Karyopherin? proteins mediate nucleocytoplasmic transport through recognition of distinct nuclear localization or export signals (NLSs or NESs). Although there are 19 known Kaps in humans, only three classes of signals for Kap?/Kap?1, Kap?2 (or Transportin) and CRM1, respectively, are known at this time. Most other Kaps recognize diverse sequences that occlude the identity of their signals. This proposal describes structural and biochemical analyses of import systems Kap?2 and Imp5/Kap121 as well as the export-Kap CRM1. Kap?2 mediates nuclear import of RNA binding proteins through their PY-NLSs. Our discovery and understanding of the PY-NLS contributed to the discovery of a defective PY-NLS that causes a subset of amyotrophic lateral sclerosis (ALS). Here, we propose to understand the role of Kap?2 in protein mislocalization and aggregation in ALS. In another aim, we will apply the combined structural, biochemical and bioinformatics approach that we used to discover the PY-NLS to the Imp5/Kap121p pathway with the goal of discovering a set of characteristics to unify the diverse sequences recognized by the Kaps, hence revealing a new class of NLS. Finally, we will study CRM1, which mediates nuclear export of hundreds of proteins;most of them identified using the small molecule inhibitor Leptomycin B. This proposal aims to determine the mechanism of how CRM1 mediates conjugation of leptomycin B to inhibit nuclear export.

Public Health Relevance

Many proteins are mislocalized in diseases such as amyotrophic lateral sclerosis and cancer. It is important to understand how proteins are targeted correctly since correcting protein mislocalization may be a valid disease therapy.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
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Ainsztein, Alexandra M
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University of Texas Sw Medical Center Dallas
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Fu, Szu-Chin; Fung, Ho Yee Joyce; Ca?atay, Tolga et al. (2018) Correlation of CRM1-NES affinity with nuclear export activity. Mol Biol Cell 29:2037-2044
Ça?atay, Tolga; Chook, Yuh Min (2018) Karyopherins in cancer. Curr Opin Cell Biol 52:30-42
Pinarbasi, Emile S; Ca?atay, Tolga; Fung, Ho Yee Joyce et al. (2018) Active nuclear import and passive nuclear export are the primary determinants of TDP-43 localization. Sci Rep 8:7083
Yoshizawa, Takuya; Ali, Rustam; Jiou, Jenny et al. (2018) Nuclear Import Receptor Inhibits Phase Separation of FUS through Binding to Multiple Sites. Cell 173:693-705.e22
Guo, Lin; Kim, Hong Joo; Wang, Hejia et al. (2018) Nuclear-Import Receptors Reverse Aberrant Phase Transitions of RNA-Binding Proteins with Prion-like Domains. Cell 173:677-692.e20
Fung, Ho Yee Joyce; Fu, Szu-Chin; Chook, Yuh Min (2017) Nuclear export receptor CRM1 recognizes diverse conformations in nuclear export signals. Elife 6:
Volpon, Laurent; Culjkovic-Kraljacic, Biljana; Osborne, Michael J et al. (2016) Importin 8 mediates m7G cap-sensitive nuclear import of the eukaryotic translation initiation factor eIF4E. Proc Natl Acad Sci U S A 113:5263-8
Soniat, Michael; Chook, Yuh Min (2016) Karyopherin-?2 Recognition of a PY-NLS Variant that Lacks the Proline-Tyrosine Motif. Structure 24:1802-1809
Soniat, Michael; Ca?atay, Tolga; Chook, Yuh Min (2016) Recognition Elements in the Histone H3 and H4 Tails for Seven Different Importins. J Biol Chem 291:21171-21183
Hing, Z A; Fung, H Y J; Ranganathan, P et al. (2016) Next-generation XPO1 inhibitor shows improved efficacy and in vivo tolerability in hematological malignancies. Leukemia 30:2364-2372

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