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1.
Immunity ; 47(6): 1067-1082.e12, 2017 12 19.
Article in English | MEDLINE | ID: mdl-29246441

ABSTRACT

Roquin proteins preclude spontaneous T cell activation and aberrant differentiation of T follicular helper (Tfh) or T helper 17 (Th17) cells. Here we showed that deletion of Roquin-encoding alleles specifically in regulatory T (Treg) cells also caused the activation of conventional T cells. Roquin-deficient Treg cells downregulated CD25, acquired a follicular Treg (Tfr) cell phenotype, and suppressed germinal center reactions but could not protect from colitis. Roquin inhibited the PI3K-mTOR signaling pathway by upregulation of Pten through interfering with miR-17∼92 binding to an overlapping cis-element in the Pten 3' UTR, and downregulated the Foxo1-specific E3 ubiquitin ligase Itch. Loss of Roquin enhanced Akt-mTOR signaling and protein synthesis, whereas inhibition of PI3K or mTOR in Roquin-deficient T cells corrected enhanced Tfh and Th17 or reduced iTreg cell differentiation. Thereby, Roquin-mediated control of PI3K-mTOR signaling prevents autoimmunity by restraining activation and differentiation of conventional T cells and specialization of Treg cells.


Subject(s)
Colitis/immunology , Phosphatidylinositol 3-Kinases/immunology , Repressor Proteins/immunology , TOR Serine-Threonine Kinases/immunology , Ubiquitin-Protein Ligases/immunology , Animals , B-Lymphocytes/immunology , B-Lymphocytes/pathology , Cell Differentiation , Colitis/genetics , Colitis/pathology , Disease Models, Animal , Female , Forkhead Box Protein O1/genetics , Forkhead Box Protein O1/immunology , Gene Expression Regulation , Germinal Center/immunology , Germinal Center/pathology , Interleukin-2 Receptor alpha Subunit/genetics , Interleukin-2 Receptor alpha Subunit/immunology , Lymphocyte Activation , Mice , Mice, Inbred C57BL , Mice, Transgenic , MicroRNAs/genetics , MicroRNAs/immunology , PTEN Phosphohydrolase/genetics , PTEN Phosphohydrolase/immunology , Phosphatidylinositol 3-Kinases/genetics , Primary Cell Culture , Repressor Proteins/deficiency , Repressor Proteins/genetics , Signal Transduction , Spleen/immunology , Spleen/pathology , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes, Regulatory/pathology , TOR Serine-Threonine Kinases/genetics , Th17 Cells/immunology , Th17 Cells/pathology , Ubiquitin-Protein Ligases/deficiency , Ubiquitin-Protein Ligases/genetics
2.
Mol Cell ; 65(6): 1096-1108.e6, 2017 Mar 16.
Article in English | MEDLINE | ID: mdl-28306505

ABSTRACT

Protein aggregation is associated with age-related neurodegenerative disorders, such as Alzheimer's and polyglutamine diseases. As a causal relationship between protein aggregation and neurodegeneration remains elusive, understanding the cellular mechanisms regulating protein aggregation will help develop future treatments. To identify such mechanisms, we conducted a forward genetic screen in a C. elegans model of polyglutamine aggregation and identified the protein MOAG-2/LIR-3 as a driver of protein aggregation. In the absence of polyglutamine, MOAG-2/LIR-3 regulates the RNA polymerase III-associated transcription of small non-coding RNAs. This regulation is lost in the presence of polyglutamine, which mislocalizes MOAG-2/LIR-3 from the nucleus to the cytosol. We then show biochemically that MOAG-2/LIR-3 can also catalyze the aggregation of polyglutamine-expanded huntingtin. These results suggest that polyglutamine can induce an aggregation-promoting activity of MOAG-2/LIR-3 in the cytosol. The concept that certain aggregation-prone proteins can convert other endogenous proteins into drivers of aggregation and toxicity adds to the understanding of how cellular homeostasis can be deteriorated in protein misfolding diseases.


Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/enzymology , Neurodegenerative Diseases/enzymology , Peptides/metabolism , Protein Aggregates , Protein Aggregation, Pathological , RNA Polymerase III/metabolism , Transcription Factors/metabolism , Active Transport, Cell Nucleus , Animals , Animals, Genetically Modified , Binding Sites , Caenorhabditis elegans/genetics , Caenorhabditis elegans Proteins/genetics , Cell Nucleus/enzymology , Cytosol/enzymology , Disease Models, Animal , Neurodegenerative Diseases/genetics , Neurodegenerative Diseases/pathology , Promoter Regions, Genetic , Protein Binding , RNA Interference , RNA Polymerase III/genetics , RNA, Small Untranslated/genetics , RNA, Small Untranslated/metabolism , Transcription Factors/genetics , Transcription, Genetic
3.
Trends Genet ; 36(2): 71-80, 2020 02.
Article in English | MEDLINE | ID: mdl-31822355

ABSTRACT

Changes in epigenetic DNA methylation are the most promising predictor of biological age and lifespan in humans, but whether methylation changes affect ageing is unresolved. Here, we discuss converging data, which indicate that one mode by which aberrant DNA methylation can affect ageing is via CCAAT/enhancer binding protein beta (C/EBPß). This basic leucine-zipper (bZIP) transcription factor is controlled by the lifespan regulator mechanistic/mammalian target of rapamycin complex 1 (mTORC1) and plays an important role in energy homeostasis and adipose tissue differentiation. Emerging evidence indicates that access of C/EBPß proteins to cognate binding sites is regulated by DNA demethylation via ten-eleven translocation (TET) methylcytosine dioxygenases and their adaptor proteins growth arrest and DNA damage-inducible protein 45 alpha (GADD45α) and inhibitor of growth 1 (ING1). We discuss the emerging causal nexus between C/EBPß, energy metabolism, and DNA demethylation in organismal ageing.


Subject(s)
Aging/genetics , CCAAT-Enhancer-Binding Protein-beta/genetics , Cell Cycle Proteins/genetics , DNA Methylation/genetics , Inhibitor of Growth Protein 1/genetics , Aging/pathology , Cell Differentiation/genetics , Energy Metabolism/genetics , Epigenesis, Genetic/genetics , Humans
4.
EMBO J ; 37(21)2018 11 02.
Article in English | MEDLINE | ID: mdl-30237309

ABSTRACT

The tuberous sclerosis complex (TSC) 1/2 is a negative regulator of the nutrient-sensing kinase mechanistic target of rapamycin complex (mTORC1), and its function is generally associated with tumor suppression. Nevertheless, biallelic loss of function of TSC1 or TSC2 is rarely found in malignant tumors. Here, we show that TSC1/2 is highly expressed in Burkitt's lymphoma cell lines and patient samples of human Burkitt's lymphoma, a prototypical MYC-driven cancer. Mechanistically, we show that MYC induces TSC1 expression by transcriptional activation of the TSC1 promoter and repression of miR-15a. TSC1 knockdown results in elevated mTORC1-dependent mitochondrial respiration enhanced ROS production and apoptosis. Moreover, TSC1 deficiency attenuates tumor growth in a xenograft mouse model. Our study reveals a novel role for TSC1 in securing homeostasis between MYC and mTORC1 that is required for cell survival and tumor maintenance in Burkitt's lymphoma. The study identifies TSC1/2 inhibition and/or mTORC1 hyperactivation as a novel therapeutic strategy for MYC-driven cancers.


Subject(s)
Burkitt Lymphoma/metabolism , Gene Expression Regulation, Neoplastic , Proto-Oncogene Proteins c-myc/metabolism , Tuberous Sclerosis Complex 1 Protein/metabolism , Tuberous Sclerosis Complex 2 Protein/metabolism , Animals , Burkitt Lymphoma/genetics , Burkitt Lymphoma/pathology , HEK293 Cells , Heterografts , Humans , MCF-7 Cells , Mechanistic Target of Rapamycin Complex 1/genetics , Mechanistic Target of Rapamycin Complex 1/metabolism , Mice , Mice, Inbred NOD , Mice, SCID , MicroRNAs/genetics , MicroRNAs/metabolism , Neoplasm Transplantation , Proto-Oncogene Proteins c-myc/genetics , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Tuberous Sclerosis Complex 1 Protein/genetics , Tuberous Sclerosis Complex 2 Protein/genetics
5.
PLoS Genet ; 14(3): e1007272, 2018 03.
Article in English | MEDLINE | ID: mdl-29570707

ABSTRACT

The genetics of lifespan determination is poorly understood. Most research has been done on short-lived animals and it is unclear if these insights can be transferred to long-lived mammals like humans. Some African mole-rats (Bathyergidae) have life expectancies that are multiple times higher than similar sized and phylogenetically closely related rodents. To gain new insights into genetic mechanisms determining mammalian lifespans, we obtained genomic and transcriptomic data from 17 rodent species and scanned eleven evolutionary branches associated with the evolution of enhanced longevity for positively selected genes (PSGs). Indicating relevance for aging, the set of 250 identified PSGs showed in liver of long-lived naked mole-rats and short-lived rats an expression pattern that fits the antagonistic pleiotropy theory of aging. Moreover, we found the PSGs to be enriched for genes known to be related to aging. Among these enrichments were "cellular respiration" and "metal ion homeostasis", as well as functional terms associated with processes regulated by the mTOR pathway: translation, autophagy and inflammation. Remarkably, among PSGs are RHEB, a regulator of mTOR, and IGF1, both central components of aging-relevant pathways, as well as genes yet unknown to be aging-associated but representing convincing functional candidates, e.g. RHEBL1, AMHR2, PSMG1 and AGER. Exemplary protein homology modeling suggests functional consequences for amino acid changes under positive selection. Therefore, we conclude that our results provide a meaningful resource for follow-up studies to mechanistically link identified genes and amino acids under positive selection to aging and lifespan determination.


