title: Separate responses of karyopherins to glucose and amino acid availability regulate nucleocytoplasmic transport.
abstract: The importin-β family members (karyopherins) mediate the majority of nucleocytoplasmic transport. Msn5 and Los1, members of the importin-β family, function in tRNA nuclear export. tRNAs move bidirectionally between the nucleus and the cytoplasm. Nuclear tRNA accumulation occurs upon amino acid (aa) or glucose deprivation. To understand the mechanisms regulating tRNA subcellular trafficking, we investigated whether Msn5 and Los1 are regulated in response to nutrient availability. We provide evidence that tRNA subcellular trafficking is regulated by distinct aa-sensitive and glucose-sensitive mechanisms. Subcellular distributions of Msn5 and Los1 are altered upon glucose deprivation but not aa deprivation. Redistribution of tRNA exportins from the nucleus to the cytoplasm likely provides one mechanism for tRNA nuclear distribution upon glucose deprivation. We extended our studies to other members of the importin-β family and found that all tested karyopherins invert their subcellular distributions upon glucose deprivation but not aa deprivation. Glucose availability regulates the subcellular distributions of karyopherins likely due to alteration of the RanGTP gradient since glucose deprivation causes redistribution of Ran. Thus nuclear-cytoplasmic distribution of macromolecules is likely generally altered upon glucose deprivation due to collapse of the RanGTP gradient and redistribution of karyopherins between the nucleus and the cytoplasm.
authors: Department of Molecular Genetics and Center for RNA Biology, Ohio State University, Columbus, OH 43210 Graduate Program in Molecular, Cellular, and Developmental Biology, Ohio State University, Columbus, OH 43210.
authors: Hsiao-Yun
authors: HY
authors: Huang
authors: Department of Molecular Genetics and Center for RNA Biology, Ohio State University, Columbus, OH 43210 hopper.64@osu.edu.
authors: Anita K
authors: AK
authors: Hopper
mesh_terms: D021581:Active Transport, Cell Nucleus; D000596:Amino Acids / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D005947:Glucose / Q000502:physiology*; D028884:Karyopherins / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D028961:beta Karyopherins / Q000378:metabolism
chemical_list: D000596:Amino Acids; D028884:Karyopherins; C408090:Los1 protein, S cerevisiae; C401306:MSN5 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D029701:Saccharomyces cerevisiae Proteins; D028961:beta Karyopherins; D005947:Glucose