Role In Repression Research Articles

Molecular basis of anti-CRISPR operon repression by Aca10.

CRISPR-Cas systems are bacterial defense systems for fighting against invaders such as bacteriophages and mobile genetic elements. To escape destruction by these bacterial immune systems, phages have co-evolved multiple anti-CRISPR (Acr) proteins, which inhibit CRISPR-Cas function. Many acr genes form an operon with genes encoding transcriptional regulators, called anti-CRISPR-associated (Aca) proteins. Aca10 is the most recently discovered Aca family that is encoded within an operon containing acrIC7 and acrIC6 in Pseudomonas citronellolis. Here, we report the high-resolution crystal structure of an Aca10 protein to unveil the molecular basis of transcriptional repressor role of Aca10 in the acrIC7-acrIC6-aca10 operon. We identified that Aca10 forms a dimer in solution, which is critical for binding specific DNA. We also showed that Aca10 directly recognizes a 21 bp palindromic sequence in the promoter of the acr operon. Finally, we revealed that R44 of Aca10 is a critical residue involved in the DNA binding, which likely results in a high degree of DNA bending.

SMNDC1 links chromatin remodeling and splicing to regulate pancreatic hormone expression.

Insulin expression is primarily restricted to the pancreatic β cells, which are physically or functionally depleted in diabetes. Identifying targetable pathways repressing insulin in non-β cells, particularly in the developmentally related glucagon-secreting α cells, is an important aim of regenerative medicine. Here, we perform an RNA interference screen in a murine α cell line to identify silencers of insulin expression. We discover that knockdown of the splicing factor Smndc1 triggers a global repression of α cell gene-expression programs in favor of increased β cell markers. Mechanistically, Smndc1 knockdown upregulates the β cell transcription factor Pdx1 by modulating the activities of the BAF and Atrx chromatin remodeling complexes. SMNDC1's repressive role is conserved in human pancreatic islets, its loss triggering enhanced insulin secretion and PDX1 expression. Our study identifies Smndc1 as a key factor connecting splicing and chromatin remodeling to the control of insulin expression in human and mouse islet cells.

CDK9 activity switch associated with AFF1 and HEXIM1 controls differentiation initiation from epidermal progenitors

Progenitors in epithelial tissues, such as human skin epidermis, continuously make fate decisions between self-renewal and differentiation. Here we show that the Super Elongation Complex (SEC) controls progenitor fate decisions by directly suppressing a group of “rapid response” genes, which feature high enrichment of paused Pol II in the progenitor state and robust Pol II elongation in differentiation. SEC’s repressive role is dependent on the AFF1 scaffold, but not AFF4. In the progenitor state, AFF1-SEC associates with the HEXIM1-containing inactive CDK9 to suppress these rapid-response genes. A key rapid-response SEC target is ATF3, which promotes the upregulation of differentiation-activating transcription factors (GRHL3, OVOL1, PRDM1, ZNF750) to advance terminal differentiation. SEC peptidomimetic inhibitors or PKC signaling activates CDK9 and rapidly induces these transcription factors within hours in keratinocytes. Thus, our data suggest that the activity switch of SEC-associated CDK9 underlies the initial processes bifurcating progenitor fates between self-renewal and differentiation.

Financial inclusion and banking stability: Does interest rate repression matter?

The role of interest rate repression in affecting banks’ behavior has been well-studied in the literature. What has not been examined is how financial inclusion affects this relationship. Using cross-country data, we test the association between financial inclusion and banking stability in the presence of interest rate repression. Using bank-level data, we find that financial inclusion exerts a positive and statistically significant impact on banking stability, notwithstanding interest rate repression. The findings support the fact that financial inclusion is beneficial for banking stability, even after accounting for interest rate controls.

