNF26 promoted K11-linked polyubiquitination of MITA at lysine 150, a residue also targeted by RNF5 for K48-linked polyubiquitination. Further experiments indicated that RNF26 protected MITA from RNF5-mediated K48-linked polyubiquitination and degradation that was required for quick and efficient type I IFN and proinflammatory cytokine induction after viral infection. On the other hand, RNF26 was required to limit excessive type I IFN response but not proinflammatory cytokine induction by promoting autophagic degradation of IRF3. Consistently, knockdown of RNF26 inhibited the expression of <i>IFNB1</i> gene in various cells at the early phase and promoted it at the late phase of viral infection, respectively. Furthermore, knockdown of RNF26 inhibited viral replication, indicating that RNF26 antagonizes cellular antiviral response. Our findings thus suggest that RNF26 temporally regulates innate antiviral response by two distinct mechanisms.</p></div

RNF26 protects MITA from K48-linked polyubiquitination and degradation.

<p>(A) Effects of RNF26 knockdown on virus-induced polyubiquitination of endogenous MITA. The THP-1-RNF26-RNAi or control cells (2×10⁷) were infected with SeV or HSV-1 for the indicated time points or left uninfected. Cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-Ub(K48) (upper panel), anti-Ub(K63) (middle panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins. (B) Effects of RNF5 knockdown on virus-induced K11-linked polyubiquitination of endogenous MITA. The 293-HA-Ub-K11O cells (2×10⁷) were transfected with the indicated RNAi plasmid (10 µg each). Twelve hours after transfection, the cells were selected with puromycin (1 µg/mL) for twenty-four hours and infected with SeV for the indicated time points or left uninfected. Cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated antibodies. (C) RNF26 and RNF5 competed with each other on MITA polyubiquitination. The 293 cells (5×10⁶) were transfected with MITA (5 µg), Flag-Ub-K48O and HA-Ub-K11O (1 µg each) together with indicated amount of RNF26 and RNF5. Twenty-four hours after transfection, cell lysates were subjected to IP under denatured conditions with anti-MITA and the immunoprecipitates were analyzed by immunoblots with anti-Flag (upper panel), anti-HA (middle panel) or anti-MITA (lower panel). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins. (D) Effects of RNF26 knockdown on virus-triggered MITA degradation. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with SeV or HSV-1 for the indicated time points or left uninfected. Cells were lysed and whole cell lysates were analyzed by immunoblots with antibodies against the indicated proteins (upper immunoblots). The relative protein levels of MITA in reference to β-actin were analyzed by Quantity One program and data shown are mean ± S.D. of three independent experiments (lower histographs).</p

RNF26 modulates virus-triggered induction of type I IFNs.

<p>(A) Effects of RNF26 knockdown on SeV-triggered activation of the IFN-β promoter. The 293 cells (2×10⁵) were transfected with the IFN-β promoter reporter (0.1 µg) and the indicated RNAi plasmid (0.5 µg each). Thirty hours after transfection, cells were infected with SeV for 12 hours or left uninfected before reporter assays were performed. (B and C) Effects of RNF26 knockdown on virus-triggered induction of IFN-β in THP-1 cells. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with SeV or HSV-1 for the indicated time points or left uninfected followed by quantitative real-time PCR (B) or ELISA analysis (C). ND, not detected. (D) Effects of RNF26 knockdown on virus-triggered induction of <i>IFNB1</i> gene in THP-1 cells. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with VSV, EMCV or ECTV for the indicated time points or left uninfected before quantitative real-time PCR analysis was performed as in (B). (E and F) Effects of RNF26 knockdown on virus-triggered induction of TNFα in THP-1 cells. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with SeV or HSV-1 for the indicated time points or left uninfected followed by quantitative real-time PCR (E) and ELISA analysis (F). (G) Effects of RNF26 knockdown on virus-triggered phosphorylation of TBK1, IRF3 and IκBα. The THP-1-RNF26-RNAi or control cells (1×10⁶) were infected with SeV or HSV-1 for the indicated time points or left uninfected, whole cell lysates were analyzed by immunoblots with anti-p-TBK1, anti-TBK1, anti-p-IRF3, anti-IRF3, anti-p-IκBα, anti-IκBα, anti-RNF26 or anti-β-actin as indicated. All experiments were repeated for at least three times with similar results. The bar graphs show mean ± S.D. (<i>n</i> = 3) of a representative experiment performed in triplicate.</p

RNF26 catalyzes K11-linked polyubiquitination of MITA.

