DRAK2 participates in a negative feedback loop to control TGF-β/Smads signaling by binding to type I TGF-β receptor

Predictive value of dendritic cell-related genes for prognosis and immunotherapy response in lung adenocarcinoma

BACKGROUND

Patients with lung adenocarcinoma (LUAD) receiving drug treatment often have an unpredictive response and there is a lack of effective methods to predict treatment outcome for patients. Dendritic cells (DCs) play a significant role in the tumor microenvironment and the DCs-related gene signature may be used to predict treatment outcome. Here, we screened for DC-related genes to construct a prognostic signature to predict prognosis and response to immunotherapy in LUAD patients.

METHODS

DC-related biological functions and genes were identified using single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing. DCs-related gene signature (DCRGS) was constructed using integrated machine learning algorithms. Expression of key genes in clinical samples was examined by real-time q-PCR. Performance of the prognostic model, DCRGS, for the prognostic evaluation, was assessed using a multiple time-dependent receiver operating characteristic (ROC) curve, the R package, "timeROC", and validated using GEO datasets.

RESULTS

Analysis of scRNA-seq data showed that there is a significant upregulation of LGALS9 expression in DCs isolated from malignant pleural effusion samples. Leveraging the Coxboost and random survival forest combination algorithm, we filtered out six DC-related genes on which a prognostic prediction model, DCRGS, was established. A high predictive capability nomogram was constructed by combining DCRGS with clinical features. We found that patients with a high-DCRGS score had immunosuppression, activated tumor-associated pathways, and elevated somatic mutational load and copy number variant load. In contrast, patients in the low-DCRGS subgroup were resistant to chemotherapy but sensitive to the CTLA-4 immune checkpoint inhibitor and targeted therapy.

CONCLUSION

We have innovatively established a deep learning-based prediction model, DCRGS, for the prediction of the prognosis of patients with LUAD. The model possesses a strong prognostic prediction performance with high accuracy and sensitivity and could be clinically useful to guide the management of LUAD. Furthermore, the findings of this study could provide an important reference for individualized clinical treatment and prognostic prediction of patients with LUAD.

Methionine deprivation inhibits glioma proliferation and EMT via the TP53TG1/miR-96-5p/STK17B ceRNA pathway

Recent research highlights the significant impact of methionine metabolism on glioma progression. An increasing amount of compelling evidence bridges long non-coding RNAs to abnormal metabolism in gliomas. However, the specific role of long non-coding RNAs in methionine metabolism regulating glioma progression remains unclear. This study reveals that methionine deprivation inhibits the proliferation, migration, and invasion capabilities of gliomas. Interestingly, the expression of TP53TG1, a long non-coding RNA, is also suppressed. TP53TG1 is highly expressed in gliomas and associated with poor patient outcomes. Subsequently, our data proves that inhibition of TP53TG1 suppresses glioma cell proliferation and the epithelial-mesenchymal transition process both in vitro and in vivo. Ultimately, we found that the underlying mechanism involves a competing endogenous RNA regulating network, in which TP53TG1 modulates the target protein STK17B by competitively binding to miR-96-5p, thus regulating glioma progression. These findings suggest that targeting methionine deprivation could be a promising approach for the clinical treatment of glioma.

DRAK2 regulates myosin light chain phosphorylation in T cells

Death-associated protein kinase-related apoptosis-inducing kinase-2 (DRAK2; also known as STK17B) is a serine/threonine kinase expressed in T cells. Drak2-deficient (Drak2-/-) mice respond effectively to tumors and pathogens while displaying resistance to T cell-mediated autoimmune disease. However, the molecular mechanisms by which DRAK2 impacts T cell function remain unclear. Gaining further insight into the function of DRAK2 in T cells will shed light on differentially regulated pathways in autoreactive and pathogen-specific T cells, which is crucial for improving autoimmune therapies. Here, we demonstrate that DRAK2 contributes to activation of myosin light chain (MLC2, encoded by Myl2) in both murine and human T cells. In the absence of Drak2, the amount of polymerized actin was decreased, suggesting that DRAK2 modulates actomyosin dynamics. We further show that myosin-dependent T cell functions, such as migration, T cell receptor microcluster accumulation, and conjugation to antigen presenting cells are decreased in the absence of Drak2. These findings reveal that DRAK2 plays an important role in regulating MLC activation within T cells.

Evaluation of STK17B as a cancer immunotherapy target utilizing highly potent and selective small molecule inhibitors

Introduction

The serine/threonine kinase 17B (STK17B) is involved in setting the threshold for T cell activation and its absence sensitizes T cells to suboptimal stimuli. Consequently, STK17B represents an attractive potential target for cancer immunotherapy.

Methods

To assess the potential of STK17B as an immuno-oncology target, we developed potent and selective tool compounds from starting points in Blueprint Medicines Corporation's proprietary kinase inhibitor library. To characterize these molecules, enzyme and cellular assays for STK17A and STK17B were established to drive chemistry optimization. Mass spectrometry-based phosphoproteomics profiling with tool inhibitors led to the identification of Ser19 on myosin light chain 2 as STK17B substrate, which is then developed into a flow cytometry-based pharmacodynamic readout of STK17B inhibition both in vitro and in vivo.

