Tristetraprolin inhibits macrophage IL-27-induced activation of antitumour cytotoxic T cell responses

Tristetraprolin promotes survival of mammary progenitor cells by restraining TNFα levels

Tristetraprolin (TTP) is an RNA binding protein that destabilizes mRNAs of factors involved in proliferation, invasiveness, and inflammation. Disruption of the gene that codes for TTP (Zfp36) led to severe arthritis, autoimmunity, cachexia and dermatitis in mice. It has been shown that these phenotypes were mostly due to excessive TNFα levels in the affected tissues. We have previously reported that TTP expression is required for lactation maintenance. Our results indicated that conditional MG TTP-KO female mice displayed early involution due to the untimely induction of pro-inflammatory pathways led mostly by TNFα overexpression. Here we show that reducing TTP levels not only affects the fully differentiated mammary gland, but also harms morphogenesis of this tissue by impairing the progenitor cell population. We found that Zfp36 expression is linked to mammary stemness in human and mice. In addition, diminishing TTP expression and activity induced apoptosis of stem-like mouse mammary cells, reduced its ability to form mammospheres in culture and to develop into complete glands when implanted into cleared mammary fat pads in vivo. Our results show that survival of the stem-like cells is compromised by increased levels of inflammatory cytokines and stimulation of signaling cascades involving NFκB, STAT3 and MAPK-p38 activation. Moreover, TNFα overexpression and the consequent p38 phosphorylation would be the leading cause of progenitor cell death upon TTP expression restriction. Taken together, our results reveal the relevance of TTP for the maintenance of the mammary progenitor cell compartment by maintaining local TNFα levels at bay.

Immunogenic Extracellular Vesicles Derived from Endoplasmic Reticulum-Stressed Tumor Cells: Implications as the Therapeutic Cancer Vaccine

Tumor-derived extracellular vesicles (TDEs) have potential for therapeutic cancer vaccine applications since they innately possess tumor-associated antigens, mediate antigen presentation, and can incorporate immune adjuvants for enhanced vaccine efficacy. However, the original TDEs also contain immune-suppressive proteins. To address this, we proposed a simple yet powerful preconditioning method to improve the overall immunogenicity of the TDEs. This approach involved inducing endoplasmic reticulum (ER) stress on parental tumor cells via N-glycosylation inhibition with tunicamycin. The generated immunogenic TDEs (iTDEs) contained down-regulated immunosuppressive proteins and up-regulated immune adjuvants, effectively activating dendritic cells (DCs) in vitro. Furthermore, in vivo evidence from a tumor-bearing mouse model showed that iTDEs activated DCs, enabling cytotoxic T lymphocytes (CTLs) to target tumors, and eventually established a systemic antitumor immune response. Additionally, iTDEs significantly delayed tumor recurrence in a postsurgery model compared with control groups. These findings highlight the immense potential of our strategy for utilizing TDEs to develop effective cancer vaccines.

Ferroptosis of macrophages facilitates bone loss in apical periodontitis via NRF2/FSP1/ROS pathway

Apical periodontitis (AP) is an infectious disease that causes periapical tissue inflammation and bone destruction. Ferroptosis, a novel type of regulated cell death, is closely associated with inflammatory diseases and the regulation of bone homeostasis. However, the exact involvement of ferroptosis in the bone loss of AP is not fully understood. In this study, human periapical tissues were collected, and a mouse model was established to investigate the role of ferroptosis in AP. Colocalization staining revealed that ferroptosis in macrophages contributes to the inflammatory bone loss associated with AP. A cell model was constructed using RAW 264.7 cells stimulated with LPS to further explore the mechanism underlying ferroptosis in macrophages upon inflammatory conditions, which exhibited ferroptotic characteristics. Moreover, downregulation of NRF2 was observed in ferroptotic macrophages, while overexpression of NRF2 upregulated the level of FSP1, leading to a reduction in reactive oxygen species (ROS) in macrophages. Additionally, ferroptotic macrophages released TNF-α, which activated the p38 MAPK signaling pathway and further increased ROS accumulation in macrophages. In vitro co-culture experiments demonstrated that the osteogenic ability of mouse bone marrow stromal cells (BMSCs) was suppressed with the stimulation of TNF-α from ferroptotic macrophages. These findings suggest that the TNF-α autocrine-paracrine loop in ferroptotic macrophages can inhibit osteogenesis in BMSCs through the NRF2/FSP1/ROS signaling pathway, leading to bone loss in AP. This study highlights the potential therapeutic value of targeting ferroptosis in the treatment of inflammatory bone diseases.