<p>(A and B) RNF26 targeted MITA for K11-linked polyubiquitination. The 293 cells (5×10⁶) were transfected with Flag-MITA (5 µg) and RNF26 (1 µg) together with HA-Ub or its mutants (1 µg each). Twenty-four hours after transfection, cells were subjected for IP under denatured conditions with limited amount of anti-Flag (0.5 µg) so that equal amount of Flag-MITA is pulled down. The immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-Flag (lower panel). The whole cell lysates were analyzed by immunoblots with anti-Flag or anti-RNF26 as indicated. Ub-AKR, all lysine residues of ubiquitin were mutated to arginine. (C) Effects of RNF26-RNAi plasmids on the expression of RNF26. In the upper panels, the 293 cells (1×10⁶) were transfected with the expression plasmids for RNF26-Flag (0.5 µg) and HA-β-actin (0.1 µg) together with the indicated RNAi plasmids (1 µg each). Twenty-four hours after transfection, whole cell lysates were analyzed by immunoblots with anti-Flag or anti-HA. In the lower panels, 293 cells were transduced with a control or RNF26-RNAi by retrovirus mediated gene transfer. Cells (1×10⁶) were lysed and whole cell lysates were analyzed by immunoblots with anti-RNF26 or anti-β-actin. (D) Immunoblot analysis of Flag-tagged ubiquitin expression in THP-1 cells stably transfected with Flag-Ub-K11O plasmid. Whole cell lysates of THP-1-Flag-Ub-K11O-RNF26-RNAi and control cells (1×10⁶) were analyzed by immunoblots with antibodies against the indicated proteins. RNF26-RNAi #1 was used here and in the following experiments if not noted. (E and F) Effects of RNF26 knockdown on virus-induced K11-linked polyubiquitination of endogenous MITA. In (E), THP-1-Flag-Ub-K11O-RNF26-RNAi or control cells (2×10⁷) were infected with SeV or HSV-1 for the indicated time points or left uninfected followed by IP under denatured conditions with anti-MITA. The immunoprecipitates were analyzed by immunoblots with anti-Flag (upper panels) or anti-MITA (lower panels). The whole cell lysates were analyzed by immunoblots with antibodies against the indicated cellular or viral proteins. In (F), 293-HA-Ub-K11O cells (2×10⁷) were transfected with a control or RNF26-RNAi plasmid (10 µg each). Twelve hours after transfection, puromycin (1 µg/mL) was added into the culture medium. The cells were selected for twenty-four hours and infected with SeV or left uninfected for the indicated time points followed by IP under denatured conditions and immunoblot analysis as in (E). All experiments were repeated for at least three times with similar results.</p

RNF26 interacts with MITA.

<p>(A) RNF26 interacted with MITA. The 293 cells (5×10⁶) were transfected with the indicated plasmids (5 µg each). Twenty-four hours later, cells were lysed and cell lysates were immunoprecipitated with anti-Flag or control IgG. The immunoprecipitates and whole cell lysates were analyzed by immunoblots with anti-HA or anti-Flag. (B) RNF26 was physiologically associated with MITA. THP-1 cells (2×10⁷) were infected with SeV or HSV-1 for the indicated time points or left uninfected. Cells were lysed and immunoprecipitation and immunoblot analysis was performed with antibodies against the indicated proteins. NC, negative control. (C) RNF26 is localized to the ER and mitochondria. HeLa cells (2×10⁵) were transfected with the indicated plasmids (0.5 µg each). Twenty-four hours after transfection, the cells were stained with Mito-Tracker Red for 15 minutes or left untreated. The cells were fixed with 4% paraformaldehyde and subjected for confocal microscopy analysis. (D) Subcellular distribution of RNF26. The 293 cells (5×10⁷) were infected with SeV for the indicated time points or left uninfected. Subcellular fractionation assays were performed and the cellular fractions were analyzed by immunoblots with antibodies against the indicated proteins. (E) RNF26 and MITA were colocalized to the ER. HeLa cells (2×10⁵) were transfected with the indicated plasmids (0.5 µg each). Eighteen hours after transfection, cells were infected with SeV or HSV-1 for 6 hours or left uninfected, followed by ER-Tracker Blue/White staining for 30 minutes. Cells were fixed with 4% paraformaldehyde and subjected for confocal microscopy analysis. All experiments were repeated for at least three times with similar results.</p

RNF26 regulates IRF3 stability.

