Long non-coding RNA Neat1 and paraspeckle components are translational regulators in hypoxia.

Abstract

Internal ribosome entry sites (IRESs) drive translation initiation during stress. In response to hypoxia, (lymph)angiogenic factors responsible for tissue revascularization in ischemic diseases are induced by the IRES-dependent mechanism. Here we searched for IRES trans-acting factors (ITAFs) active in early hypoxia in mouse cardiomyocytes. Using knock-down and proteomics approaches, we show a link between a stressed-induced nuclear body, the paraspeckle, and IRES-dependent translation. Furthermore, smiFISH experiments demonstrate the recruitment of IRES-containing mRNA into paraspeckle during hypoxia. Our data reveal that the long non-coding RNA Neat1, an essential paraspeckle component, is a key translational regulator, active on IRESs of (lymph)angiogenic and cardioprotective factor mRNAs. In addition, paraspeckle proteins p54nrb and PSPC1 as well as nucleolin and Rps2, two p54nrb-interacting proteins identified by mass spectrometry, are ITAFs for IRES subgroups. Paraspeckle thus appears as a platform to recruit IRES-containing mRNAs and possibly host IRESome assembly. Polysome PCR array shows that Neat1 isoforms regulate IRES-dependent translation and, more widely, translation of mRNAs involved in stress response. HighlightsO_LIParaspeckle formation correlates with activation of translation via internal ribosome entry sites (IRES) in mouse hypoxic cardiomyocytes as well as in tumoral cells. C_LIO_LIThe long non-coding RNA Neat1, an essential paraspeckle component, is a key translational regulator of (lymph)angiogenic and cardioprotective factor expression in this process. C_LIO_LIIRES-containing mRNA is recruited into paraspeckles during hypoxia. C_LIO_LIParaspeckle proteins p54nrb and PSPC1 as well as two p54nrb-interacting proteins, nucleolin and RPS2, contribute to this process. C_LIO_LIParaspeckle appears as a platform for IRESome formation in the nucleus. C_LIO_LIThe Neat1 isoforms widely regulate the translation of mRNAs containing IRESs and of genes involved in the stress response. C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/430272v2_ufig1.gif" ALT="Figure 1"> View larger version (98K): org.highwire.dtl.DTLVardef@1741648org.highwire.dtl.DTLVardef@62e741org.highwire.dtl.DTLVardef@13c86a8org.highwire.dtl.DTLVardef@acae63_HPS_FORMAT_FIGEXP M_FIG C_FIG