Results

In a mouse T cell activation assay, STK17B inhibitors demonstrated the ability to enhance interleukin-2 (IL-2) production. Similarly, treatment with STK17B inhibitors resulted in stronger cytokine secretion in human T cells activated using a T cell bispecific antibody. Subsequent chemistry optimization led to the identification of a highly selective and orally bioavailable tool compound, BLU7482. In vivo, STK17B inhibition led to dose-dependent modulation of myosin light chain 2 phosphorylation and enhanced priming of naïve T cells, as determined by upregulation of CD69, IL-2 and interferon-γ secretion. In line with increased T cell activation, treatment with STK17B inhibitor enhanced antitumor activity of anti-PD-L1 antibody in the MCA205 model.

Conclusions

In summary, we successfully identified and optimized STK17B kinase inhibitors which led to increased T cell responses in vitro and in vivo. This allowed us to evaluate the potential of STK17B inhibition as an approach for cancer immunotherapy.

DRAK2 contributes to type 1 diabetes by negatively regulating IL-2 sensitivity to alter regulatory T cell development

Drak2-deficient (Drak2-/-) mice are resistant to multiple models of autoimmunity yet effectively eliminate pathogens and tumors. Thus, DRAK2 represents a potential target to treat autoimmune diseases. However, the mechanisms by which DRAK2 contributes to autoimmunity, particularly type 1 diabetes (T1D), remain unresolved. Here, we demonstrate that resistance to T1D in non-obese diabetic (NOD) mice is due to the absence of Drak2 in T cells and requires the presence of regulatory T cells (Tregs). Contrary to previous hypotheses, we show that DRAK2 does not limit TCR signaling. Rather, DRAK2 regulates IL-2 signaling by inhibiting STAT5A phosphorylation. We further demonstrate that enhanced sensitivity to IL-2 in the absence of Drak2 augments thymic Treg development. Overall, our data indicate that DRAK2 contributes to autoimmunity in multiple ways by regulating thymic Treg development and by impacting the sensitivity of conventional T cells to Treg-mediated suppression.

Targeting Death-Associated Protein Kinases for Treatment of Human Diseases: Recent Advances and Future Directions

The death-associated protein kinase (DAPK) family is a member of the calcium/calmodulin-regulated serine/threonine protein kinase family, and studies have shown that its role, as its name suggests, is mainly to regulate cell death. The DAPK family comprises five members, including DAPK1, DAPK2, DAPK3, DRAK1 and DRAK2, which show high homology in the common N-terminal kinase domain but differ in the extra-catalytic domain. Notably, previous research has suggested that the DAPK family plays an essential role in both the development and regulation of human diseases. However, only a few small-molecule inhibitors have been reported. In this Perspective, we mainly discuss the structure, biological function, and role of DAPKs in diseases and the currently discovered small-molecule inhibitors, providing valuable information for the development of the DAPK field.

New insights into the characteristics of DRAK2 and its role in apoptosis: From molecular mechanisms to clinically applied potential

As a member of the death-associated protein kinase (DAPK) family, DAP kinase-associated apoptosis-inducing kinase 2 (DRAK2) performs apoptosis-related functions. Compelling evidence suggests that DRAK2 is involved in regulating the activation of T lymphocytes as well as pancreatic β-cell apoptosis in type I diabetes. In addition, DRAK2 has been shown to be involved in the development of related tumor and non-tumor diseases through a variety of mechanisms, including exacerbation of alcoholic fatty liver disease (NAFLD) through SRSF6-associated RNA selective splicing mechanism, regulation of chronic lymphocytic leukemia and acute myeloid leukemia, and progression of colorectal cancer. This review focuses on the structure, function, and upstream pathways of DRAK2 and discusses the potential and challenges associated with the clinical application of DRAK2-based small-molecule inhibitors, with the aim of advancing DRAK2 research.

Death-associated protein kinases and intestinal epithelial homeostasis

The family of death-associated protein kinases (DAPKs) and DAPK-related apoptosis-inducing protein kinases (DRAKs) act as molecular switches for a multitude of cellular processes, including apoptotic and autophagic cell death events. This review summarizes the mechanisms for kinase activity regulation and discusses recent molecular investigations of DAPK and DRAK family members in the intestinal epithelium. In general, recent literature convincingly supports the importance of this family of protein kinases in the homeostatic processes that govern the proper function of the intestinal epithelium. Each of the DAPK family of proteins possesses distinct biochemical properties, and we compare similarities in the information available as well as those cases where functional distinctions are apparent. As the prototypical member of the family, DAPK1 is noteworthy for its tumor suppressor function and association with colorectal cancer. In the intestinal epithelium, DAPK2 is associated with programmed cell death, potential tumor-suppressive functions, and a unique influence on granulocyte biology. The impact of the DRAKs in the epithelium is understudied, but recent studies support a role for DRAK1 in inflammation-mediated tumor growth and metastasis. A commentary is provided on the potential importance of DAPK3 in facilitating epithelial restitution and wound healing during the resolution of colitis. An update on efforts to develop selective pharmacologic effectors of individual DAPK members is also supplied.

