Inhibition of mitochondrial fission and protein kinase R improves progesterone in placental stress.

Placenta synthesizes hormones that play a vital role in adapting maternal physiology and supporting fetal growth. This study aimed to explore the link between progesterone, a key steroid hormone produced by placenta, and mitochondrial fission and protein kinase R through the use of chemical inhibition in trophoblasts subjected to endotoxin lipopolysaccharide and double-stranded RNA analog polyinosinic:polycytidylic acid stress. Expressions of protein kinase R, dynamin-related protein 1, mitochondrial fission protein 1, and heat shock protein 60 were determined by applying lipopolysaccharide and polyinosinic:polycytidylic acid to BeWo trophoblast cells. Next, cells were treated with protein kinase R inhibitor 2-aminopurine and mitochondrial division inhibitor 1 to examine changes in progesterone levels and expression levels of proteins and mRNAs involved in progesterone biosynthesis. Last, effect of 2-aminopurine on mitochondrial fission was determined by immunoblotting and quantitative PCR (qPCR). Mitochondrial structural changes were also examined by transmission electron microscopy. Lipopolysaccharide and polyinosinic:polycytidylic acid stimulation induced mitochondrial fission and activated protein kinase R but decreased heat shock protein 60 levels and progesterone synthesis. Chemical inhibition of mitochondrial fission elevated progesterone synthesis and protein and mRNA levels of genes involved in progesterone biosynthesis. Inhibition of protein kinase R with 2-aminopurine prevented lipopolysaccharide and polyinosinic:polycytidylic acid induced mitochondrial fission and increased progesterone biosynthesis. Use of chemical inhibitors to treat placental stress caused by pathogens has potential to stabilize the production of progesterone. The study reveals that inhibiting mitochondrial fragmentation and reducing activity of stress kinase protein kinase R in syncytiotrophoblasts leads to an increase in progesterone synthesis when exposed to lipopolysaccharide and polyinosinic:polycytidylic acid.

Nucleoside-modified VEGFC mRNA induces organ-specific lymphatic growth and reverses experimental lymphedema.

Lack or dysfunction of the lymphatics leads to secondary lymphedema formation that seriously reduces the function of the affected organs and results in degradation of quality of life. Currently, there is no definitive treatment option for lymphedema. Here, we utilized nucleoside-modified mRNA encapsulated in lipid nanoparticles (LNPs) encoding murine Vascular Endothelial Growth Factor C (VEGFC) to stimulate lymphatic growth and function and reduce experimental lymphedema in mouse models. We demonstrated that administration of a single low-dose of VEGFC mRNA-LNPs induced durable, organ-specific lymphatic growth and formation of a functional lymphatic network. Importantly, VEGFC mRNA-LNP treatment reversed experimental lymphedema by restoring lymphatic function without inducing any obvious adverse events. Collectively, we present a novel application of the nucleoside-modified mRNA-LNP platform, describe a model for identifying the organ-specific physiological and pathophysiological roles of the lymphatics, and propose an efficient and safe treatment option that may serve as a novel therapeutic tool to reduce lymphedema.

SARS-CoV-2 Nucleocapsid Protein Targets RIG-I-Like Receptor Pathways to Inhibit the Induction of Interferon Response.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19) that has resulted in the current pandemic. The lack of highly efficacious antiviral drugs that can manage this ongoing global emergency gives urgency to establishing a comprehensive understanding of the molecular pathogenesis of SARS-CoV-2. We characterized the role of the nucleocapsid protein (N) of SARS-CoV-2 in modulating antiviral immunity. Overexpression of SARS-CoV-2 N resulted in the attenuation of retinoic acid inducible gene-I (RIG-I)-like receptor-mediated interferon (IFN) production and IFN-induced gene expression. Similar to the SARS-CoV-1 N protein, SARS-CoV-2 N suppressed the interaction between tripartate motif protein 25 (TRIM25) and RIG-I. Furthermore, SARS-CoV-2 N inhibited polyinosinic: polycytidylic acid [poly(I:C)]-mediated IFN signaling at the level of Tank-binding kinase 1 (TBK1) and interfered with the association between TBK1 and interferon regulatory factor 3 (IRF3), subsequently preventing the nuclear translocation of IRF3. We further found that both type I and III IFN production induced by either the influenza virus lacking the nonstructural protein 1 or the Zika virus were suppressed by the SARS-CoV-2 N protein. Our findings provide insights into the molecular function of the SARS-CoV-2 N protein with respect to counteracting the host antiviral immune response.

