Identification of GW182 and its novel isoform TNGW1 as translational repressors in Ago2-mediated silencing.
RNA interference is triggered by small interfering RNA and microRNA, and is a potent mechanism in post-transcriptional regulation for gene expression. GW182 (also known as TNRC6A), an 182-kDa protein encoded by TNRC6A, is important for this process, although details of its function remain unclear. Here, we report a novel 210-kDa isoform of human GW182, provisionally named trinucleotide GW1 (TNGW1) because it contains trinucleotide repeats in its mRNA sequence. TNGW1 was expressed independently of GW182 and was present in human testis and various human cancer cells. Using polyclonal and monoclonal antibodies, we detected TNGW1 in only approximately 30% of GW bodies. Expression of EGFP-tagged TNGW1 in HeLa cells was colocalized to cytoplasmic foci enriched in Ago2 (also known as EIF2C2) and RNA decay factors. Tethering TNGW1 or GW182 to the 3'-UTR of a luciferase-reporter mRNA led to strong repression activity independent of Ago2, whereas the tethered Ago2-mediated suppression was completely dependent on TNGW1 and/or GW182. Our data demonstrated that GW182 and, probably, TNGW1 acted as a repressor in Ago2-mediated translational silencing. Furthermore, TNGW1 might contribute to diversity in the formation and function of GW and/or P bodies.
Li
Songqing
S
Departments of Oral Biology and Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA.
Lian
Shang L
SL
Moser
Joanna J
JJ
Fritzler
Mark L
ML
Fritzler
Marvin J
MJ
Satoh
Minoru
M
Chan
Edward K L
EK
D000595:Amino Acid Sequence; D060565:Argonaute Proteins; D001324:Autoantigens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D045744:Cell Line, Tumor; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis / Q000235:genetics*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
C466422:AGO2 protein, human; D060565:Argonaute Proteins; D001324:Autoantigens; D015852:Eukaryotic Initiation Factor-2; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C465663:TNRC6A protein, human