<p>(A) Effects of RNF26 knockdown on IRF3 level. In the left panel, whole cell lysates of THP-1-RNF26-RNAi or control cells (1×10⁶) were analyzed by immunoblots with the indicated antibodies. In the right panel, cells (1×10⁶) were subjected to quantitative real-time PCR analysis. (B) Effects of RNF26 on IRF3 stability. The 293 cells (1×10⁶) were transfected with HA-IRF3 (0.5 µg) and HA-β-actin (0.1 µg) together with RNF26 or its mutant (0.3 µg each). Twenty-four hours later, whole cell lysates were analyzed by immunoblots with anti-HA or anti-RNF26. (C) Effects of RNF26 and its mutant on SeV-triggered activation of the IFN-β promoter. The 293 cells (2×10⁵) were transfected with the IFN-β promoter reporter (0.1 µg) and RNF26 or its mutant (0.1 µg each). Twenty hours after transfection, cells were infected with SeV for 12 hours or left uninfected before reporter assays were performed. (D) Effects of RNF26 on IRF3 ubiquitination. The 293 cells (5×10⁶) were transfected with Flag-IRF3 (5 µg) and RNF26 (1 µg) together with HA-Ub or its mutants (1 µg each). Eighteen hours after transfection, 3-MA (500 ng/mL) was added into culture medium for 4 hours to protect IRF3 from autophagosomal degradation during the experiment. The cell lysates were subjected to IP under denatured conditions with anti-Flag and the immunoprecipitates were analyzed by immunoblots with anti-HA (upper panels) or anti-Flag (lower panels). The whole cell lysates were analyzed by immunoblots with anti-Flag or anti-RNF26 as indicated. (E) Effects of inhibitors on RNF26-mediated destabilization of IRF3. The 293 cells (1×10⁶) were transfected with the indicated plasmids as described in (B). Eighteen hours after transfection, 3-MA (500 ng/mL), NH₄Cl (25 mM) or MG132 (100 µM) was added into culture medium for four hours. Whole cell lysates were analyzed by immunoblots with anti-HA or anti-RNF26. (F) Effects of ATG12 knockdown on RNF26-mediated destabilization of IRF3. The 293-ATG12-RNAi or control cells (1×10⁶) were transfected with the indicated plasmids. Twenty-four hours later, whole cell lysates were analyzed by immunoblots with anti-HA, anti-RNF26 or anti-ATG12 as indicated. All experiments were repeated for at least three times with similar results. The bar graphs show mean ± S.D. (<i>n</i> = 3) of a representative experiment performed in triplicate.</p

RNF26 promotes polyubiquitination of MITA at K150.

<p>(A) RNF26 mediated polyubiquitination of MITA at K150. The 293 cells (5×10⁶) were transfected with HA-Ub (1 µg) and RNF26 (1 µg) together with Flag-MITA or the indicated mutants (5 µg each). Twenty-four hours after transfection, cells were subjected IP under denatured conditions with anti-Flag and immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-Flag (lower panel). The whole cell lysates were analyzed by immunoblots with anti-Flag or anti-RNF26 as indicated. (B) RNF26 targeted MITA for polyubiquitination at K150 <i>in vitro</i>. RNF26, MITA and its mutants were obtained by <i>in vitro</i> transcription and translation. Biotin-Ub, E1, UbcH5 and RNF26 were incubated with MITA or its mutants. The ubiquitination of MITA was examined by immunoblot analysis with HRP-streptavidin (top panel). The inputs of RNF26 and MITA were analyzed by immunoblots with anti-MITA and anti-RNF26 (bottom panels). All experiments were repeated for at least three times with similar results.</p

RNF26 is an E3 ubiquitin ligase for MITA.

<p>(A) Overexpression of RNF26 promoted polyubiquitination of MITA. The 293 cells (5×10⁶) were transfected with Flag-MITA (5 µg) and HA-Ub (1 µg) together with a control or RNF26 expression plasmid (0.5, 1, 2 µg). Twenty-four hours after transfection, cells were subjected to immunoprecipitation (IP) under denatured conditions with anti-Flag and the immunoprecipitates were analyzed by immunoblots with anti-HA (upper panel) or anti-Flag (lower panel). The whole cell lysates were analyzed by immunoblots with anti-HA (upper panel), anti-Flag (middle panel) and anti-RNF26 (bottom panel). Ub, ubiquitin. (B) RNF26-mediated polyubiquitination of MITA depends on the enzymatic activity of RNF26. The 293 cells (5×10⁶) were transfected with Flag-MITA (5 µg) and HA-Ub (1 µg) together with RNF26 or its mutants (1 µg each). IP under denatured conditions and ubiquitination assay was performed as described in (A). (C) UbcH5 mediated polyubiquitination of MITA by RNF26. The RNF26 and MITA proteins were obtained by <i>in vitro</i> transcription and translation, then incubated with biotin-Ub, E1 and the indicated E2s. Polyubiquitination of MITA was examined by immunoblot analysis with HRP-streptavidin (top panel). The inputs of RNF26 and MITA were analyzed by immunoblots with anti-MITA and anti-RNF26 (bottom panels). (D) RNF26 but not its enzymatic inactive mutants targeted MITA for polyubiquitination <i>in vitro</i>. MITA, RNF26 and its mutants were obtained by <i>in vitro</i> transcription and translation. Biotin-Ub, E1, UbcH5 and MITA were incubated with RNF26 or its mutants, followed by ubiquitination and immunoblot analysis as described in (C). All experiments were repeated for at least three times with similar results.</p

A model on the roles of RNF26 in virus-triggered induction of downstream genes.

<p>See text for details.</p