Long noncoding RNAs are substrates for cytoplasmic capping enzyme.

Cytoplasmic capping returns a cap to specific mRNAs, thus protecting uncapped RNAs from decay. Prior to the identification of cytoplasmic capping, uncapped mRNAs were thought to be degraded. Here, we test whether long noncoding RNAs (lncRNAs) are substrates of the cytoplasmic capping enzyme (cCE). The subcellular localisation of 14 lncRNAs associated with sarcomas were examined in U2OS osteosarcoma cells. We used 5' rapid amplification of cDNA ends (RACE) to assay uncapped forms of these lncRNAs. Inhibiting cytoplasmic capping elevated uncapped forms of selected lncRNAs indicating a plausible role of cCE in targeting them. Analysis of published cap analysis of gene expression (CAGE) data shows increased prevalence of certain 5'-RACE cloned sequences, suggesting that these uncapped lncRNAs are targets of cytoplasmic capping.

Molecular regulation of hypoxia through the lenses of noncoding RNAs and epitranscriptome.

Cells maintain homeostasis in response to environmental stress through specific cell stress responses. Hypoxic stress, well known to be associated with diverse solid tumors, is one of the main reasons for cancer-related mortality. Although cells can balance themselves well during hypoxic stress, the underlying molecular mechanisms are not well understood. The enhanced appreciation of diverse roles played by noncoding transcriptome and epigenome in recent years has brought to light the involvement of noncoding RNAs and epigenetic modifiers in hypoxic regulation. The emergence of techniques like deep sequencing has facilitated the identification of large numbers of long noncoding RNAs (lncRNAs) that are differentially regulated in various cancers. Similarly, proteomic studies have identified diverse epigenetic modifiers such as HATs, HDACs, DNMTs, polycomb groups of proteins, and their possible roles in the regulation of hypoxia. The crosstalk between lncRNAs and epigenetic modifiers play a pivotal role in hypoxia-induced cancer initiation and progression. Besides the lncRNAs, several other noncoding RNAs like circular RNAs, miRNAs, and so forth are also expressed during hypoxic conditions. Hypoxia has a profound effect on the expression of noncoding RNAs and epigenetic modifiers. Conversely, noncoding RNAs/epigenetic modifies can regulate the hypoxia signaling axis by modulating the stability of the hypoxia-inducible factors (HIFs). The focus of this review is to illustrate the molecular orchestration underlying hypoxia biology, especially in cancers, which can help in identifying promising therapeutic targets in hypoxia-induced cancers. This article is categorized under: RNA Turnover and Surveillance > Regulation of RNA Stability RNA in Disease and Development > RNA in Disease RNA Structure and Dynamics > RNA Structure, Dynamics and Chemistry.

Harnessing Autophagic Network Is Essential for Trophoblast Stem Cell Differentiation.

Differentiation of trophoblast stem (TS) cells into various cell lineages of the placenta during mammalian development is accompanied by dynamic changes in its proteome for exerting the highly specialized functions of various cell subtypes. In the present study, we demonstrate that the autophagic machinery, which includes proteins for initiation, vesicle nucleation, and autophagosome maturation are robustly upregulated during differentiation of TS cells. Interestingly, basal levels of autophagy were detectable in the developing mouse placenta as well as TS cells. However, autophagic flux was actively triggered by induction of differentiation evident from LC3 maturation. Formation of Beclin1, Vps34, and PIK3R4 ternary complex at the phagophore assembly site that is typically known to induce autophagy was also enhanced during differentiation. Degradation of the p62/SQSTM1 cargo protein and its colocalization with LC3, a mature autophagosome marker, was most prevalent in the trophoblast giant cells (TGCs) and negligible in other trophoblast cells at day 6 of differentiation. Furthermore, disruption of autophagy by impairing lysosomal fusion in TS cells before induction of differentiation led to a decrease in the giant cell and spongiotrophoblast cell markers Prl3d1, Prl2c2, Prl4a1, and Tpbpα upon differentiation. In addition, inhibition of autophagy was associated with a decrease in nuclear size of TGCs. Taken together, these data highlight that autophagy is a necessary prelude in commitment of trophoblast differentiation from the multipotent TS cells probably by regulating protein turnover at the onset of differentiation.