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Hallberg, Einar
Publications (10 of 23) Show all publications
Figueroa, R., Gudise, S., Larsson, V. & Hallberg, E. (2010). A transmembrane inner nuclear membrane protein in the mitotic spindle. Nucleus, 1(3), 249-253
Open this publication in new window or tab >>A transmembrane inner nuclear membrane protein in the mitotic spindle
2010 (English)In: Nucleus, ISSN 1949-1042, Vol. 1, no 3, p. 249-253Article in journal (Refereed) Published
Abstract [en]

We have recently characterized a novel transmembrane protein of the inner nuclear membrane of mammalian cells. The protein has two very interesting features. First, despite being an integral membrane protein it is able to concentrate in the membranes colocalizing with the mitotic spindle in metaphase and anaphase. Hence, the protein was named Samp1, Spindle associated membrane protein 1. Secondly, it displays a functional connection to centrosomes. This article discusses various aspects of Samp1 in relation to possible cellular function(s).

National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-17499 (URN)10.4161/nucl.1.3.11740 (DOI)000208668400006 ()21327071 (PubMedID)2-s2.0-77957681891 (Scopus ID)
Available from: 2012-12-14 Created: 2012-12-14 Last updated: 2017-07-18Bibliographically approved
Buch, C., Lindberg, R., Figueroa, R., Gudise, S., Onischenko, E. & Hallberg, E. (2009). An integral protein of the inner nuclear membrane localizes to the mitotic spindle in mammalian cells. Journal of Cell Science, 122(12), 2100-2107
Open this publication in new window or tab >>An integral protein of the inner nuclear membrane localizes to the mitotic spindle in mammalian cells
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2009 (English)In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 122, no 12, p. 2100-2107Article in journal (Refereed) Published
Abstract [en]

Here, we characterize a transmembrane protein of the nuclear envelope that we name spindle-associated membrane protein 1 (Samp1). The protein is conserved in metazoa and fission yeast and is homologous to Net5 in rat and Ima1 in Schizosaccharomyces pombe. We show that, in human cells, the protein is a membrane-spanning polypeptide with an apparent molecular mass of 43 kDa. This is consistent with a predicted polypeptide of 392 amino acids that has five transmembrane segments and its C-terminus exposed to the nucleoplasm. During interphase, Samp1 was specifically distributed in the inner nuclear membrane. Post-transcriptional silencing of Samp1 expression resulted in separation of centrosomes from the nuclear envelope, indicating that it is functionally connected to the cytoskeleton. At the onset of mitosis, most of the protein dispersed out into the ER, as expected. However, during mitosis, a significant fraction of the protein specifically localized to the polar regions of the mitotic spindle. We demonstrate for the first time, in human cells, the existence of a membranous structure overlapping with the mitotic spindle. Interestingly, another integral inner nuclear membrane protein, emerin, was absent from the spindle-associated membranes. Thus, Samp1 defines a specific membrane domain associated with the mitotic spindle.

National Category
Cell Biology
Identifiers
urn:nbn:se:sh:diva-13897 (URN)10.1242/jcs.047373 (DOI)000266634800018 ()2-s2.0-68949170696 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-14 Created: 2011-12-14 Last updated: 2017-12-08Bibliographically approved
Buch, C., Hunt, M. C., Alexson, S. E. H. & Hallberg, E. (2009). Localization of peroxisomal matrix proteins by photobleaching. Biochemical and Biophysical Research Communications - BBRC, 388(2), 355-359
Open this publication in new window or tab >>Localization of peroxisomal matrix proteins by photobleaching
2009 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 388, no 2, p. 355-359Article in journal (Refereed) Published
Abstract [en]

The distribution of some enzymes between peroxisomes and cytosol, or a dual localization in both these compartments, can be difficult to reconcile. We have used photobleaching in live cells expressing green fluorescent protein (GFP)-fusion proteins to show that imported bona fide peroxisomal matrix proteins are retained in the peroxisome. The high mobility of the GFP-fusion proteins in the cytosol and absence of peroxisomal escape makes it possible to eliminate the cytosolic fluorescence by photobleaching, to distinguish between exclusively cytosolic proteins and proteins that are also present at low levels in peroxisomes. Using this technique we found that GFP tagged bile acid-CoA:amino acid N-acyltransferase (BAAT) was exclusively localized in the cytosol in HeLa cells. We conclude that the cytosolic localization was due to its carboxyterminal non-consensus peroxisomal targeting signal (-SQL) since mutation of the -SQL to -SKL resulted in BAAT being efficiently imported into peroxisomes.

National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:sh:diva-13880 (URN)10.1016/j.bbrc.2009.08.013 (DOI)000274534300033 ()19666004 (PubMedID)2-s2.0-69249215125 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation.

