The L1 Retroelement-related p40 Protein Induces p38δ MAP Kinase

Kuchen, Stefan; Seemayer, Christian A.; Rethage, Janine; Knoch, R von; Kuenzler, Peter; Michel, Beat A.; Gay, Renate E.; Gay, Steffen; Neidhart, Michel

doi:10.1080/08916930310001637977

Cited by 60 publications

(35 citation statements)

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“…Trex-1 was also detected by immunohistochemistry on paraffin-embedded sections of synovial tissue, as described previously (4)(5)(6). Rabbit anti-Trex-1 polyclonal antibodies (Abcam), goat anti-rabbit biotinylated antibodies, and streptavidin conjugated to alkaline phosphatase were used for tissue staining, and Dako Fast Red substrate was used to reveal the staining.…”

Section: Methodsmentioning

confidence: 99%

“…The promoter of the L1 retroelement is hypomethylated in RASFs (5), reflecting global DNA hypomethylation. The L1-related p40 protein (L1-ORF1p) has nucleic acid binding properties and favors the transcription of specific genes (6). The L1-encoded p150 protein (L1-ORF2p) has a reverse transcription activity, transmobilizing Alu RNA and Pol II transcripts, which yields new autoantigenic, hypomethylated DNA fragments (7).…”

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confidence: 99%

“…Among those genes carrying such binding motifs in their promoters are p38␦ MAPK (6) and the c-Met oncogene (13). Polyclonal antibodies directed against human L1-ORF1p were generated, and chromatin immunoprecipitation (ChIP) was performed; the obtained DNA fragments were amplified by polymerase chain reaction (PCR), sequenced, and inserted in front of a luciferase reporter gene.…”

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Trex‐1 deficiency in rheumatoid arthritis synovial fibroblasts

Neidhart

Karouzakis

Schumann

2010

Arthritis & Rheumatism

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Objective. To explore whether the increased expression of long interspersed nuclear element 1 (LINE-1; L1) messenger RNA (mRNA) and protein in rheumatoid arthritis synovial fibroblasts (RASFs) is associated with decreased expression of Trex-1, an exonuclease involved in the metabolization of L1 DNA: RNA hybrids.Methods. Chromatin immunoprecipitation was used to detect L1-related p40 protein (L1-ORF1p) binding sequences in RASFs. Luciferase activity was measured in the synovial fibroblasts following cotransfection of the episomal plasmid with pJM105 expressing L1-ORF1p and pGL3-TS3 carrying the target sequence for L1-ORF1p. This luciferase reporter assay was used to compare the activity between RASFs and osteoarthritis synovial fibroblasts (OASFs) and to assess correlations of luciferase activity with the expression of Trex-1 measured by flow cytometry. The expression of Trex-1 mRNA and protein was also compared using real-time polymerase chain reaction, immunohistochemistry, and Western blot analyses. The role of Trex-1 in the L1-ORF1p-mediated luciferase activity assay was studied using interfering RNAs (iRNA) and a Trex-1 expression vector.Results. Increased luciferase activity occurred after cotransfection of synovial fibroblasts with pJM105 and pGL3-TS3. L1-ORF1p activity was increased in RASFs as compared with OASFs, and this was correlated inversely with the expression of Trex-1. Levels of Trex-1 mRNA and protein were lower in RASFs than in OASFs. After transfection of the L1 expression plasmid, Trex-1 mRNA levels increased in OASFs, but not in RASFs. The addition of iRNA against Trex-1, however, resulted in an enhancement of L1-ORF1p activity in OASFs to the levels measured in RASFs. Overexpression of Trex-1 inhibited 5-azacytidine-induced expression of p38␦ MAPK, a gene carrying the TS3 sequence. Conclusion. The deficiency of Trex-1 in RASFs allows a longer half-life of gene products encoded by active endogenous L1 retrotransposons. This pathway may play a role in diseases in which the cells exhibit a "spontaneous" aggressive behavior.Trex-1 is the major 3Ј35Ј DNA exonuclease in mammalian cells, and mutations in the human trex-1 gene can cause Aicardi-Goutières syndrome (1), a disease that is characterized by perturbed immunity. Such mutations also appear to be involved in systemic lupus erythematosus (SLE) (2), in which the failure to process intermediates of nucleic acid metabolism can result in the activation of uncontrolled autoimmunity. Trex-1 prevents the accumulation of single-stranded DNA (ssDNA) fragments derived from endogenous long interspersed nuclear element 1 (LINE-1; L1) retrotransposons (3), the expression of which has been reported in rheumatoid arthritis synovial fibroblasts (RASFs) (4). The promoter of the L1 retroelement is hypomethylated in RASFs (5), reflecting global DNA hypomethylation. The L1-related p40 protein (L1-ORF1p) has nucleic acid binding properties and favors the transcription of specific genes (6). The L1-encoded p150 protein (L1-ORF2p) has a reverse transcription acti...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Trex‐1 deficiency in rheumatoid arthritis synovial fibroblasts

Neidhart

Karouzakis

Schumann

2010

Arthritis & Rheumatism

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“…Gay, synovial tissue DNA in RA patients is hypomethylated, and when normal synovial fibroblasts are treated with the DNMT inhibitor 5-AZA (5-aza-2′-deoxycytidine), they develop a RASF-like phenotype [6,7]. A recently published report also provides evidence of histone hyperacetylation in synovial tissue samples from animals with a RA-like condition compared to animals with osteoarthritis (OA).…”