Development and Evaluation of a Novel Radiotracer 125I-rIL-27 to Monitor Allotransplant Rejection by Specifically Targeting IL-27Rα

Noninvasive monitoring of allograft rejection is beneficial for the prognosis of patients with organ transplantation. Recently, IL-27/IL-27Rα was proved in close relation with inflammatory diseases, and 125I-anti-IL-27Rα mAb our group developed demonstrated high accumulation in the rejection of the allograft. However, antibody imaging has limitations in the imaging background due to its large molecular weight. Therefore, we developed a novel radiotracer (iodine-125-labeled recombinant IL-27) to evaluate the advantage in the targeting and imaging of allograft rejection. In vitro specific binding of 125I-rIL-27 was determined by saturation and competitive assay. Blood clearance, biodistribution, phosphor autoradioimaging, and IL-27Rα expression were studied on day 10 after transplantation (top period of allorejection). Our results indicated that 125I-rIL-27 could bind with IL-27Rα specifically and selectively in vitro. The blood clearance assay demonstrated fast blood clearance with 13.20 μl/h of 125I-rIL-27 staying in the blood after 24 h. The whole-body phosphor autoradiography and biodistribution assay indicated a higher specific uptake of 125I-rIL-27 and a clear radioimage in allograft than in syngraft at 24 h, while a similar result was obtained at 48 h in the group of 125I-anti-IL-27Rα mAb injection. Meanwhile, a higher expression of IL-27Rα was found in the allograft by Western blot. The accumulation of radioactivity of 125I-rIL-27 was highly correlated with the expression of IL-27Rα in the allograft. In conclusion, 125I-rIL-27 could be a promising probe for acutely monitoring allograft rejection with high specific binding towards IL-27Rα on allograft and low imaging background.

Multiomics analysis couples mRNA turnover and translational control of glutamine metabolism to the differentiation of the activated CD4+ T cell

The ZFP36 family of RNA-binding proteins acts post-transcriptionally to repress translation and promote RNA decay. Studies of genes and pathways regulated by the ZFP36 family in CD4⁺ T cells have focussed largely on cytokines, but their impact on metabolic reprogramming and differentiation is unclear. Using CD4⁺ T cells lacking Zfp36 and Zfp36l1, we combined the quantification of mRNA transcription, stability, abundance and translation with crosslinking immunoprecipitation and metabolic profiling to determine how they regulate T cell metabolism and differentiation. Our results suggest that ZFP36 and ZFP36L1 act directly to limit the expression of genes driving anabolic processes by two distinct routes: by targeting transcription factors and by targeting transcripts encoding rate-limiting enzymes. These enzymes span numerous metabolic pathways including glycolysis, one-carbon metabolism and glutaminolysis. Direct binding and repression of transcripts encoding glutamine transporter SLC38A2 correlated with increased cellular glutamine content in ZFP36/ZFP36L1-deficient T cells. Increased conversion of glutamine to α-ketoglutarate in these cells was consistent with direct binding of ZFP36/ZFP36L1 to Gls (encoding glutaminase) and Glud1 (encoding glutamate dehydrogenase). We propose that ZFP36 and ZFP36L1 as well as glutamine and α-ketoglutarate are limiting factors for the acquisition of the cytotoxic CD4⁺ T cell fate. Our data implicate ZFP36 and ZFP36L1 in limiting glutamine anaplerosis and differentiation of activated CD4⁺ T cells, likely mediated by direct binding to transcripts of critical genes that drive these processes.

