Selective localization of PCBP2 to cytoplasmic processing bodies.
Processing bodies (P-bodies) are cytoplasmic domains that have been implicated in critical steps of the regulation of gene expression, including mRNA decay and post-transcriptional gene silencing. Previously, we reported that PCBP2 (Poly-(rC) Binding Protein 2), a facilitator of IRES-mediated translation, is a novel P-body component. Interestingly, PCBP2 is recruited to only a subset of Dcp1a-positive P-bodies, which may reflect functional diversity among these structures. In this study, we examined the selective P-body localization of PCBP2 in detail. Co-localization studies between Dcp1a and PCBP2 revealed that PCBP2 is present in approximately 40% of P-bodies. While PCBP2 was more likely to reside in larger P-bodies, P-body size did not seem to be the sole determinant, and puromycin-induced enlargement of P-bodies only modestly increased the percentage of PCBP2-positive P-bodies. Photobleaching experiments demonstrated that the accumulation of PCBP2 to specific P-bodies is a dynamic process, which does not involve the protein's transcription-dependent nucleo-cytoplasmic shuttling activity. Finally, we found that PCBP1, a close relative of PCBP2, localizes to P-bodies in a similar manner to PCBP2. Taken together, these results establish the compositional diversity among P-bodies, and that PCBP2, probably in complex with other mRNP factors, may dynamically recognize such differences and accumulate to specific P-bodies.
Fujimura
Ken
K
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan. kfuji@bio.c.u-tokyo.ac.jp
Katahira
Jun
J
Kano
Fumi
F
Yoneda
Yoshihiro
Y
Murata
Masayuki
M
D060565:Argonaute Proteins; D003593:Cytoplasm / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D004268:DNA-Binding Proteins; D004722:Endoribonucleases / Q000378:metabolism; D039642:Eukaryotic Initiation Factors / Q000235:genetics / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D005456:Fluorescent Dyes / Q000378:metabolism; D006367:HeLa Cells; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D011691:Puromycin / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism
C115848:AGO1 protein, human; D060565:Argonaute Proteins; D004268:DNA-Binding Proteins; D039642:Eukaryotic Initiation Factors; D005456:Fluorescent Dyes; D034441:Heterogeneous-Nuclear Ribonucleoproteins; C094604:PCBP1 protein, human; C501903:PCBP2 protein, human; D011500:Protein Synthesis Inhibitors; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D011691:Puromycin; D004722:Endoribonucleases; C466279:DCP1A protein, human