Project description:Background and Aims: The LIM protein AJUBA participates in the regulation of cell adhesion, mitosis, DNA damage, cell differentiation, proliferation, migration and gene transcription, yet its roles in tumor development and progression are poorly defined. The aim is to determine the role of AJUBA in colorectal tumorigenesis. Methods: We performed data mining in Oncomine databases and immunohistochemistry (IHC) assays on 67 paired colorectal cancer (CRC) samples; we manipulated the AJUBA expression in SW-1116 and Caco-2 cells using specific shRNA and overexpression plasmids and performed assays for cell viability, cell cycle and apoptosis; we performed RNA-seq and qRT-PCR assays to identify genes regulated by AJUBA; we performed western blot, co-immunoprecipitation assays to study the interaction of AJUBA and JAK/STAT; Results: We discovered that AJUBA is highly expressed in CRC and promotes CRC cell growth in culture and in xenograted mice via an inhibition of apoptosis by repression of the IFIT2 gene. AJUBA specifically binds the FERM domain of JAK1 to dissociate JAK1 from the IFNγ recepter, resulted in inhibition of STAT1 phosporylation and concomitantly its nuclear translocation. Clinically, the level of AJUBA in CRC specimens is negatively correlated with the levels of IFIT2 and pSTAT1. Conclusion: Ajuba functions as a specific suppressor of the Interferon-activated JAK1/STAT1 signaling to promote colorectal cancer development via an inhibition of Interferon induced apoptosis.
Project description:RNA-seq of Colon cancer cell line Sw480 with Ajuba OE and KD.Colon cancer, along with its potential for recurrence and metastasis is a major health problem. Understanding the proteins and pathways that regulate cell growth and metastasis may provide new targets for patient care. Ajuba is a LIM domain protein often found overexpressed in cancers, however the exact function role of Ajuba in colon cancer is not known. Our data demonstrates that Ajuba is highly expressed in colon cancer cell lines and tumour tissue compared to adjacent non-tumour tissue. Using publicly available data from The Cancer Genome Atlas, we correlated poor colon cancer patient survival with high Ajuba expression. To investigate the function of Ajuba in colon cancer metastasis we transduced cells with lentiviral constructs to knock down and overexpress Ajuba protein and performed an RNA-seq transcriptomic analysis on each modified line. Analysing the pathways enriched in the differentially expressed genes, we found Ajuba to be involved in cell proliferation, migration and differentiation. We confirmed our findings in biological assays, cells depleted of Ajuba were less proliferative, more sensitive to irradiation, migrated less and were less efficient in colony formation. Our data indicates that increased Ajuba expression observed in colon cancer supports proliferation, epithelial-to-mesenchymal transition and metastasis.
Project description:Bladder cancer (BC) is one of the most common cancers in the world. T-cell immunoglobulin and mucin domain 1 (TIM-1) are involved in the progression of multiple tumors. However the role of TIM-1 in BC progression is poorly understood. In this study, we searched the Gene Expression Profiling Interactive Analysis (GEPIA) database and performed immunohistochemistry (IHC) to assess TIM-1 protein expression in bladder cancer (BC) patients. The results demonstrated that BC with high TIM-1 expression was associated with longer overall survival (OS) and disease-specific survival (DSS) than BC with low TIM-1 expression. Overexpression of TIM-1 inhibits BC cell proliferation in both cell culture and animal experiments. RNA sequencing data indicated that interferon-induced protein with tetratricopeptide repeats (IFIT) genes induced by interferon-α (IFN-α) were significantly enriched among the genes upregulated by TIM-1 overexpression. Mechanistically, our data revealed that TIM-1 promotes IFN-α release and activates the IFIT2/p-STAT1 pathway, which is known to be related to tumor cell proliferation. Moreover, knockdown of IFIT2 in TIM-1-overexpressing BC cells hinders the tumor suppressive effect of TIM-1. Our results revealed that TIM-1 is a potential molecular marker for BC prognosis and indicate that high TIM-1 expression suppresses BC cell proliferation in an IFIT2/p-STAT1-dependent manner.
Project description:Dysregulated inflammation is a key driver of disease following infection with the globally important human pathogens, Zika virus (ZIKV) and dengue virus. However, specific mechanisms of inflammation are not well defined. Here, we demonstrate that ZIKV antagonizes mitophagy, or the process of selective degradation of damaged mitochondria. The mechanism of antagonism was through interactions between NS5 and the host protein Ajuba to prevent Ajuba translocation to depolarized mitochondria. We further identify a role of Ajuba in mitophagy through augmenting PINK1 kinase activity. Mitophagy suppression in infected Ajuba-/- cells amplified the cellular integrated stress response (ISR) to promote ZIKV replication, and increased pro-inflammatory cytokine expression dependent on the ISR kinase, PKR. Thus, ZIKV suppresses mitophagy to favor replication and this failure of mitochondrial quality control is translated to inflammation by PKR, suggesting new therapeutic targets to treat flavivirus disease.
