Identification of nuclear localization signal that governs nuclear import of BRD7 and its essential roles in inhibiting cell cycle progression

2006 ◽  
Vol 98 (4) ◽  
pp. 920-930 ◽  
Author(s):  
Ming Zhou ◽  
Huaying Liu ◽  
Xiaojie Xu ◽  
Houde Zhou ◽  
Xiaoling Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Cell Cycle Progression ◽  
Cycle Progression ◽  
Localization Signal

Distinct mechanisms of nuclear accumulation regulate the functional consequence of E2F transcription factors

1997 ◽  
Vol 110 (22) ◽  
pp. 2819-2831 ◽  
Author(s):  
K.E. Allen ◽  
S. de la Luna ◽  
R.M. Kerkhoven ◽  
R. Bernards ◽  
N.B. La Thangue
Keyword(s):  
Cell Cycle ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Cell Cycle Progression ◽  
Nuclear Accumulation ◽  
Cycle Progression ◽  
Pocket Proteins ◽  
Functional Consequence ◽  
Pocket Protein ◽  
Localization Signal

Transcription factor E2F plays an important role in coordinating and integrating early cell cycle progression with the transcription apparatus. It is known that physiological E2F arises when a member of two families of proteins, E2F and DP, interact as E2F/DP heterodimers and that transcriptional activity is regulated through the physical association of pocket proteins such as pRb. However, little information is available regarding the mechanisms which control the levels of functional E2F. In this study, we have characterised one such mechanism which regulates the nuclear accumulation and activity of E2F. Specifically, we show that E2F proteins fall into two distinct categories according to their ability to accumulate in nuclei, one being exemplified by E2F-1 and the other by E2F-4 and -5. Thus, E2F-1 possesses an intrinsic nuclear localization signal whereas E2F-4 and -5 are devoid of such a signal. Furthermore, we find for E2F-4 and -5 that two distinct processes govern their nuclear accumulation whereby the nuclear localization signal is supplied in trans from either a DP heterodimer partner or a physically associated pocket protein. It is consistent with the role of pocket proteins in regulating nuclear accumulation that we find E2F-5 to be nuclear during early cell cycle progression with an increased cytoplasmic concentration in cycling cells. Our data show that the mechanism of nuclear accumulation determines the functional consequence of E2F on cell cycle progression: pocket protein-mediated accumulation impedes cell cycle progression, whereas DP-regulated nuclear accumulation promotes cell cycle progression. Moreover, the inactivation of pocket proteins by the adenovirus Ela protein, and subsequent release of E2F, failed to displace nuclear E2F. Our study identifies a new level of regulation in the control of E2F activity exerted at the level of nuclear accumulation where subunit composition and interaction with pocket proteins dictates the functional consequence on cell cycle progression.

scholarly journals The cell cycle-dependent nuclear import of v-Jun is regulated by phosphorylation of a serine adjacent to the nuclear localization signal.

1995 ◽  
Vol 130 (2) ◽  
pp. 255-263 ◽  
Author(s):  
T Tagawa ◽  
T Kuroki ◽  
P K Vogt ◽  
K Chida
Keyword(s):  
Cell Cycle ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Protein Kinase Inhibitors ◽  
Nuclear Accumulation ◽  
Dependent Manner ◽  
Localization Signal ◽  
Cycle Dependent

Cell cycle-dependent phosphorylation and nuclear import of the tumorigenic transcription factor viral Jun (v-Jun) were investigated in chicken embryo fibroblasts. Nuclear accumulation of v-Jun but not of cellular Jun (c-Jun) is cell cycle dependent, decreasing in G1 and increasing in G2. The cell cycle-dependent regulation of v-Jun was mapped to a single serine residue at position 248 (Ser248), adjacent to the nuclear localization signal (NLS). Ser248 of v-Jun represents an amino acid substitution, replacing cysteine of c-Jun. It was shown by peptidase digestion and immunoprecipitation with antibody to the NLS that v-Jun is phosphorylated at Ser248 in the cytoplasm but not in the nucleus. This phosphorylation is high in G1 and low in G2. Nuclear accumulation of v-Jun is correlated with underphosphorylation at Ser248. The regulation of nuclear import by phosphorylation was also examined using NLS peptides with Ser248 of v-Jun. Phosphorylation of the serine inhibited nuclear import mediated by the NLS peptide in vivo and in vitro. The protein kinase inhibitors staurosporine and H7 stimulated but the phosphatase inhibitor okadaic acid inhibited nuclear import mediated by the NLS peptide. The cytosolic activity of protein kinases phosphorylating Ser248 increased in G0 and decreased during cell cycle progression, reaching a minimum in G2, whereas phosphatase activity dephosphorylating Ser248 was not changed. These results show that nuclear import of v-Jun is negatively regulated by phosphorylation at Ser248 in the cytoplasm in a cell cycle-dependent manner.

scholarly journals Mutant Parathyroid Hormone-Related Protein, Devoid of the Nuclear Localization Signal, Markedly Inhibits Arterial Smooth Muscle Cell Cycle and Neointima Formation by Coordinate Up-Regulation of p15Ink4b and p27kip1

Endocrinology ◽  
2008 ◽  
Vol 150 (3) ◽  
pp. 1429-1439 ◽  
Author(s):  
Nathalie Fiaschi-Taesch ◽  
Brian Sicari ◽  
Kiran Ubriani ◽  
Irene Cozar-Castellano ◽  
Karen K. Takane ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Localization Signal ◽  
Cell Cycle Progression ◽  
Related Protein ◽  
Cycle Progression ◽  
Vsmc Proliferation ◽  
Adenoviral Delivery ◽  
Arterial Restenosis ◽  
Localization Signal