Disulfiram inhibits liver fibrosis in rats by suppressing hepatic stellate cell activation and viability

BackgroundLiver fibrosis is a wound-healing response to chronic injury, featuring with excess accumulation of extracellular matrix secreted by the activated hepatic stellate cells (HSC). Disulfiram (DSF), also known as Antabuse, has been used for the treatment of alcohol addiction and substance abuse. Recently, overwhelming studies had revealed anti-cancer effects of DSF in multiple cancers, including liver cancer. But the actual effects of DSF on liver fibrosis and liver function remain unknown.MethodsIn this study, we evaluated the effects of low-dose DSF in CCl4- and Bile Duct Ligation (BDL)—induced hepatic fibrosis rat models. Cell proliferation was detected by using the Cell-Light™ EdU Apollo®567 Cell Tracking Kit. Cell apoptosis was analyzed using a TdT-mediated dUTP nick end labeling (TUNEL) kit, viability was measured with Cell Counting Kit-8(CCK8). Relative mRNA expression of pro-fibrogenic was assessed using quantitative RT-PCR. The degree of liver fibrosis, activated HSCs, were separately evaluated through Sirius Red-staining, immunohistochemistry and immunofluorescence. Serum alanine aminotransferase (ALT) and asparagine aminotransferase (AST) activities were detected with ALT and AST detecting kits using an automated analyzer.ResultsLiver fibrosis was distinctly attenuated while liver functions were moderately ameliorated in the DSF-treated group. Activation and proliferation of primary rat HSCs isolated from rat livers were significantly suppressed by low-dose DSF. DSF also inhibited the viability of in vitro cultured rat or human HSC cells dose-dependently but had no repressive role on human immortalized hepatocyte THLE-2 cells. Interestingly, upon DSF treatment, the viability of LX-2 cells co-cultured with THLE-2 was significantly inhibited, while that of THLE-2 co-cultured with LX-2 was increased. Further study indicated that HSCs apoptosis was increased in DSF/CCl4-treated liver samples. These data indicated that DSF has potent anti-fibrosis effects and protective effects toward hepatocytes and could possibly be repurposed as an anti-fibrosis drug in the clinic.ConclusionsDSF attenuated ECM remodeling through suppressing the transformation of quiet HSCs into proliferative, fibrogenic myofibroblasts in hepatic fibrosis rat models. DSF provides a novel approach for the treatment of liver fibrosis.

Reciprocal Interactions Between Regulatory T Cells and Intestinal Epithelial Cells.

It has been well established that Foxp3+ regulatory T cells (Treg cells) play a crucial role for immune repression and tolerance, protecting the body from autoimmunity and inflammation. Previous studies indicate that intestinal Treg cells are one specialized population of Treg cells, distinct from those in other organ compartments, both functionally and phenotypically. Specific external and internal signals, particularly the presence of microbiota, shape these Treg cells to better cooperate with the gut ecosystem, controlling intestinal physiology. The integrity of intestinal epithelial barrier represents a key feature of gut immune tolerance, which can be regulated by multiple factors. Emerging evidence suggests that bidirectional interactions between gut epithelium and resident T cells significantly contribute to intestinal barrier function. Understanding how Treg cells regulate intestinal barrier integrity provides insights into immune tolerance-mediated mucosal homeostasis, which can further illuminate potential therapeutic strategies for treating inflammatory bowel disease and colon cancer.

Novel L-RNA Aptamer Controls APP Gene Expression in Cells by Targeting RNA G-Quadruplex Structure.

Guanine quadruplex (G4) structure is a four-stranded nucleic acid secondary structure motif with unique chemical properties and important biological roles. Amyloid precursor protein (APP) is an Alzheimer's disease (AD)-related gene, and recently, we reported the formation of RNA G4 (rG4) at the 3'UTR of APP mRNA and demonstrated its repressive role in translation. Herein, we apply rG4-SELEX to develop a novel L-RNA aptamer, L-Apt.8f, which binds to APP 3'UTR D-rG4 strongly with subnanomolar affinity. We structurally characterize the aptamer and find that it contains a thermostable and parallel G4 motif, and mutagenesis analysis identifies the key nucleotides that are involved in the target recognition. We also reveal that the L-Apt.8f-APP D-rG4 interaction is enantiomeric-, magnesium ion-, and potassium ion-dependent. Notably, L-Apt.8f preferentially recognizes APP rG4 over other structural motifs, and it can control the APP reporter gene and native transcript translation in cells. Our work introduces a novel strategy and reports a new L-aptamer candidate to target APP 3'UTR rG4 structure, which laid the foundation for further applying L-RNA as an important class of biomolecule for practical L-aptamer-based targeting and controlling of gene expression in cells.

