Search

Background: Tousled-like kinase 2 (TLK2) is integral to DNA repair, replication, and cell cycle regulation, crucial for maintaining genome stability and integrity. However, the expression and prognostic value of TLK2 in hepatitis B viral (HBV)-related hepatocellular carcinoma (HCC) remains unclear. Methods: We examined TLK2 expression and prognostic implications in pancancer by using diverse databases. Subsequently, TLK2 expression in HBV-related HCC tissues and adjacent tissues was assessed using quantitative real-time PCR and immunohistochemistry. The prognostic value of TLK2 was assessed through ROC curves, time-dependent ROC curves, Cox regression, Kaplan-Meier curve, and decision curve analysis. Additionally, analyses of immune infiltration, proteinprotein interactions, key molecules of tumor-related signaling pathways, molecular subtypes, and TLK2-associated differentially expressed genes (DEGs) were conducted, along with GO/KEGG and GSEA enrichment analyses. Results: TLK2 expression was significantly higher in HCC tissues compared to adjacent tissues and correlated with gender, AFP levels, albumin-bilirubin (ALBI) grade, microvascular invasion (MVI), maximum tumor diameter, tumor number, and TNM stage. TLK2 overexpression emerged as an independent risk factor for overall survival (OS) and recurrence-free survival (RFS) in HBV-related HCC patients. An integrated OS nomogram model, incorporating TLK2, age, ALBI grade, MVI, and tumor number, displayed enhanced prognostic capability (C-index: 0.765, 95% CI: 0.732-0.798) in predicting OS and has a higher net benefit than the TNM stage. Moreover, TLK2 expression correlated closely with immune cell infiltration and key molecules of signaling pathways. Functional enrichment analyses highlighted significant associations with DNA duplex unwinding, double-strand break repair, DNA replication, cell cycle, E2F targets, G2M checkpoint, and MYC targets V1. Conclusion: TLK2 is notably overexpressed in HBV-related HCC and emerges as a promising prognostic biomarker, necessitating further validation. [ABSTRACT FROM AUTHOR]

Background: Dermatofibrosarcoma protuberans (DFSP) is a rare cutaneous sarcoma characterized by local invasion and recurrence. RNA sequencing (RNA-seq) allows the qualification of cellular RNA populations and provides information on the transcriptional state. However, few studies have comprehensively analyzed DFSP transcriptional data. Methods: Fourteen DFSP samples with paired non-neoplastic soft tissue from Chinese patients undergoing Mohs micrographic surgery were used for RNAseq analysis. Differential expression analysis and enrichment analysis for RNAseq data were performed to identify fusion genes, biomarkers, and microenvironment characteristics of DFSP. Results: This study systemically describes the transcriptomic characteristics of DFSP. First, we performed gene fusion analysis and identified a novel FBN1-CSAD fusion event in a DFSP patient with fibrosarcomatous transformation. Then, we identified TLK2 as a biomarker for DFSP based on functional enrichment analysis, and validated its accuracy for diagnosing DFSP by immunohistochemical staining and joint analysis with public data. Finally, microenvironment analysis described the infiltration characteristics of immune and stromal cells in DFSP. Conclusion: This study demonstrates that RNA-seq can serve as a promising strategy for exploring molecular mechanisms in DFSP. Our results provide new insights into accurate diagnosis and therapeutic targets of DFSP. [ABSTRACT FROM AUTHOR]

Objective To explore the effects of TLK2 in breast cancer (BC) cells and its possible mechanism. Methods Immunohistochemistry and Western blot were used to detect the expression of TLK2 in BC tissues and cell lines. RT-qPCR was employed to detect the expression of TLK2 mRNA and miR-622 in BC tissues and cell lines. CCK-8, BrdU and Transwell assays were used to detect the effects of TLK2 over-expression plasmid and miR-622 inhibitors on the proliferation, migration and invasion of HCC70 cells. The targeted regulatory relationship between miR-622 and TLK2 was predicted and verified by Target scanning online analysis database and dual-luciferase reporter gene, respectively. Results The expression of TLK2 in BC tissues or cell lines was significantly up-regulated (P＜0.05), and TLK2 significantly promoted the proliferation, migration and invasion of HCC70 cells (P＜0.01). The possible mechanism suggested that miR-622 can bind to the 3′UTR of TLK2. Conclusions TLK2 is involved in promoting the proliferation, migration and invasion of BC cells, and is negatively regulated by miR-622.