Tristetraprolin regulates phagocytosis through interaction with CD47 in head and neck cancer

CD47 is expressed in all human cancer cells, including head and neck cancer, and initiates a signaling cascade to inhibit macrophage phagocytosis. However, the mechanism underlying CD47 overexpression has not been elucidated in radioresistant head and neck cancer. The present study demonstrated that decreased Tristetraprolin (TTP) expression induced a sustained overexpression of CD47 using reverse transcription-quantitative PCR and western blotting, and that CD47 overexpression prevented phagocytosis using a phagocytosis assay in a radioresistant HN31R cell line. Subsequently, using TTP transfection, RNA interference, duel-luciferase assay and EMSA, it was revealed that TTP transfection enhanced phagocytosis through degradation of CD47 mRNA by directly binding to CD47 AREs within the CD47 3'UTR. Based on our previous study, methylation-specific PCR and western blotting revealed that DNMT1 was overexpressed in radioresistant HN31R cell line and TTP expression was decreased epigenetically by DMNT1 associated DNA methylation. Overall, these findings provided novel insight into the role of TTP as a biomarker of CD47-positive head and neck cancer patients.

Biogenesis and engineering of interleukin 12 family cytokines

Interleukin 12 (IL-12) family cytokines are secreted proteins that regulate immune responses. Each family member is a heterodimer and nature uses shared building blocks to assemble the functionally distinct IL-12 cytokines. In recent years we have gained insights into the molecular principles and cellular regulation of IL-12 family biogenesis. For each of the family members, generally one subunit depends on its partner to acquire its native structure and be secreted from immune cells. If unpaired, molecular chaperones retain these subunits in cells. This allows cells to regulate and control secretion of the highly potent IL-12 family cytokines. Molecular insights gained into IL-12 family biogenesis, structure, and function now allow us to engineer IL-12 family cytokines to develop novel immunotherapeutic approaches.

The timing of differentiation and potency of CD8 effector function is set by RNA binding proteins

CD8+ T cell differentiation into effector cells is initiated early after antigen encounter by signals from the T cell antigen receptor and costimulatory molecules. The molecular mechanisms that establish the timing and rate of differentiation however are not defined. Here we show that the RNA binding proteins (RBP) ZFP36 and ZFP36L1 limit the rate of differentiation of activated naïve CD8+ T cells and the potency of the resulting cytotoxic lymphocytes. The RBP function in an early and short temporal window to enforce dependency on costimulation via CD28 for full T cell activation and effector differentiation by directly binding mRNA of NF-κB, Irf8 and Notch1 transcription factors and cytokines, including Il2. Their absence in T cells, or the adoptive transfer of small numbers of CD8+ T cells lacking the RBP, promotes resilience to influenza A virus infection without immunopathology. These findings highlight ZFP36 and ZFP36L1 as nodes for the integration of the early T cell activation signals controlling the speed and quality of the CD8+ T cell response.

PD-L1 and ICOSL discriminate human Secretory and Helper dendritic cells in cancer, allergy and autoimmunity

Dendritic cells (DC) are traditionally classified according to their ontogeny and their ability to induce T cell response to antigens, however, the phenotypic and functional state of these cells in cancer does not necessarily align to the conventional categories. Here we show, by using 16 different stimuli in vitro that activated DCs in human blood are phenotypically and functionally dichotomous, and pure cultures of type 2 conventional dendritic cells acquire these states (termed Secretory and Helper) upon appropriate stimuli. PD-L1highICOSLlow Secretory DCs produce large amounts of inflammatory cytokines and chemokines but induce very low levels of T helper (Th) cytokines following co-culturing with T cells. Conversely, PD-L1lowICOSLhigh Helper DCs produce low levels of secreted factors but induce high levels and a broad range of Th cytokines. Secretory DCs bear a single-cell transcriptomic signature indicative of mature migratory LAMP3+ DCs associated with cancer and inflammation. Secretory DCs are linked to good prognosis in head and neck squamous cell carcinoma, and to response to checkpoint blockade in Melanoma. Hence, the functional dichotomy of DCs we describe has both fundamental and translational implications in inflammation and immunotherapy.

Phenotypic and functional states of dendritic cells critically influence the outcome of cancer and inflammation. Authors here show by single cell transcriptomics and in vitro validation assays that dichotomous PD-L1 and ICOSL expression assign dendritic cells to secretory and helper functions, with respective predominance of inflammatory cytokine expression or T helper cytokine induction.