Impaired innate immune gene profiling in airway smooth muscle cells from chronic cough patients.

Chronic cough is associated with airway inflammation and remodelling. Abnormal airway smooth muscle cell (ASMC) function may underlie mechanisms of chronic cough. Our objective was to examine the transcriptome and focused secretome of ASMCs from chronic cough patients and healthy non-cough volunteers. ASMC gene expression profiling was performed at baseline and/or after stimulation with polyinosinic:polycytidylic acid (poly(I:C)) to mimic viral infection. Supernatants were collected for multiplex analysis. Our results showed no significant differentially expressed genes (DEGs, false discovery rate (FDR) <0.05) between chronic cough and healthy non-cough ASMCs at baseline. Poly(I:C) stimulation resulted in 212 DEGs (>1.5 fold-change, FDR <0.05) in ASMCs from chronic cough patients compared with 1674 DEGs in healthy non-cough volunteers. The top up-regulated genes included chemokine (C-X-C motif) ligand (CXCL) 11 (CXCL11), CXCL10, chemokine (C-C motif) ligand (CCL) 5 (CCL5) and interferon-induced protein 44 like (IFI44L) corresponding with inflammation and innate immune response pathways. ASMCs from cough subjects had enhanced activation of viral response pathways in response to poly(I:C) compared with healthy non-cough subjects, reduced activation of pathways involved in chronic inflammation and equivalent activation of neuroregulatory genes. The poly(I:C)-induced release of inflammatory mediators, including CXCL8, interleukin (IL)-6 and CXCL1, from ASMCs from cough patients was significantly impaired compared with healthy non-cough subjects. Addition of fluticasone propionate (FP) to poly(I:C)-treated ASMCs resulted in greater gene expression changes in healthy non-cough ASMCs. FP had a differential effect on poly(I:C)-induced mediator release between chronic cough and healthy non-cough volunteers. In conclusion, altered innate immune and inflammatory gene profiles within ASMCs, rather than infiltrating cells or nerves, may drive the cough response following respiratory viral infection.

Hippocampal Aß expression, but not phosphorylated tau, predicts cognitive deficits following repeated peripheral poly I:C administration.

Alzheimer's disease is marked by the accumulation of the amyloid-beta (Aß) peptide, and increases in phosphorylation of the microtubule associated protein, tau. Changes in these proteins are considered responsible, in part, for the progressive neuronal degeneration and cognitive deficits seen in AD. We examined the effect of repeated consecutive peripheral poly I:C injections on cognitive deficits, central Aß, and phosphorylated tau accumulation, following three treatment durations: 7, 14, and 21 days. Forty-eight hours after the final injection, animals were trained in a contextual fear-conditioning paradigm, and tested 24h later. Immediately after testing, the hippocampus was collected to quantify Aß and phosphorylated tau accumulation. Results showed that, although poly I:C-induced Aß was significantly elevated at all time points examined, poly I:C only disrupted cognition after 14 and 21 days of administration. Moreover, elevations in phosphorylated tau were not seen until the 14-day time point. Interestingly, phosphorylated tau expression then declined at the 21-day time point. Finally, we demonstrated that Aß levels are a stronger predictor of cognitive dysfunction, explaining 37% of the variance, whereas phosphorylated tau levels only accounted for 0.2%. Taken together, these results support the hypothesis that inflammation-induced elevation in Aß disrupts cognition, independently of phosphorylated tau, and suggest that long-term administration of poly I:C may provide a model to investigate the contribution of long-term inflammation toward the development of Alzheimer's-like pathology.

Berberine reduces Toll-like receptor-mediated macrophage migration by suppression of Src enhancement.