Subject(s)
Longevity/genetics , Rodentia/genetics , Selection, Genetic , Animals , Genome , Homeostasis , Ion Transport , Oxidative Stress , Species Specificity , Transcriptome
6.
Nucleic Acids Res ; 44(9): 4134-46, 2016 05 19.
Article in English | MEDLINE | ID: mdl-26762974

ABSTRACT

Mutations in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene cause Shwachman-Diamond Syndrome (SDS), a rare congenital disease characterized by bone marrow failure with neutropenia, exocrine pancreatic dysfunction and skeletal abnormalities. The SBDS protein is important for ribosome maturation and therefore SDS belongs to the ribosomopathies. It is unknown, however, if loss of SBDS functionality affects the translation of specific mRNAs and whether this could play a role in the development of the clinical features of SDS. Here, we report that translation of the C/EBPα and -ß mRNAs, that are indispensible regulators of granulocytic differentiation, is altered by SBDS mutations or knockdown. We show that SBDS function is specifically required for efficient translation re-initiation into the protein isoforms C/EBPα-p30 and C/EBPß-LIP, which is controlled by a single cis-regulatory upstream open reading frame (uORF) in the 5' untranslated regions (5' UTRs) of both mRNAs. Furthermore, we show that as a consequence of the C/EBPα and -ß deregulation the expression of MYC is decreased with associated reduction in proliferation, suggesting that failure of progenitor proliferation contributes to the haematological phenotype of SDS. Therefore, our study provides the first indication that disturbance of specific translation by loss of SBDS function may contribute to the development of the SDS phenotype.


Subject(s)
Bone Marrow Diseases/metabolism , CCAAT-Enhancer-Binding Protein-beta/genetics , CCAAT-Enhancer-Binding Proteins/genetics , Exocrine Pancreatic Insufficiency/metabolism , Lipomatosis/metabolism , Proteins/physiology , RNA, Messenger/genetics , 5' Untranslated Regions , Bone Marrow Diseases/genetics , CCAAT-Enhancer-Binding Protein-beta/metabolism , CCAAT-Enhancer-Binding Proteins/metabolism , Cell Differentiation , Cell Line, Tumor , Exocrine Pancreatic Insufficiency/genetics , Gene Expression , Gene Expression Regulation , Humans , Lipomatosis/genetics , Neutrophils/physiology , Peptide Chain Initiation, Translational , Proto-Oncogene Proteins c-myc/genetics , Proto-Oncogene Proteins c-myc/metabolism , RNA, Messenger/metabolism , Shwachman-Diamond Syndrome
7.
Genes Dev ; 24(1): 15-20, 2010 Jan 01.
Article in English | MEDLINE | ID: mdl-20047998

ABSTRACT

Upstream ORFs (uORFs) are translational control elements found predominantly in transcripts of key regulatory genes. No mammalian genetic model exists to experimentally validate the physiological relevance of uORF-regulated translation initiation. We report that mice deficient for the CCAAT/enhancer-binding protein beta (C/EBPbeta) uORF initiation codon fail to initiate translation of the autoantagonistic LIP (liver inhibitory protein) C/EBPbeta isoform. C/EBPbeta(DeltauORF) mice show hyperactivation of acute-phase response genes, persistent repression of E2F-regulated genes, delayed and blunted S-phase entry of hepatocytes after partial hepatectomy, and impaired osteoclast differentiation. These data and the widespread prevalence of uORFs in mammalian transcriptomes suggest a comprehensive role of uORF-regulated translation in (patho)physiology.


