Isolation and characterization of Saccharomyces cerevisiae mRNA transport-defective (mtr) mutants [published erratum appears in J Cell Biol 1994 Sep;126(6):1627]

Abstract

Abstract. To understand the mechanisms of mRNA transport in eukaryotes, we have isolated Saccharomyces cerevisiae temperature-sensitive (ts) mutants which accumulate poly(A) + RNA ha the nucleus at the restrictive temperature. A total of 21 recessive mutants were isolated and classified into 16 complementation groups. Backcrossed mRNA transportdefective strains from each complementation group have been analyzed. A strain which is ts for heat shock transcription factor was also analyzed since it also shows nuclear accumulation of poly(A) + RNA at 37°C. At 37°C the mRNA of each mutant is characterized by atypically long polyA tails. Unlike ts pre-mRNA splithag mutants, these strains do not interrupt splicing of pre-mRNA at 370C; however four strains accumulate oversized RNA polymerase II transcripts. Some show inhibition of rRNA processing and a further subset of these strains is also characterized by inhibition of tRNA maturation. Several strains accumulate nuclear proteins ha the cytoplasm when incubated at semipermissive temperature. Remarkably, many strains exhibit nucleolar fragmentation or enlargement at the restrictive temperature. Most strains show dramatic ultrastructural alterations of the nucleoplasm or nuclear membrane. Distinct mutants accumulate poly(A) + RNA in characteristic patterns ha the nucleus.

Functional Proteomic Analysis of Human Nucleolus

“…Therefore, this study, by allowing the classification of a total of ϳ350 nucleolar proteins according to the biological processes in which they are involved, firmly confirms the plurifunctional nature of nucleoli and outlines biological processes taking place within these nuclear domains (Andersen et al, 2002;this study). In particular, the present analysis shows clearly that translational regulators, chaperones, and also proteins involved in mRNA processing are found within nucleoli, in addition to other components of the translation machinery such as ribosomes (Leary and Huang, 2001), tRNAs (Bertrand et al, 1998;Pederson and Politz, 2000), signal recognition particle ; this study), and even mRNAs (Kalland et al, 1991;Bond and Wold, 1993;Kadowaki et al, 1994a). This provides molecular evidence to the recent demonstration that translation can occur within nuclei of human cells (Iborra et al, 2001) and suggests that nucleoli themselves could play a central role in the control of this process.…”

Importin 7 and Importin α/Importin β Are Nuclear Import Receptors for the Glucocorticoid Receptor

“…The localization of GR-GFP was monitored in 14 yeast strains each deficient in a different nuclear transport receptor: CRMI (Stade et al, 1997), CSEI (Xiao et al, 1993), Kap95 (Iovine et al, 1995), Kap104 (Aitchison et al, 1996), Kap123 (Seedorf and Silver, 1997), LOS1 (Hopper et al, 1980), MSN5 (Kaffman et al, 1998a), MTR10 (Kadowaki et al, 1994), NMD5 (He and Jacobson, 1995), PSEI (Seedorf and Silver, 1997), SRP1 (Yano et al, 1992), SXM1 (Seedorf and Silver, 1997), Kap114 (Morehouse et al, 1999;Pemberton et al, 1999), and PDR6 (Titov and Blobel, 1999). Yeast strains PSY580, pse1-1, PSY1200, and PSY902 have been described (Seedorf and Silver, 1997).…”

GLE2, a Saccharomyces cerevisiae homologue of the Schizosaccharomyces pombe export factor RAE1, is required for nuclear pore complex structure and function.

“…Collections of temperaturesensitive mutant yeast strains have been directly screened for blocks in polyadenylated poly(A)+ RNA export (Amberg et al, 1992;Kadowaki et al, 1992Kadowaki et al, , 1994. Interestingly, numerous rat mutants isolated by Cole and coworkers encode for nucleoporins (rat2/ nup120, rat3/nupl33, rat7/nupl59, and rat9/nup85; Gorsch et al, 1995;Heath et al, 1995;Li et al, 1995;Goldstein et al, 1996) that may play a direct role in export.…”