Berberine is an isoquinoline with anti-inflammatory activity. We previously demonstrated that there was a loop of signal amplification between nuclear factor kappa B and Src for macrophage mobility triggered by the engagement of Toll-like receptors (TLRs). The simultaneous suppression of lipopolysaccharide (LPS)-mediated upregulation of inducible nitric oxide synthase, cyclooxygenase 2, and cell mobility in berberine-treated macrophages suggested Src might be a target of berberine. Indeed, th reduced migration, greatly suppressed Src induction in both protein and RNA transcript by berberine were observed in macrophages exposed to LPS, peptidoglycan, polyinosinic-polycytidylic acid, and CpG-oligodeoxynucleotides. In addition to Src induction, berberine also inhibited LPS-mediated Src activation in Src overexpressing macrophages and S-nitroso-N-acetylpenicillamine (a nitric oxide donor) could partly restore it. Moreover, berberine suppressed Src activity in fibronectin-stimulated macrophages and in v-Src transformed cells. These results implied that by effectively reducing Src expression and activity, berberine inhibited TLR-mediated cell motility in macrophages.

Analyzing gene function in adult long-term hematopoietic stem cells using the interferon inducible Mx1-Cre mouse system.

Long-term hematopoietic stem cells (LT-HSCs) have the ability to self-renew and differentiate into all blood cell lineages. Understanding the genetic networks that regulate LT-HSC function in the adult bone marrow requires inducible gene targeting and bone marrow transplantations. In this chapter we describe the use of the inducible Mx1-Cre mouse model to delete genes in LT-HSCs and methodologies for examining the function of LT-HSCs following deletion.

The neurotoxic effect of astrocytes activated with toll-like receptor ligands.

Toll-like receptors (TLRs) are key molecules in the innate immune system in the central nervous system. Although astrocytes are believed to play physiological roles in regulating neuronal activity and synaptic transmission, activated astrocytes may also be toxic to neurons. Here, we show that the ligands for TLRs 2, 4, 5 and 6 induce neuronal cell death in neuron-astrocytes co-cultures through the production of reactive oxygen species (ROS). Inhibition of ROS production by NADPH oxidase inhibitor apocynin significantly suppresses neuronal cell death. ROS induced in astrocytes via TLRs may be involved in neuroinflammation and a therapeutic target for neurotoxicity by activated astrocytes.

Isolation and characterization of cDNAs encoding Ars2 and Pasha homologues, two components of the RNA interference pathway in Litopenaeus vannamei.

The RNA interference (RNAi) is an evolutionarily conserved protective mechanism in eukaryotes against parasitic foreign nucleic acids. Previous studies demonstrated that the RNAi mechanism is important for shrimp antiviral immunity. Here, we report the identification and functional analysis of two key components of the shrimp RNAi activity: Litopenaeus vannamei arsenite resistance gene 2 (LvArs2) and partner of drosha (LvPasha). The full-length cDNA of LvArs2 was 3470 bp, including a 5' untranslated region (UTR) of 167 bp, a 3' UTR of 639 bp, and an open reading frame (ORF) of 2664 bp that encoded 887 amino acid residues with an estimated molecular mass of 102.5 kDa. The full-length cDNA of LvPasha was 2654 bp, including a 5' UTR of 99 bp, a 3' UTR of 560 bp, and an ORF of 1995 bp that encoded 664 amino acid residues with an estimated molecular mass of 74.2 kDa. Co-immunoprecipitation demonstrated that LvArs2 interacted with L. vannamei Dicer2 (LvDcr2) and LvPasha in Drosophila Schneider 2 (S2) cells, suggesting that LvArs2 may be involved in regulation of the miRNA/siRNA pathways in L.vannamei. Subcellular localization assays demonstrated both LvArs2 and LvPasha proteins mainly presented in the nucleus. After Poly(C-G) stimulation, the expression of LvArs2 was suppressed and expression of LvPasha was enhanced in shrimp gills. These results suggest that LvArs2 and LvPasha may participate in the defense against RNA viruses in crustacea.

Influence of preparation method on polynucleotide conformation and pharmacological activity of lipoplex.

Conformations of polyinosinic acid [poly(I)] and polycytidylic acid [poly(C)] in liposomes (lipoplex) were investigated by both circular dichroism (CD) spectroscopy and fluorescence resonance energy transfer (FRET) measurements, and compared with those in aqueous solution. The results indicate that poly(I) and poly(C) take double-stranded structure in aqueous solution at pH 6.5-7.5 in the presence of NaCl at higher concentration than 50mM. Although lipoplex was prepared without NaCl to avoid aggregation of lipoplex particles, poly(I) and poly(C) were double-stranded in pre-mixed poly(I)/poly(C) lipoplex (pre-mixed LIC), prepared by adding a mixed solution of poly(I) and poly(C) to the cationic liposomes. However, poly(I) and poly(C) did not take double-stranded structure in separately mixed LIC, prepared by separate addition of poly(I) solution and poly(C) solution to the cationic liposomes. The physicochemical properties (particle diameter and zeta potential) of pre-mixed LIC and separately mixed LIC were not different, but the anti-proliferative effect of pre-mixed LIC on human epidermoid carcinoma A431 cells was about eight times greater than that of separately mixed LIC. Our results indicate that polynucleotide conformation in lipoplex is markedly influenced by the preparation method, and the polynucleotide conformation in lipoplex has a substantial effect on pharmacological activity.