Prognostic and immune-related value of STK17B in skin cutaneous melanoma

Skin cutaneous melanoma (SKCM) is a common cancer of which mortality is increasing continuously. Our study conducted a series of analyses on the clinical significance of Serine/threonine kinase 17B (STK17B) in SKCM to provide a new biomarker for diagnosis and treatment. The RNA-sequence data were obtained from The Cancer Genome Atlas and Genotype-Tissue Expression databases. The data of 468 SKCM patients were divided into STK17B high- and low-expression groups and analyzed by Bioconductor package to identify the differential expressed genes. The R package of "clusterProfiler" was used for Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene-Set Enrichment Analysis analyses. A protein-protein interaction network and immune infiltration landscape were respectively constructed via STRING database and ssGSEA. STK17B had lower expression in SKCM than normal tissues. Besides, STK17B expression was significantly related to some clinicopathological characteristics in SKCM patients including T stage, Breslow depth, radiation therapy, melanoma Clark level, and pathologic stage. The Kaplan-Meier curve analyses revealed that the low expression of STK17B was correlated with poor overall survival and disease-specific survival. We constructed nomograms to predict the 1-, 3-, and 5-year survival of SKCM patients. The function enrichment analyses showed STK17B-related differential expressed genes were enriched in cellular differentiation and immune-related progress. STK17B expression level were positively correlated with infiltrating level of immune cells. In this study, we found that STK17B, which played an important role in immune infiltration, could be a new biomarker for diagnosis and prognosis in SKCM patients.

The Role of TGF-β Signaling Pathways in Cancer and Its Potential as a Therapeutic Target

The transforming growth factor-β (TGF-β) signaling pathway mediates various biological functions, and its dysregulation is closely related to the occurrence of malignant tumors. However, the role of TGF-β signaling in tumorigenesis and development is complex and contradictory. On the one hand, TGF-β signaling can exert antitumor effects by inhibiting proliferation or inducing apoptosis of cancer cells. On the other hand, TGF-β signaling may mediate oncogene effects by promoting metastasis, angiogenesis, and immune escape. This review summarizes the recent findings on molecular mechanisms of TGF-β signaling. Specifically, this review evaluates TGF-β's therapeutic potential as a target by the following perspectives: ligands, receptors, and downstream signaling. We hope this review can trigger new ideas to improve the current clinical strategies to treat tumors related to the TGF-β signaling pathway.

NUAK1 and NUAK2 Fine-Tune TGF-β Signaling

Simple Summary

TGF-β is a growth factor implicated in a plethora of processes and malignancies, which include cancer and fibrosis. Via binding to its receptor, TGF-β activates a complex intracellular signal transduction pathway, which is controlled by many forms of positive as well as negative feedback. The integrated sum of this feedback determines the outcome and cellular response to TGF-β. In this review, we discuss the role of NUAK1 and NUAK2, a subgroup of the 5′AMP-activated protein kinase family, in providing feedback on intracellular TGF-β signaling. In addition, we discuss how NUAKs mechanistically augment or attenuate the TGF-β response to steer the cell towards a specific output. Understanding the role of NUAKs may aid in developing specific therapeutic agents to combat TGF-β-dependent disease.

Abstract

Transforming growth factor-β (TGF-β) signaling plays a key role in governing various cellular processes, extending from cell proliferation and apoptosis to differentiation and migration. Due to this extensive involvement in the regulation of cellular function, aberrant TGF-β signaling is frequently implicated in the formation and progression of tumors. Therefore, a full understanding of the mechanisms of TGF-β signaling and its key components will provide valuable insights into how this intricate signaling cascade can shift towards a detrimental course. In this review, we discuss the interplay between TGF-β signaling and the AMP-activated protein kinase (AMPK)-related NUAK kinase family. We highlight the function and regulation of these kinases with focus on the pivotal role NUAK1 and NUAK2 play in regulating TGF-β signaling. Specifically, TGF-β induces the expression of NUAK1 and NUAK2 that regulates TGF-β signaling output in an opposite manner. Besides the focus on the TGF-β pathway, we also present a broader perspective on the expression and signaling interactions of the NUAK kinases to outline the broader functions of these protein kinases.

Anti-pyroptotic function of TGF-β is suppressed by a synthetic dsRNA analogue in triple negative breast cancer cells

Development of innovative therapeutic modalities would address an unmet clinical need in the treatment of triple negative breast cancer (TNBC). Activation of retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs) such as melanoma differentiation-associated gene 5 (MDA5) and RIG-I in cancer cells is suggested to suppress tumor progression by inducing cell death. Transfection of polyI:C, a conventionally used synthetic double-stranded RNA (dsRNA) analogue that activates RLRs, has been evaluated in clinical trials. However, detailed mechanisms of tumor suppression by RLRs, especially interactions with other signaling pathways, remain elusive. Here, we showed that transfection of polyI:C suppressed transforming growth factor-β (TGF-β) signaling in a MDA5- and RIG-I-dependent manner. We found that suppression of TGF-β signaling by polyI:C promoted cancer cell death, which was attenuated by forced expression of constitutively active Smad3. More detailed analysis suggested that cell death by polyI:C transfection exhibited characteristics of pyroptosis, which is distinct from apoptosis. Therapeutic efficacy of polyI:C transfection was also demonstrated using a mouse model. These results indicated that intratumor administration of polyI:C and related dsRNA analogues may be promising treatments for TNBC through inhibition of the anti-pyroptotic function of TGF-β.

