Probes for LONG

Neurons are well suited for computations on millisecond timescales, but some neuronal circuits set behavioral states over long time periods, such as those involved in energy homeostasis. We found that multiple types of hypothalamic neurons, including those that oppositely regulate body weight, are specialized as near-perfect synaptic integrators that summate inputs over extended timescales. Excitatory postsynaptic potentials (EPSPs) are greatly prolonged, outlasting the neuronal membrane time-constant up to 10-fold. This is due to the voltage-gated sodium channel Nav1.7 (Scn9a), previously associated with pain-sensation but not synaptic integration. Scn9a deletion in AGRP, POMC, or paraventricular hypothalamic neurons reduced EPSP duration, synaptic integration, and altered body weight in mice. In vivo whole-cell recordings in the hypothalamus confirmed near-perfect synaptic integration. These experiments show that integration of synaptic inputs over time by Nav1.7 is critical for body weight regulation and reveal a mechanism for synaptic control of circuits regulating long term homeostatic functions.

A progressive increase in MECP2 protein levels is a crucial and precisely regulated event during neurodevelopment, but the underlying mechanism is unclear. We report that MECP2 is regulated post-transcriptionally during in vitro differentiation of human embryonic stem cells (hESCs) into cortical neurons. Using reporters to identify functional RNA sequences in the MECP2 3' UTR and genetic manipulations to explore the role of interacting factors on endogenous MECP2, we discover combinatorial mechanisms that regulate RNA stability and translation. The RNA-binding protein PUM1 and pluripotent-specific microRNAs destabilize the long MECP2 3' UTR in hESCs. Hence, the 3' UTR appears to lengthen during differentiation as the long isoform becomes stable in neurons. Meanwhile, translation of MECP2 is repressed by TIA1 in hESCs until HuC predominates in neurons, resulting in a switch to translational enhancement. Ultimately, 3' UTR-directed translational fine-tuning differentially modulates MECP2 protein in the two cell types to levels appropriate for normal neurodevelopment.

Phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3 or PIP3) mediates signalling pathways as a second messenger in response to extracellular signals. Although primordial functions of phospholipids and RNAs have been hypothesized in the 'RNA world', physiological RNA-phospholipid interactions and their involvement in essential cellular processes have remained a mystery. We explicate the contribution of lipid-binding long non-coding RNAs (lncRNAs) in cancer cells. Among them, long intergenic non-coding RNA for kinase activation (LINK-A) directly interacts with the AKT pleckstrin homology domain and PIP3 at the single-nucleotide level, facilitating AKT-PIP3 interaction and consequent enzymatic activation. LINK-A-dependent AKT hyperactivation leads to tumorigenesis and resistance to AKT inhibitors. Genomic deletions of the LINK-A PIP3-binding motif dramatically sensitized breast cancer cells to AKT inhibitors. Furthermore, meta-analysis showed the correlation between LINK-A expression and incidence of a single nucleotide polymorphism (rs12095274: A > G), AKT phosphorylation status, and poor outcomes for breast and lung cancer patients. PIP3-binding lncRNA modulates AKT activation with broad clinical implications.

Aggressive breast cancer is difficult to treat as it is unresponsive to many hormone-based therapies; therefore, it is imperative to identify novel, targetable regulators of progression. Long non-coding RNAs (lncRNAs) are important regulators in breast cancer and have great potential as therapeutic targets; however, little is known about how the majority of lncRNAs function within breast cancer. This study, characterizes a novel lncRNA, MANCR (mitotically-associated long non-coding RNA; LINC00704), which is upregulated in breast cancer patient specimens and cells. Depletion of MANCR in triple-negative breast cancer (TNBC) cells significantly decreases cell proliferation and viability, with concomitant increases in DNA damage. Transcriptome analysis, based on RNA sequencing (RNA-seq), following MANCR knockdown reveals significant differences in the expression of >2000 transcripts, and gene set enrichment analysis (GSEA) identifies changes in multiple categories related to cell cycle regulation. Furthermore, MANCR expression is highest in mitotic cells by both RT-qPCR and RNA in situ hybridization. Consistent with a role in cell cycle regulation, MANCR-depleted cells have a lower mitotic index and higher incidences of defective cytokinesis and cell death. Taken together, these data reveal a role for the novel lncRNA, MANCR, in genomic stability of aggressive breast cancer, and identify it as a potential therapeutic target.

IMPLICATIONS:

The novel lncRNA, MANCR (LINC00704), is upregulated in breast cancer and is functionally linked with cell proliferation, viability, and genomic stability.

The androgen receptor (AR) plays a critical role in the development of the normal prostate as well as prostate cancer. Using an integrative transcriptomic analysis of prostate cancer cell lines and tissues, we identified ARLNC1 (AR-regulated long noncoding RNA 1) as an important long noncoding RNA that is strongly associated with AR signaling in prostate cancer progression. Not only was ARLNC1 induced by the AR protein, but ARLNC1 stabilized the AR transcript via RNA–RNA interaction. ARLNC1 knockdown suppressed AR expression, global AR signaling and prostate cancer growth in vitro and in vivo. Taken together, these data support a role for ARLNC1 in maintaining a positive feedback loop that potentiates AR signaling during prostate cancer progression and identify ARLNC1 as a novel therapeutic target.

Long noncoding RNAs (lncRNAs) have been acknowledged as significant regulators in the progression of various cancers, including malignant meningioma. Being a newly identified lncRNA, long intergenic non-protein coding RNA 702 (LINC00702) has not been comprehensively studied in malignant meningioma. In this study, the role of LINC00702 was identified and explored in malignant meningioma. The LINC00702 expression was determined in malignant meningioma tissues and cell lines by qRT-PCR. Then the association between LINC00702 expression and the prognosis of malignant meningioma patients was analyzed by Kaplan-Meier analysis. The functional role of LINC00702 in malignant meningioma cell proliferation and migration was analyzed by loss-of function assays. Subcellular fractionation assay and FISH assay revealed the cytoplasmic localization of LINC00702. Bioinformatics analysis and mechanism experiments demonstrated that LINC00702 acted as the molecular sponge of miR-4652-3p to upregulate ZEB1 in malignant meningioma. Furthermore, high level of LINC00702 was demonstrated to be associated with the activity of Wnt/β-catenin signaling. Moreover, miR-4652-3p and ZEB1 involved in LINC00702-mediated Wnt/β-catenin signaling. At last, rescue assays revealed that miR-4652-3p and ZEB1 attenuated LINC00702-mediated cell proliferation and migration.