P1407: CDK6 IN HEMATOPOIETIC STEM CELLS: MORE THAN A CELL CYCLE KINASE

Background: Cell cycle kinase CDK6 acts as a transcriptional regulator and links cell cycle progression to differentiation and cellular homeostasis. CDK6 has been implicated in the initiation and progression of lymphoid and myeloid malignancies and regulates the balance of long-term hematopoietic stem cell (LT-HSC) dormancy and activation. CDK6 acts in a kinase-dependent and kinase-independent way to regulate haematopoiesis. Aims: As CDK4/6 inhibitors have entered the clinics, we aim at understanding and dissecting kinase-dependent and independent-functions of CDK6 in adult HSCs with application of different stress conditions. Methods: To investigate kinase-independent effects of CDK6 in HSCs, we made use of a mouse model harbouring a kinase inactivated mutant of CDK6 (Cdk6KM/KM). We performed in vivo serial transplantation and homing assays to study HSC re-population capacity. Low-input RNA-Seq of LT-HSCs after the 2nd serial transplantation round was used to understand transcriptional effects. Stressed haematopoiesis was further induced by chemical treatment with polyI:C. Results:Cdk6-/- HSCs are impaired in their ability to re-populate. This was not the case for Cdk6KM/KM hematopoietic cells evidenced by re-plating assays in vitro and serial transplantation settings in vivo. Cdk6KM/KM derived LT-HSCs maintain a stem-cell signature and express genes indicative for HSC dormancy at high levels compared to wild type LT-HSCs. Transcriptional analysis pointed to an altered and improved homing of Cdk6KM/KM LT-HSCs, which was confirmed in homing assays in vivo. This indicates a repressive role of CDK6 in stem cell homing. Upon polyI:C treatment, Cdk6KM/KM mice reacted with decreased stimulation as more Lin-Sca-1+c-kit+ (LSK) cells were residing in the bone marrow. Summary/Conclusion: Our data uncovers kinase-dependent and kinase-independent functions of CDK6 for HSC self-renewal and homing. Whereas serial transplantation settings and homing depend on kinase-inactive CDK6, poly-I:C treatment relies on kinase-activity.

A novel kinase subverts aluminium resistance by boosting ornithine decarboxylase‐dependent putrescine biosynthesis

Rice, as one of the most aluminium (Al)-resistant cereal crops, has developed more complicated Al resistance mechanisms than others. By using forward genetic screening from a rice ethyl methanesulfonate mutant library, we obtained a mutant showing specifically high sensitivity to Al. Through MutMap analysis followed by a complementation test, we identified the causal gene, Al-related Protein Kinase (ArPK) for Al-sensitivity. ArPK expression was induced by a relatively longer exposure to high Al concentration in the roots. The result of RNA-sequencing indicated the functional disorder in arginine metabolism pathway with downregulation of N-acetylornithine deacetylase (NAOD) expression and upregulation of Ornithine decarboxylase1 (ODC1) expression in arpk mutant. Al specifically and rapidly upregulated ODC1 expression and causes overaccumulation of putrescine (Put), whereas the ODC inhibitor difluoromethylornithine reverted Al-sensitive phenotype of arpk, suggesting that overaccumulation of endogenous Put might be harmful for root growth, and that ArPK seems to act as an endogenous inhibitor of ODC1 action to maintain suitable endogenous Put level under Al treatment. Overall, we identified ArPK and its putative repressive role in controlling a novel ODC-dependent Put biosynthesis pathway specifically affecting rice Al resistance, thus enriching the fundamental understanding of plant Al resistance.