Subject(s)
CCAAT-Enhancer-Binding Protein-beta/genetics , Gene Expression Regulation , Models, Animal , Open Reading Frames/genetics , Animals , Cell Cycle/genetics , Female , Liver/metabolism , Male , Mice , Mutation
8.
EMBO Rep ; 16(8): 1022-36, 2015 Aug.
Article in English | MEDLINE | ID: mdl-26113365

ABSTRACT

The mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of physiological adaptations in response to changes in nutrient supply. Major downstream targets of mTORC1 signalling are the mRNA translation regulators p70 ribosomal protein S6 kinase 1 (S6K1p70) and the 4E-binding proteins (4E-BPs). However, little is known about vertebrate mRNAs that are specifically controlled by mTORC1 signalling and are engaged in regulating mTORC1-associated physiology. Here, we show that translation of the CCAAT/enhancer binding protein beta (C/EBPß) mRNA into the C/EBPß-LIP isoform is suppressed in response to mTORC1 inhibition either through pharmacological treatment or through calorie restriction. Our data indicate that the function of 4E-BPs is required for suppression of LIP. Intriguingly, mice lacking the cis-regulatory upstream open reading frame (uORF) in the C/EBPß-mRNA, which is required for mTORC1-stimulated translation into C/EBPß-LIP, display an improved metabolic phenotype with features also found under calorie restriction. Thus, our data suggest that translational adjustment of C/EBPß-isoform expression is one of the key processes that direct metabolic adaptation in response to changes in mTORC1 activity.


Subject(s)
CCAAT-Enhancer-Binding Protein-beta/genetics , Lipid Metabolism , Multiprotein Complexes/metabolism , RNA, Messenger/genetics , TOR Serine-Threonine Kinases/metabolism , Adipogenesis/genetics , Animals , CCAAT-Enhancer-Binding Protein-beta/deficiency , CCAAT-Enhancer-Binding Protein-beta/metabolism , Caloric Restriction , Fatty Acids/metabolism , Gene Expression Regulation , Mechanistic Target of Rapamycin Complex 1 , Mice , Multiprotein Complexes/antagonists & inhibitors , Multiprotein Complexes/genetics , Open Reading Frames , Oxidation-Reduction , Phenotype , Protein Biosynthesis , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Signal Transduction , Sirolimus , TOR Serine-Threonine Kinases/antagonists & inhibitors , TOR Serine-Threonine Kinases/genetics
9.
EMBO J ; 29(5): 897-909, 2010 Mar 03.
Article in English | MEDLINE | ID: mdl-20075868

ABSTRACT

The messenger RNA of the intronless CEBPA gene is translated into distinct protein isoforms through the usage of consecutive translation initiation sites. These translational isoforms have distinct functions in the regulation of differentiation and proliferation due to the presence of different N-terminal sequences. Here, we describe the function of an N-terminally extended protein isoform of CCAAT enhancer-binding protein alpha (C/EBPalpha) that is translated from an alternative non-AUG initiation codon. We show that a basic amino-acid motif within its N-terminus is required for nucleolar retention and for interaction with nucleophosmin (NPM). In the nucleoli, extended-C/EBPalpha occupies the ribosomal DNA (rDNA) promoter and associates with the Pol I-specific factors upstream-binding factor 1 (UBF-1) and SL1 to stimulate rRNA synthesis. Furthermore, during differentiation of HL-60 cells, endogenous expression of extended-C/EBPalpha is lost concomitantly with nucleolar C/EBPalpha immunostaining probably reflecting the reduced requirement for ribosome biogenesis in differentiated cells. Finally, overexpression of extended-C/EBPalpha induces an increase in cell size. Altogether, our results suggest that control of rRNA synthesis is a novel function of C/EBPalpha adding to its role as key regulator of cell growth and proliferation.


Subject(s)
CCAAT-Enhancer-Binding Protein-alpha/metabolism , Cell Nucleolus/metabolism , DNA, Ribosomal/genetics , Blotting, Northern , Blotting, Western , Cell Size , Chromatin Immunoprecipitation , Genetic Vectors/genetics , HL-60 Cells , Humans , Immunoprecipitation , Lentivirus/genetics , Nuclear Proteins/metabolism , Nucleophosmin , Phosphorylation , Pol1 Transcription Initiation Complex Proteins/metabolism , Promoter Regions, Genetic/genetics , Protein Isoforms/metabolism , Protein Isoforms/physiology , RNA Polymerase I/metabolism , Retroviridae/genetics , Transcription, Genetic/genetics , U937 Cells
10.
J Biol Chem ; 287(26): 21936-49, 2012 Jun 22.
Article in English | MEDLINE | ID: mdl-22556424