STK17B promotes the progression of ovarian cancer

Background

Protein kinase is increasingly receiving widespread attention because of its role in the tumor progression. Serine/threonine protein kinase (STK) is an important family involved in the development of a variety of cancers. Many studies have shown that serine/threonine kinase 17B (STK17B) is highly expressed in a variety of malignant tumors and participate in proliferation and metastasis. However, the exact function of STK17B remains uncertain in ovarian cancer. Our study aims to investigate whether STK17B plays a role in the occurrence and development of epithelial ovarian cancer.

Methods

We employed quantitative reverse transcription polymerase chain reaction to detect the relative expression of STK17B in ovarian cancer tissues. STK17B was down-regulated and up-regulated in ovarian cancer cell lines by small interfering RNA and overexpressed plasmid, respectively. The effects of STK17B on proliferation, invasion and migration of ovarian cancer cells in vitro were analyzed by CCK-8 test, Transwell test, scratch test and EDU test. The tumorigenicity of subcutaneous xenograft tumor in nude mice to study the role of STK17B in tumorigenesis in vivo. Western Blotting analysis revealed that STK17B and EMT.

Results

STK17B expression was significantly increased in ovarian cancer tissues. The STK17B silencing suppressed cell progression, while the overexpression of STK17B promoted progression in vivo or in vitro. Western bolt showed that STK17B increased the invasion and migration of ovarian cancer cell by promoting the EMT process.

Conclusions

STK17B was highly expressed in epithelial ovarian cancer tissues and increased the proliferation, invasion and migration of ovarian cancer cells by promoting EMT process.

Harrison C, Eswaran J, Soundararajan M. DAP Kinase-Related Apoptosis-Inducing Protein Kinase 2 (DRAK2) Is a Key Regulator and Molecular Marker in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the Western World and it is characterized by a marked degree of clinical heterogeneity. An impaired balance between pro- and anti-apoptotic stimuli determines chemorefractoriness and outcome. The low proliferation rate of CLL cells indicates that one of the primary mechanisms involved in disease development may be an apoptotic failure. Here, we study the clinical and functional significance of DRAK2, a novel stress response kinase that plays a critical role in apoptosis, T-cell biology, and B-cell activation in CLL. We have analyzed CLL patient samples and showed that low expression levels of DRAK2 were significantly associated with unfavorable outcome in our CLL cohort. DRAK2 expression levels showed a positive correlation with the expression of DAPK1, and TGFBR1. Consistent with clinical data, the downregulation of DRAK2 in MEC-1 CLL cells strongly increased cell viability and proliferation. Further, our transcriptome data from MEC-1 cells highlighted MAPK, NF-κB, and Akt and as critical signaling hubs upon DRAK2 knockdown. Taken together, our results indicate DRAK2 as a novel marker of CLL survival that plays key regulatory roles in CLL prognosis.

Expression pattern of p-Smad2/Smad4 as a predictor of survival in invasive breast ductal carcinoma

The present study examined SMAD family member 4 (Smad4), SMAD family member 2 (Smad2) and phosphorylated (p-)Smad2 expression in biopsy specimens from patients with invasive breast ductal carcinoma, in order to assess their abilities as prognostic markers. A total of 126 tissue samples were selected, and the expression of Smad2, p-Smad2 and Smad4 in carcinoma tissues was detected by immunostaining, and the association between protein expression and clinicopathological variables was analyzed. Smad4 expression was negatively correlated with human epidermal growth factor receptor 2 in carcinoma tissues, and Smad4 expression was consistent with that of p-Smad2. Although multivariate analysis revealed that Smad2, p-Smad2 and Smad4 were not independent predictors, Kaplan-Meier curves demonstrated that Smad4 positivity was correlated with a longer overall survival (OS) and progression-free survival (PFS) time. However, upon analysis of combined markers, there was a significant difference between the p-Smad2/Smad4 co-positive and co-negative patients; the latter tended to exhibit a shorter OS and PFS time, and multivariate analysis revealed that the combined expression of p-Smad2 and Smad4 may be used as an independent prognostic factor. These results suggested that the assessment of p-Smad2 and Smad4 protein expression in breast ductal carcinoma biopsy specimens may provide additional prognostic information.

On-chip crystallization for serial crystallography experiments and on-chip ligand-binding studies

Efficient and reliable sample delivery has remained one of the bottlenecks for serial crystallography experiments. Compared with other methods, fixed-target sample delivery offers the advantage of significantly reduced sample consumption and shorter data collection times owing to higher hit rates. Here, a new method of on-chip crystallization is reported which allows the efficient and reproducible growth of large numbers of protein crystals directly on micro-patterned silicon chips for in-situ serial crystallography experiments. Crystals are grown by sitting-drop vapor diffusion and previously established crystallization conditions can be directly applied. By reducing the number of crystal-handling steps, the method is particularly well suited for sensitive crystal systems. Excessive mother liquor can be efficiently removed from the crystals by blotting, and no sealing of the fixed-target sample holders is required to prevent the crystals from dehydrating. As a consequence, 'naked' crystals are obtained on the chip, resulting in very low background scattering levels and making the crystals highly accessible for external manipulation such as the application of ligand solutions. Serial diffraction experiments carried out at cryogenic temperatures at a synchrotron and at room temperature at an X-ray free-electron laser yielded high-quality X-ray structures of the human membrane protein aquaporin 2 and two new ligand-bound structures of thermolysin and the human kinase DRAK2. The results highlight the applicability of the method for future high-throughput on-chip screening of pharmaceutical compounds.