Abstract 5721: c-Myc expression coupled with loss of cytoplasmic Miz-1 expression and its re-localization to a nuclear expression in high grade cholangio and hepatocholangio carcinomas

Abstract Miz-1 (Myc-interacting zinc finger) activates target genes through transcription factors that are regulated by specific antimitogenic signals. Association with Myc converts Miz-1 from being a transcriptional activator to a repressor. This binding and the formation of Myc/Miz-1 complex induces a change in the biophysical properties of the Miz-1 protein, rendering the complex insoluble and causing to relocalize inside the nucleus. In addition, this association stabilizes Myc and as a result represses transcription. With uncontrolled tumor progress, metastatic tumor expansion can occur through epithelial-to-mesenchymal transition (EMT) and the induction of ZEB-1 (Zinc Finger E-Box Binding Homeobox-1). Zeb-1 expression is highly associated with aggressive behavior tumor types. A cohort of 98 human cholangiocarcinoma carcinoma (CC) including 14 with mixed (CC)/(HCC) resected cases whose formalin fixed paraffin embedded (FFPE) tissue sections containing adjacent benign and malignant tumor lesions were examined by immunohistochemistry (IHC) using Miz-1 (ZBTB17), ZEB-1 (OT13G6), c-Myc (Y69), and Ki-67 (Mib-1) monoclonal antibodies. The clinicopathologic variables, including viral hepatitis, cirrhosis, tumor size, grade and number, vascular invasion, tumor-node-metastasis (TNM) stage, were obtained from each patient’s medical records. The variables were assessed for correlation with the immunohistochemical results. Compared to the adjacent benign liver section, reduction of Miz-1 expression was observed in 98/98 (100%) (P<0.0001) cases, while positive expression of c-Myc, Ki-67 (> 5%), and ZEB-1 was observed in 18/98 (18.36%) (P<0.0001), 27/98 (27.55%) (P=0.000003), and 15/98 (15.30%) (P<0.00001) cases respectively. Of note, complete loss of Miz-1 expression was noted in 20/36 (55.55%) (P=0.106) high grade tumors (III/IV) associated with positive c-Myc, Ki-67 (>5%), ZEB-1, and nuclear Miz-1 expression in 12/20 (60%) (P=0.12) cases (4 CC and 8 mixed (CC)/(HCC) cases). All 12 cases with positive ZEB-1 had confirmed positive lymph node involvement. These results support the role of Miz-1 as one of the intermediary checkpoints required for the induction of cell cycle arrest and apoptosis. Positive c-Myc/ZEB-1 coupled with Miz-1 reduced cytoplasmic and its re-localization to a nuclear expression confirms the transcriptional repressor role of the Myc/Miz-1 complex and the activation of the ZEB-1 gene as a predictor of increased metastatic expansion, therapy resistance, and poor survival in high grade CC, and CC/HCC cases. These findings correlate with a cohort of an adequate number of differently graded lesions from 147 HCC cases that showed similar expression pattern of Miz-1, c-Myc and Zeb-1 to better confirm our hypothesis in epithelial derived human malignancies with frequently amplified 8q24 chromosome. Citation Format: Joeffrey J. Chahine, Sumeyye Culfaci, DongHyang Kwon, Pamela Tuma, Bhaskar V.S. Kallakury. c-Myc expression coupled with loss of cytoplasmic Miz-1 expression and its re-localization to a nuclear expression in high grade cholangio and hepatocholangio carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5721.

Abstract 974: Genome-wide analysis of estrogen receptor b binding sites: Implications for endogenous anti-metastatic activity in inflammatory breast cancer