ABSTRACT

Different environmental stresses induce the phosphorylation of eIF2 (eIF2∼P), repressing global protein synthesis coincident with preferential translation of ATF4. ATF4 is a transcriptional activator of genes involved in metabolism and nutrient uptake, antioxidation, and regulation of apoptosis. Because ATF4 is a common downstream target that integrates signaling from different eIF2 kinases and their respective stress signals, the eIF2∼P/ATF4 pathway is collectively referred to as the integrated stress response. Although eIF2∼P elicits translational control in response to many different stresses, there are selected stresses, such as exposure to UV irradiation, that do not increase ATF4 expression despite robust eIF2∼P. The rationale for this discordant induction of ATF4 expression and eIF2∼P in response to UV irradiation is that transcription of ATF4 is repressed, and therefore ATF4 mRNA is not available for preferential translation. In this study, we show that C/EBPß is a transcriptional repressor of ATF4 during UV stress. C/EBPß binds to critical elements in the ATF4 promoter, resulting in its transcriptional repression. Expression of C/EBPß increases in response to UV stress, and the liver-enriched inhibitory protein (LIP) isoform of C/EBPß, but not the liver-enriched activating protein (LAP) version, represses ATF4 transcription. Loss of the liver-enriched inhibitory protein isoform results in increased ATF4 mRNA levels in response to UV irradiation and subsequent recovery of ATF4 translation, leading to enhanced expression of its target genes. Together these results illustrate how eIF2∼P and translational control combined with transcription factors regulated by alternative signaling pathways can direct programs of gene expression that are specifically tailored to each environmental stress.


Subject(s)
Activating Transcription Factor 4/metabolism , CCAAT-Enhancer-Binding Protein-beta/metabolism , Animals , Cell Proliferation , Chromatin Immunoprecipitation , Eukaryotic Initiation Factor-2/metabolism , Fibroblasts/cytology , Gene Deletion , Gene Expression Regulation , Mice , Promoter Regions, Genetic , Protein Biosynthesis , Protein Isoforms , RNA/metabolism , Signal Transduction
11.
J Cell Sci ; 124(Pt 9): 1465-76, 2011 May 01.
Article in English | MEDLINE | ID: mdl-21486951

ABSTRACT

A shift from osteoblastogenesis to adipogenesis is one of the underlying mechanisms of decreased bone mass and increased fat during aging. We now uncover a new role for the transcription factor Fra-1 in suppressing adipogenesis. Indeed, Fra1 (Fosl1) transgenic (Fra1tg) mice, which developed progressive osteosclerosis as a result of accelerated osteoblast differentiation, also developed a severe general lipodystrophy. The residual fat of these mice appeared immature and expressed lower levels of adipogenic markers, including the fatty acid transporter Cd36 and the CCAAT/enhancer binding protein Cebpa. Consequently accumulation of triglycerides and free fatty acids were detected in the serum of fasting Fra1tg mice. Fra-1 acts cell autonomously because the adipogenic differentiation of Fra1 transgenic primary osteoblasts was drastically reduced, and overexpression of Fra-1 in an adipogenic cell line blocked their differentiation into adipocytes. Strikingly, Cebpa was downregulated in the Fra-1-overexpressing cells and Fra-1 could bind to the Cebpa promoter and directly suppress its activity. Thus, our data add to the known common systemic control of fat and bone mass, a new cell-autonomous level of control of cell fate decision by which the osteogenic transcription factor Fra-1 opposes adipocyte differentiation by inhibiting C/EBPα.


Subject(s)
Lipodystrophy/etiology , Lipodystrophy/metabolism , Proto-Oncogene Proteins c-fos/metabolism , Adipocytes/cytology , Adipocytes/metabolism , Adipogenesis/genetics , Adipogenesis/physiology , Animals , Blotting, Western , CCAAT-Enhancer-Binding Proteins/genetics , CCAAT-Enhancer-Binding Proteins/metabolism , CD36 Antigens/genetics , CD36 Antigens/metabolism , Cells, Cultured , Chromatin Immunoprecipitation , Immunoprecipitation , Lipodystrophy/genetics , Magnetic Resonance Imaging , Mice , Mice, Inbred C57BL , Mice, Transgenic , Osteoblasts/cytology , Osteoblasts/metabolism , Osteogenesis/genetics , Osteogenesis/physiology , Polymerase Chain Reaction , Protein Binding , Proto-Oncogene Proteins c-fos/genetics
12.
Mol Metab ; 72: 101726, 2023 06.
Article in English | MEDLINE | ID: mdl-37062524

