The role of 3' poly(A) tail metabolism in tumor necrosis factor-alpha regulation.
In unstimulated RAW 264.7 macrophage-like cells, tumor necrosis factor-alpha (TNF-alpha) mRNA was transcribed and accumulated in the cytoplasm, but the TNF-alpha transcripts failed to associate with polysomes, and TNF-alpha protein was not detected. Stimulation with lipopolysaccharide (LPS) induced an increase in TNF-alpha transcription, cytoplasmic TNF-alpha mRNA accumulation, polysome association, and secretion of TNF-alpha protein. This process was associated with a 200-nucleotide increase in the apparent length of the TNF-alpha mRNA. The difference in TNF-alpha mRNA size was caused by marked truncation of the 3' poly(A) tail in unstimulated cells. Fully adenylated TNF-alpha mRNA appeared within 15 min of LPS stimulation. We speculate that removal of the poly(A) tail blocks initiation of TNF-alpha translation in unstimulated macrophages. LPS inactivates this process, allowing synthesis of translatable polyadenylated TNF-alpha mRNA.
Crawford
E K
EK
Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Ensor
J E
JE
Kalvakolanu
I
I
Hasday
J D
JD
D017398:Alternative Splicing; D000818:Animals; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000502:physiology; D051379:Mice; D009000:Monocytes / Q000502:physiology; D011061:Poly A / Q000235:genetics* / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012323:RNA Processing, Post-Transcriptional; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D008070:Lipopolysaccharides; D011500:Protein Synthesis Inhibitors; D014409:Tumor Necrosis Factor-alpha; D011061:Poly A