Abstract Inflammatory breast cancer (IBC) is a highly metastatic breast carcinoma with high frequency of estrogen receptor a (ERa) negativity. We previously explored the second ER subtype, (ERb) and reported expression in IBC tumors and its correlation with reduced metastasis in patients. We have also seen decreased metastasis of IBC tumors when ERb is expressed or activated by chemical agonists. In contrast, ablation of ERb in IBC cells increased migration and stimulated signaling pathways that activate Rho GTPases promoting actin reorganization. We have now mapped all ERb binding sites in IBC cells and by interrogating this information together with gene expression data we identified genomic targets that mediate its tumor repressive effects. Through a combined analysis of cells that express endogenous ERb and knockout cells engineered to re-express the receptor we have defined how a biologically relevant ERb interacts with the cancer cell genome to control metastatic signals in IBC. We reveal key binding motifs and cis-regulatory chromatin sites and associate target genes with clinical outcomes to strengthen the relevance of ERb signaling for the progression of IBC. Our findings thus offer an opportunity to better understand the mechanism of ERb action that is critical step in validating its tumor repressive role in breast cancer. Citation Format: Ilias V. Karagounis, Spyros Tastsoglou, Anna Karavangeli, Amit Maity, Artemis Chatzigeorgiou, Christoforos Thomas. Genome-wide analysis of estrogen receptor b binding sites: Implications for endogenous anti-metastatic activity in inflammatory breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 974.

Prognostic value of EZH2 expression for immunotherapy-based schemes in advanced soft-tissue sarcoma: A translational research from Spanish Group of Research on Sarcoma (GEIS).

11549 Background: Immunotherapy-based treatments had shown to be active in several solid tumors, including in selected subtypes of sarcomas. IMMUNOSARC (NCT03277924) is a phase Ib/II trial [from Spanish (GEIS) and Italian (ISG) sarcoma groups], that tested the combination of nivolumab (anti-PD-1 inhibitor) plus sunitinib (anti-angiogenic agent) in advanced sarcomas. Among the 65 soft-tissue sarcoma (STS) patients (pts) enrolled, 48% were free of progression at 6 months, meeting the trial’s primary endpoint. EZH2 is the catalytic subunit of the Polycomb Repressive Complex 2 and it has been described to play an important role in the transcriptional repression of genes involved in T-cell migration and T-cell-mediated anti-tumor activity. The aim of this study was to explore the value of EZH2 gene expression as potential prognostic biomarker of the activity of immunotherapy-based schemes. Methods: The expression of EZH2 was evaluated in 64 paraffin tumor blocks, by direct transcriptomics, using HTG EdgeSeq Oncology Biomarkers Panel (HTG Molecular Diagnostics, Inc.; Tucson, AZ, USA). Data was normalized with DESeq2 and the cut-off of EZH2 expression was calculated with MAXSTAT R package. Gene expression was correlated with progression-free survival (PFS) by RECIST, overall survival (OS) and clinical benefit (patients with response or stable disease vs patients with progressive disease as best response). Results: Among the 64 pts analyzed, 52 (81%) showed overexpression of EZH2, considering a cut-off of 570.15 read counts. Undifferentiated pleomorphic sarcoma (UPS) and epithelioid sarcoma were the subtypes with higher expression of EZH2 with a median of read counts of 1888.04 (n = 10) and 1261.79 (n = 7), respectively. The lowest expressions were observed in extraskeletal myxoid chondrosarcoma (ECM) and alveolar soft-part sarcoma (ASPS) with a median of read counts of 461.42 (n = 4) and 680.84 (n = 7), respectively. Low expression of EZH2 was associated with better PFS (16.8 months vs. 3.9 months; p = 0.001) and better OS (NR vs. 20.0 months; p = 0.006). Moreover, low expression of EZH2 was also significantly associated with a clinical benefit of the patients treated with nivolumab plus sunitinib [relative risk (RR): 13; 95% CI: 3.0-56.9; p = < 0.001). Conclusions: Low expression of EZH2 was associated with better outcome in advanced STS patients treated with immunotherapy-based schemes. These results might support the rationale for the combination of EZH2 inhibitors with immune-modulating agents for future studies.

Beyond Defection: Explaining the Tunisian and Egyptian militaries’ divergent roles in the Arab Spring

ABSTRACT This article challenges conventional accounts of the Tunisian and Egyptian militaries’ role in the Arab Spring, emphasizing the very different bargaining versus containing logic through which the countries’ autocrats maintained political control of the military. Whereas traditional approaches emphasize the common outcome that neither military fired on protesters, this article highlights three areas of difference in military behavior: the militaries’ role in repression (beyond nor firing on protesters); managing the regime crises; and removing or sustaining the regime. In so doing, it also argues against interpretations of the Tunisian military that it remained loyal or passive. To the contrary, the article shows how the Tunisian military was a decidedly political actor, playing a profound role in ending the regime.