We describe clinical details, including novel findings, of two further children with the newly defined TLK2‐related disorder. One patient was recruited to the Deciphering Developmental Delay (DDD) Study to identify underlying etiology of global developmental delay. The other was detected on whole‐exome sequencing as part of second line investigations following normal microarray. Both patients were found to have de novo heterozygous pathogenic TLK2 variants. A novel c.6del p.(Glu3Lysfs*) loss‐of‐function frameshift variant was found in Patient 1. A c.1121+1G>A splice‐donor variant was detected in Patient 2. TLK2‐related neurodevelopmental disorder is a specific syndrome that has been recently described. Global developmental delay, behavioral problems, gastrointestinal disorders, and typical facial dysmorphism are common features. Neuropsychiatric disorders, ophthalmic, musculoskeletal and cranial abnormalities, as well as short stature, have also all been described. The novel findings we describe include sleep disturbance, nondifferentiation of lateral semi‐circular canals (where asymmetric semi‐circular canals were a feature in the previous cohort), vesico‐ureteric reflux, and bilateral periauricular skin tags. Here, we report a novel TLK2 variant and previously undescribed features of TLK2‐related disorder, to expand the clinical phenotype and provide further genotype–phenotype correlation. [ABSTRACT FROM AUTHOR]

Background: Hepatocellular carcinoma is a widespread cancer worldwide, ranking as the fifth most frequent cancer and the fourth leading cause of cancer-related deaths. According to comprehensive research, TLK2 , a phosphorylated kinase, has been discovered to play a crucial role in promoting tumor development. However, the prognostic significance and influence of TLK2 on hepatocellular carcinoma tumor cells and the immune microenvironment remain unexplored, warranting further investigation. The aim of this study was to investigate the role of TLK2 in promoting the development of hepatocellular carcinoma., Methods: The present study utilized The Cancer Genome Atlas (TCGA) database and other databases as training sets to examine the expression of TLK2 and its prognostic significance. The findings were subsequently validated through cell proliferation assays and cell colony assays. Gene set enrichment analysis (GSEA) was employed to investigate the tumor-related biological processes associated with TLK2 in hepatocellular carcinoma, while the relationship between TLK2 expression and Wnt/β-catenin signaling pathway was analyzed via TCGA dataset analysis. Western blotting and immunofluorescence assays were used to confirm the experimental results., Results: TLK2 showed higher expression levels in tumor tissues than in normal tissues. Alpha fetoprotein (AFP), T stage, pathological stage, and histological grade were significantly associated with TLK2 expression. High TLK2 expression correlated with worse overall survival (OS) [hazard ratio (HR) =1.62, 95% confidence interval (CI): 1.14-2.29, P=0.007], progression-free survival (PFS) (HR =1.88, 95% CI: 1.40-2.52, P<0.001) and disease specific survival (DSS) (HR =1.86, 95% CI: 1.18-2.93, P=0.007) in the training and validation sets. Both univariate and multivariate analyses showed that TLK2 was an independent prognostic factor. GSEA showed that TLK2 was significantly enriched in tumor-related biological processes. TLK2 induced the activation of β-catenin signaling, resulting in sustained tumor growth. Methyl thiazolyl tetrazolium (MTT) and colony formation assays demonstrated that TLK2 could promote hepatocellular carcinoma progression. Furthermore, TLK2 showed a significant association with β-catenin in the Wnt pathway., Conclusions: TLK2 represents an independent prognostic factor in hepatocellular carcinoma and can promote cancer progression via the β-catenin signaling pathway., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tcr.amegroups.com/article/view/10.21037/tcr-23-2264/coif). The authors have no conflicts of interest to declare., (2024 Translational Cancer Research. All rights reserved.)

Summary: The Tousled-like kinases 1 and 2 (TLK1/2) control histone deposition through the ASF1 histone chaperone and influence cell cycle progression and genome maintenance, yet the mechanisms underlying TLK-mediated genome stability remain uncertain. Here, we show that TLK loss results in severe chromatin decompaction and altered genome accessibility, particularly affecting heterochromatic regions. Failure to maintain heterochromatin increases spurious transcription of repetitive elements and induces features of alternative lengthening of telomeres (ALT). TLK depletion culminates in a cGAS-STING-TBK1-mediated innate immune response that is independent of replication-stress signaling and attenuated by the depletion of factors required to produce extra-telomeric DNA. Analysis of human cancers reveals that chromosomal instability correlates with high TLK2 and low STING levels in many cohorts. Based on these findings, we propose that high TLK levels contribute to immune evasion in chromosomally unstable and ALT+ cancers.

