The nuclear transport machinery integrates cytoplasmic and nuclear functions through multiple import and export. These pathways rely on targeting signals within cargo, recognition by soluble receptors, and physical translocation of cargo/receptor complexes through the nuclear pore. Our long-term goal is to define the mechanisms responsible for nuclear protein export in mammalian cells. Our approach is to use functional assays to purify and characterize the soluble export receptors and their regulators. We developed an assay that reconstitute nuclear export mediated by the leucine-rich nuclear export signal (NES) in protein kinase inhibitor (PKI). We have used the PKI assay to purify a new cytosolic export factor, and we have shown that this biochemical, cellular, and molecular approaches. We will determine the molecular identity of the new export using biochemical, cellular, and molecular approaches. We will determine the molecular identity of the new export factor and whether it requires co-factors for its nuclear export function. We will examine its subcellular distribution and determine if it shuttles between the nucleus and cytoplasm. A structure-function analyses of the export factor will reveal whether it physically contacts the NES and whether the Ran GTPase regulates this interaction. We will determine how the export factor interacts with the nuclear pore complex and describe its mechanisms for recycling. The in vivo function of the export factor will be addressed by examining its ability to mediate export of two medically-relevant substrates: the glucocorticoid receptor, and the HIV-1 protein rev complexes with RNA. These macromolecules are likely substrates of the new export factor because it mediates the nuclear export in vitro. Our hypothesis is that mammalian cells use multiple export pathways that feature distinct NES receptors. Elucidating the biochemistry and molecular details of these pathways is of general interest because the same machinery is used to sort proteins and RNAS of both cellular and viral origin.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM058639-01A2
Application #
6129417
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Ainsztein, Alexandra M
Project Start
2000-04-01
Project End
2005-03-31
Budget Start
2000-04-01
Budget End
2001-03-31
Support Year
1
Fiscal Year
2000
Total Cost
$206,334
Indirect Cost
Name
University of Virginia
Department
Biochemistry
Type
Schools of Medicine
DUNS #
001910777
City
Charlottesville
State
VA
Country
United States
Zip Code
22904
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Sun, Kai; Montana, Vedrana; Chellappa, Karthikeyani et al. (2007) Phosphorylation of a conserved serine in the deoxyribonucleic acid binding domain of nuclear receptors alters intracellular localization. Mol Endocrinol 21:1297-311
Gioeli, Daniel; Black, Ben E; Gordon, Vicki et al. (2006) Stress kinase signaling regulates androgen receptor phosphorylation, transcription, and localization. Mol Endocrinol 20:503-15
Pemberton, Lucy F; Paschal, Bryce M (2006) Scientists share nuclear secrets at Jekyll Island. Traffic 7:751-60
Levesque, Lyne; Bor, Yeou-Cherng; Matzat, Leah H et al. (2006) Mutations in tap uncouple RNA export activity from translocation through the nuclear pore complex. Mol Biol Cell 17:931-43
Holaska, James M; Black, Ben E; Rastinejad, Fraydoon et al. (2002) Ca2+-dependent nuclear export mediated by calreticulin. Mol Cell Biol 22:6286-97
Holaska, J M; Black, B E; Love, D C et al. (2001) Calreticulin Is a receptor for nuclear export. J Cell Biol 152:127-40
Steggerda, S M; Paschal, B M (2001) Identification of a conserved loop in Mog1 that releases GTP from Ran. Traffic 2:804-11
Black, B E; Holaska, J M; Rastinejad, F et al. (2001) DNA binding domains in diverse nuclear receptors function as nuclear export signals. Curr Biol 11:1749-58
Black, B E; Holaska, J M; Levesque, L et al. (2001) NXT1 is necessary for the terminal step of Crm1-mediated nuclear export. J Cell Biol 152:141-55

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