ABSTRACT

OBJECTIVE: Cancer cells use glycolysis for generation of metabolic intermediates and ATP needed for cell growth and proliferation. The transcription factor C/EBPß-LIP stimulates glycolysis and mitochondrial respiration in cancer cells. We initially observed that high expression of C/EBPß-LIP makes cells vulnerable to treatment with the glycolysis inhibitor 2-deoxyglucose. The aim of the study was to uncover the involved mechanisms of C/EBPß-LIP induced sensitivity to glycolysis inhibition. METHODS: We used genetically engineered cell lines to examine the effect of C/EBPß-LIP and -LAP protein isoforms on glycolysis and NADH/NAD+ metabolism in mouse embryonic fibroblasts (MEFs), and triple negative breast cancer (TNBC) cells that endogenously express high levels of C/EBPß-LIP. Analyses included assays of cell proliferation, cell survival and metabolic flux (OCR and ECAR by Seahorse XF96). Small molecule inhibitors were used to identify underlying metabolic pathways that mediate sensitivity to glycolysis inhibition induced by C/EBPß-LIP. RESULTS: The transcription factor C/EBPß-LIP stimulates both glycolysis and the malate-aspartate shuttle (MAS) and increases the sensitivity to glycolysis inhibition (2-deoxyglucose) in fibroblasts and breast cancer cells. Inhibition of glycolysis with ongoing C/EBPß-LIP-induced MAS activity results in NADH depletion and apoptosis that can be rescued by inhibiting either the MAS or other NAD+-regenerating processes. CONCLUSION: This study indicates that a low NADH/NAD+ ratio is an essential mediator of 2-deoxyglucose toxicity in cells with high cytoplasmic NAD+-regeneration capacity and that simultaneous inhibition of glycolysis and lowering of the NADH/NAD+ ratio may be considered to treat cancer.


Subject(s)
Aspartic Acid , CCAAT-Enhancer-Binding Protein-beta , Animals , Mice , CCAAT-Enhancer-Binding Protein-beta/metabolism , Aspartic Acid/metabolism , Malates/metabolism , NAD/metabolism , Fibroblasts/metabolism , Glycolysis , Deoxyglucose
13.
Cancer Res ; 82(12): 2201-2212, 2022 06 15.
Article in English | MEDLINE | ID: mdl-35303057

ABSTRACT

The epitranscriptome represents the more than 140 types of chemically varying and reversable RNA modifications affecting RNA fate. Among these, the most relevant for this review are the mRNA modifications N6-methyladenosine and N6,2'-O-dimethyladenosine. Epitranscriptomic mRNA biology involves RNA methyltransferases (so-called "writers"), RNA demethylases ("erasers"), and RNA-binding proteins ("readers") that interact with methylation sites to determine the functional outcome of the modification. In this review, we discuss the role of a specific RNA demethylase encoded by the fat mass and obesity-associated gene (FTO) in cancer. FTO initially became known as the strongest genetic link for human obesity. Only in 2010, 16 years after its discovery, was its enzymatic function as a demethylase clarified, and only recently has its role in the development of cancer been revealed. FTO functions are challenging to study and interpret because of its genome-wide effects on transcript turnover and translation. We review the discovery of FTO and its enzymatic function, the tumor-promoting and suppressive roles of FTO in selected cancer types, and its potential as a therapeutic target.


Subject(s)
Neoplasms , RNA , Adenosine/genetics , Adenosine/metabolism , Alpha-Ketoglutarate-Dependent Dioxygenase FTO/genetics , Alpha-Ketoglutarate-Dependent Dioxygenase FTO/metabolism , Carcinogenesis/genetics , Humans , Neoplasms/genetics , Obesity , RNA/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism
14.
Elife ; 112022 04 22.
Article in English | MEDLINE | ID: mdl-35451956

ABSTRACT

Chronic obesity is correlated with severe metabolic and cardiovascular diseases as well as with an increased risk for developing cancers. Obesity is usually characterized by fat accumulation in enlarged - hypertrophic - adipocytes that are a source of inflammatory mediators, which promote the development and progression of metabolic disorders. Yet, in certain healthy obese individuals, fat is stored in metabolically more favorable hyperplastic fat tissue that contains an increased number of smaller adipocytes that are less inflamed. In a previous study, we demonstrated that loss of the inhibitory protein-isoform C/EBPß-LIP and the resulting augmented function of the transactivating isoform C/EBPß-LAP promotes fat metabolism under normal feeding conditions and expands health- and lifespan in mice. Here, we show that in mice on a high-fat diet, LIP-deficiency results in adipocyte hyperplasia associated with reduced inflammation and metabolic improvements. Furthermore, fat storage in subcutaneous depots is significantly enhanced specifically in LIP-deficient male mice. Our data identify C/EBPß as a regulator of adipocyte fate in response to increased fat intake, which has major implications for metabolic health and aging.