Project description:In tumorous conditions, the transcription factor STAT1, traditionally recognized for its anti-tumor role in immunology, exhibits pro-survival characteristics, though the underlying mechanisms remain unclear. Investigating STAT1's function in isogenic colorectal tumor cells with wild-type or mutant KRAS, we found that STAT1 specifically promotes the survival and proliferation of cells with mutant KRAS. Through gene expression profiling, we discovered a previously unknown role of STAT1 in upregulating sterol and lipid biosynthetic genes specifically in mutant KRAS cells. This effect is driven by STAT1’s phosphorylation at serine 727 and its cooperation with STAT3 and STAT5 for the transcriptional upregulation of sterol regulatory element-binding proteins (SREBP) 1 and 2, which boost de novo sterol and lipid biosynthesis. In mutant KRAS cells, STAT1 amplifies the mevalonate pathway, maintaining its serine 727 phosphorylation through the upregulation of RHO GTPase signaling and establishing a positive feedback loop through the transcription factors YAP1 and TEAD4, further driving lipid biosynthesis and tumor growth. Through xenograft tumor assays in mice, we discovered that the STAT1-YAP1 axis plays a role in mutant KRAS tumor cells' resistance to mevalonate pathway inhibitors, which can be overcome by pharmacologically targeting the YAP1-TEAD interaction. Additionally, the STAT1-YAP1 arm is essential for the intrinsic resistance to EGFR-targeting therapy in the mutant KRAS colon cancer cells. These findings indicate that the STAT1-YAP1 pathway plays a significant role in therapy resistance and presents a potential therapeutic target in mutant KRAS colorectal cancer. We used microarrays to detail the global programme of gene expression underlying genes commonly regulated by STAT1 and YAP1 in HCT116 cells.
Project description:Deciphering the intricate dynamic events governing type I interferon (IFN) signaling is critical to unravel key regulatory mechanisms in host antiviral defense. Here, we leveraged TurboID-based proximity labeling coupled with affinity purification-mass spectrometry to comprehensively map temporal changes to the proximal human proteomes of all seven canonical type I IFN signaling cascade members following IFN stimulation. This established a network of 108 proteins in close proximity to the core members IFNAR1, IFNAR2, JAK1, TYK2, STAT1, STAT2, and IRF9, and validated several known protein assemblies, while also revealing novel, transient associations between key signaling molecules.
Project description:STAT1 gain-of-function (GOF) variants lead to defective Th17 cell development and chronic mucocutaneous candidiasis (CMC), but frequently also to autoimmunity. STAT1 GOF mutations result in hyperphosphorylation and delayed dephosphorylation of STAT1. However, how the delayed dephosphorylation exactly causes the increased expression of STAT1-dependent genes, and how the intracellular signal transduction from cytokine receptors is affected, remains unknown. In this study we show that the circulating levels of IFN-α in STAT1 GOF patients were not persistently elevated. Nevertheless, the interferon signature was evident even in the patient with low or undetectable IFN-α levels. Chromatin immunoprecipitation (ChIP) experiments showed that the active chromatin mark H3K4me3, was significantly enriched in areas associated with interferon-stimulated genes in STAT1 GOF cells in comparison to normal cells. This suggests that GOF STAT1, while binding to chromatin, promotes epigenetic changes compatible with higher gene expression and elevated reactivity to type I interferons, and interferon-related autoimmunity. We suggest that epigenetic rewiring may be responsible for treatment failure of JAK1/2 inhibitors in certain patients. We also found that after IL-21 stimulation the balance of p-STAT3/p-STAT1 was significantly impaired in patients, which could potentially be applied as a diagnostic test for STAT1 GOF.
Project description:The hair follicle stem cell niche is an immune-privileged microenvironment, characterized by reduced antigen presentation, thus shielding against permanent immune-mediated tissue damage. In this study, we demonstrated the protective role of hair follicle-specific epidermal growth factor receptor (EGFR) against scarring hair follicle destruction. Mechanistically, disruption of EGFR signalling generated a cell-intrinsic hypersensitivity within the JAK-STAT1 pathway, which, synergistically with interferon gamma expressing CD8 T-cell and NK-cell-mediated inflammation, compromised the stem cell niche. Hair follicle-specific genetic depletion of either JAK1/2 or STAT1 or therapeutic inhibition of JAK1/2 ameliorated the inflammation, restored skin barrier function and activated the residual stem cells to resume hair growth in mouse models of epidermal and hair follicle-specific EGFR deletion. Skin biopsies from EGFR inhibitor-treated and cicatricial alopecia patients indicated active STAT1 signalling and interferon target expression. Notably, a case study of folliculitis decalvans, characterized by progressive hair loss, scaling and perifollicular erythema, demonstrated successful treatment with JAK1/2 inhibition. Our findings offer molecular insights and present a mechanism-based therapeutic strategy for addressing chronic folliculitis associated with EGFR-inhibitor anti-cancer therapy and cicatricial alopecia.
Project description:The hair follicle stem cell niche is an immune-privileged microenvironment, characterized by reduced antigen presentation, thus shielding against permanent immune-mediated tissue damage. In this study, we demonstrated the protective role of hair follicle-specific epidermal growth factor receptor (EGFR) against scarring hair follicle destruction. Mechanistically, disruption of EGFR signalling generated a cell-intrinsic hypersensitivity within the JAK-STAT1 pathway, which, synergistically with interferon gamma expressing CD8 T-cell and NK-cell-mediated inflammation, compromised the stem cell niche. Hair follicle-specific genetic depletion of either JAK1/2 or STAT1 or therapeutic inhibition of JAK1/2 ameliorated the inflammation, restored skin barrier function and activated the residual stem cells to resume hair growth in mouse models of epidermal and hair follicle-specific EGFR deletion. Skin biopsies from EGFR inhibitor-treated and cicatricial alopecia patients indicated active STAT1 signalling and interferon target expression. Notably, a case study of folliculitis decalvans, characterized by progressive hair loss, scaling and perifollicular erythema, demonstrated successful treatment with JAK1/2 inhibition. Our findings offer molecular insights and present a mechanism-based therapeutic strategy for addressing chronic folliculitis associated with EGFR-inhibitor anti-cancer therapy and cicatricial alopecia.