IL-27 mediates anti-inflammatory effect in cigarette smoke induced emphysema by negatively regulating IFN-γ producing cytotoxic CD8+ T cells in mice

Chronic airway inflammation mediated by CD8+ T lymphocytes contributes to the pathogenesis of Chronic obstructive pulmonary disease (COPD). Deciphering the fingerprint of the chronic inflammation orchestrated by CD8+ T cells may allow the development of novel approaches to COPD management. Here, the expression of IL-27 and IFN-γ+ CD8+ Tc1 cells were evaluated in patients with COPD and in cigarette smoke-exposed mice. The production of IL-27 by marrow-derived dendritic cells (mDCs) in response to cigarette smoke extract (CSE) was assessed. The role of IL-27 in IFN-γ+ CD8+ Tc1 cells was explored. We demonstrated that elevated IL-27 was accompanied by an exaggerated IFN-γ+ CD8+ Tc1 response in a smoking mouse model of emphysema. We noted that lung dendritic cells were one of the main sources of IL-27 during chronic cigarette smoke exposure. Moreover, CSE directly induced the production of IL-27 by mDCs in vitro. IL-27 negatively regulated the differentiation of IFN-γ+ CD8+ Tc1 cells isolated from cigarette smoke-exposed mice in a STAT1- and STAT3-independent manner. Systemic administration of recombinant IL-27 attenuated IFN-γ+ CD8+ Tc1 response in the late phase of cigarette smoke exposure. Our results uncovered that IL-27 negatively regulates IFN-γ+ CD8+ Tc1 response in the late stage of chronic cigarette smoke exposure, which may provide a new strategy for the anti-inflammatory treatment of smoking-related COPD/emphysema.

Biochemistry-Guided Prediction of the Absolute Configuration of Fungal Reduced Polyketides

Highly reducing polyketide synthases (HR-PKSs) produce structurally diverse polyketides (PKs). The PK diversity is constructed by a variety of factors, including the β-keto processing, chain length, methylation pattern, and relative and absolute configurations of the substituents. We examined the stereochemical course of the PK processing for the synthesis of polyhydroxy PKs such as phialotides, phomenoic acid, and ACR-toxin. Heterologous expression of a HR-PKS gene, a trans-acting enoylreductase gene, and a truncated non-ribosomal peptide synthetase gene resulted in the formation of a linear PK with multiple stereogenic centers. The absolute configurations of the stereogenic centers were determined by chemical degradation followed by comparison of the degradation products with synthetic standards. A stereochemical rule was proposed to explain the absolute configurations of other reduced PKs and highlights an error in the absolute configurations of a reported structure. The present work demonstrates that focused functional analysis of functionally related HR-PKSs leads to a better understanding of the stereochemical course.

The dual role of IL-27 in CD4+T cells

Interleukin-27 (IL-27), a member of the IL-6/IL-12 family, has diverse regulatory functions in various immune responses, and is recognised as a potent agonist and antagonist of CD4+T cells in different contexts. However, this dual role and underlying mechanisms have not been completely defined. In the present review, we summarise the dual role of IL-27 in CD4+T cells. In particular, we aimed to decipher its mechanism to better understand the context-dependent function of IL-27 in CD4+T cells. Furthermore, we propose a possible mechanism for the dual role of IL-27. This may be helpful for the development of appropriate IL-27 treatments in various clinical settings.

Tristetraprolin destabilizes NOX2 mRNA and protects dopaminergic neurons from oxidative damage in Parkinson's disease

