scholarly journals The structure of importin α and the nuclear localization peptide of ChREBP, and small compound inhibitors of ChREBP–importin α interactions

2020 ◽  
Vol 477 (17) ◽  
pp. 3253-3269
Author(s):  
Hunmin Jung ◽  
Tomomi Takeshima ◽  
Tsutomu Nakagawa ◽  
Karen S. MacMillan ◽  
R. Max Wynn ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Critical Role ◽  
Amino Acid Residues ◽  
Glucose Levels ◽  
Small Compound ◽  
Blood Glucose Levels ◽  
Element Binding Protein ◽  
Importin Α ◽  
Localization Signal ◽  
Treatment Of Obesity

The carbohydrate response element binding protein (ChREBP) is a glucose-responsive transcription factor that plays a critical role in glucose-mediated induction of genes involved in hepatic glycolysis and lipogenesis. In response to fluctuating blood glucose levels ChREBP activity is regulated mainly by nucleocytoplasmic shuttling of ChREBP. Under high glucose ChREBP binds to importin α and importin β and translocates into the nucleus to initiate transcription. We have previously shown that the nuclear localization signal site (NLS) for ChREBP is bipartite with the NLS extending from Arg158 to Lys190. Here, we report the 2.5 Å crystal structure of the ChREBP-NLS peptide bound to importin α. The structure revealed that the NLS binding is monopartite, with the amino acid residues K171RRI174 from the ChREBP-NLS interacting with ARM2–ARM5 on importin α. We discovered that importin α also binds to the primary binding site of the 14-3-3 proteins with high affinity, which suggests that both importin α and 14-3-3 are each competing with the other for this broad-binding region (residues 117–196) on ChREBP. We screened a small compound library and identified two novel compounds that inhibit the ChREBP-NLS/importin α interaction, nuclear localization, and transcription activities of ChREBP. These candidate molecules support developing inhibitors of ChREBP that may be useful in treatment of obesity and the associated diseases.

scholarly journals Importin-α Protein Binding to a Nuclear Localization Signal of Carbohydrate Response Element-Binding Protein (ChREBP)

2011 ◽  
Vol 286 (32) ◽  
pp. 28119-28127 ◽  
Author(s):  
Qiang Ge ◽  
Tsutomu Nakagawa ◽  
R. Max Wynn ◽  
Yuh Min Chook ◽  
Bonnie C. Miller ◽  
...  
Keyword(s):  
Protein Binding ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Binding Protein ◽  
Response Element ◽  
Element Binding Protein ◽  
Importin Α ◽  
Localization Signal

scholarly journals Signal-mediated localization of Candida albicans pheromone response pathway components

2020 ◽  
Author(s):  
Anna Carolina Borges Pereira Costa ◽  
Raha Parvizi Omran ◽  
Chris Law ◽  
Vanessa Dumeaux ◽  
Malcolm Whiteway
Keyword(s):  
Candida Albicans ◽  
Map Kinase ◽  
Nuclear Localization ◽  
Map Kinases ◽  
Critical Role ◽  
Cell Periphery ◽  
Pheromone Response ◽  
Pheromone Response Pathway ◽  
Localization Signal ◽  
In Cells

Abstract Candida albicans opaque cells release pheromones to stimulate cells of opposite mating type to activate their pheromone response pathway. Although this fungal pathogen shares orthologous proteins involved in the process with Saccharomyces cerevisiae, the pathway in each organism has unique characteristics. We have used GFP-tagged fusion proteins to investigate the localization of the scaffold protein Cst5, as well as the MAP kinases Cek1 and Cek2, during pheromone response in C. albicans. In wild-type cells, pheromone treatment directed Cst5-GFP to surface puncta concentrated at the tips of mating projections. These puncta failed to form in cells defective in either the Gα or β subunits. However, they still formed in response to pheromone in cells missing Ste11, but with the puncta distributed around the cell periphery in the absence of mating projections. These puncta were absent from hst7Δ/Δ cells, but could be detected in the ste11Δ/Δ hst7Δ/Δ double mutant. Cek2-GFP showed a strong nuclear localization late in the response, consistent with a role in adaptation, while Cek1-GFP showed a weaker, but early increase in nuclear localization after pheromone treatment. Activation loop phosphorylation of both Cek1 and Cek2 required the presence of Ste11. In contrast to Cek2-GFP, which showed no localization signal in ste11Δ/Δ cells, Cek1-GFP showed enhanced nuclear localization that was pheromone independent in the ste11Δ/Δ mutant. The results are consistent with CaSte11 facilitating Hst7-mediated MAP kinase phosphorylation and also playing a potentially critical role in both MAP kinase and Cst5 scaffold localization.

