Asymmetric dimethylation of ribosomal S6 kinase 2 regulates its cellular localisation and pro-survival function

Ribosomal S6 kinases (S6Ks) are critical regulators of cell growth, homeostasis, and survival, with dysregulation of these kinases found to be associated with various malignancies. While S6K1 has been extensively studied, S6K2 has been neglected despite its clear involvement in cancer progression. Protein arginine methylation is a widespread post-translational modification regulating many biological processes in mammalian cells. Here, we report that p54-S6K2 is asymmetrically dimethylated at Arg-475 and Arg-477, two residues conserved amongst mammalian S6K2s and several AT-hook-containing proteins. We demonstrate that this methylation event results from the association of S6K2 with the methyltransferases PRMT1, PRMT3, and PRMT6 in vitro and in vivo and leads to nuclear the localisation of S6K2 that is essential to the pro-survival effects of this kinase to starvation-induced cell death. Taken together, our findings highlight a novel post-translational modification regulating the function of p54-S6K2 that may be particularly relevant to cancer progression where general Arg-methylation is often elevated

Slewing Mirror Telescope optics for the early observation of UV/optical photons from Gamma-Ray Bursts

We report on design, manufacture, and testing of a Slewing Mirror Telescope (SMT), the first of its kind and a part of Ultra-Fast Flash Observatory-pathfinder (UFFO-p) for space-based prompt measurement of early UV/optical light curves from Gamma-Ray Bursts (GRBs). Using a fast slewing mirror of 150 mm diameter mounted on a 2 axis gimbal stage, SMT can deliver the images of GRB optical counterparts to the intensified CCD detector within 1.5∼1.8 s over ± 35 degrees in the slewing field of view. Its Ritchey-Chrétien telescope of 100 mm diameter provides a 17 × 17 arcmin2 instantaneous field of view. Technical details of design, construction, the laboratory performance tests in space environments for this unique SMT are described in conjunction with the plan for in-orbit operation onboard the Lomonosov satellite in 2013. © 2013 Optical Society of America.This research was supported by the Korean Creative Research Initiatives (RCMST) of MEST/NRF, the Basic Science Research program of MEST/NRF (2010-0025056), the World Class University program of MEST/NRF (R32-2009-000-10130-0), the Spanish MINECO project AYA-2009-14027-C05-01, AYA-2011-29936-C05-01, AYA-2012-39727-C03-01, and AYA 2009-14000-C03-01/ESP, Taiwan's National Science Council Vanguard Program (100-2119-M-002-025) LeCosPA of National Taiwan University, Program of development of Lomonosov Moscow State University and Korean programs NRF 2012-0006632, 20100029390 and Yonsei-KASI joint research for the Frontiers of Astronomy and Space Science Program 2012Peer Reviewe

Slewing Mirror Telescope and the Data-Acquisition System for the UFFO-Pathfinder

The Ultra-Fast Flash Observatory (UFFO) aims to detect the earliest moment of Gamma-Ray Bursts (GRBs) which is not well known, resulting into the enhancement of GRB mechanism understanding. The pathfinder mission was proposed to be a scaled-down version of UFFO, and only contains the UFFO Burst Alert & Trigger Telescope (UBAT) measuring the X-ray/gamma-ray with the wide-field of view and the Slewing Mirror Telescope (SMT) with a rapid-response for the UV/optical photons. Once the UBAT detects a GRB candidate with the position accuracy of 10 arcmin, the SMT steers the UV/optical photons from the candidate to the telescope by the fast rotatable mirror and provides the early UV/optical photons measurements with 4 arcsec accuracy. The SMT has a modified Ritchey-Chrètien telescope with the aperture size of 10 cm diameter including the rotatable mirror and the image readout by the intensified charge-coupled device. There is a key board called the UFFO Data Acquisition system (UDAQ) that manages the communication of each telescope and also of the satellite and the UFFO overall operation. This pathfinder is designed and built within the limited size and weight of  ~20 kg and the low power consumption up to  ~30 W. We will discuss the design and performance of the UFFO-pathfinder, and its integration to the Lomonosov satellite

Design and implementation of electronics and data acquisition system for Ultra-Fast Flash Observatory

The Ultra-Fast Flash Observatory (UFFO) Pathfinder for Gamma-Ray Bursts (GRBs) consists of two telescopes. The UFFO Burst Alert & Trigger Telescope (UBAT) handles the detection and localization of GRBs, and the Slewing Mirror Telescope (SMT) conducts the measurement of the UV/optical afterglow. UBAT is equipped with an X-ray detector, analog and digital signal readout electronics that detects X-rays from GRBs and determines the location. SMT is equipped with a stepping motor and the associated electronics to rotate the slewing mirror targeting the GRBs identified by UBAT. First the slewing mirror points to a GRB, then SMT obtains the optical image of the GRB using the intensified CCD and its readout electronics. The UFFO Data Acquisition system (UDAQ) is responsible for the overall function and operation of the observatory and the communication with the satellite main processor. In this paper we present the design and implementation of the electronics of UBAT and SMT as well as the architecture and implementation of UDAQ