Tristetraprolin (TTP), an RNA-binding protein encoded by the ZFP36 gene, is vital for neural differentiation; however, its involvement in neurodegenerative diseases such as Parkinson's disease (PD) remains unclear. To explore the role of TTP in PD, an in vitro 1-methyl-4-phenylpyridinium (MPP⁺ ) cell model and an in vivo 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) of PD were used. Transfection of small interfering (si)-TTP RNA upregulated pro-oxidative NOX2 expression and ROS formation, downregulated anti-oxidative GSH and SOD activity；si-TTP upregulated pro-apoptotic cleaved-caspase-3 expression, and downregulated antiapoptotic Bcl-2 expression; while overexpression (OE)-TTP lentivirus caused opposite effects. Through database prediction, luciferase experiment, RNA immunoprecipitation (RIP), and mRNA stability analysis, we evaluated the potential binding sites of TTP to 3'-untranslated regions (3'-UTR) of NOX2 mRNA. TTP affected the NOX2 luciferase activity by binding to two sites in the NOX2 3'-UTR. RIP-qPCR confirmed TTP binding to both sites, with a higher affinity for site-2. In addition, TTP reduced the NOX2 mRNA stability. si-NOX2 and antioxidant N-acetyl cysteine (NAC) reversed si-TTP-induced cell apoptosis. In MPTP-treated mice, TTP expression increased and was co-located with dopaminergic neurons. TTP also inhibited NOX2 and decreased the oxidative stress in vivo. In conclusion, TTP protects against dopaminergic oxidative injury by promoting NOX2 mRNA degradation in the MPP⁺ /MPTP model of PD, suggesting that TTP could be a potential therapeutic target for regulating the oxidative stress in PD.

Construction and validation of a TP53-associated immune prognostic model for gastric cancer

Increasing evidence indicates that TP53 mutation impacts the patients' prognosis by regulating the gastric cancer (GC) immunophenotype. An immune prognostic signature (IPS) was constructed based on TP53 status. The effects of the IPS on the immune microenvironment of GC were analyzed. We also constructed a nomogram integrating the IPS and other clinical factors. An IPS was constructed in the TCGA cohort and validated in the meta-GEO cohort. TP53 mutation resulted in the downregulation of the immune response in GC. Concretely, high-risk patients were characterized by increased monocyte, macrophage M0 and T cell follicular helper infiltration; increased stromal score, ESTIMATE score and immune score; higher TIM3 and BTLA expression; and decreased dendritic cell and T cell CD4 memory-activated infiltration and tumor purity. The nomogram also showed good predictive performance. These results suggest that the IPS is an effective prognostic indicator for GC patients, which might provide a theoretical foundation for immunotherapy.

Tristetraprolin Regulates TH17 Cell Function and Ameliorates DSS-Induced Colitis in Mice

TH17 cells have been extensively investigated in inflammation, autoimmune diseases, and cancer. The precise molecular mechanisms for TH17 cell regulation, however, remain elusive, especially regulation at the post-transcriptional level. Tristetraprolin (TTP) is an RNA-binding protein important for degradation of the mRNAs encoding several proinflammatory cytokines. With newly generated T cell-specific TTP conditional knockout mice (CD4CreTTPf/f), we found that aging CD4CreTTPf/f mice displayed an increase of IL-17A in serum and spontaneously developed chronic skin inflammation along with increased effector TH17 cells in the affected skin. TTP inhibited TH17 cell development and function by promoting IL-17A mRNA degradation. In a DSS-induced colitis model, CD4CreTTPf/f mice displayed severe colitis and had more TH17 cells and serum IL-17A compared with wild-type mice. Furthermore, neutralization of IL-17A reduced the severity of colitis. Our results reveal a new mechanism for regulating TH17 function and TH17-mediated inflammation post-transcriptionally by TTP, suggests that TTP might be a novel therapeutic target for the treatment of TH17-mediated diseases.

Wnt/CTNNB1 Signal Transduction Pathway Inhibits the Expression of ZFP36 in Squamous Cell Carcinoma, by Inducing Transcriptional Repressors SNAI1, SLUG and TWIST

The Wnt/CTNNB1 pathway is often deregulated in epithelial tumors. The ZFP36 gene, encoding the mRNA binding protein Tristetraprolin (TTP), is downregulated in several cancers, where it has been described to behave as a tumor suppressor. By this report, we show that Wnt/CTNNB1 pathway is constitutively activated, and ZFP36 expression is downregulated in Squamous Cell Carcinoma (SCC) cell lines compared to normal keratinocytes. Moreover, we suggest that the decrease of ZFP36 expression might depend on the activity of transcriptional repressors SNAI1, SLUG and TWIST, whose expression is induced by Wnt/CTNNB1, highlighting a potential regulatory mechanism underlying ZFP36 downregulation in epithelial cancers.