Hairless is translocated to the nucleus via a novel bipartite nuclear localization signal and is associated with the nuclear matrix

2001 ◽  
Vol 114 (2) ◽  
pp. 367-376
Author(s):  
K. Djabali ◽  
V.M. Aita ◽  
A.M. Christiano
Keyword(s):  
Amino Acid ◽  
Hair Follicle ◽  
Nuclear Localization ◽  
Nuclear Matrix ◽  
Nuclear Localization Signal ◽  
Amino Acid Residues ◽  
Bipartite Nuclear Localization Signal ◽  
Hairless Gene ◽  
Fractionation Analysis ◽  
Localization Signal

Hair follicle cycling is an exquisitely regulated and dynamic process consisting of phases of growth, regression and quiescence. The transitions between the phases are governed by a growing number of regulatory proteins, including transcription factors. The hairless (hr) gene encodes a putative transcription factor that is highly expressed in the skin, where it appears to be an essential regulator during the regression of the catagen hair follicle. In hairless mice, as well as humans with congenital atrichia, the absence of hr gene function initiates a premature and abnormal catagen due to a dysregulation of apoptosis and cell adhesion, and defects in the signaling required for hair follicle remodeling. Here, we report structure-function studies of the hairless gene product, in which we identify a novel bipartite nuclear localization signal (NLS) of the form KRA(X13) PKR. Deletion analysis of the mouse hr gene mapped the NLS to amino acid residues 409–427. Indirect immunofluorescence microscopy of cells transiently transfected with hairless-green fluorescent fusion proteins demonstrated that these amino acid residues are necessary and sufficient for nuclear localization. Furthermore, nuclear fractionation analysis revealed that the hr protein is associated with components of the nuclear matrix.

scholarly journals Dissecting the Brain/Islet Axis in Metabesity

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 350 ◽  
Author(s):  
Esther Fuente-Martín ◽  
Jose M. Mellado-Gil ◽  
Nadia Cobo-Vuilleumier ◽  
Alejandro Martín-Montalvo ◽  
Silvana Y. Romero-Zerbo ◽  
...  
Keyword(s):  
Common Factor ◽  
Critical Role ◽  
Cell Mass ◽  
Cell Types ◽  
Β Cell ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
High Prevalence ◽  
The Central Nervous System ◽  
Metabolic Dysfunctions

The high prevalence of type 2 diabetes mellitus (T2DM), together with the fact that current treatments are only palliative and do not avoid major secondary complications, reveals the need for novel approaches to treat the cause of this disease. Efforts are currently underway to identify therapeutic targets implicated in either the regeneration or re-differentiation of a functional pancreatic islet β-cell mass to restore insulin levels and normoglycemia. However, T2DM is not only caused by failures in β-cells but also by dysfunctions in the central nervous system (CNS), especially in the hypothalamus and brainstem. Herein, we review the physiological contribution of hypothalamic neuronal and glial populations, particularly astrocytes, in the control of the systemic response that regulates blood glucose levels. The glucosensing capacity of hypothalamic astrocytes, together with their regulation by metabolic hormones, highlights the relevance of these cells in the control of glucose homeostasis. Moreover, the critical role of astrocytes in the response to inflammation, a process associated with obesity and T2DM, further emphasizes the importance of these cells as novel targets to stimulate the CNS in response to metabesity (over-nutrition-derived metabolic dysfunctions). We suggest that novel T2DM therapies should aim at stimulating the CNS astrocytic response, as well as recovering the functional pancreatic β-cell mass. Whether or not a common factor expressed in both cell types can be feasibly targeted is also discussed.