Tropical calcific pancreatitis (TCP) is a juvenile form of non-alcoholic chronic pancreatitis seen exclusively in tropical countries. The disease poses a high risk of complications, including pancreatic diabetes and cancer, leading to significant mortality due to poor diagnosis and ineffective treatments. This study employed whole exome sequencing (WES) of 5 TCP patient samples to identify genetic variants associated with TCP. Advanced computational techniques were used to gain atomic-level insights into disease progression, including microsecond-scale long MD simulations and essential dynamics. In silico virtual screening was performed to identify potential therapeutic compounds targeting the mutant protein using the Asinex and DrugBank compound library. WES analysis predicted several single nucleotide variants (SNVs) associated with TCP, including a novel missense variant (c.T1802A or p.V601E) in the TLK2 gene. Computational analysis revealed that the p.V601E mutation significantly affected the structure of the TLK2 kinase domain and its conformational dynamics, altering the interaction profile between ATP and the binding pocket. These changes could impact TLK2's kinase activity and functions, potentially correlating with TCP progression. Promising lead compounds that selectively bind to the TLK2 mutant protein were identified, offering potential for therapeutic interventions in TCP. These findings hold great potential for future research.Communicated by Ramaswamy H. Sarma.

The Tousled-like kinases (TLKs) are an evolutionarily conserved family of serine–threonine kinases that have been implicated in DNA replication, DNA repair, transcription, chromatin structure, viral latency, cell cycle checkpoint control and chromosomal stability in various organisms. The functions of the TLKs appear to depend largely on their ability to regulate the H3/H4 histone chaperone ASF1, although numerous TLK substrates have been proposed. Over the last few years, a clearer picture of TLK function has emerged through the identification of new partners, the definition of specific roles in development and the elucidation of their structural and biochemical properties. In addition, the TLKs have been clearly linked to human disease; both TLK1 and TLK2 are frequently amplified in human cancers and TLK2 mutations have been identified in patients with neurodevelopmental disorders characterized by intellectual disability (ID), autism spectrum disorder (ASD) and microcephaly. A better understanding of the substrates, regulation and diverse roles of the TLKs is needed to understand their functions in neurodevelopment and determine if they are viable targets for cancer therapy. In this review, we will summarize current knowledge of TLK biology and its potential implications in development and disease. [ABSTRACT FROM AUTHOR]

Glioblastoma are among the most common forms of cancer affecting the central nervous system, and yet there is currently no effective means of treating them. In the current study, we reported that tousled-like kinase 2 (TLK2) is a key factor in glioblastoma that modulates SRC signaling, thereby driving tumor malignancy. TLK2 is commonly upregulated in glioblastoma, and such upregulation was associated with poor patient outcomes. TLK2 overexpression induced cell growth, migration, invasion, and epithelial-mesenchymal transition, and cell cycle arrest, while TLK2 knockdown had the opposite effect. SRC pathway inhibition by Saracatinib resulted in reduced TLK2-mediated glioblastoma migration, invasion, confirming a key role for SRC signaling in regulating the functions of TLK2. Together, our findings demonstrate that glioblastoma TLK2 overexpression acts as a key driver of tumor malignancy via SRC signaling pathway. [ABSTRACT FROM AUTHOR]

