The stability of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells varies with growth rate.
The decay rates of eucaryotic elongation factor Tu (eEF-Tu) mRNA and eucaryotic initiation factor 4A (eIF-4A) mRNA in Friend erythroleukemia (FEL) cells were determined under several different growth conditions. In FEL cells which were no longer actively dividing (stationary phase), eEF-Tu mRNA was found to be rather stable, with a t1/2 of about 24 h. In rapidly growing FEL cells eEF-Tu mRNA was considerably less stable, with a t1/2 of about 9 h. In both cases a single rate of mRNA decay was observed. However, when stationary-phase cells resumed growth after treatment with fresh medium, we observed that eEF-Tu mRNA decay followed a biphasic process. The faster of the two decay rates involved approximately 50% of the eEF-Tu mRNA and had a t1/2 of about 1 h. The decay rates for eIF-4A (t1/2 = 2 h) and total poly(A)+ RNA (t1/2 = 3 h) were unaffected by changes in growth conditions. The t1/2 for polysomal eEF-Tu mRNA was found to be about 8 h when stationary FEL cells were treated with fresh medium. Previous work in this laboratory has shown (T. R. Rao and L. I. Slobin, Mol. Cell. Biol. 7:687-697, 1987) that when FEL cells are allowed to grow to stationary phase, approximately 60% of the mRNA for eEF-Tu is found in a nontranslating postpolysomal messenger ribonucleoprotein (mRNP) particle. eEF-Tu mRNP was rapidly cleared from stationary cells after treatment with fresh medium. The data presented in this report indicate that the stability of eEF-Tu mRNP is rapidly altered and the particle is targeted for degradation when stationary FEL cells resume growth.
Rao
T R
TR
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4505.
Slobin
L I
LI
D002455:Cell Division; D002460:Cell Line; D003470:Culture Media; D004247:DNA / Q000235:genetics; D005622:Friend murine leukemia virus; D005786:Gene Expression Regulation; D006207:Half-Life; D004915:Leukemia, Erythroblastic, Acute; D009693:Nucleic Acid Hybridization; D010444:Peptide Elongation Factor Tu / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics; D012261:Ribonucleoproteins / Q000378:metabolism
D003470:Culture Media; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D004247:DNA; D010444:Peptide Elongation Factor Tu