Pre-mRNA processing enhancer (PPE) elements from intronless genes play additional roles in mRNA biogenesis than do ones from intron-containing genes.
Most mRNA-encoding genes require introns for efficient expression in high eukaryotes. However, mRNAs can efficiently accumulate in the cytoplasm without intron excision if they contain cis-acting elements such as the post-transcriptional regulatory element (PRE) of hepatitis B virus (HBV), the constitutive transport element (CTE) of Mason-Pfizer monkey virus (MPMV), or the pre-mRNA processing enhancer (PPE) of herpes simplex virus' thymidine kinase (HSV-TK) gene. We compared the activities of these viral elements, the Rev-responsive element (RRE) of the human immunodeficiency virus (HIV), and the human c-Jun gene's enhancer (CJE), an element newly identified here, to enable expression of an intronless variant of the human beta-globin gene. The PRE, PPE and CJE from naturally intronless genes, but not the CTE or RRE from intron-containing genes, significantly enhanced stability, 3' end processing and cytoplasmic accumulation. When the transcripts included the beta-globin gene's first intron, the PRE, PPE and CJE still enhanced mRNA biogenesis, in some cases without intron excision. Thus, elements enabling stability, 3' end formation and nucleocytoplasmic export, not the presence of introns or their excision per se, are necessary for mRNA biogenesis. While the CTE and RRE primarily enhance nucleocytoplasmic export, PPE-like elements from naturally intronless genes facilitate polyadenylation as well.
Guang
Shouhong
S
McArdle Laboratory for Cancer Research 1400 University Avenue University of Wisconsin Medical School Madison, WI 53706-1599, USA.
Mertz
Janet E
JE
D021581:Active Transport, Cell Nucleus; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D016758:Genes, jun; D005914:Globins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007438:Introns; D026723:Polyadenylation; D026721:RNA 3' End Processing; D012322:RNA Precursors / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry; D038621:Regulatory Sequences, Ribonucleic Acid; D014158:Transcription, Genetic
D012322:RNA Precursors; D012333:RNA, Messenger; D012367:RNA, Viral; D038621:Regulatory Sequences, Ribonucleic Acid; D005914:Globins