ABSTRACT
Innate immune signaling relies on the deposition of non-degradative polyubiquitin at receptor-signaling complexes, but how these ubiquitin modifications are regulated by deubiquitinases remains incompletely understood. Met1-linked ubiquitin (Met1-Ub) is assembled by the linear ubiquitin assembly complex (LUBAC), and this is counteracted by the Met1-Ub-specific deubiquitinase OTULIN, which binds to the catalytic LUBAC subunit HOIP. In this study, we report that HOIP also interacts with the deubiquitinase CYLD but that CYLD does not regulate ubiquitination of LUBAC components. Instead, CYLD limits extension of Lys63-Ub and Met1-Ub conjugated to RIPK2 to restrict signaling and cytokine production. Accordingly, Met1-Ub and Lys63-Ub were individually required for productive NOD2 signaling. Our study thus suggests that LUBAC, through its associated deubiquitinases, coordinates the deposition of not only Met1-Ub but also Lys63-Ub to ensure an appropriate response to innate immune receptor activation.
Subject(s)
Deubiquitinating Enzymes/metabolism , Immunity, Innate , Lysine/metabolism , Methionine/metabolism , Signal Transduction , Ubiquitin/metabolism , Catalytic Domain , Cell Line, Tumor , Cytokines/metabolism , Deubiquitinating Enzymes/antagonists & inhibitors , Deubiquitinating Enzymes/genetics , Endopeptidases/chemistry , Endopeptidases/genetics , Endopeptidases/metabolism , HEK293 Cells , Humans , Lysine/chemistry , Methionine/chemistry , Mutagenesis, Site-Directed , NF-kappa B/metabolism , RNA Interference , RNA, Small Interfering/metabolism , Receptor-Interacting Protein Serine-Threonine Kinase 2/metabolism , Ubiquitin/chemistry , Ubiquitin/genetics , Ubiquitin-Protein Ligases/antagonists & inhibitors , Ubiquitin-Protein Ligases/chemistry , Ubiquitin-Protein Ligases/metabolism , UbiquitinationABSTRACT
BACKGROUND: Epigenetic alterations of specific genes have been reported to be related to colorectal cancer (CRC) transformation and would also appear to be involved in the early stages of colorectal carcinogenesis. Little data are available on the role of these alterations in determining a different risk of colorectal lesion recurrence. The aim of the present study was to verify whether epigenetic alterations present in pre-neoplastic colorectal lesions detected by colonoscopy can predict disease recurrence. METHODS: A retrospective series of 78 adenomas were collected and classified as low (35) or high-risk (43) for recurrence according to National Comprehensive Cancer Network guidelines. Methylation alterations were analyzed by the methylation-specific multiplex ligation probe assay (MS-MLPA) which is capable of quantifying methylation levels simultaneously in 24 different gene promoters. MS-MLPA results were confirmed by pyrosequencing and immunohistochemistry. RESULTS: Higher levels of methylation were associated with disease recurrence. In particular, MLH1, ATM and FHIT gene promoters were found to be significantly hypermethylated in recurring adenomas. Unconditional logistic regression analysis used to evaluate the relative risk (RR) of recurrence showed that FHIT and MLH1 were independent variables with an RR of 35.30 (95% CI 4.15-300.06, P = 0.001) and 17.68 (95% CI 1.91-163.54, P = 0.011), respectively. CONCLUSIONS: Histopathological classification does not permit an accurate evaluation of the risk of recurrence of colorectal lesions. Conversely, results from our methylation analysis suggest that a classification based on molecular parameters could help to define the mechanisms involved in carcinogenesis and prove an effective method for identifying patients at high risk of recurrence.
Subject(s)
Colorectal Neoplasms/genetics , DNA Methylation , Genes, Tumor Suppressor , Neoplasm Recurrence, Local/genetics , Precancerous Conditions/genetics , Adult , Aged , Aged, 80 and over , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Carcinogenesis/genetics , Carcinogenesis/pathology , Colorectal Neoplasms/pathology , Epigenomics , Genetic Predisposition to Disease , Humans , Male , Middle Aged , Neoplasm Recurrence, Local/pathology , Precancerous Conditions/pathology , Retrospective StudiesABSTRACT
Recurrent mutations in histone-modifying enzymes imply key roles in tumorigenesis, yet their functional relevance is largely unknown. Here, we show that JARID1B, encoding a histone H3 lysine 4 (H3K4) demethylase, is frequently amplified and overexpressed in luminal breast tumors and a somatic mutation in a basal-like breast cancer results in the gain of unique chromatin binding and luminal expression and splicing patterns. Downregulation of JARID1B in luminal cells induces basal genes expression and growth arrest, which is rescued by TGFß pathway inhibitors. Integrated JARID1B chromatin binding, H3K4 methylation, and expression profiles suggest a key function for JARID1B in luminal cell-specific expression programs. High luminal JARID1B activity is associated with poor outcome in patients with hormone receptor-positive breast tumors.
