Ring1b-dependent epigenetic remodelling is an essential prerequisite for pancreatic carcinogenesis.

BACKGROUND AND AIMS: Besides well-defined genetic alterations, the dedifferentiation of mature acinar cells is an important prerequisite for pancreatic carcinogenesis. Acinar-specific genes controlling cell homeostasis are extensively downregulated during cancer development; however, the underlying mechanisms are poorly understood. Now, we devised a novel in vitro strategy to determine genome-wide dynamics in the epigenetic landscape in pancreatic carcinogenesis. DESIGN: With our in vitro carcinogenic sequence, we performed global gene expression analysis and ChIP sequencing for the histone modifications H3K4me3, H3K27me3 and H2AK119ub. Followed by a comprehensive bioinformatic approach, we captured gene clusters with extensive epigenetic and transcriptional remodelling. Relevance of Ring1b-catalysed H2AK119ub in acinar cell reprogramming was studied in an inducible Ring1b knockout mouse model. CRISPR/Cas9-mediated Ring1b ablation as well as drug-induced Ring1b inhibition were functionally characterised in pancreatic cancer cells. RESULTS: The epigenome is vigorously modified during pancreatic carcinogenesis, defining cellular identity. Particularly, regulatory acinar cell transcription factors are epigenetically silenced by the Ring1b-catalysed histone modification H2AK119ub in acinar-to-ductal metaplasia and pancreatic cancer cells. Ring1b knockout mice showed greatly impaired acinar cell dedifferentiation and pancreatic tumour formation due to a retained expression of acinar differentiation genes. Depletion or drug-induced inhibition of Ring1b promoted tumour cell reprogramming towards a less aggressive phenotype. CONCLUSIONS: Our data provide substantial evidence that the epigenetic silencing of acinar cell fate genes is a mandatory event in the development and progression of pancreatic cancer. Targeting the epigenetic repressor Ring1b could offer new therapeutic options.

Nimodipine confers clinical improvement in two models of experimental autoimmune encephalomyelitis.

Multiple sclerosis is characterised by inflammatory neurodegeneration, with axonal injury and neuronal cell death occurring in parallel to demyelination. Regarding the molecular mechanisms responsible for demyelination and axonopathy, energy failure, aberrant expression of ion channels and excitotoxicity have been suggested to lead to Ca2+ overload and subsequent activation of calcium-dependent damage pathways. Thus, the inhibition of Ca2+ influx by pharmacological modulation of Ca2+ channels may represent a novel neuroprotective strategy in the treatment of secondary axonopathy. We therefore investigated the effects of the L-type voltage-gated calcium channel blocker nimodipine in two different models of mouse experimental autoimmune encephalomyelitis (EAE), an established experimental paradigm for multiple sclerosis. We show that preventive application of nimodipine (10 mg/kg per day) starting on the day of induction had ameliorating effects on EAE in SJL/J mice immunised with encephalitic myelin peptide PLP139-151 , specifically in late-stage disease. Furthermore, supporting these data, administration of nimodipine to MOG35-55 -immunised C57BL/6 mice starting at the peak of pre-established disease, also led to a significant decrease in disease score, indicating a protective effect on secondary CNS damage. Histological analysis confirmed that nimodipine attenuated demyelination, axonal loss and pathological axonal ß-amyloid precursor protein accumulation in the cerebellum and spinal cord in the chronic phase of disease. Of note, we observed no effects of nimodipine on the peripheral immune response in EAE mice with regard to distribution, antigen-specific proliferation or activation patterns of lymphocytes. Taken together, our data suggest a CNS-specific effect of L-type voltage-gated calcium channel blockade to inflammation-induced neurodegeneration.

Natalizumab restores aberrant miRNA expression profile in multiple sclerosis and reveals a critical role for miR-20b.

OBJECTIVE: To identify microRNAs (miRNAs) regulated by anti-α4 integrin monoclonal antibody therapy (natalizumab) in the peripheral blood of patients with relapsing-remitting (RR) multiple sclerosis (MS) and to confirm their role in experimental settings in vivo. METHODS: In a longitudinal study of 17 RR-MS patients, we investigated blood miRNA expression profiles at baseline and after 1 year of natalizumab therapy by microarray technique and quantitative PCR validation. We compared the baseline expression profiles of these patients to those of 18 age- and sex-matched healthy controls. We confirmed the contribution of resulting candidate miRNAs in an animal model of MS, experimental autoimmune encephalomyelitis (EAE) induced by adoptive transfer of proteolipid protein (PLP)139-151-activated lymphocytes in SJL/J mice or by active immunization of miR-106a∼363-deficient C57BL/6 mice (or wildtype litter mates) with myelin oligodendrocyte glycoprotein (MOG)35-55. RESULTS: Our longitudinal analysis revealed that miR-18a, miR-20b, miR-29a, and miR-103 were upregulated and predominantly expressed by CD4(+) T cells, whereas miR-326 was downregulated upon natalizumab treatment. A comparison of untreated RR-MS patients at baseline with healthy controls revealed that the four natalizumab-upregulated targets were initially downregulated in MS. All confirmed targets showed disease-dependent expression in splenocytes of mice suffering from EAE. Genetic deletion of the miRNA cluster miR-106a∼363 (containing natalizumab-regulated miR-20b) resulted in a more severe EAE course and an in vivo upregulation of the miR-20b target genes rorgt, stat3, and vegfa. INTERPRETATION: Our study indicates that natalizumab restores dysregulated miRNA patterns in MS and reveals the contribution of miR-20b in autoimmune demyelination in vivo.

Aryl hydrocarbon receptor is critical for homeostasis of invariant gammadelta T cells in the murine epidermis.

An immunoregulatory role of aryl hydrocarbon receptor (AhR) has been shown in conventional αß and γδ T cells, but its function in skin γδ T cells (dendritic epidermal T cells [DETC]) is unknown. In this study, we demonstrate that DETC express AhR in wild-type mice, and are specifically absent in the epidermis of AhR-deficient mice (AhR-KO). We show that DETC precursors are generated in the thymus and home to the skin. Proliferation of DETC in the skin was impaired in AhR-KO mice, resulting in a >90% loss compared with wild type. Surprisingly, DETC were not replaced by αß T cells or conventional γδ T cells, suggesting a limited time frame for seeding this niche. We found that DETC from AhR-KO mice failed to express the receptor tyrosine kinase c-Kit, a known growth factor for γδ T cells in the gut. Moreover, we found that c-kit is a direct target of AhR, and propose that AhR-dependent c-Kit expression is potentially involved in DETC homeostasis. DETC are a major source of GM-CSF in the skin. Recently, we had shown that impaired Langerhans cell maturation in AhR-KO is related to low GM-CSF levels. Our findings suggest that the DETCs are necessary for LC maturation, and provide insights into a novel role for AhR in the maintenance of skin-specific γδ T cells, and its consequences for the skin immune network.