52 research outputs found

    MITF has a central role in regulating starvation-induced autophagy in melanoma.

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    The MITF transcription factor is a master regulator of melanocyte development and a critical factor in melanomagenesis. The related transcription factors TFEB and TFE3 regulate lysosomal activity and autophagy processes known to be important in melanoma. Here we show that MITF binds the CLEAR-box element in the promoters of lysosomal and autophagosomal genes in melanocytes and melanoma cells. The crystal structure of MITF bound to the CLEAR-box reveals how the palindromic nature of this motif induces symmetric MITF homodimer binding. In metastatic melanoma tumors and cell lines, MITF positively correlates with the expression of lysosomal and autophagosomal genes, which, interestingly, are different from the lysosomal and autophagosomal genes correlated with TFEB and TFE3. Depletion of MITF in melanoma cells and melanocytes attenuates the response to starvation-induced autophagy, whereas the overexpression of MITF in melanoma cells increases the number of autophagosomes but is not sufficient to induce autophagic flux. Our results suggest that MITF and the related factors TFEB and TFE3 have separate roles in regulating a starvation-induced autophagy response in melanoma. Understanding the normal and pathophysiological roles of MITF and related transcription factors may provide important clinical insights into melanoma therapy

    The microphthalmia-associated transcription factor (Mitf) gene and its role in regulating eye function.

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    To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadMutations in the microphthalmia-associated transcription factor (Mitf) gene can cause retinal pigment epithelium (RPE) and retinal dysfunction and degeneration. We examined retinal and RPE structure and function in 3 month old mice homo- or heterozygous or compound heterozygous for different Mitf mutations (Mitfmi-vga9/+, Mitfmi-enu22(398)/Mitfmi-enu22(398), MitfMi-Wh/+ and MitfMi-Wh/Mitfmi) which all have normal eye size with apparently normal eye pigmentation. Here we show that their vision and retinal structures are differentially affected. Hypopigmentation was evident in all the mutants while bright-field fundus images showed yellow spots with non-pigmented areas in the Mitfmi-vga9/+ mice. MitfMi-Wh/+ and MitfMi-Wh/Mitfmi mice showed large non-pigmented areas. Fluorescent angiography (FA) of all mutants except Mitfmi-vga9/+ mice showed hyperfluorescent areas, whereas FA from both Mitf-Mi-Wh/+ and MitfMi-Wh/Mitfmi mice showed reduced capillary network as well as hyperfluorescent areas. Electroretinogram (ERG) recordings show that MitfMi-Wh/+ and MitfMi-Wh/Mitfmi mice are severely impaired functionally whereas the scotopic and photopic ERG responses of Mitfmi-vga9/+ and Mitfmi-enu22(398)/Mitfmi-enu22(398) mice were not significantly different from wild type mice. Histological sections demonstrated that the outer retinal layers were absent from the MitfMi-Wh/+ and MitfMi-Wh/Mitfmi blind mutants. Our results show that Mitf mutations affect eye function, even in the heterozygous condition and that the alleles studied can be arranged in an allelic series in this respect.Icelandic Research Fund National University Hospital Research Fund Helga Jonsdottir and Sigurlioi Kristjansson Memorial Fun

    The Novel Inducer of Innate Immunity HO53 Stimulates Autophagy in Human Airway Epithelial Cells

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    Aroylated phenylenediamines (APDs) are novel modulators of innate immunity with respect to enhancing the expression of antimicrobial peptides and maintaining epithelial barrier integrity. Here, we present a new study on induction of autophagy in human lung epithelial cells by the APD HO53. Interestingly, HO53 affected autophagy in a dose-dependent manner, demonstrated by increased microtubule-associated proteins 1A/1B light-chain 3B (LC3B) processing in mature polarized bronchial epithelial cells. The quantification of LC3B puncta showed increased autophagy flux and formation of autophagosomes visualized by transmission electron microscopy. The phenotypic changes indicated that autophagy induction was associated with activation of 5 ' adenosine monophosphate-activated protein kinase (AMPK), nuclear translocation of transcription factor EB (TFEB), and changes in expression of autophagy-related genes. The kinetics of the explored signaling pathways indicated on activation of AMPK followed by the nuclear translocation of TFEB. Moreover, our data suggest that HO53 modulates epigenetic changes related to induction of autophagy manifested by transcriptional regulation of histone-modifying enzymes. These changes were reflected by decreased ubiquitination of histone 2B at the lysine 120 residue that is associated with autophagy induction. Taken together, HO53 modulates autophagy, a part of the host defense system, through a complex mechanism involving several pathways and epigenetic events

    A short isoform of ATG7 fails to lipidate LC3/GABARAP

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    Publisher's version (útgefin grein)Autophagy is a degradation pathway important for cellular homeostasis. The E1-like enzyme ATG7 is a key component of the autophagy machinery, with the main function of mediating the lipidation of LC3/GABARAP during autophagosome formation. By analysing mRNA-sequencing data we found that in addition to the full-length ATG7 isoform, various tissues express a shorter isoform lacking an exon of 27 amino acids in the C-terminal part of the protein, termed ATG7(2). We further show that ATG7(2) does not bind LC3B and fails to mediate the lipidation of members of the LC3/GABARAP family. We have thus identified an isoform of ATG7 that is unable to carry out the best characterized function of the protein during the autophagic response. This short isoform will have to be taken into consideration when further studying the role of ATG7.This work was supported by a START Marie Curie/Icelandic Research Fund grant (M.H.O.; grant number 120457-041), Icelandic Research Fund grant (M.H.O.; grant number 184727-051), an Icelandic Cancer Society Research Fund grant (M.H.O.), Icelandic Research Fund grant (E.S.; grant number 152715) and by an Erwin Schrödinger fellowship grant from the Austrian Science Fund (V.F.; grant number: J 3864-B26).Peer Reviewe