The Tristetraprolin Family of RNA-Binding Proteins in Cancer: Progress and Future Prospects

Post-transcriptional regulation of gene expression plays a key role in cellular proliferation, differentiation, migration, and apoptosis. Increasing evidence suggests dysregulated post-transcriptional gene expression as an important mechanism in the pathogenesis of cancer. The tristetraprolin family of RNA-binding proteins (RBPs), which include Zinc Finger Protein 36 (ZFP36; commonly referred to as tristetraprolin (TTP)), Zinc Finger Protein 36 like 1 (ZFP36L1), and Zinc Finger Protein 36 like 2 (ZFP36L2), play key roles in the post-transcriptional regulation of gene expression. Mechanistically, these proteins function by binding to the AU-rich elements within the 3′-untranslated regions of their target mRNAs and, in turn, increasing mRNA turnover. The TTP family RBPs are emerging as key regulators of multiple biological processes relevant to cancer and are aberrantly expressed in numerous human cancers. The TTP family RBPs have tumor-suppressive properties and are also associated with cancer prognosis, metastasis, and resistance to chemotherapy. Herein, we summarize the various hallmark molecular traits of cancers that are reported to be regulated by the TTP family RBPs. We emphasize the role of the TTP family RBPs in the regulation of trait-associated mRNA targets in relevant cancer types/cell lines. Finally, we highlight the potential of the TTP family RBPs as prognostic indicators and discuss the possibility of targeting these TTP family RBPs for therapeutic benefits.

Effects of tristetraprolin on doxorubicin (adriamycin)-induced experimental kidney injury through inhibiting IL-13/STAT6 signal pathway

To study the effects of Tristetraprolin (TTP) on Doxorubicin (DOX)-induced experimental kidney injury (KI). DOX was used to induce kidney injury in Balb/c male mice (in vivo) and in human kidney proximal tubular epithelial cell line (HK-2) and normal rat kidney epithelial cell line (NRK-52E) (in vitro). Body weight of experimental mice were recorded daily. Histological changes were observed using hematoxylin-eosin (HE) staining, and levels of blood urea nitrogen, serum creatinine and serum cystatin C in KI mice, and MDA, LDH and SOD in cells were detected using the corresponding kits. Meanwhile, the 2, 7-dichlorodihydrofluorescein diacetate (DCF-DA) fluorescent staining was used to assess intracellular levels of reactive oxygen species (ROS). TTP and Kim-1 expressions were measured by immunohistochemistry and western blot. The TNF-α, IL-1β and IL-6 levels were evaluated by ELISA. Expressions of IL-13, STAT6, p-STAT6, Bcl-2, Bax, cleaved-caspase3 were detected using western blot, respectively. Cell Counting Kit-8 (CCK-8) was conducted for analyzing cell viability, and cells apoptosis were assessed by DAPI staining and flow cytometry. DOX treatment decreased body weight and aggravated renal injury without changes in water and food intake. DOX significantly reduced TTP expression, stimulated IL-13/STAT6 pathway and elevated the levels of several factors related to renal injury, including inflammatory response, oxidative stress and cell apoptosis, which were significantly restored by the treatment of overexpression TTP in vitro. Overexpression of TTP significantly reduces DOX-induced adverse outcomes so as to prevent renal injury. Inhibition of IL-13/STAT6 pathway may be the functional mechanism under TTP in experimental KI.

Tristetraprolin targets Nos2 expression in the colonic epithelium

Tristetraprolin (TTP), encoded by the Zfp36 gene, is a zinc-finger protein that regulates RNA stability primarily through association with 3′ untranslated regions (3′ UTRs) of target mRNAs. While TTP is expressed abundantly in the intestines, its function in intestinal epithelial cells (IECs) is unknown. Here we used a cre-lox system to remove Zfp36 in the mouse epithelium to uncover a role for TTP in IECs and to identify target genes in these cells. While TTP was largely dispensable for establishment and maintenance of the colonic epithelium, we found an expansion of the proliferative zone and an increase in goblet cell numbers in the colon crypts of Zfp36^ΔIEC mice. Furthermore, through RNA-sequencing of transcripts isolated from the colons of Zfp36^fl/fl and Zfp36^ΔIEC mice, we found that expression of inducible nitric oxide synthase (iNos or Nos2) was elevated in TTP-knockout IECs. We demonstrate that TTP interacts with AU-rich elements in the Nos2 3′ UTR and suppresses Nos2 expression. In comparison to control Zfp36^fl/fl mice, Zfp36^ΔIEC mice were less susceptible to dextran sodium sulfate (DSS)-induced acute colitis. Together, these results demonstrate that TTP in IECs targets Nos2 expression and aggravates acute colitis.