scholarly journals CRM1-mediated Recycling of Snurportin 1 to the Cytoplasm

1999 ◽  
Vol 145 (2) ◽  
pp. 255-264 ◽  
Author(s):  
Efrosyni Paraskeva ◽  
Elisa Izaurralde ◽  
F. Ralf Bischoff ◽  
Jochen Huber ◽  
Ulrike Kutay ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Nuclear Export ◽  
Activation Domain ◽  
Large Domain ◽  
High Affinity ◽  
Importin Α ◽  
Localization Signal ◽  
Major Mediator ◽  
Rev Protein

Importin β is a major mediator of import into the cell nucleus. Importin β binds cargo molecules either directly or via two types of adapter molecules, importin α, for import of proteins with a classical nuclear localization signal (NLS), or snurportin 1, for import of m3G-capped U snRNPs. Both adapters have an NH2-terminal importin β–binding domain for binding to, and import by, importin β, and both need to be returned to the cytoplasm after having delivered their cargoes to the nucleus. We have shown previously that CAS mediates export of importin α. Here we show that snurportin 1 is exported by CRM1, the receptor for leucine-rich nuclear export signals (NESs). However, the interaction of CRM1 with snurportin 1 differs from that with previously characterized NESs. First, CRM1 binds snurportin 1 50-fold stronger than the Rev protein and 5,000-fold stronger than the minimum Rev activation domain. Second, snurportin 1 interacts with CRM1 not through a short peptide but rather via a large domain that allows regulation of affinity. Strikingly, snurportin 1 has a low affinity for CRM1 when bound to its m3G-capped import substrate, and a high affinity when substrate-free. This mechanism appears crucial for productive import cycles as it can ensure that CRM1 only exports snurportin 1 that has already released its import substrate in the nucleus.

scholarly journals Phospholipid Scramblase 1 Contains a Nonclassical Nuclear Localization Signal with Unique Binding Site in Importin α

2004 ◽  
Vol 280 (11) ◽  
pp. 10599-10606 ◽  
Author(s):  
Min-Hsuan Chen ◽  
Iris Ben-Efraim ◽  
Gregory Mitrousis ◽  
Nancy Walker-Kopp ◽  
Peter J. Sims ◽  
...  
Keyword(s):  
Binding Site ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Phospholipid Scramblase ◽  
Importin Α ◽  
Localization Signal ◽  
Phospholipid Scramblase 1

scholarly journals Phosphorylation adjacent to the nuclear localization signal of human dUTPase abolishes nuclear import: structural and mechanistic insights

2013 ◽  
Vol 69 (12) ◽  
pp. 2495-2505 ◽  
Author(s):  
Gergely Róna ◽  
Mary Marfori ◽  
Máté Borsos ◽  
Ildikó Scheer ◽  
Enikő Takács ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Nucleocytoplasmic Transport ◽  
Wild Type ◽  
Post Translational Modification ◽  
Nuclear Localization Signals ◽  
M Phase ◽  
Importin Α ◽  
Localization Signal

Phosphorylation adjacent to nuclear localization signals (NLSs) is involved in the regulation of nucleocytoplasmic transport. The nuclear isoform of human dUTPase, an enzyme that is essential for genomic integrity, has been shown to be phosphorylated on a serine residue (Ser11) in the vicinity of its nuclear localization signal; however, the effect of this phosphorylation is not yet known. To investigate this issue, an integrated set of structural, molecular and cell biological methods were employed. It is shown that NLS-adjacent phosphorylation of dUTPase occurs during the M phase of the cell cycle. Comparison of the cellular distribution of wild-type dUTPase with those of hyperphosphorylation- and hypophosphorylation-mimicking mutants suggests that phosphorylation at Ser11 leads to the exclusion of dUTPase from the nucleus. Isothermal titration microcalorimetry and additional independent biophysical techniques show that the interaction between dUTPase and importin-α, the karyopherin molecule responsible for `classical' NLS binding, is weakened significantly in the case of the S11E hyperphosphorylation-mimicking mutant. The structures of the importin-α–wild-type and the importin-α–hyperphosphorylation-mimicking dUTPase NLS complexes provide structural insights into the molecular details of this regulation. The data indicate that the post-translational modification of dUTPase during the cell cycle may modulate the nuclear availability of this enzyme.

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