A study of experimental techniques for prealigning and clamping inertial measurement sensors without major system recalibration

Experimental techniques for prealigning and clamping inertial measurement sensors without major system recalibratio

Development of optimum clamp combinations for strap-down inertial measuring units with field replaceable sensors

Optimum clamp combinations for strap down inertial measuring units with field replaceable sensor

Distribution and biodiversity of Singapore gorgonians (sub-class Octocorallia) - a preliminary survey

10.1007/BF00005658Hydrobiologia2851-3101-109HYDR

Heterogeneous Nuclear Ribonucleoprotein A1 Regulates Cyclin D1 and c-myc Internal Ribosome Entry Site Function through Akt Signaling*S⃞

The translation of the cyclin D1 and c-myc mRNAs occurs via internal ribosome entry site (IRES)-mediated initiation under conditions of reduced eIF-4F complex formation and Akt activity. Here we identify hnRNP A1 as an IRES trans-acting factor that regulates cyclin D1 and c-myc IRES activity, depending on the Akt status of the cell. hnRNP A1 binds both IRESs in vitro and in intact cells and enhances in vitro IRES-dependent reporter expression. Akt regulates this IRES activity by inducing phosphorylation of hnRNP A1 on serine 199. Serine 199-phosphorylated hnRNP A1 binds to the IRESs normally but is unable to support IRES activity in vitro. Reducing expression levels of hnRNP A1 or overexpressing a dominant negative version of the protein markedly inhibits rapamycin-stimulated IRES activity in cells and correlated with redistribution of cyclin D1 and c-myc transcripts from heavy polysomes to monosomes. Importantly, knockdown of hnRNP A1 also renders quiescent Akt-containing cells sensitive to rapamycin-induced G1 arrest. These results support a role for hnRNP A1 in mediating rapamycin-induced alterations of cyclin D1 and c-myc IRES activity in an Akt-dependent manner and provide the first direct link between Akt and the regulation of IRES activity