LncRNA-MIAT regulates fibrosis in hypertrophic cardiomyopathy (HCM) by mediating the expression of miR-29a-3p

AIM

This study aimed to investigate the molecular mechanism underlying the fibrosis in hypertrophic cardiomyopathy (HCM).

METHOD

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to measure the expression of potentially relevant microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) in patients with HCM suffering from fibrosis and patients with HCM free of fibrosis. In addition, the regulatory relationship between lncRNAs and miR-29a was studied using a luciferase assay. Subsequently, area under the receiver-operating characteristics (ROC) curve (AUC) analysis was conducted to predict the diagnostic value of myocardial infarction-associated transcript (MIAT), miR-29a, H19, and MEG3 in patients with HCM. Finally, the predicted regulatory relationship betwe en miR-29a and MIAT was validated by transfecting cells with different plasmids.

RESULT

miR-29a and MIAT were differently expressed between the fibrosis (+) HCM group and the fibrosis (-) HCM group, thus establishing a negative relationship between the expression of these two genes. In addition, both MIAT and miR-29a showed the ability to accurately predict the prognosis in patients with HCM. Furthermore, the luciferase activity of wild-type MIAT was evidently suppressed in cells transfected with miR-29a mimics, suggesting that the expression of miR-29a was apparently downregulated in the presence of MIAT.

CONCLUSION

The results obtained in this study collectively indicated that the MIAT might be associated with the development of fibrosis (+) HCM via negatively regulating the expression of miR-29a.

Serine Threonine Kinase 17A Maintains the Epithelial State in Colorectal Cancer Cells

Serine threonine kinase 17A (STK17A) is a ubiquitously expressed kinase originally identified as a regulator of apoptosis; however, whether it functionally contributes to colorectal cancer has not been established. Here, we have analyzed STK17A in colorectal cancer and demonstrated decreased expression of STK17A in primary tumors, which is further reduced in metastatic lesions, indicating a potential role in regulating the metastatic cascade. Interestingly, changes in STK17A expression did not modify proliferation, apoptosis, or sensitivity of colorectal cancer cell lines to treatment with the chemotherapeutic 5-fluorouracil. Instead, STK17A knockdown induced a robust mesenchymal phenotype consistent with the epithelial-mesenchymal transition, including spindle-like cell morphology, decreased expression of adherens junction proteins, and increased migration and invasion. Additionally, overexpression of STK17A decreased cell size and induced widespread membrane blebbing, a phenotype often associated with activation of cell contractility. Indeed, STK17A-overexpressing cells displayed heightened phosphorylation of myosin light chain in a manner dependent on STK17A catalytic activity. Finally, patient-derived tumor organoid cultures were used to more accurately determine STK17A's effect in primary human tumor cells. Loss of STK17A induced morphologic changes, decreased E-cadherin, increased invasion, and augmented organoid attachment on 2D substrates, all together suggesting a more metastatic phenotype. Collectively, these data indicate a novel role for STK17A in the regulation of epithelial phenotypes and indicate its functional contribution to colorectal cancer invasion and metastasis. IMPLICATIONS: Loss of serine threonine kinase 17A occurs in colorectal cancer metastasis, induces mesenchymal morphologies, and contributes to tumor cell invasion and migration in colorectal cancer.

Discovery and Functional Annotation of Quantitative Trait Loci Affecting Resistance to Sea Lice in Atlantic Salmon

Sea lice (Caligus rogercresseyi) are ectoparasitic copepods which have a large negative economic and welfare impact in Atlantic salmon (Salmo salar) aquaculture, particularly in Chile. A multi-faceted prevention and control strategy is required to tackle lice, and selective breeding contributes via cumulative improvement of host resistance to the parasite. While host resistance has been shown to be heritable, little is yet known about the individual loci that contribute to this resistance, the potential underlying genes, and their mechanisms of action. In this study we took a multifaceted approach to identify and characterize quantitative trait loci (QTL) affecting host resistance in a population of 2,688 Caligus-challenged Atlantic salmon post-smolts from a commercial breeding program. We used low and medium density genotyping with imputation to collect genome-wide SNP marker data for all animals. Moderate heritability estimates of 0.28 and 0.24 were obtained for lice density (as a measure of host resistance) and growth during infestation, respectively. Three QTL explaining between 7 and 13% of the genetic variation in resistance to sea lice (as represented by the traits of lice density) were detected on chromosomes 3, 18, and 21. Characterisation of these QTL regions was undertaken using RNA sequencing and pooled whole genome sequencing data. This resulted in the identification of a shortlist of potential underlying causative genes, and candidate functional mutations for further study. For example, candidates within the chromosome 3 QTL include a putative premature stop mutation in TOB1 (an anti-proliferative transcription factor involved in T cell regulation) and an uncharacterized protein which showed significant differential allelic expression (implying the existence of a cis-acting regulatory mutation). While host resistance to sea lice is polygenic in nature, the results of this study highlight significant QTL regions together explaining between 7 and 13 % of the heritability of the trait. Future investigation of these QTL may enable improved knowledge of the functional mechanisms of host resistance to sea lice, and incorporation of functional variants to improve genomic selection accuracy.