Targeting the "undruggable" RAS - new strategies - new hope?

K-RAS is the most frequently mutated oncogene in solid tumors, such as pancreatic, colon or lung cancer. The GTPase K-RAS can either be in an active (GTP-loaded) or inactive (GDP-loaded) form. In its active form K-RAS forwards signals from growth factors, cytokines or hormones to the nucleus, regulating essential pathways, such as cell proliferation and differentiation. In turn, activating somatic mutations of this proto-oncogene deregulate the complex interplay between GAP (GTPase-activating) - and GEF (Guanine nucleotide exchange factor) - proteins, driving neoplastic transformation. Due to a rather shallow surface, K-RAS lacks proper binding pockets for small molecules, hindering drug development over the past thirty years. This review summarizes recent progress in the development of low molecular antagonists and further shows insights of a newly described interaction between mutant K-RAS signaling and PD-L1 induced immunosuppression, giving new hope for future treatments of K-RAS mutated cancer.

Genomic analysis reveals selection signatures of the Wannan Black pig during domestication and breeding

Objective

The Wannan Black pig is a typical Chinese indigenous, disease-resistant pig breed with high fertility, and a crude-feed tolerance that has been bred by artificial selection in the south of Anhui province for a long time. However, genome variation, genetic relationships with other pig breeds, and domestication, remain poorly understood. Here, we focus on elucidating the genetic characteristics of the Wannan Black pig and identifying selection signatures during domestication and breeding.

Methods

We identified the whole-genome variation in the Wannan Black pig and performed population admixture analyses to determine genetic relationships with other domesticated pig breeds and wild boars. Then, we identified the selection signatures between the Wannan Black pig and Asian wild boars in 100-kb windows sliding in 10 kb steps by using two approaches: the fixation index (F_ST) and π ratios.

Results

Resequencing the Wannan Black pig genome yielded 501.52 G of raw data. After calling single-nucleotide variants (SNVs) and insertions/deletions (InDels), we identified 21,316,754 SNVs and 5,067,206 InDels (2,898,582 inserts and 2,168,624 deletions). Additionally, we found genes associated with growth, immunity, and digestive functions.

Conclusion

Our findings help in explaining the unique genetic and phenotypic characteristics of Wannan Black pigs, which in turn can be informative for future breeding programs of Wannan Black pigs.

RAS and PD-L1: A Masters' Liaison in Cancer Immune Evasion

Mutant RAS is a major oncoprotein in human cancer and PD-L1 is a key driver of cancer immune evasion. In this issue of Immunity, Coelho et al. (2017) demonstrate that oncogenic RAS signaling promotes tumor immune escape by stabilizing PD-L1 mRNA.

Cardiovascular inflammation: RNA takes the lead

Inflammation has recently gained tremendous attention as a key contributor in several chronic diseases. While physiological inflammation is essential to counter a wide variety of damaging stimuli and to improve wound healing, dysregulated inflammation such as in the myocardium and vasculature can promote cardiovascular diseases. Given the high severity, prevalence, and economic burden of these diseases, understanding the factors involved in the regulation of physiological inflammation is essential. Like other complex biological phenomena, RNA-based processes are emerging as major regulators of inflammatory responses. Among such processes are cis-regulatory elements in the mRNA of inflammatory genes, noncoding RNAs directing the production or localization of inflammatory cytokines/chemokines, or pathogenic RNA driving inflammatory responses. In this review, we describe several specific RNA-based molecular mechanisms by which physiological inflammation pertaining to cardiovascular diseases is regulated. These include the role of AU-rich element-containing mRNAs, long non-coding RNAs, microRNAs, and viral RNAs.