A novel gene of tumor necrosis factor ligand superfamily from kuruma shrimp, Marsupenaeus japonicus.

A tumor necrosis factor (TNF) gene has been isolated and characterized in kuruma shrimp, Marsupenaeus japonicus, providing the first conclusive evidence for the existence of the TNF ligand in shrimp. The kuruma shrimp TNF (MjTNF) cDNA was composed of 1868 bp with a 262 bp 5'-untranslated region (UTR) and a 220 bp 3'-UTR, which was translated into a protein of 462 amino acid residues that included a predicted transmembrane domain of 23 amino acid residues (Trp20-Val42) and the TNF family signature (Pro321-Leu448). Homology analysis of MjTNF showed 30.7% and 26.7% identities with fruit fly (Drosophila melanogaster) Eiger and human (Homo sapiens) ectodysplasin A, respectively. The MjTNF gene was constitutively expressed in unstimulated organs of shrimp such as the muscle, stomach, brain and gill. In lymphoid organ cells, an enhanced expression of the MjTNF gene was observed following stimulation with peptidoglycan and polycytidylic acid. A high expression level of MjTNF was observed in vivo 2 h and 4 h after stimulation with lipopolysaccharide and Vibrio penaeicida, respectively. These observations suggest that MjTNF plays a role in the innate immune defense in kuruma shrimp. The discovery of shrimp TNF will allow a more complete and concrete understanding of shrimp inflammatory responses.

IL-6 and IFN-alpha from dsRNA-stimulated dendritic cells control expansion of regulatory T cells.

Foxp3(+)CD4(+) regulatory T cells (Treg) control not only autoimmunity but also the effective immune response against RNA virus infections, which produces virus-derived double-stranded RNA (dsRNA). To induce effective anti-viral immunity, it is a key issue to learn how Treg respond to dsRNA in vitro and in vivo. We here showed that synthetic dsRNA, polyI:C, caused peripheral expansion of functional Treg in a TICAM-1- and IL-6-dependent manner in vivo. PolyI:C did not expand Treg directly, but promoted the expansion of naturally occurring Treg indirectly through IL-6 produced from dendritic cells (DCs). In addition, the expansion of Treg by IL-6 was inhibited by IFN-alpha from polyI:C-stimulated DCs. These data suggest that the balance of IL-6 and IFN-alpha in the region of RNA virus infection may determine the number of peripheral Treg, which affects the effective immune responses against viruses.

Tricking melanoma to self-digest: a deal of a meal!

Melanoma cells acquire multiple genetic and epigenetic alterations that promote their metastasis and resistance to available therapies. In this issue of Cancer Cell, Soengas and colleagues reveal that the induction of endosome-mediated autophagy results in efficient melanoma cell death, thereby offering new potential means for treatment of this devastating cancer.

Targeted activation of innate immunity for therapeutic induction of autophagy and apoptosis in melanoma cells.

Inappropriate drug delivery, secondary toxicities, and persistent chemo- and immunoresistance have traditionally compromised treatment response in melanoma. Using cellular systems and genetically engineered mouse models, we show that melanoma cells retain an innate ability to recognize cytosolic double-stranded RNA (dsRNA) and mount persistent stress response programs able to block tumor growth, even in highly immunosuppressed backgrounds. The dsRNA mimic polyinosine-polycytidylic acid, coadministered with polyethyleneimine as carrier, was identified as an unanticipated inducer of autophagy downstream of an exacerbated endosomal maturation program. A concurrent activity of the dsRNA helicase MDA-5 driving the proapoptotic protein NOXA resulted in an efficient autodigestion of melanoma cells. These results reveal tractable links for therapeutic intervention among dsRNA helicases, endo/lysosomes, and apoptotic factors.