Subject(s)
Diet, High-Fat , Fatty Liver , Adipose Tissue/metabolism , Animals , Diet, High-Fat/adverse effects , Fatty Liver/metabolism , Hyperplasia/metabolism , Hypertrophy , Male , Mice , Obesity/metabolism , Protein Isoforms/metabolism
15.
NPJ Breast Cancer ; 8(1): 11, 2022 Jan 18.
Article in English | MEDLINE | ID: mdl-35042889

ABSTRACT

The transcription factor C/EBPß is a master regulator of mammary gland development and tissue remodelling during lactation. The CEBPB-mRNA is translated into three distinct protein isoforms named C/EBPß-LAP1, -LAP2 and -LIP that are functionally different. The smaller isoform LIP lacks the N-terminal transactivation domains and is considered to act as an inhibitor of the transactivating LAP1/2 isoforms by competitive binding for the same DNA recognition sequences. Aberrantly high expression of LIP is associated with mammary epithelial proliferation and is found in grade III, estrogen receptor (ER) and progesterone (PR) receptor-negative human breast cancer. Here, we show that reverting the high LIP/LAP ratios in triple-negative breast cancer (TNBC) cell lines into low LIP/LAP ratios by overexpression of LAP reduces migration and matrix invasion of these TNBC cells. In addition, in untransformed MCF10A human mammary epithelial cells overexpression of LIP stimulates migration. Knockout of CEBPB in TNBC cells where LIP expression prevails, resulted in strongly reduced migration that was accompanied by a downregulation of genes involved in cell migration, extracellular matrix production and cytoskeletal remodelling, many of which are epithelial to mesenchymal transition (EMT) marker genes. Together, this study suggests that the LIP/LAP ratio is involved in regulating breast cancer cell migration and invasion. This study together with studies from others shows that understanding the functions the C/EBPß-isoforms in breast cancer development may reveal new avenues of treatment.

16.
Haematologica ; 96(9): 1261-8, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21565905

ABSTRACT

BACKGROUND: The control of translation initiation is a crucial component in the regulation of gene expression. The eukaryotic initiation factor 2α (eIF2α) mediates binding of the initiator transfer-messenger-RNA to the AUG initiation codon, and thus controls a rate-limiting step in translation initiation. Phosphorylation of eIF2α at serine 51 is linked to cellular stress response and attenuates translation initiation. The biochemistry of translation inhibition mediated by eIF2α phosphorylation is well characterized, yet the physiological importance in hematopoiesis remains only partially known. DESIGN AND METHODS: Using hematopoietic stem cells carrying a non-phosphorylatable mutant form of eIF2α (eIF2αAA), we examined the efficiency of reconstitution in wild-type and B-cell-deficient microMT C57BL/6 recipients in two independent models. RESULTS: We provide evidence that phosphorylation-deficient eIF2α mutant hematopoietic stem cells may repopulate lethally irradiated mice but have a defect in the development and maintenance of newly formed B cells in the bone marrow and of naïve follicular B cells in the periphery. The mature B-cell compartment is markedly reduced in bone marrow, spleen and peripheral blood, and B-cell receptor-mediated proliferation in vitro and serum immunoglobulin secretion in vivo are impaired. CONCLUSIONS: The data suggest that regulation of translation through eIF2α phosphorylation is dispensable in hematopoietic reconstitution but essential during late B-cell development.


Subject(s)
B-Lymphocytes/immunology , Eukaryotic Initiation Factor-2/metabolism , Animals , Antibody Formation/genetics , B-Lymphocytes/cytology , B-Lymphocytes/metabolism , Cell Differentiation , Chimera , Eukaryotic Initiation Factor-2/genetics , Gene Expression Regulation, Developmental , Genotype , Mice , Mice, Inbred C57BL , Mice, Transgenic , Mutation/genetics , Phosphorylation , Stem Cells/metabolism , Transduction, Genetic
17.
J Mol Med (Berl) ; 99(7): 899-915, 2021 07.
Article in English | MEDLINE | ID: mdl-33824998

ABSTRACT

The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic has proven a challenge to healthcare systems since its first appearance in late 2019. The global spread and devastating effects of coronavirus disease 2019 (COVID-19) on patients have resulted in countless studies on risk factors and disease progression. Overweight and obesity emerged as one of the major risk factors for developing severe COVID-19. Here we review the biology of coronavirus infections in relation to obesity. In particular, we review literature about the impact of adiposity-related systemic inflammation on the COVID-19 disease severity, involving cytokine, chemokine, leptin, and growth hormone signaling, and we discuss the involvement of hyperactivation of the renin-angiotensin-aldosterone system (RAAS). Due to the sheer number of publications on COVID-19, we cannot be completed, and therefore, we apologize for all the publications that we do not cite.