PACT establishes a posttranscriptional brake on mitochondrial biogenesis by promoting the maturation of miR-181c

The double-stranded RNA-dependent protein kinase activating protein (PACT), an RNA-binding protein that is part of the RNA-induced silencing complex, plays a key role in miR-mediated translational repression. Previous studies showed that PACT regulates the expression of various miRs, selects the miR strand to be loaded onto RNA-induced silencing complex, and determines proper miR length. Apart from PACT’s role in mediating the antiviral response in immune cells, what PACT does in other cell types is unknown. Strikingly, it has also been shown that cold exposure leads to marked downregulation of PACT protein in mouse brown adipose tissue (BAT), where mitochondrial biogenesis and metabolism play a central role. Here, we show that PACT establishes a posttranscriptional brake on mitochondrial biogenesis (mitobiogenesis) by promoting the maturation of miR-181c, a key suppressor of mitobiogenesis that has been shown to target mitochondrial complex IV subunit I (Mtco1) and sirtuin 1 (Sirt1). Consistently, we found that a partial reduction in PACT expression is sufficient to enhance mitobiogenesis in brown adipocytes in culture as well as during BAT activation in mice. In conclusion, we demonstrate an unexpected role for PACT in the regulation of mitochondrial biogenesis and energetics in cells and BAT.

Retinoblastoma-E2F Transcription Factor Interplay Is Essential for Testicular Development and Male Fertility.

The retinoblastoma (RB) protein family members (pRB, p107 and p130) are key regulators of cell cycle progression, but also play crucial roles in apoptosis, and stem cell self-renewal and differentiation. RB proteins exert their effects through binding to E2F transcription factors, which are essential developmental and physiological regulators of tissue and organ homeostasis. According to the canonical view, phosphorylation of RB results in release of E2Fs and induction of genes needed for progress of the cell cycle. However, there are eight members in the E2F transcription factor family with both activator (E2F1-3a) and repressor (E2F3b–E2F8) roles, highlighting the functional diversity of RB-E2F pathway. In this review article we summarize the data showing that RB-E2F interaction is a key cell-autonomous mechanism responsible for establishment and maintenance of lifelong male fertility. We also review the expression pattern of RB proteins and E2F transcription factors in the testis and male germ cells. The available evidence supports that RB and E2F family members are widely and dynamically expressed in the testis, and they are known to have versatile roles during spermatogenesis. Knowledge of the function and significance of RB-E2F interplay for testicular development and spermatogenesis comes primarily from gene knock-out (KO) studies. Several studies conducted in Sertoli cell-specific pRB-KO mice have demonstrated that pRB-mediated inhibition of E2F3 is essential for Sertoli cell functional maturation and cell cycle exit, highlighting that RB-E2F interaction in Sertoli cells is paramount to male fertility. Similarly, ablation of either pRB or E2F1 in the germline results in progressive testicular atrophy due to germline stem cell (GSC) depletion, emphasizing the importance of proper RB-E2F interplay for germline maintenance and lifelong sperm production. In summary, while balanced RB-E2F interplay is essential for cell-autonomous maintenance of GSCs and, the pRB-E2F3 system in Sertoli cells is critical for providing GSC niche thus laying the basis for spermatogenesis.