A murine scavenger receptor MARCO recognizes polystyrene nanoparticles.

Recent toxicological studies indicate that nanoparticles or ultrafine particles (< 100 nm) are more toxic than fine particles (< 2 microm) because of their greater surface area. It is well known that alveolar macrophages play an important role in the first defense against various environmental particles and microorganisms. This is accomplished by binding to a macrophage receptor with collagenous structure (MARCO), one of several scavenger-type receptors expressed on the cell surface of macrophages. MARCO has been shown to mediate the ingestion of unopsonized environmental particles such as TiO(2) and Fe(2)O(3) (1.3 microm in diameter). However, very little is known about the cellular uptake of nanoparticles. In the present study, we investigated whether MARCO mediates the uptake of nanoparticles by using fluorescent-tagged polystyrene particles (20 nm, 200 nm, and 1 microm in diameter). COS-7 cells were transfected with either MARCO cDNA or an empty vector, and the association of the particles with the cells were observed by fluorescence microscopy and atomic force microscopy. MARCO-transfected cells associated with all three sizes of particles in a time-dependent manner, while no obvious binding of particles occurred after 5 h to the empty vector-transfected cells. The uptake of particles by MARCO-transfected cells was partially inhibited by polyG. These results suggest that macrophages associate with nanoparticles (20 nm) at least in part through MARCO and that MARCO plays a role in clearing nanoparticles which can deposit in the alveolar region.

Defective antitumor responses in CX3CR1-deficient mice.

Innate immunity is critically important for tumor surveillance and regulating tumor metastasis. Fractalkine (FKN, CX3CL1), operating through the receptor CX3CR1, is an effective chemoattractant and adhesion receptor for NK cells and monocytes, important constituents of the innate immune response. Previous studies have shown that over-expression of CX3CL1 by tumor cells enhances antitumor responses. However, since most tumors do not express CX3CL1, it remains unclear if CX3CL1/CX3CR1 has a role in tumor immunity in the absence of ligand over-expression. To determine the role of CX3CL1 and CX3CR1 in regulating antitumor immune responses, we tested the response of wildtype and CX3CR1-deficient animals to unmanipulated B16 melanoma that does not express CX3CL1. We studied the distribution and trafficking of mononuclear cells (MNC) under homeostatic conditions and in the presence of B16 metastatic melanoma, cytotoxic activity, and cytokine production in wild-type and CX3CR1-deficient animals. We found that B16-treated CX3CR1-/- mice had increased lung tumor burden and cachexia. There was a selective reduction of monocytes and NK cells in the lungs of CX3CR1-deficient animals under homeostatic conditions and in response to B16. CX3CR1-deficient NK cells effectively killed B16 cells in cytotoxicity assays. However, CX3CR1-deficient NK cells exhibited a tumorigenic cytokine production profile with defective IFN-gamma expression and enhanced IL-6 production in response to TLR3 activation with polyIC. Our studies indicate that CX3CR1 is an important contributor to innate immunity at multiple levels. Its role in tumor immunity is not limited by expression of CX3CL1 by tumor cells.

Induction of antiviral genes, Mx and vig-1, by dsRNA and Chum salmon reovirus in rainbow trout monocyte/macrophage and fibroblast cell lines.

The expression of potential antiviral genes, Mx1, Mx2, Mx3 and vig-1, was studied in two rainbow trout cell lines: monocyte/macrophage RTS11 and fibroblast-like RTG-2. Transcripts were monitored by RT-PCR; Mx protein by Western blotting. In unstimulated cultures Mx1 and vig-1 transcripts were seen occasionally in RTS11 but rarely in RTG-2. A low level of Mx protein was seen in unstimulated RTS11 but not in RTG-2. In both cell lines, Mx and vig-1 transcripts were induced by a dsRNA, poly inosinic: poly cytidylic acid (poly IC), and by Chum salmon reovirus (CSV). Medium conditioned by cells previously exposed to poly IC or CSV and assumed to contain interferon (IFN) induced the antiviral genes in RTS11. However, RTG-2 responded only to medium conditioned by RTG-2 exposed previously to CSV. In both cell lines, poly IC and CSV induced Mx transcripts in the presence of cycloheximide, suggesting a direct induction mechanism, independent of IFN, was also possible. For CSV, ribavirin blocked induction in RTS11 but not in RTG-2, suggesting viral RNA synthesis was required for induction only in RTS11. In both RTS11 and RTG-2 cultures, Mx protein showed enhanced accumulation by 24h after exposure to poly IC and CSV, but subsequently Mx protein levels declined back to control levels in RTS11 but not in RTG-2. These results suggest that Mx can be regulated differently in macrophages and fibroblasts.

