title: Dynamic association-dissociation and harboring of endogenous mRNAs in stress granules.
abstract: In response to environmental stress, cytoplasmic mRNAs aggregate to form stress granules (SGs). SGs have mainly been studied indirectly using protein markers, but the real-time behavior of endogenous mRNAs in SGs remains uncertain. Here, we visualized endogenous cytoplasmic poly(A)(+) mRNAs in living mammalian cells using a linear antisense 2'-O-methyl RNA probe. In arsenite-stressed cells, endogenous mRNAs aggregated in granules that colocalized with SGs marked by TIA-1-GFP. Moreover, analysis of mRNA dynamics using fluorescence recovery after photobleaching showed that approximately one-third of the endogenous mRNAs in SGs was immobile, another one-third was diffusive, and the remaining one-third was in equilibrium between binding to and dissociating from SGs, with a time constant of approximately 300 seconds. These dynamic characteristics of mRNAs were independent of the duration of stress and microtubule integrity. Similar characteristics were also observed from fos mRNA labeled with an antisense 2'-O-methyl RNA probe. Our results revealed the behavior of endogenous mRNAs, and indicated that SGs act as dynamic harbors of untranslated poly(A)(+) mRNAs.
authors.affiliation: Laboratory of Bio-Analytical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033,  Japan.
authors.forename: Junwei
authors.initials: J
authors.lastname: Zhang
authors.forename: Kohki
authors.initials: K
authors.lastname: Okabe
authors.forename: Tokio
authors.initials: T
authors.lastname: Tani
authors.forename: Takashi
authors.initials: T
authors.lastname: Funatsu
mesh_terms: D000818:Animals; D018053:Arsenites / Q000494:pharmacology; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000187:drug effects; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004058:Diffusion; D036681:Fluorescence Recovery After Photobleaching; D008845:Microinjections; D008870:Microtubules / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D015347:RNA Probes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D017670:Sodium Compounds / Q000494:pharmacology; D013312:Stress, Physiological; D013997:Time Factors; D014162:Transfection
chemical_list: D018053:Arsenites; D015347:RNA Probes; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D017670:Sodium Compounds; D011061:Poly A; C017947:sodium arsenite