Anti-CD8 monoclonal antibody-mediated depletion alters the phenotype and behavior of surviving CD8+ T cells

It is common practice for researchers to use antibodies to remove a specific cell type to infer its function. However, it is difficult to completely eliminate a cell type and there is often limited or no information as to how the cells which survive depletion are affected. This is particularly important for CD8+ T cells for two reasons. First, they are more resistant to mAb-mediated depletion than other lymphocytes. Second, targeting either the CD8α or CD8β chain could induce differential effects. We show here that two commonly used mAbs, against either the CD8α or CD8β subunit, can differentially affect cellular metabolism. Further, in vivo treatment leaves behind a population of CD8+ T cells with different phenotypic and functional attributes relative to each other or control CD8+ T cells. The impact of anti-CD8 antibodies on CD8+ T cell phenotype and function indicates the need to carefully consider the use of these, and possibly other "depleting" antibodies, as they could significantly complicate the interpretation of results or change the outcome of an experiment. These observations could impact how immunotherapy and modulation of CD8+ T cell activation is pursued.

IL-27 Production and Regulation in Human Dendritic Cells Treated with the Chemical Sensitizer NiSO4

Allergic contact dermatitis (ACD) is a major cause of occupational skin disease, and nickel is among the most prevalent contact allergens. Dendritic cells (DC) play an important role in ACD and in the type of the ensuing immune response through differential phenotypes and cytokine production. The interleukin (IL)-12 cytokine family is composed of heterodimeric cytokines sharing homology at the subunit, receptors and signaling levels. We previously showed that nickel can upregulate the production of IL-12p40 and IL-23, both known to be pro-inflammatory. In this work, we aimed to extend our knowledge on nickel regulation of the IL-12 cytokine family by focusing on IL-27, a recently identified immunomodulatory cytokine from this family. We showed that nickel induced the production of IL-27 in human monocyte-derived DC (MoDC), regulating IL-22 production by human CD4+ T cells. We also showed that nickel was able to induce the expression of the two subunits of IL-27: il-27p28 and ebi3. Furthermore, we demonstrated that the production of IL-27 was dependent on the TLR4, p38 MAPK, NF-κB, and Jak-STAT signaling. However, IL-27 subunits were differentially regulated by these pathways. Indeed, both subunits were positively regulated by the TLR4 and NF-κB pathways, but only il-27p28 was also dependent on p38 MAPK and Jak-STAT pathways. Our results contribute to a better understanding of nickel-induced ACD by focusing on the IL-12 cytokine family and elucidating the mechanism of IL-27 regulation in human dendritic cells.

Tristetraprolin activation by resveratrol inhibits the proliferation and metastasis of colorectal cancer cells

Resveratrol (RSV) is a polyphenolic compound that naturally occurs in grapes, peanuts and berries. Considerable research has been conducted to determine the benefits of RSV against various human cancer types. Tristetraprolin (TTP) is an AU-rich element-binding protein that regulates mRNA stability and has decreased expression in human cancer. The present study investigated the biological effect of RSV on TTP gene regulation in colon cancer cells. RSV inhibited the proliferation and invasion/metastasis of HCT116 and SNU81 colon cancer cells. Furthermore, RSV induced a dose-dependent increase in TTP expression in HCT116 and SNU81 cells. The microarray experiment revealed that RSV significantly increased TTP expression by downregulating E2F transcription factor 1 (E2F1), a downstream target gene of TTP and regulated genes associated with inflammation, cell proliferation, cell death, angiogenesis and metastasis. Although TTP silencing inhibited TTP mRNA expression, the expression was subsequently restored by RSV. Small interfering RNA-induced TTP inhibition attenuated the effects of RSV on cell growth. In addition, RSV induced the mRNA-decaying activity of TTP and inhibited the relative luciferase activity of baculoviral IAP repeat containing 3 (cIAP2), large tumor suppressor kinase 2 (LATS2), E2F1, and lin‑28 homolog A (Lin28) in HCT116 and SNU81 cells. Therefore, RSV enhanced the inhibitory activity of TTP in HCT116 and SNU81 cells by negatively regulating cIAP2, E2F1, LATS2, and Lin28 expression. In conclusion, RSV suppressed the proliferation and invasion/metastasis of colon cancer cells by activating TTP.