Evaluation of CRISPR/Cas9 mediated TGIF gene editing to inhibit corneal fibrosis in vitro

Corneal wound healing is influenced by many factors including transcriptional co-repressors and co-activators. Interactions of co-activators and co-repressors with Smads influence mechanistic loop facilitating transcription of alpha-smooth muscle actin (α-SMA), a key profibrotic gene, in corneal repair. The role of a transcriptional repressor, 5′TG3′-interacting factor (TGIF), in the regulation of α-SMA and myofibroblast formation in the cornea was shown previously by our group. This study tested a hypothesis if TGIF1 gene editing via CRISPR/Cas9 can ease myofibroblast formation in the cornea using an in vitro model. Primary human corneal stromal fibroblasts (hCSFs) generated from donor corneas received gene-editing plasmid facilitating loss (CRISPR/Cas9 knockout) or gain (CRISPR activation) of TGIF function by UltraCruz transfection reagent. Phase-contrast microscopy, immunoblotting, immunocytochemistry and quantitative polymerase chain reaction (qPCR) were used to measure levels of myofibroblast profibrotic genes (α-SMA, fibronectin, Collagen-I, and Collagen-IV) in hCSFs lacking or overexpressing TGIF1 after growing them in± transforming growth factor beta1 (TGF-β1) under serum-free conditions. The CRISPR-assisted TGIF1 activation (gain of function) in hCSFs demonstrated significantly decreased myofibroblast formation and messenger ribonucleic acid (mRNA) and protein levels of profibrotic genes. Conversely, CRISPR/Cas9-assisted TGIF knockdown (loss of function) in hCSFs demonstrated no significant change in the levels of myofibroblast formation or profibrotic genes under similar conditions. These results suggest that TGIF gene-editing approach can be employed to modulate the transcriptional activity of α-SMA in controlling pathological and promoting physiological wound healing in an injured cornea.

Aiolos restrains the acquisition of cytotoxic features by CD4+ T cells

Abstract Classically, CD4+ T cells have been defined as “helper” type cells, providing aid to other immune cell populations via the secretion of cytokines and direct cell-cell interactions. More recently, a subset of CD4+ T cells with cytotoxic capabilities, termed CD4+ cytotoxic T lymphocytes (CD4-CTLs), have been observed in both mice and humans, performing protective functions in the settings of infection and cancer while conversely contributing to the pathogenesis of autoimmunity. Despite their well-documented importance in several disease contexts, the complete mechanisms that underlie their differentiation and function remain unknown. Here, we identify the Ikaros family member, Aiolos, as a novel regulator of CD4+ CTL differentiation and function. We find that Aiolos deficiency results in increased expression of key CD4+ CTL transcription factors and effector molecules both in vitro and in an in vivo murine model of influenza infection. Mechanistically, we find that Aiolos deficiency results in increased IL-2/STAT5 signaling, supporting a repressive role for Aiolos in CD4+ CTL differentiation via negative regulation of the IL-2/STAT5 pathway. Collectively, this work identifies Aiolos as a novel negative regulator of CD4+ cytotoxic gene programming, and thus may represent a therapeutic target for the treatment of autoimmune diseases and enhanced anti-tumor immunity. Sponsored by a grant from NIAID (NIH-RO1 AI134972) and funds through The Ohio State University College of Medicine

Combined multiple transcriptional repression mechanisms generate ultrasensitivity and oscillations.

Transcriptional repression can occur via various mechanisms, such as blocking, sequestration and displacement. For instance, the repressors can hold the activators to prevent binding with DNA or can bind to the DNA-bound activators to block their transcriptional activity. Although the transcription can be completely suppressed with a single mechanism, multiple repression mechanisms are used together to inhibit transcriptional activators in many systems, such as circadian clocks and NF-κB oscillators. This raises the question of what advantages arise if seemingly redundant repression mechanisms are combined. Here, by deriving equations describing the multiple repression mechanisms, we find that their combination can synergistically generate a sharply ultrasensitive transcription response and thus strong oscillations. This rationalizes why the multiple repression mechanisms are used together in various biological oscillators. The critical role of such combined transcriptional repression for strong oscillations is further supported by our analysis of formerly identified mutations disrupting the transcriptional repression of the mammalian circadian clock. The hitherto unrecognized source of the ultrasensitivity, the combined transcriptional repressions, can lead to robust synthetic oscillators with a previously unachievable simple design.

Role of mTOR through Autophagy in Esophageal Cancer Stemness.