Network Pharmacology and Reverse Molecular Docking-Based Prediction of the Molecular Targets and Pathways for Avicularin Against Cancer

AIM AND OBJECTIVE

Avicularin has been found to inhibit the proliferation of HepG-2 cells in vitro in the screening of our laboratory. We intended to explain the molecular mechanism of this effect. Therefore, the combined methods of reverse molecular docking and network pharmacology were used in order to illuminate the molecular mechanisms for Avicularin against cancer.

MATERIALS AND METHODS

Potential targets associated with anti-tumor effects of Avicularin were screened by reverse molecular docking, then a protein database was established through constructing the drugprotein network from literature mining data, and the protein-protein network was built through an in-depth exploration of the relationships between the proteins, and then the network topology analysis was performed. Additionally, gene function and signaling pathways were analyzed by Go bio-enrichment and KEGG Pathway.

RESULTS

The result showed that Avicularin was closely related to 16 targets associated with cancer, and it may significantly influence the pro-survival signals in MAPK signaling pathway that can activate and regulate a series of cellular activities and participate in the regulation of cell proliferation, differentiation, transformation and apoptosis.

CONCLUSION

The network pharmacology strategy used herein provided a powerful means for the mechanisms of action for bioactive ingredients.

TrkC promotes colorectal cancer growth and metastasis

The current work reveals that TrkC receptor is crucial to many aspects of tumorigenicity and metastasis of cancer. However, with only a few exceptions, such as colorectal cancer (CRC), where suppressing tumorigenic and metastatic ability via expression of TrkC as tumor suppressor have been proposed. These diverse lines of evidence led us to investigate whether TrkC is involved in CRC progression. By using mouse models and molecular biology analyses, we demonstrate that TrkC acts as an activator in tumorigenicity and metastasis of colorectal cancer. In this study, TrkC was frequently overexpressed in CRC cells, patients’ tumor samples and an azoxymethane/dextran sulphate sodium-induced mouse model of colitis-associated CRCs. TrkC expression was associated with a high-grade CRC phenotype, leading to significantly poorer survival. Also, TrkC expression promoted the acquisition of motility and invasiveness in CRC. Moreover, TrkC increased the ability to form tumor spheroids, a property associated with cancer stem cells. Importantly, knockdown of TrkC in malignant mouse or human CRC cells inhibited tumor growth and metastasis in a mouse xenograft model. Furthermore, TrkC enhanced metastatic potential and induced proliferation by aberrant gain of AKT activation and suppression of transforming growth factor (TGF)-β signalling. Interestingly, TrkC not only modulated the actions of TGF-β type II receptor, but also attenuated expression of this receptor. These findings reveal an unexpected physiological role of TrkC in the pathogenesis of CRC. Therefore, TrkC is a potential target for designing effective therapeutic strategies for CRC development.

STK17B promotes carcinogenesis and metastasis via AKT/GSK-3β/Snail signaling in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a lethal malignancy worldwide with frequent intrahepatic and distant metastasis. Elucidating the underlying molecular mechanism that modulates HCC progression is critical for exploring novel therapeutic strategies. Serine/Threonine Kinase 17B (STK17B) is upregulated in HCC tissues, but its role in HCC progression remains elusive. In the present studies, we reported that STK17B had a critical role in HCC progression. STK17B was significantly upregulated in HCC cell lines and specimens, and patients with ectopic STK17B expression characterized with poor clinicopathological features. In vitro and in vivo assay demonstrated that inhibition of STK17B markedly inhibits HCC tumorigenesis and metastasis, while STK17B overexpression promoted these processes. Furthermore, we found that STK17B promoted EMT process via activating AKT/GSK-3β/Snail signal pathway, and miR-455-3p was identified as the upstream regulator of STK17B. Combination of high level of STK17B and low level of miR-455-3p predicted poor prognosis with higher accuracy for HCC patients. In conclusion, our research demonstrated that STK17B promotes HCC progression, induces EMT process via activating AKT/GSK-3β/Snail signal and predicts poor prognosis in HCC.

Feedback regulation of TGF-β signaling

Transforming growth factor beta (TGF-β) is a multi-functional polypeptide that plays a critical role in regulating a broad range of cellular functions and physiological processes. Signaling is initiated when TGF-β ligands bind to two types of cell membrane receptors with intrinsic Ser/Thr kinase activity and transmitted by the intracellular Smad proteins, which act as transcription factors to regulate gene expression in the nucleus. Although it is relatively simple and straight-forward, this TGF-β/Smad pathway is regulated by various feedback loops at different levels, including the ligand, the receptor, Smads and transcription, and is thus fine-tuned in terms of signaling robustness, duration, specificity, and plasticity. The precise control gives rise to versatile and context-dependent pathophysiological functions. In this review, we firstly give an overview of TGF-β signaling, and then discuss how each step of TGF-β signaling is finely controlled by distinct modes of feedback mechanisms, involving both protein regulators and miRNAs.

Effects of miR-29a and miR-101a Expression on Myocardial Interstitial Collagen Generation After Aerobic Exercise in Myocardial-infarcted Rats

BACKGROUND AND AIMS

Myocardial infarction (MI) is accompanied by increased collagen deposition, cell necrosis and angiogenesis in cardiac tissue, which results in reduced ventricular compliance. Both microRNA-29a (miR-29a) and microRNA-101a (miR-101a) target the mRNAs encoding collagens and other proteins involved in fibrosis.

