BackgroundRecent reports indicate that retrotransposons – a type of mobile DNA – can contribute to neuronal genetic diversity in mammals. Retrotransposons are genetic elements that mobilize via an RNA intermediate by a “copy-and-paste” mechanism termed retrotransposition. Long Interspersed Element-1 (LINE-1 or L1) is the only active autonomous retrotransposon in humans and its activity is responsible for ~ 30% of genomic mass. Historically, L1 retrotransposition was thought to be restricted to the germline; however, new data indicate L1 s are active in somatic tissue with certain regions of the brain being highly permissive. The functional implications of L1 insertional activity in the brain and how host cells regulate it are incomplete. While deep sequencing and qPCR analysis have shown that L1 copy number is much higher in certain parts of the human brain, direct in vivo studies regarding detection of L1-encoded proteins is lacking due to ineffective reagents.ResultsUsing a polyclonal antibody we generated against the RNA-binding (RRM) domain of L1 ORF1p, we observe widespread ORF1p expression in post-mortem human brain samples including the hippocampus which has known elevated rates of retrotransposition. In addition, we find that two brains from different individuals of different ages display very different expression of ORF1p, especially in the frontal cortex.ConclusionsWe hypothesize that discordance of ORF1p expression in parts of the brain reported to display elevated levels of retrotransposition may suggest the existence of factors mediating post-translational regulation of L1 activity in the human brain. Furthermore, this antibody reagent will be useful as a complementary means to confirm findings related to retrotransposon biology and activity in the brain and other tissues in vivo.Electronic supplementary materialThe online version of this article (10.1186/s13100-017-0101-4) contains supplementary material, which is available to authorized users.

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The azo dye methyl red, which has carboxylato and azo functional groups, was used as a ligand for the synthesis of the cyclometalated RuIII complex [Ru(L1)(PPh3)2Cl] (1, L1H2 = 2‐{[4‐(dimethylamino)phenyl]diazenyl}benzoic acid) through C–H bond activation. Complex 1 was treated with nitric oxide to afford the organometallic ruthenium nitrosyl complex [Ru(L2H)(PPh3)2(NO)Cl][ClO4] (1a, L2H = 2‐{[4‐(dimethylamino)‐3‐nitrophenyl]diazenyl}benzoic acid). The molecular structures of 1·CH3OH and 1a·CH3OH were determined by X‐ray crystallography. The diamagnetic complex 1a with S = 0 ground state was studied by 1H and 31P NMR spectroscopy. In the nitrosyl complex, the coordinated NO is photolabile under UV and visible light, and the liberated NO was trapped by reduced myoglobin. The NO, photoreleased under visible light, was utilized in antiproliferation activity studies on human (A549, HEK293T, and HeLa) and mouse (NIH3T3) cancer cell lines.

Background Oral Squamous Cell Carcinoma (OSCC) results from a series of genetic alteration in squamous cells. This particular type of cancer considers one of the most aggressive malignancies to control because of its frequent local invasions to the regional lymph node. Although several biomarkers have been reported, the key marker used to predict the behavior of the disease is largely unknown. Here we report Long INterpersed Element-1 (LINE1 or L1) retrotransposon activity in post-operative oral cancer samples. L1 is the only active retrotransposon occupying around 17% of the human genome with an estimated 500,000 copies. An active L1 encodes two proteins (L1ORF1p and L1ORF2p); both of which are critical in the process of retrotransposition. Several studies report that the L1 retrotransposon is highly active in many cancers. L1 activity is generally determined by assaying L1ORF1p because of its high expression and availability of the antibody. However, due to its lower expression and unavailability of a robust antibody, detection of L1ORF2p has been limited. L1ORF2p is the crucial protein in the process of retrotransposition as it provides endonuclease and reverse transcriptase (RT) activity. Methods Immunohistochemistry and Western blotting were performed on the post-operative oral cancer samples and murine tissues. Results Using in house novel antibodies against both the L1 proteins (L1ORF1p and L1ORF2p), we found L1 retrotransposon is extremely active in post-operative oral cancer tissues. Here, we report a novel human L1ORF2p antibody generated using an 80-amino-acid stretch from the RT domain, which is highly conserved among different species. The antibody detects significant L1ORF2p expression in human oral squamous cell carcinoma (OSCC) samples and murine germ tissues. Conclusions We report exceptionally high L1ORF1p and L1ORF2p expression in post-operative oral cancer samples. The novel L1ORF2p antibody reported in this study will serve as a useful tool to understand why L1 activity is deregulated in OSCC and how it contributes to the progression of this particular cancer. Cross-species reactivity of L1ORF2p antibody due to the conserved epitope will be useful to study the retrotransposon biology in mice and rat germ tissues.

Retrotransposons are sequences which transpose within genomes using RNA as an intermediate. Long INterpersed Element-1 (LINE1 or L1) is the only active retrotransposon occupying around 17% of the human genome with an estimated 500,000 copies. An active L1 encodes two proteins (L1ORF1p and L1ORF2p); both of which are critical in the process of retrotransposition. In-order to propagate to the nextgeneration, L1s remain active in germ tissues and at an early stage of development. Surprisingly, by some unknown mechanism, L1 also shows activity in certain parts of the normal brain and many cancers. L1 activity is generally determined by assaying L1ORF1p because of its high expression and availability of the antibody. However, due to its lowerexpression and the unavailability of a robust antibody, detection of L1ORF2p has been limited. L1ORF2p is the crucial protein in the process of retrotransposition as it provides endonuclease and reverse transcriptase (RT) activity. Here, we report a novel human L1ORF2p antibody generated using an 80-amino-acid stretch from the RT domain, which is highly conserved among different species. The antibody detects significant L1ORF2p expression in murine germ tissues and human oral squamous cell carcinoma (OSCC) samples. This particular cancer is prevalent in India due to excessive use of tobacco. Here, using our in-house antibodies against L1 proteins, we show that more than fifty percent of samples are positive for L1 proteins. Overall, we reported a novel L1ORF2p antibody that detects L1 activity in germ tissues and OSCC