The yeast hnRNP-like protein Hrp1/Nab4 sccumulates in the cytoplasm after hyperosmotic stress: a novel Fps1-dependent response.
The Hrp1/Nab4 shuttling protein belongs to a family of RNA binding proteins that bind to nascent RNA polymerase II transcripts and form hnRNP complexes. Members of this family function in a staggering array of cellular activities, ranging from transcription and pre-mRNA processing in the nucleus to cytoplasmic mRNA translation and turnover. It has recently been recognized that the yeast stress response can include alterations in hnRNP-mediated mRNA export. We now report that the steady-state localization of Hrp1p rapidly shifts from the nucleus to the cytoplasm in response to osmotic stress. In contrast to a general stress response resulting in a transient relocation, Hrp1p redistribution is specific to hyperosmotic stress and is only reversed after stress removal. Hrp1p relocalization requires both the CRM1/XPO1 exportin and the FPS1 glycerol transporter genes but is independent of ongoing RNA transcription and protein arginine methylation. However, mutations in the high osmolarity glycerol and protein kinase C osmosensing pathways do not impact the Hrp1p hyperosmotic response. We present a working model for the cytoplasmic accumulation of Hrp1 and discuss the implications of this relocalization on Hrp1p function.
Henry
Michael F
MF
Department of Molecular Biology, University of Medicine and Dentistry, New Jersey School of Osteopathic Medicine, Stratford, New Jersey 08084, USA. henrymf@umdnj.edu
Mandel
Daniel
D
Routson
Valerie
V
Henry
Pamela A
PA
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D028884:Karyopherins / Q000378:metabolism*; D008565:Membrane Proteins; D008745:Methylation; D009997:Osmotic Pressure; D014176:Protein Biosynthesis / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D012319:RNA Polymerase II; D034443:RNA Transport / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D000097606:Exportin 1 Protein
D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D028884:Karyopherins; D008565:Membrane Proteins; D011493:Protein Kinase C; D012319:RNA Polymerase II; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; D000097606:Exportin 1 Protein; C093263:FPS1 protein, S cerevisiae