Development of Motorized Slewing Mirror Stage for the UFFO Project

The Ultra-Fast Flash Observatory (UFFO) is a space observatory for optical follow-ups of gamma ray bursts (GRBs), aiming to explore the first 60 seconds of GRBs optical emission. UFFO is utilized to catch early optical emissions from GRBs within few sec after trigger using a Gimbal mirror which redirects the optical path rather than slewing entire spacecraft. We have developed a 15 cm two-axis Gimbal mirror stage for the UFFO-Pathfinder which is going to be on board the Lomonosov satellite which is to be launched in 2013. The stage is designed for fast and accurate motion with given budgets of 3 kg of mass and 3 Watt of power. By employing stepping motors, the slewing mirror can rotate faster than 15 deg/sec so that objects in the UFFO coverage (60 deg × 60 deg) can be targeted in ~1 sec. The obtained targeting resolution is better 2 arcmin using a close-loop control with high precision rotary encoder. In this presentation, we will discuss details of design, manufacturing, space qualification tests, as well as performance tests

Calibration and Simulation of the GRB trigger detector of the Ultra Fast Flash Observatory

The UFFO (Ultra-Fast Flash Observatory) is a GRB detector on board the Lomonosov satellite, to be launched in 2013. The GRB trigger is provided by an X-ray detector, called UBAT (UFFO Burst Alarm & Trigger Telescope), which detects X-rays from the GRB and then triggers to determine the direction of the GRB and then alerts the Slewing Mirror Telescope (SMT) to turn in the direction of the GRB and record the optical photon fluxes. This report details the calibration of the two components: the MAPMTs and the YSO crystals and simulations of the UBAT. The results shows that this design can observe a GRB within a field of view of ±35° and can trigger in a time scale as short as 0.2 – 1.0 s after the appearance of a GRB X-ray spike

In-Flight Calibrations of UFFO-Pathfinder

The Ultra-Fast Flash Observatory (UFFO), which will be launched onboard the Lomonosov spacecraft, contains two crucial instruments: UFFO Burst Alert & Trigger Telescope (UBAT) for detection and localization of Gamma-Ray Bursts (GRBs) and the fast-response Slewing Mirror Telescope (SMT) designed for the observation of the prompt optical/UV counterparts. Here we discuss the in-space calibrations of the UBAT detector and SMT telescope. After the launch, the observations of the standard X-ray sources such as pulsar in Crab nebula will provide data for necessary calibrations of UBAT. Several standard stars will be used for the photometric calibration of SMT. The celestial X-ray sources, e.g. X-ray binaries with bright optical sources in their close angular vicinity will serve for the cross-calibration of UBAT and SMT

The atmospheric science of JEM-EUSO

An Atmospheric Monitoring System (AMS) is critical suite of instruments for JEM-EUSO whose aim is to detect Ultra-High Energy Cosmic Rays (UHECR) and (EHECR) from Space. The AMS comprises an advanced space qualified infrared camera and a LIDAR with cross checks provided by a ground-based and airborne Global Light System Stations. Moreover the Slow Data Mode of JEM-EUSO has been proven crucial for the UV background analysis by comparing the UV and IR images. It will also contribute to the investigation of atmospheric effects seen in the data from the GLS or even to our understanding of Space Weather

Ultra-Fast Flash Observatory: Fast Response Space Missions for Early Time Phase of Gamma Ray Bursts

One of the unexplored domains in the study of gamma-ray bursts (GRBs) is the early time phase of the optical light curve. We have proposed Ultra-Fast Flash Observatory (UFFO) to address this question through extraordinary opportunities presented by a series of small space missions. The UFFO is equipped with a fast-response Slewing Mirror Telescope that uses a rapidly moving mirror or mirror array to redirect the optical beam rather than slewing the entire spacecraft or telescope to aim the optical instrument at the GRB position. The UFFO will probe the early optical rise of GRBs with sub-second response, for the first time, opening a completely new frontier in GRB and transient studies. Its fast response measurements of the optical emission of dozens of GRB each year will provide unique probes of the burst mechanism and test the prospect of GRB as a new standard candle, potentially opening up the z > 10 universe. We describe the current limit in early photon measurements, the aspects of early photon physics, our soon-to-be-launched UFFO-pathfinder mission, and our next planned mission, the UFFO-100