Section: Rheumatoid Arthritismentioning

confidence: 99%

Epigenetics in autoimmune disorders: Highlights of the 10th Sjögren's Syndrome Symposium

Lu¹,

Renaudineau²,

Cha

et al. 2010

Autoimmunity Reviews

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During the 10th International Symposium on Sjögren's Syndrome held in Brest, France, from October 1-3, 2009 (http://www.sjogrensymposium-brest2009.org), the creation of an international epigenetic autoimmune group has been proposed to establish gold standards and to launch collaborative studies. During this "epigenetics session", leading experts in the field presented and discussed the most recent developments of this topic in Sjögren's Syndrome research. The "Brest epigenetic task force" was born and has scheduled a meeting in Ljubljana, Slovenia during the 7th Autoimmunity congress in May 2010.The following is a report of that session.  Increased activity and destructive potential of synovial fibroblasts in rheumatoid arthritis is due in part to the deregulation of epigenetic factors. Development of an epigenetic bank and the establishment of gold standards in an epigenetic consortium to analyse epigenetic modifications are needed. Epigenetic alterations in autoimmune diseases could be used as prognostic/diagnostic tools and markers of immune cell activation.2

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“…Recent studies have shown that phosphorylation-related proteins can be coimmunoprecipitated with ORF1p or L1 RNPs (39,40). In addition, the mitogen-activated protein kinase (MAPK) p38 has been implicated in L1 activation by environmental toxins (41,42), and its expression can be increased by exogenous ORF1p (43). Although large-scale proteomic studies can only identify a subset of phospho sites (44), a phosphoproteomic study of human embryonal stem cells, in which L1 is active, identified an ORF1p fragment phosphorylated on S18 (45).…”

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Phosphorylation of ORF1p is required for L1 retrotransposition

Cook

Jones

Furano

2015

Proc. Natl. Acad. Sci. U.S.A.

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Although members of the L1 (LINE-1) clade of non-LTR retrotransposons can be deleterious, the L1 clade has remained active in most mammals for ∼100 million years and generated almost 40% of the human genome. The details of L1-host interaction are largely unknown, however. Here we report that L1 activity requires phosphorylation of the protein encoded by the L1 ORF1 (ORF1p). Critical phospho-acceptor residues (two serines and two threonines) reside in four conserved proline-directed protein kinase (PDPK) target sites. The PDPK family includes mitogen-activated protein kinases and cyclin-dependent kinases. Mutation of any PDPK phospho-acceptor inhibits L1 retrotransposition. The phosphomimetic aspartic acid can restore activity at the two serine sites, but not at either threonine site, where it is strongly inhibitory. ORF1p also contains conserved PDPK docking sites, which promote specific interaction of PDPKs with their targets. As expected, mutations in these sites also inhibit L1 activity. PDPK mutations in ORF1p that inactivate L1 have no significant effect on the ability of ORF1p to anneal RNA in vitro, an important biochemical property of the protein. We show that phosphorylated PDPK sites in ORF1p are required for an interaction with the peptidyl prolyl isomerase 1 (Pin1), a critical component of PDPK-mediated regulation. Pin1 acts via isomerization of proline side chains at phosphorylated PDPK motifs, thereby affecting substrate conformation and activity. Our demonstration that L1 activity is dependent on and integrated with cellular phosphorylation regulatory cascades significantly increases our understanding of interactions between L1 and its host.L 1 (or LINE-1) activity over the last ∼100 million years of primate evolution has generated ∼40% of the human genome (1, 2); thus, succeeding families of L1 elements are the main drivers of genetic expansion. These autonomously replicating elements convert their RNA transcripts and those of other genetic elements, particularly SINEs, into genomic DNA (3). A generic L1 element is 6-7 kb and contains the following: a 5′ UTR; ORF1, which encodes the coiled-coil mediated trimeric nucleic acid chaperone protein ORF1p; ORF2, which encodes a DNA endonuclease and reverse-transcriptase ORF2p; and a 3′ UTR terminated in a polyA sequence (reviewed in refs. 3 and 4). ORF1p, ORF2p, and L1 RNA form ribonucleoprotein particles (RNPs) that are likely intermediates in L1 retrotransposition (5-8). The L1-encoded proteins ORF1p and ORF2p are essential in cell culture-based retrotransposition assays (9) and in vitro assays using RNPs from cells transfected with L1 retrotransposition vectors (7). Although the role of ORF1p in retrotransposition is not known, mutations that affect its nucleic acid binding and chaperone activities can inactivate L1 (7, 9, 10).L1 activity can damage DNA (11), can generate genetic diversity and rearrangements (12-16), and is activated in certain tumors (17-19) and other somatic cells (20), including neuronal cells (21-23). Despite being deleterious (2...

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The L1 Retroelement-related p40 Protein Induces p38δ MAP Kinase

Cited by 60 publications

References 28 publications

Trex‐1 deficiency in rheumatoid arthritis synovial fibroblasts

Trex‐1 deficiency in rheumatoid arthritis synovial fibroblasts

Epigenetics in autoimmune disorders: Highlights of the 10th Sjögren's Syndrome Symposium

Phosphorylation of ORF1p is required for L1 retrotransposition

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