Selective inhibitors of terminal deoxyribonucleotidyltransferase (TdT): baicalin and genistin.

Studies of mammalian terminal deoxyribonucleotidyltransferase (TdT) are facilitated by use of inhibitors that selectively knock down the activity of the enzyme. We have screened for selective inhibitors of TdT and identified a natural compound with this property in the Japanese vegetable, Arctium lappa. The compound has little effect on the activities of mammalian DNA polymerases, such as alpha, beta, delta or lambda polymerase, and prokaryotic DNA polymerases, such as Taq DNA polymerase, T4 DNA polymerase and Klenow fragment. H1- and C13-NMR spectroscopic analyses showed the compound to be baicalin, a compound previously reported as an anti-inflammatory or antipyretic agent. The IC50 value of baicalin to TdT was 18.6 microM. We also found that genistin, a baicalin derivative known to be antimutagenic, more selectively inhibited TdT activity than baicalin, although its IC50 value was weaker (28.7 microM). Genistin and baicalin also inhibited the activity of truncated TdT (the so-called pol beta core domain) in which the BRCT motif was deleted in its N-terminal region. In kinetic analyses, inhibition by either genistin or baicalin was competitive with the primer and non-competitive with the dNTP substrate. The compounds may, therefore, bind directly to the primer-binding site of TdT and simultaneously disturb dNTP substrate incorporation into the primer. Genistin and baicalin should prove to be useful agents for studying TdT.

Involvement of natural killer cells in PolyI:C-induced liver injury.

BACKGROUND/AIMS: The roles of T cells, natural killer T cells (NKT) and macrophages in autoimmune hepatitis have been well documented. However, the roles of natural killer (NK) cells in liver injury remain obscure. Here we examined the effect of Polyinosinic: polycytidylic acid (PolyI:C)-activated NK cells on liver injury. METHODS: Mice were intraperitoneally injected with PolyI:C at a dose of 20mug/g body wt. The percentage and absolute number of NK cells in the liver were analyzed with flow cytometry. Serum alanine transaminase (ALT) and aspartate aminotransferase (AST) assay and H-E staining were used to evaluate the liver injury. RESULTS: Following PolyI:C injection, NK cells accumulation and activation occurred in the liver. Meanwhile, slight elevation of ALT/AST in the serum, mild inflammation and focal necrosis in the liver were also observed. Depletion of NK cells markedly attenuated PolyI:C-induced liver injury. Neutralization of endogenous Interleukin-12 produced by Kupffer cells abrogated the accumulation of NK cells in the liver and subsequent liver injury. The liver injury was also alleviated by neutralization of vascular cell adhesive molecule-1. CONCLUSIONS: These findings suggest that PolyI:C preferentially recruits and activates hepatic NK cells, which may be responsible for the mild hepatitis.

[Activity of dsRNA-dependent protein kinase in rat lymphoid cells under the effect of X-ray irradiation]. / Aktyvnist' dsRNK-zalezhnoï proteïnkinazy v limfoïdnykh klitynakh shchuriv za diï na nykh renthenivs'koho vyprominiuvannia.

The activity of dsRNA-dependent protein kinase, which is the key enzyme of the interferon signal system, was studied in the rat spleen and thymus lymphocytes under the influence of X-ray irradiation at 0.5 and 1 Gy doses and interferon inducers administration. An increase of the enzyme activity was established in the presence of FGA, concanavaline A, poly(I).poly(C) in vitro. The effect is intensified under the irradiation by 0.5 Gy dose. The protein kinase activity in lymphocytes is amplified in proportion to poly(I).poly(C) concentration, that was most pronounced in the irradiated animals. The comparative analysis of the action of interferon inducers on the dsRNA-dependent protein kinase activity was carried out. Two biological systems were used: in vivo (when the preparations were injected to the experimental animals) and in vivo (under the preincubation of isolated lymphocytes with the inducers). It was shown that the combined action of radiation and interferon inducers causes the stimulation of dsRNA-dependent protein kinase activity.