Cultural Characterization of Animal Cells

A mutation in the c-myc-IRES leads to enhanced internal ribosome entry in multiple myeloma: A novel mechanism of oncogene de-regulation

“…Thus suggesting that control of translation is important in regulating cellular levels of c-myc in addition to the other mechanisms that have been described. These include alterations in rates of transcription of the mRNA, and the stability of both the mRNA and protein (Ross, 1995;Lee et al, 1998;LuÈ scher and Eisenmann, 1988;Shindo et al, 1993). The number of levels that c-myc expression is controlled at is probably a re¯ection of the diverse cellular processes in which this proto-oncogene is thought to function e.g.…”

Evidence for a 3′-5′ Decay Pathway for c-mycmRNA in Mammalian Cells

“…An early step in the cytoplasmic decay of many mRNAs in eukaryotes is exoribonucleolytic shortening of the poly(A) tail (reviewed in Refs. [1][2][3][4]. In the yeast Saccharomyces cerevisiae, the 5Ј-3Ј and 3Ј-5Ј pathways appear to be the two major pathways for mRNA decay.…”

“…In both pathways, a poly(A) nuclease shortens the poly(A) tract to 10 -15 nt. 1 In the 5Ј-3Ј pathway, the enzyme Dcp1p then removes the 5Ј cap structure, and the Xrn1p exoribonuclease degrades the mRNA 5Ј-3Ј (2,(5)(6)(7). In the 3Ј-5Ј pathway, decay of the 10-nt poly(A) tract continues after the initial phase of deadenylation.…”

“…The same enzymes operative in vivo presumably generate these intermediates in vitro. However, detection of such mRNA decay intermediates in cells has proven difficult (1,14). Thus, an unanswered question is whether 3Ј-5Ј decay of polyadenylated mRNAs occurs in mammalian cells as indicated by 3Ј-terminal decay intermediates.…”

Regulation of c-myc mRNA Decay in Vitro by a Phorbol Ester-inducible, Ribosome-associated Component in Differentiating Megakaryoblasts

“…Although gene expression can be regulated at many levels, the rates at which individual mRNAs decay is a major factor contributing to steady-state mRNA levels (reviewed in Ref. 2). The degradation rates of individual mRNAs can vary by an order of magnitude or more.…”