Simple SummaryEsophageal cancer (EC) is a highly aggressive disease with a poor prognosis, which seems related to esophageal cancer stem-like cells (CSCs), which reside in a hypoxic niche. We demonstrated, using EC cell lines and patient-derived organoids, that the hypoxia-responding mammalian target of rapamycin (mTOR) can suppress autophagy and stemness of esophageal CSCs. In addition, mTOR inhibitor Torin-1-mediated CSCs upregulation was significantly reduced in cells treated with autophagy inhibitor, hydroxychloroquine (HCQ). Collectively, our data suggest that autophagy may play a crucial role in mTOR-mediated CSCs repression. The mTOR pathway could be a novel therapeutic target for putative esophageal CSCs.Esophageal cancer (EC) is a highly aggressive disease with a poor prognosis. Therapy resistance and early recurrences are major obstacles in reaching a better outcome. Esophageal cancer stem-like cells (CSCs) seem tightly related with chemoradiation resistance, initiating new tumors and metastases. Several oncogenic pathways seem to be involved in the regulation of esophageal CSCs and might harbor novel therapeutic targets to eliminate CSCs. Previously, we identified a subpopulation of EC cells that express high levels of CD44 and low levels of CD24 (CD44+/CD24−), show CSC characteristics and reside in hypoxic niches. Here, we aim to clarify the role of the hypoxia-responding mammalian target of the rapamycin (mTOR) pathway in esophageal CSCs. We showed that under a low-oxygen culture condition and nutrient deprivation, the CD44+/CD24− population is enriched. Since both low oxygen and nutrient deprivation may inhibit the mTOR pathway, we next chemically inhibited the mTOR pathway using Torin-1. Torin-1 upregulated SOX2 resulted in an enrichment of the CD44+/CD24− population and increased sphere formation potential. In contrast, stimulation of the mTOR pathway using MHY1485 induced the opposite effects. In addition, Torin-1 increased autophagic activity, while MHY1485 suppressed autophagy. Torin-1-mediated CSCs upregulation was significantly reduced in cells treated with autophagy inhibitor, hydroxychloroquine (HCQ). Finally, a clearly defined CD44+/CD24− CSC population was detected in EC patients-derived organoids (ec-PDOs) and here, MHY1485 also reduced this population. These data suggest that autophagy may play a crucial role in mTOR-mediated CSCs repression. Stimulation of the mTOR pathway might aid in the elimination of putative esophageal CSCs.

Contribution of TWIST1-EVX1 Axis in Invasiveness of Esophageal Squamous Cell Carcinoma; a Functional Study.

Epithelial-mesenchymal transition (EMT) is a biological process in embryonic development and cancer progression, and different gene families, such as HOX genes, are closely related to this process. Our aim in this study was to investigate the correlation between TWIST1 and EVX1 mRNA expression in ESCC patients and also examine the probable regulatory function of TWIST1 on EVX1 expression in human ESCC cell line. TWIST1 and EVX1 gene expression patterns were assessed in ESCC patients by relative comparative Real-time PCR then correlated with their clinical characteristics. In silico analysis of the EVX1 gene was conducted. KYSE-30 cells were transduced by a retroviral system to ectopically express TWIST1, followed by qRT-PCR to reveal the correlation between TWIST1 and EVX1 gene expression. The expression of TWIST1 and EVX1 was correlated to each other significantly (p=0.005) in ESCC. Of 28 patients with under/normal expression of TWIST1, 22 samples (78.57%) had over/normal expression of EVX1. TWIST1 overexpression was correlated with advanced stages of the tumor (III, IV) (P = 0.019) and lymph node metastasis. However, EVX1 under expression was associated with lymph node metastasis (p = 0.027) and invasiveness of the disease (P = 0.037) in ESCC. Furthermore, retroviral transduction enforced significant overexpression of TWIST1 in GFP-hTWIST-1 approximately 9-fold compared to GFP control cells, causing a - 8.83- fold reduction in EVX1 mRNA expression significantly. Our results indicated the repressive role of TWIST1 on EVX1 gene expression in ESCC. Therefore, our findings can help dissect the molecular mechanism of ESCC tumorigenesis and discover novel therapeutic targets for ESCC invasion and metastasis.