METHODS

We assessed the effects of intermittent aerobic exercise on the expression of cardiac miR-29a and miR-101a and following effects on the TGFβ, fos, Smad2/3, COL1A1 and COL3A1 in MI model of rats. Intermittent aerobic exercise for MI rats was begun from the second week and ended at the ninth week postsurgery. Expressions of microRNAs (miRNAs) and fibrosis-associated genes were detected from the infarction adjacent region located in the left ventricle. The heart coefficient (HC = heart weight/body weight) and hemodynamics assay were used to evaluate cardiac function level.

RESULTS

Intermittent aerobic exercise inhibited myocardial interstitial collagen deposition and significantly improved cardiac function of MI rats. The results of real-time PCR and Western blot indicate that intermittent aerobic exercise enhanced the expression of miR-29a and miR-101a and inhibited TGFβ pathway in the MI rats.

CONCLUSIONS

Our results suggest that controlled intermittent aerobic exercise can inhibit TGFβ pathway via up-regulation to the expression of miR-29a and miR-101a and finally cause a reduced fibrosis and scar formation in cardiac tissue. We believe that controlled intermittent aerobic exercise is beneficial to the healing and discovery of damaged cardiac tissues and their function after MI.

TGF-β Signaling from Receptors to Smads

Transforming growth factor β (TGF-β) and related growth factors are secreted pleiotropic factors that play critical roles in embryogenesis and adult tissue homeostasis by regulating cell proliferation, differentiation, death, and migration. The TGF-β family members signal via heteromeric complexes of type I and type II receptors, which activate members of the Smad family of signal transducers. The main attribute of the TGF-β signaling pathway is context-dependence. Depending on the concentration and type of ligand, target tissue, and developmental stage, TGF-β family members transmit distinct signals. Deregulation of TGF-β signaling contributes to developmental defects and human diseases. More than a decade of studies have revealed the framework by which TGF-βs encode a context-dependent signal, which includes various positive and negative modifiers of the principal elements of the signaling pathway, the receptors, and the Smad proteins. In this review, we first introduce some basic components of the TGF-β signaling pathways and their actions, and then discuss posttranslational modifications and modulatory partners that modify the outcome of the signaling and contribute to its context-dependence, including small noncoding RNAs.

Discovery of indirubin derivatives as new class of DRAK2 inhibitors from high throughput screening

DRAK2 is a serine/threonine kinase belonging to the death-associated protein kinase (DAPK) family and has emerged as a promising drug target for the treatment of autoimmune diseases and cancers. To identify small molecule inhibitors for DRAK2, we performed a high throughput screening campaign using in-house chemical library and identified indirubin-3'-monoximes as novel class of DRAK2 inhibitors. Among the compounds tested, compound 16 exhibited the most potent inhibitory activity against DRAK2 (IC50=0.003μM). We also propose that compound 16 may bind to the ATP-binding site of the enzyme based on enzyme kinetics and molecular docking studies.

Treatment of cholestatic fibrosis by altering gene expression of Cthrc1: Implications for autoimmune and non-autoimmune liver disease

Collagen triple helix repeat containing-1 (Cthrc1) is a documented specific inhibitor of TGF-β signaling. Based on this observation, we developed the hypothesis that knocking in/knocking out the Cthrc1 gene in murine models of cholestasis would alter the natural history of cholestatic fibrosis. To study this thesis, we studied two murine models of fibrosis, first, common bile duct ligation (CBDL) and second, feeding of 3, 5-diethoxy-carbonyl-1, 4-dihydrocollidine (DDC). In both models, we administered well-defined adenoviral vectors that expressed either Cthrc1 or, alternatively, a short hairpin RNA (shRNA)-targeting Cthrc1 either before or after establishment of fibrosis. Importantly, when Cthrc1 gene expression was enhanced, we noted a significant improvement of hepatic fibrosis, both microscopically and by analysis of fibrotic gene expression. In contrast, when Cthrc1 gene expression was deleted, there was a significant exacerbation of fibrosis. To identify the mechanism of action of these significant effects produced by knocking in/knocking out Cthrc gene expression, we thence studied the interaction of Cthrc1 gene expression using hepatic stellate cells (HSCs) and human LX-2 cells. Importantly, we demonstrate that Cthrc1 is induced by TGF-β1 via phospho-Smad3 binding to the promoter with subsequent transcription activation. In addition, we demonstrate that Cthrc1 inhibits TGF-β signaling by accelerating degradation of phospho-Smad3 through a proteosomal pathway. Importantly, the anti-fibrotic effects can be recapitulated with a truncated fragment of Cthrc1. In conclusion, our findings uncover a critical negative feedback regulatory loop in which TGF-β1 induces Cthrc1, which can attenuate fibrosis by accelerating degradation of phospho-Smad3.

