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Members of the anthozoan green fluorescent protein (GFP) family display a diversity of photo-physical properties that can be associated with normal and damaged coral tissues. Poritid coral species often exhibit localized pink pigmentation in diseased or damaged tissues. Our spectral and histological analyses of pink-pigmented Porites lobata lesions show co-localization of bright red fluorescence with putative amoebocytes concentrating in the epidermis, suggesting an activated innate immune response. Here we report the cloning, expression, and characterization of a novel red fluorescent protein (plobRFP) from the pink-pigmented tissues associated with lesions on Porites lobata. In vitro, the recombinant plobRFP exhibits a distinct red emission signal of 614 nm (excitation maximum: 578 nm), making plobRFP the furthest red-shifted natural fluorescent protein isolated from a scleractinian coral. The recombinant protein has a high molar extinction coefficient (84,000 M-1 cm-1) and quantum yield (0.74), conferring a notable brightness to plobRFP. Sequence analysis suggests the distinct brightness and marked red shift may be inherent features of plobRFP's chromophore conformation. While plobRFP displays a tendency to aggregate, its high pH stability, photostability, and spectral properties make it a candidate for cell imaging applications and a potential template for engineering optimized RFPs. The association of plobRFP with a possible immune response furthers its potential use as a visual diagnostic and molecular biomarker for monitoring coral health.

Accelerated glycolysis is the main metabolic change observed in cancer, but the underlying molecular mechanisms and their role in cancer progression remain poorly understood. Here we show that deletion of the long noncoding RNA (lncRNA) Neat1 in MMTV-PyVT mice profoundly impairs tumor initiation, growth and metastasis, while specifically switching off the penultimate step of glycolysis. Mechanistically, NEAT1 directly binds and forms a scaffold bridge for the assembly of PGK1/PGAM1/ENO1 complexes, and thereby promotes substrate channeling for high and efficient glycolysis. Notably, NEAT1 is upregulated in cancer patients and correlates with high levels of these complexes, and genetic and pharmacological blockade of penultimate glycolysis ablates NEAT1-dependent tumorigenesis. Finally, we demonstrate that Pinin mediates glucose-stimulated nuclear export of NEAT1, through which it exerts isoform-specific and paraspeckle-independent functions. These findings establish a direct role for NEAT1 in regulating tumor metabolism, provide new insights into the Warburg effect, and identify potential targets for therapy.

The adherens junctions (AJs) are essential architectural elements of epithelial tissues. Compromised junctional integrity is a common precursor to colon cancer. Recently, we identified a novel mechanism whereby the AJs of non-transformed colon cells recruit the microprocessor and RISC, core elements of the RNAi machinery, as well as miRNAs, to suppress oncogenic mRNAs. Knockdown of the AJ component PLEKHA7, disrupts this RNAi-mediated signaling program, leading to pro-tumorigenic cell transformation. Interestingly, PLEKHA7 RNA-CLIP and subsequent RNA-Seq analysis identified association with numerous long non-coding RNAs (lncRNAs). While a number of lncRNAs have been associated with tumorigenesis, the underlying mechanisms of their regulation during tumor progression are still unclear. As lncRNAs can interact with the RNAi machinery, we hypothesize that the AJs regulate lncRNAs via this localized RNAi mechanism. Examination of PLEKHA7-depleted cells by RNA-seq revealed differential expression of 49 junction-associated lncRNAs. From this set, the top upregulated lncRNA is MIR17HG, an oncogenic polycistronic host transcript of the miR-17-92 cluster. Junctional localization of MIR17HG was confirmed by RNA-FISH. Adherens junctions destabilization by E-cadherin knockdown also led to the upregulation of MIR17HG, demonstrating the role of junctional integrity in MIR17HG suppression. Data from Ago2 knockdown, anti-miR, and miRNA mimic experiments show that PLEKHA7 suppresses the levels of the MIR17HG transcript through the junction-associated RISC and two miRNAs, miR-203a and miR-372. PLEKHA7 depletion also results in increased levels of a subset of MIR17HG hosted miRNAs, including miR-19a and miR-19b, both known cancer promoters. Ectopic expression of PLEKHA7 in the aggressive HCT116 colon cancer cells that lack endogenous PLEKHA7 expression, suppressed anchorage independent growth, as well as MIR17HG levels, which are elevated in these cells. We are currently examining the role of MIR17HG as a functional intermediate of PLEKHA7’s loss on colon cell transformation. In summary, our data point towards a novel mechanism of lncRNA regulation that tethers epithelial architecture with cell behavior. Note: This abstract was not presented at the meeting. Citation Format: Mary C. Bridges, Joyce Nair-Menon, Antonis Kourtidis. Epithelial adherens junctions suppress the pro-tumorigenic MIR17HG lncRNA by recruiting RISC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1825.