Interaction of AU-rich sequence binding proteins with actin: possible involvement of the actin cytoskeleton in lymphokine mRNA turnover.
In the current study, we report that cytochalasin-induced disruption of microfilaments stabilizes lymphokine mRNAs in activated human peripheral blood lymphocytes. Parallel with this, a dose- and time-dependent increase in AU-rich sequence binding protein (AUPB) activities is apparent in the nonionic detergent-resistant fractions of these cells, suggesting that cytochalasin-induced modulation of lymphokine mRNA stability might be mediated through cytoplasmic AUBPs. We provide evidence that some of the AUBPs can be immunoprecipitated with anti-actin antibodies, implicating the potential of these proteins to associate with the actin-based cytoskeleton in vivo. Moreover, disruption of the microfilament network by cytochalasins produces increased immunoprecipitable actin-AUBP complexes in the detergent-resistant cytoplasmic subfractions of lymphocytes. We show that cytochalasin-induced changes in AUBP activities are parallel with their higher binding affinity to RNA containing AU-rich instability sequence element as judged by in vitro competition and in vivo ultraviolet-crosslinking analysis. Correlation of these findings with changes in mRNA stability indicates that the actin cytoskeleton may play a physiologically important role in posttranscriptional regulation of lymphokine gene expression during early lymphocyte activation.
Henics
T
T
Department of Microbiology, University Medical School of Pécs, Hungary. thenics@apacs.pote.hu
Nagy
E
E
Szekeres-Barthó
J
J
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D000199:Actins / Q000276:immunology / Q000378:metabolism*; D015152:Blotting, Northern; D003572:Cytochalasins / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000378:metabolism*; D008222:Lymphokines / Q000235:genetics* / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000494:pharmacology; D011233:Precipitin Tests; D015347:RNA Probes; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D014466:Ultraviolet Rays
D000199:Actins; D003572:Cytochalasins; D007376:Interleukin-2; D008222:Lymphokines; D010835:Phytohemagglutinins; D015347:RNA Probes; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D003609:Dactinomycin; D017830:Octoxynol