Subject(s)
COVID-19/genetics , Inflammation/genetics , Obesity/genetics , SARS-CoV-2/genetics , COVID-19/complications , COVID-19/pathology , COVID-19/virology , Disease Progression , Humans , Inflammation/complications , Inflammation/pathology , Inflammation/virology , Obesity/complications , Obesity/pathology , Obesity/virology , Pandemics , Peptidyl-Dipeptidase A/genetics , Renin-Angiotensin System/genetics , Risk Factors , SARS-CoV-2/pathogenicity
18.
Heliyon ; 6(8): e04696, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32844126

ABSTRACT

Obesity is a risk factor for SARS-CoV-2 infected patients to develop respiratory failure. Leptin produced in visceral fat might play a role in the deterioration to mechanical ventilation. A cross sectional study was performed. The mean BMI was 31 kg/m2 (range 24.8-48.4) for the 31 SARS-CoV-2 ventilated patients and 26 kg/m2 (range 22.4-33.5) for 8 critically ill non-infected control patients. SARS-CoV-2 infected patients with a similar BMI as control patients appear to have significantly higher levels of serum leptin. The mean leptin level was 21.2 (6.0-85.2) vs 5.6 (2.4-8.2) ug/L for SARS-CoV-2 and controls respectively (p = 0.0007). With these findings we describe a clinical and biological framework that may explain these clinical observations. The ACE2 utilization by the virus leads to local pulmonary inflammation due to ACE2-ATII disbalance. This might be enhanced by an increase in leptin production induced by SARS-CoV-2 infection of visceral fat. Leptin receptors in the lungs are now more activated to enhance local pulmonary inflammation. This adds to the pre-existent chronic inflammation in obese patients. Visceral fat, lung tissue and leptin production play an interconnecting role. This insight can lead the way to further research and treatment.

19.
Commun Biol ; 2: 208, 2019.
Article in English | MEDLINE | ID: mdl-31240246

ABSTRACT

The transcription factors LAP1, LAP2 and LIP are derived from the Cebpb-mRNA through the use of alternative start codons. High LIP expression has been associated with human cancer and increased cancer incidence in mice. However, how LIP contributes to cellular transformation is poorly understood. Here we present that LIP induces aerobic glycolysis and mitochondrial respiration reminiscent of cancer metabolism. We show that LIP-induced metabolic programming is dependent on the RNA-binding protein LIN28B, a translational regulator of glycolytic and mitochondrial enzymes with known oncogenic function. LIP activates LIN28B through repression of the let-7 microRNA family that targets the Lin28b-mRNA. Transgenic mice overexpressing LIP have reduced levels of let-7 and increased LIN28B expression, which is associated with metabolic reprogramming as shown in primary bone marrow cells, and with hyperplasia in the skin. This study establishes LIP as an inducer of cancer-type metabolic reprogramming and as a regulator of the let-7/LIN28B regulatory circuit.


Subject(s)
CCAAT-Enhancer-Binding Protein-beta/metabolism , MicroRNAs/genetics , Neoplasms/metabolism , Animals , Carcinogenesis/genetics , Cell Line, Tumor , Cell Proliferation , Cell Transformation, Neoplastic/genetics , Codon , Fibroblasts/metabolism , Glycolysis , HEK293 Cells , Humans , Male , Mice , Mice, Knockout , Mice, Transgenic , Mitochondria/metabolism , Oxygen Consumption , Proteome , RNA Interference , RNA, Messenger/metabolism , RNA-Binding Proteins/metabolism , Rats , Signal Transduction
20.
Aging (Albany NY) ; 11(22): 9971-9981, 2019 11 21.
Article in English | MEDLINE | ID: mdl-31770722

ABSTRACT

An increasing aging population poses a significant challenge to societies worldwide. A better understanding of the molecular, cellular, organ, tissue, physiological, psychological, and even sociological changes that occur with aging is needed in order to treat age-associated diseases. The field of aging research is rapidly expanding with multiple advances transpiring in many previously disconnected areas. Several major pharmaceutical, biotechnology, and consumer companies made aging research a priority and are building internal expertise, integrating aging research into traditional business models and exploring new go-to-market strategies. Many of these efforts are spearheaded by the latest advances in artificial intelligence, namely deep learning, including generative and reinforcement learning. To facilitate these trends, the Center for Healthy Aging at the University of Copenhagen and Insilico Medicine are building a community of Key Opinion Leaders (KOLs) in these areas and launched the annual conference series titled "Aging Research and Drug Discovery (ARDD)" held in the capital of the pharmaceutical industry, Basel, Switzerland (www.agingpharma.org). This ARDD collection contains summaries from the 6th annual meeting that explored aging mechanisms and new interventions in age-associated diseases. The 7th annual ARDD exhibition will transpire 2nd-4th of September, 2020, in Basel.


Subject(s)
Aging , Drug Discovery , Research , Drug Industry , Humans
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