    Sono Osato (far right) as a Maiden, and artists of the company, in Protée, The Original Ballet Russe, Australian tour, His Majesty's Theatre, Melbourne, April 1940 (1) [picture] /

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    From: Protée : choreographic tableau / by David Lichine and Henry Clifford ; music by Claude Debussy from Danses sacree et profane.; Inscription: "3W/3 (10)".; Part of the collection: Hugh P. Hall collection of photographs, 1938-1940.; Choreography by Michel Fokine ; scenery and costumes by Giorgio de Chirico ; costumes executed by B. Karinska ; scenery executed by Prince A. Schervachidze.; Also available in an electronic version via the internet at: http://nla.gov.au/nla.pic-vn4194073. One of a collection of photographs taken by Hugh P. Hall of 28 ballet productions performed by the Covent Garden Russian Ballet (toured Australia 1938-1939) and the Original Ballet Russe (toured Australia 1939-1940). These are the second and third of the three Ballets Russes companies which toured Australasia between 1936 and 1940. The photographs were taken from the auditorium during a live performance in His Majesty's Theatre, Melbourne and mounted on cardboard for display purposes. For conservation and storage, the photographs have been demounted. The original arrangement of the photographs has been recorded, and details are available from the Pictures Branch of the National Library

    Familial predisposition to monoclonal gammopathy of unknown significance, Waldenström's macroglobulinemia, and multiple myeloma

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldThe medical literature contains reports of around 130 families with two or more cases of MM, MGUS, or WM. An Icelandic family with multiple cases of MGUS, WM, and lymphoma was first described in 1978. In vitro testing of peripheral blood lymphocytes revealed increased production of immunoglobulins in response to poke-weed mitogen in 10 out of 35 family members, referred to as hyperresponders (HR). Enhanced B-cell survival after stimulation was associated with prolonged expression of Bcl-2. A population-based cancer registry study of 218 MM patients identified 7 additional families. Nine new cases of monoclonal gammopathy were detected by the screening of 350 family members. Further testing confirmed previously identified HR in the originally described family as well as detecting new cases. Only two HR were found in the recently identified families. The long-term aim is to identify the genetic background(s) and biology predisposing to the emergence of a persistent clone of immunoglobulin-producing cells

    Proton-pump inhibitors among adults: a nationwide drug-utilization study

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    Background: The use of proton-pump inhibitors (PPIs) has grown worldwide, and there are concerns about increased unsubstantiated long-term use. The aim of the study was to describe the real-world use of PPIs over the past decade in an entire national population. Methods: This was a nationwide population-based drug-utilization study. Patterns of outpatient PPI use among adults in Iceland between 2003 and 2015 were investigated, including annual incidence and prevalence, duration of use, and dose of tablet used (lower versus higher), as well as the proportion of PPI use attributable to gastroprotection. Results: We observed 1,372,790 prescription fills over the entire study period, of which 95% were for higher-dose PPIs. Annual incidence remained stable across time (3.3–4.1 per 100 persons per year), while the annual prevalence increased from 8.5 per 100 persons to 15.5 per 100 persons. Prevalence increased with patient age and was higher among women than men. Duration of treatment increased with patients’ age (36% of users over 80 years remained on treatment after 1 year compared with 13% of users aged 19–39 years), and was longer among those initiating on a higher dose compared with a lower dose. The proportion of PPI users concurrently using nonsteroidal anti-inflammatory drugs decreased over the study period, while the proportion concurrently using acetylsalicylic acid, oral anticoagulants, or platelet inhibitors increased. Conclusions: In this nationwide study, a considerable increase in overall outpatient use of PPIs over a 13-year period was observed, particularly among older adults. Patients were increasingly treated for longer durations than recommended by clinical guidelines and mainly with higher doses

    Antitumour activity of Angelica archangelica leaf extract

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldBACKGROUND: The purpose of this study was to examine the effect of a leaf extract from A. archangelica on the growth of Crl mouse breast cancer cells in vitro and in vivo. Materials and METHODS: The antiproliferative activity of the extract was measured by 3H-thymidine uptake in the Crl cells in vitro. Twenty mice were injected with the Crl cells, and 11 of them were fed A. archangelica leaf extract, and the progress of the tumours was followed. RESULTS: The leaf extract was mildly antiproliferative on the Crl cells with an EC50 of 87.6 microg/ml The antitumour activity of the extract was expressed in the mice by marked reduction in tumour growth. In the experimental animals, 9 out of 11 mice developed no or very small tumours, whereas control animals, not receiving the extract, developed significantly larger tumours (p<0.01), as estimated by Mann-Whitney U-test. The antitumour activity of the leaf extract could not be explained by the antiproliferative activity of furanocoumarins present in the extract. CONCLUSION: The results demonstrate the antiproliferative activity in vitro and antitumour activity in vivo of a leaf extract from A. archangelic
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