Induction of secretory pathway components in yeast is associated with increased stability of their mRNA.
The overexpression of certain membrane proteins is accompanied by a striking proliferation of intracellular membranes. One of the best characterized inducers of membrane proliferation is the 180-kD mammalian ribosome receptor (p180), whose expression in yeast results in increases in levels of mRNAs encoding proteins that function in the secretory pathway, and an elevation in the cell's ability to secrete proteins. In this study we demonstrate that neither the unfolded protein response nor increased transcription accounts for membrane proliferation or the observed increase in secretory pathway mRNAs. Rather, p180-induced up-regulation of certain secretory pathway transcripts is due to a p180-mediated increase in the longevity of these mRNA species, as determined by measurements of transcriptional activity and specific mRNA turnover. Moreover, we show that the longevity of mRNA in general is substantially promoted through the process of its targeting to the membrane of the endoplasmic reticulum. With respect to the terminal differentiation of secretory tissues, results from this model system provide insights into how the expression of a single protein, p180, could result in substantial morphological and functional changes.
Hyde
Maureen
M
Department of Biological Chemistry, University of California, Los Angeles, School of Medicine, Los Angeles, CA 90024, USA.
Block-Alper
Laura
L
Felix
Jahaira
J
Webster
Paul
P
Meyer
David I
DI
D012634:Bodily Secretions / Q000502:physiology*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D066246:ErbB Receptors / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008055:Lipids / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000378:metabolism*; D066247:Receptor, ErbB-4; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic / Q000502:physiology
D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; C060153:KAR2 protein, yeast; D008055:Lipids; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; C065526:ribosome receptor; C082863:IRE1 protein, S cerevisiae; D066246:ErbB Receptors; D066247:Receptor, ErbB-4; D017346:Protein Serine-Threonine Kinases