Drak2 Does Not Regulate TGF-β Signaling in T Cells

Drak2 is a serine/threonine kinase expressed highest in T cells and B cells. Drak2^-/- mice are resistant to autoimmunity in mouse models of type 1 diabetes and multiple sclerosis. Resistance to these diseases occurs, in part, because Drak2 is required for the survival of autoreactive T cells that induce disease. However, the molecular mechanisms by which Drak2 affects T cell survival and autoimmunity are not known. A recent report demonstrated that Drak2 negatively regulated transforming growth factor-β (TGF-β) signaling in tumor cell lines. Thus, increased TGF-β signaling in the absence of Drak2 may contribute to the resistance to autoimmunity in Drak2^-/- mice. Therefore, we examined if Drak2 functioned as a negative regulator of TGF-β signaling in T cells, and whether the enhanced susceptibility to death of Drak2^-/- T cells was due to augmented TGF-β signaling. Using several in vitro assays to test TGF-β signaling and T cell function, we found that activation of Smad2 and Smad3, which are downstream of the TGF-β receptor, was similar between wildtype and Drak2^-/- T cells. Furthermore, TGF-β-mediated effects on naïve T cell proliferation, activated CD8⁺ T cell survival, and regulatory T cell induction was similar between wildtype and Drak2^-/- T cells. Finally, the increased susceptibility to death in the absence of Drak2 was not due to enhanced TGF-β signaling. Together, these data suggest that Drak2 does not function as a negative regulator of TGF-β signaling in primary T cells stimulated in vitro. It is important to investigate and discern potential molecular mechanisms by which Drak2 functions in order to better understand the etiology of autoimmune diseases, as well as to validate the use of Drak2 as a target for therapeutic treatment of these diseases.

Drak2 is not required for tumor surveillance and suppression

Drak2 is a promising therapeutic target to treat organ-specific autoimmune diseases such as type 1 diabetes and multiple sclerosis without causing generalized immune suppression. Inhibition of Drak2 may also prevent graft rejection following organ transplantation. However, Drak2 may function as a critical tumor suppressor, which would challenge the prospect of targeting Drak2 for therapeutic treatment. Thus, we examined the susceptibility of Drak2 (-/-) mice in several tumor models. We show that Drak2 is not required to prevent tumor formation in a variety of settings. Therefore, Drak2 does not function as an essential tumor suppressor in in vivo tumor models. These data further validate Drak2 as a viable therapeutic target to treat autoimmune disease and graft rejection. Importantly, these data also indicate that while Drak2 may induce apoptosis when overexpressed in cell lines, it is not an essential tumor suppressor.

Cytoplasmic DRAK1 overexpressed in head and neck cancers inhibits TGF-β1 tumor suppressor activity by binding to Smad3 to interrupt its complex formation with Smad4

Head and neck squamous cell carcinoma (HNSCC) is an extremely aggressive cancer with a poor prognosis and low patient survival. Because chemotherapy for advanced HNSCC is often ineffective, discovering new therapeutic targets that are important for HNSCC development and progression and elucidating their molecular mechanisms are required. In the present study, we describe the role of DRAK1 (death-associated protein kinase-related apoptosis-inducing kinase 1) as a novel negative regulator of the transforming growth factor-β (TGF-β) tumor suppressor signaling pathway for the first time in human HNSCC cells. DRAK1 was significantly overexpressed in primary human HNSCCs and in HNSCC cell lines. Through gain- and loss-of-function experiments, we demonstrated that the DRAK1 expression level regulated TGF-β1-induced transcriptional activity and expression of the tumor suppressor gene p21(Waf1/Cip1). DRAK1 depletion enhanced TGF-β1-induced growth inhibition in vitro and suppressed tumorigenicity in xenograft models in vivo. Mechanistically, DRAK1 was predominantly localized in the cytoplasm and bound to Smad3, thereby interrupting Smad3/Smad4 complex formation, which is the core process for the induction of tumor suppressor genes by TGF-β1. Thus, our findings suggest that cytoplasmic DRAK1 increases tumorigenic potential through inhibition of TGF-β1-mediated tumor suppressor activity in HNSCC cells and may be a potential therapeutic target for HNSCCs.

Defect in Runx2 gene accelerates ureteral obstruction-induced kidney fibrosis via increased TGF-β signaling pathway

Runt-related transcription factor 2 (Runx2) plays an important role in bone formation and de novo synthesis of proteins, including type 1 collagen. Runx2 has a potent effect on signaling of transforming growth factor (TGF)-β and vice versa, implicating its significant role in fibrosis. Chronic renal failure comprises fibrosis, characterized as an increase in TGF-β signaling, and expression of α-smooth muscle actin (α-SMA), and extracellular matrix proteins. Here, we evaluated the role of Runx2 in ureteral obstruction (UO)-induced kidney fibrosis using mice whose Runx2 gene expression is genetically down-regulated. UO caused tubular atrophy and dilation, expansion of interstitium, and increased expression of collagens and α-SMA with a concomitant decrease in expression of Runx2. Deficiency of Runx2 gene (Runx2(+/-) mice) showed higher expression of collagens and α-SMA in the kidney following UO compared to wild type (Runx2(+/+)) mice. UO-induced activation of TGF-β signaling was higher in the Runx2(+/-) kidney than Runx2(+/+) kidney, suggesting an inhibitory effect of Runx2 on TGF-β signaling in kidney fibrosis. Besides, overexpression of the Runx2 gene using an adenoviral vector in kidney tubule cells resulted in attenuated TGF-β-induced Smad3 phosphorylation and expressions of α-SMA and collagen I. Furthermore, Runx2 gene deficient mouse embryonic fibroblasts induced greater activation of Smad3 and expression of α-SMA in response to TGF-β. Collectively, Runx2 plays a protective role in UO-induced kidney fibrosis by inhibition of TGF-β signaling, suggesting Runx2 as a novel target for protection against fibrosis-related diseases such as chronic renal failure.