Background: The Tousled-like kinases 1 and 2 (TLK1/TLK2) regulate DNA replication, repair and chromatin maintenance. TLK2 variants are associated with 'Intellectual Disability, Autosomal Dominant 57' (MRD57), a neurodevelopmental disorder (NDD) characterized by intellectual disability (ID), autism spectrum disorder (ASD) and microcephaly. Several TLK1 variants have been reported in NDDs but their functional significance is unknown., Methods: A male patient presenting with ID, seizures, global developmental delay, hypothyroidism, and primary immunodeficiency was determined to have a novel, heterozygous variant in TLK1 (c.1435C>G, p.Q479E) by genome sequencing (GS). Single cell gel electrophoresis, western blot, flow cytometry and RNA-seq were performed in patient-derived lymphoblast cell lines. In silico, biochemical and proteomic analysis were used to determine the functional impact of the p.Q479E variant and previously reported NDD-associated TLK1 variant, p.M566T., Results: Transcriptome sequencing in patient-derived cells confirmed expression of TLK1 transcripts carrying the p.Q479E variant and revealed alterations in genes involved in class switch recombination and cytokine signaling. Cells expressing the p.Q479E variant exhibited reduced cytokine responses and higher levels of spontaneous DNA damage but not increased sensitivity to radiation or DNA repair defects. The p.Q479E and p.M566T variants impaired kinase activity but did not strongly alter localization or proximal protein interactions., Conclusion: Our study provides the first functional characterization of TLK1 variants associated with NDDs and suggests potential involvement in central nervous system and immune system development. Our results indicate that, like TLK2 variants, TLK1 variants may impact development in multiple tissues and should be considered in the diagnosis of rare NDDs., Competing Interests: Competing interests: none declared.

In order to maintain a stable genome, cells need to detect and repair DNA damage before they complete the division cycle. To this end, cell cycle checkpoints prevent entry into the next cell cycle phase until the damage is fully repaired. Proper reentry into the cell cycle, known as checkpoint recovery, requires that a cell retains its original cell cycle state during the arrest. Here, we have identified Tousled-like kinase 2 (Tlk2) as an important regulator of recovery after DNA damage in G2. We show that Tlk2 regulates the Asf1A histone chaperone in response to DNA damage and that depletion of Asf1A also produces a recovery defect. Both Tlk2 and Asf1A are required to restore histone H3 incorporation into damaged chromatin. Failure to do so affects expression of pro-mitotic genes and compromises the cellular competence to recover from damage-induced cell cycle arrests. Our results demonstrate that Tlk2 promotes Asf1A function during the DNA damage response in G2 to allow for proper restoration of chromatin structure at the break site and subsequent recovery from the arrest. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate genes for differential expression in cartilage of foals predisposed to osteochondrosis (OC). Tissue was sampled from the cranial part of the distal intermediate ridge of the tibia in the tarso-crural joint. Foals were considered predisposed to OC when parents had OC at the distal intermediate ridge of the tibia. RNA was isolated and subjected to arbitrarily primed PCR (RAP-PCR) followed by fingerprinting to screen for differentially expressed genes. By verification of results from the RAP-PCR fingerprint screening using real-time RT-PCR, we identified two genes not previously correlated with OC as differentially expressed. The two genes, which were identical to TLK2 and an equine EST, are good targets for future research on OC. [ABSTRACT FROM AUTHOR]

The Tousled-like kinases 1 and 2 (TLK1/2) control histone deposition through the ASF1 histone chaperone and influence cell cycle progression and genome maintenance, yet the mechanisms underlying TLK-mediated genome stability remain uncertain. Here, we show that TLK loss results in severe chromatin decompaction and altered genome accessibility, particularly affecting heterochromatic regions. Failure to maintain heterochromatin increases spurious transcription of repetitive elements and induces features of alternative lengthening of telomeres (ALT). TLK depletion culminates in a cGAS-STING-TBK1-mediated innate immune response that is independent of replication-stress signaling and attenuated by the depletion of factors required to produce extra-telomeric DNA. Analysis of human cancers reveals that chromosomal instability correlates with high TLK2 and low STING levels in many cohorts. Based on these findings, we propose that high TLK levels contribute to immune evasion in chromosomally unstable and ALT+ cancers. • TLK-deficient cells have increased accessibility at heterochromatin regions • TLK1/2 suppress spurious transcription and telomere hyper-recombination • Extra-telomeric DNA generated upon TLK loss promotes innate immune signaling • cGAS-STING-TBK1 signaling in TLK-deficient cells is independent of replication stress Segura-Bayona et al. find the Tousled-like kinases (TLKs) maintain chromatin at repetitive genome elements and telomeres. TLK depletion results in heterochromatin desilencing and induction of alternative lengthening of telomeres (ALT), robustly activating cGAS-STING-TBK1-mediated innate immune responses. This suggests TLKs represent a druggable vulnerability in ALT+ and chromosomally unstable tumor cells. [ABSTRACT FROM AUTHOR]