Arterial expression of PTH-related protein is markedly induced by angioplasty. PTH-related protein contains a nuclear localization signal (NLS). PTH-related protein mutants lacking the NLS (ΔNLS-PTH-related protein) are potent inhibitors of arterial vascular smooth muscle cell (VSMC) proliferation in vitro. This is of clinical relevance because adenoviral delivery of ΔNLS-PTH-related protein at angioplasty completely inhibits arterial restenosis in rats. In this study we explored the cellular mechanisms through which ΔNLS-PTH-related protein arrests the cell cycle. In vivo, adenoviral delivery of ΔNLS-PTH-related protein at angioplasty markedly inhibited VSMC proliferation as compared with angioplastied carotids infected with control adenovirus (Ad.LacZ). In vitro, ΔNLS-PTH-related protein overexpression was associated with a decrease in phospho-pRb, and a G0/G1 arrest. This pRb underphosphorylation was associated with stable levels of cdks 2, 4, and 6, the D and E cyclins, p16, p18, p19, and p21, but was associated with a dramatic decrease in cdk-2 and cdk4 kinase activities. Cyclin A was reduced, but restoring cyclin A adenovirally to normal did not promote cell cycle progression in ΔNLS-PTH-related protein VSMC. More importantly, p15INK4 and p27kip1, two critical inhibitors of the G1/S progression, were markedly increased. Normalization of both p15INK4b and p27kip1 by small interfering RNA knockdown normalized cell cycle progression. These data indicate that the changes in p15INK4b and p27kip1 fully account for the marked cell cycle slowing induced by ΔNLS-PTH-related protein in VSMCs. Finally, ΔNLS-PTH-related protein is able to induce p15INK4 and p27kip1 expression when delivered adenovirally to primary murine VSMCs. These studies provide a mechanistic understanding of ΔNLS-PTH-related protein actions, and suggest that ΔNLS-PTH-related protein may have particular efficacy for the prevention of arterial restenosis. This study provides the mechanistic underpinnings for understanding how Δ-NLS-PTHrP functions, and suggests that Δ-NLS-PTHrP may have particular efficacy for the prevention of arterial re-stenosis.

Nuclear import of glycoconjugates is distinct from the classical NLS pathway

1995 ◽  
Vol 108 (4) ◽  
pp. 1325-1332 ◽  
Author(s):  
E. Duverger ◽  
C. Pellerin-Mendes ◽  
R. Mayer ◽  
A.C. Roche ◽  
M. Monsigny
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Peptide Sequence ◽  
Nuclear Pore ◽  
Dependent Manner ◽  
Permeabilized Cells ◽  
Localization Signal ◽  
Energy Dependent ◽  
Cytosolic Factors

The nuclear import of many proteins depends on a short peptide sequence called the nuclear localization signal. However, glycosylated proteins, which lack such a nuclear localization signal, upon their injection into the cytosol by electroporation, enter the nucleus in a sugar-dependent manner. This paper brings new insights on the mechanism of this process, based on a study of neoglycoprotein nuclear uptake by digitonin-permeabilized cells. The nuclear import of neoglycoproteins is energy dependent: it does not occur when cells are maintained at 4 degrees C or when cells are ATP-depleted by treatment with apyrase. The nuclear import of neoglycoproteins occurs through the nuclear pore: it is inhibited by preincubation of cells with wheat germ agglutinin, a lectin which binds the nuclear pore glycoproteins and blocks the translocation step of nuclear localization signal bearing proteins through the nuclear pore. Furthermore, the nuclear import of neoglycoproteins does not use the pathway of nuclear localization signal bearing proteins: nuclear import of nuclear localization signal bearing proteins depends on cytosolic factors and is inhibited by treatment of cells with N-ethylmaleimide, while the nuclear import of neoglycoproteins neither requires added cytosolic factors nor is sensitive to alkylation by N-ethylmaleimide. In addition, upon incubation in the presence of a large excess of nuclear localization signal bearing protein, the nuclear import of neoglycoproteins is not inhibited.

Nuclear transport of the U2 snRNP-specific U2B'' protein is mediated by both direct and indirect signalling mechanisms

1994 ◽  
Vol 107 (7) ◽  
pp. 1807-1816 ◽  
Author(s):  
C. Kambach ◽  
I.W. Mattaj
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Nuclear Transport ◽  
U2 Snrna ◽  
Central Segment ◽  
U2 Snrnp ◽  
U1 Snrnp ◽  
Localization Signal ◽  
Protein Amino Acids

Experiments investigating the nuclear import of the U2 snRNP-specific B'' protein (U2B'') are presented. U2B'' nuclear transport is shown to be able to occur independently of binding to U2 snRNA. The central segment of the protein (amino acids 90–146) encodes an unusual nuclear localization signal (NLS) that is related to that of the U1 snRNP-specific A protein. However, nuclear import of U2B'' does not depend on this NLS. Sequences in the N-terminal RNP motif of the protein are sufficient to direct nuclear transport, and evidence is presented that the interaction of U2B'' with the U2A' protein mediates this effect. This suggests that U2B'' can ‘piggy-back’ to the nucleus in association with U2A’, and thus be imported to the nucleus by two different mechanisms. U2A' nuclear transport, on the other hand, can occur independently of both U2B'' binding and of U2 snRNA.

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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