Project description:The RanGTPase acts as a master regulator of nucleocytoplasmic transport by controlling assembly and disassembly of nuclear transport complexes. RanGTP is required in the nucleus to release nuclear localization signal (NLS)-containing cargo from import receptors, and, under steady-state conditions, Ran is highly concentrated in the nucleus. We previously showed the nuclear/cytoplasmic Ran distribution is disrupted in Hutchinson-Gilford Progeria syndrome (HGPS) fibroblasts that express the Progerin form of lamin A, causing a major defect in nuclear import of the protein, translocated promoter region (Tpr). In this paper, we show that Tpr import was mediated by the most abundant import receptor, KPNA2, which binds the bipartite NLS in Tpr with nanomolar affinity. Analyses including NLS swapping revealed Progerin did not cause global inhibition of nuclear import. Rather, Progerin inhibited Tpr import because transport of large protein cargoes was sensitive to changes in the Ran nuclear/cytoplasmic distribution that occurred in HGPS. We propose that defective import of large protein complexes with important roles in nuclear function may contribute to disease-associated phenotypes in Progeria.
Project description:This mass spectroscopy was conducted by exploring NTP binding molecules. NTP is novel cell penetrating peptide. We resarched how the NTP was transport to nucleus by molecules which binds NTP.
Project description:Nuclear pore complexes (NPCs) are the central apparatus of nucleocytoplasmic transport. Disease-specific alterations of NPCs contribute to the pathogenesis of many cancers; however, the roles of NPCs in glioblastoma (GBM) are unknown. In this study, we report genomic amplification of NUP107, a component of NPCs, in GBM and show that NUP107 is overexpressed simultaneously with MDM2, a critical E3 ligase that mediates p53 degradation. Depletion of NUP107 inhibits the growth of GBM cell lines through p53 protein stabilization. Mechanistically, NPCs establish a p53 degradation platform via an export pathway coupled with 26S proteasome tethering. NUP107 is the keystone for NPC assembly; the loss of NUP107 affects the integrity of the NPC structure, and thus the proportion of 26S proteasome in the vicinity of nuclear pores significantly decreases. Together, our findings establish roles of NPCs in transport surveillance and provide insights into p53 inactivation in GBM.
Project description:Hyperglycemia-induced damage to bone formations and function has been recognized.However, as the largest connective tissue organ, whether bone and osteocytes in turn regulate blood sugar and insulin sensitivity has not been addressed. Here we identified a novel protein termed intraflagellar transport 140 with functional importance in regulating osteogenesis, which is also related to the osteoblastic insulin sensitivity. We established Ift140 osteoblastic conditional knockout mice model, and found that blood glucose metabolism could be regulated through osteoblastic IFT140 interacting with O-GlcNAc transferase to regulate insulin signaling. The discovery provides new insight for two-way regulation between bone and glucose metabolism, and also exploring potential new target for blood glucose interventions.
Project description:Hyperglycemia-induced damage to bone formations and function has been recognized.However, as the largest connective tissue organ, whether bone and osteocytes in turn regulate blood sugar and insulin sensitivity has not been addressed. Here we identified a novel protein termed intraflagellar transport 140 with functional importance in regulating osteogenesis, which is also related to the osteoblastic insulin sensitivity. We established Ift140 osteoblastic conditional knockout mice model, and found that blood glucose metabolism could be regulated through osteoblastic IFT140 interacting with O-GlcNAc transferase to regulate insulin signaling. The discovery provides new insight for two-way regulation between bone and glucose metabolism, and also exploring potential new target for blood glucose interventions.
Project description:A whole-genome microarray containing 97.4 % of the annotated genes of L. acidophilus was employed to compare genome-wide patterns of transcription at varying pHs between the wild type parent and a histidine protein kinase mutant Keywords: ordered
Project description:There are currently at least 53 structures of components of nuclear transport in the Protein Databank. In addition to providing critical insights into molecular mechanisms of nuclear transport, these atomic resolution structures provide a large body of information that could guide biochemical and cell biological analyses involving nuclear transport proteins. This paper catalogs 53 crystal and NMR structures of nuclear transport proteins, with the emphasis on providing information useful for mutagenesis and overexpression of recombinant proteins.
Project description:The nuclear import receptor Kap114 carries transcription factors and other cargos across nuclear pores into the nucleus. Here we show that yeast Kap114 is modified by SUMO (small ubiquitin-related modifier) and that sumoylation is required for Kap114-mediated nuclear import. Among the four known SUMO-specific E3 ligases in yeast, Mms21 is the preferred E3 enzyme responsible for the covalent attachment of SUMO to the Kap114 protein. Kap114 is sumoylated on lysine residue 909, which is part of a ΨKxD/E sumoylation consensus motif. Kap114 containing a lysine-to-arginine point mutation at position 909 mislocalizes to the nucleus and is defective in promoting nuclear import. Similarly, mutants defective in sumoylation or desumoylation specifically accumulate Kap114 in the nucleus and are blocked in import of Kap114 cargos. Ran-GTP is not sufficient to disassemble Kap114/cargo complexes, which necessitates additional cargo release mechanisms in the nucleus. Remarkably, sumoylation of Kap114 greatly stimulates cargo dissociation in vitro. We propose that sumoylation occurs at the site of Kap114 cargo function and that SUMO is a cargo release factor involved in intranuclear targeting.
Project description:SummaryIn recent years, our understanding of macromolecular transport processes across the nuclear envelope has grown dramatically, and a large number of soluble transport receptors mediating either nuclear import or nuclear export have been identified. Most of these receptors belong to one large family of proteins, all of which share homology with the protein import receptor importin beta (also named karyopherin beta). Members of this family have been classified as importins or exportins on the basis of the direction they carry their cargo. To date, the family includes 14 members in the yeast Saccharomyces cerevisiae and at least 22 members in humans. Importins and exportins are regulated by the small GTPase Ran, which is thought to be highly enriched in the nucleus in its GTP-bound form. Importins recognize their substrates in the cytoplasm and transport them through nuclear pores into the nucleus. In the nucleoplasm, RanGTP binds to importins, inducing the release of import cargoes. In contrast, exportins interact with their substrates only in the nucleus in the presence of RanGTP and release them after GTP hydrolysis in the cytoplasm, causing disassembly of the export complex. Thus, common features of all importin-beta-like transport factors are their ability to shuttle between the nucleus and the cytoplasm, their interaction with RanGTP as well as their ability to recognize specific transport substrates.