Available from: 2011-12-14 Created: 2011-12-14 Last updated: 2017-12-08Bibliographically approved
Onischenko, E. A., Crafoord, E. & Hallberg, E. (2007). Phosphomimetic mutation of the mitotically phosphorylated serine 1880 compromises the interaction of the transmembrane nucleoporin gp210 with the nuclear pore complex. Experimental Cell Research, 313(12), 2744-2751
Open this publication in new window or tab >>Phosphomimetic mutation of the mitotically phosphorylated serine 1880 compromises the interaction of the transmembrane nucleoporin gp210 with the nuclear pore complex
2007 (English)In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 313, no 12, p. 2744-2751Article in journal (Refereed) Published
Abstract [en]

The nuclear pore complexes (NPCs) reversibly disassemble and reassemble during mitosis. Disassembly of the NPC is accompanied by phosphorylation of many nucleoporins although the function of this is not clear. It was previously shown that in the transmembrane nucleoporin gp210 a single serine residue at position 1880 is specifically phosphorylated during mitosis. Using amino acid substitution combined with live cell imaging, time-lapse microscopy and FRAP, we investigated the role of serine 1880 in binding of gp210 to the NPC in vivo An alanine subtitutions mutant (S1880A) was significantly more dynamic at the NPC compared to the wild-type protein, suggesting that serine 1880 is important for binding of gp210 to the NPC. Moreover a glutamate substitution (S1880E) closely mimicking phosphorylated serine specifically interfered with incorporation of gp210 into the NPC and compromised its post-mitotic recruitment to the nuclear envelope of daughter nuclei. our findings are consistent with the idea that mitotic phosphorylation acts to dissociate gp210 from the structural elements of the NPC.

National Category
Cancer and Oncology Cell Biology
Identifiers
urn:nbn:se:sh:diva-14217 (URN)10.1016/j.yexcr.2007.05.011 (DOI)000248112300019 ()17559836 (PubMedID)2-s2.0-34250885134 (Scopus ID)
Note

Som manuskript i avhandling. As manuscript in dissertation with title:

Mitotic phosphorylation regulates binding of gp210 to the nuclear pore complex

Available from: 2011-12-20 Created: 2011-12-19 Last updated: 2017-12-08Bibliographically approved
Fisher, L., Samuelsson, M., Jiang, Y., Ramberg, V., Figueroa, R., Hallberg, E., . . . Iverfeldt, K. (2007). Targeting cytokine expression in glial cells by cellular delivery of an NF-kappa B decoy. Journal of Molecular Neuroscience, 31(3), 209-219
Open this publication in new window or tab >>Targeting cytokine expression in glial cells by cellular delivery of an NF-kappa B decoy
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2007 (English)In: Journal of Molecular Neuroscience, ISSN 0895-8696, E-ISSN 1559-1166, Vol. 31, no 3, p. 209-219Article in journal (Refereed) Published
Abstract [en]

Inhibition of nuclear factor (NF)-kappa B has emerged as an important strategy for design of anti-inflammatory therapies. In neurodegenerative disorders like Alzheimer's disease, inflammatory reactions mediated by glial cells are believed to promote disease progression. Here, we report that uptake of a double-stranded oligonucleotide NF-kappa B decoy in rat primary glial cells is clearly facilitated by noncovalent binding to a cell-penetrating peptide, transportan 10, via a complementary peptide nucleic acid (PNA) sequence. Fluorescently labeled oligonucleotide decoy was detected in the cells within 1 h only when cells were incubated with the decoy in the presence of cell-penetrating peptide. Cellular delivery of the decoy also inhibited effects induced by a neurotoxic fragment of the Alzheimer beta-amyloid peptide in the presence of the inflammatory cytokine interleukin (IL)-1 beta. Pretreatment of the cells with the complex formed by the decoy and the cell-penetrating peptide-PNA resulted in 80% and 50% inhibition of the NF-kappa B binding activity and IL-6 mRNA expression, respectively.

National Category
Biochemistry and Molecular Biology Neurology
Identifiers
urn:nbn:se:sh:diva-14252 (URN)10.1385/JMN/31:03:209 (DOI)000246588800003 ()17726227 (PubMedID)2-s2.0-34548336397 (Scopus ID)
Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2017-12-08Bibliographically approved
Onischenko, E. A., Gubanova, N. V., Kiseleva, E. V. & Hallberg, E. (2005). Cdk1 and okadaic acid-sensitive phosphatases control assembly of nuclear pore complexes in Drosophila embryos. Molecular Biology of the Cell, 16(11), 5152-5162
Open this publication in new window or tab >>Cdk1 and okadaic acid-sensitive phosphatases control assembly of nuclear pore complexes in Drosophila embryos
2005 (English)In: Molecular Biology of the Cell, ISSN 1059-1524, E-ISSN 1939-4586, Vol. 16, no 11, p. 5152-5162Article in journal (Refereed) Published
Abstract [en]

Disassembly and reassembly of the nuclear pore complexes (NPCs) is one of the major events during open mitosis in higher eukaryotes. However, how this process is controlled by the mitotic machinery is not clear. To investigate this we developed a novel in vivo model system based on syncytial Drosophila embryos. We microinjected different mitotic effectors into the embryonic cytoplasm and monitored the dynamics of disassembly/reassembly of NPCs in live embryos using fluorescently labeled wheat germ agglutinin (WGA) or in fixed embryos using electron microscopy and immunostaining techniques. We found that in live embryos Cdk1 activity was necessary and sufficient to induce disassembly of NPCs as well as their cytoplasmic mimics: annulate lamellae pore complexes (ALPCs). Cdk1 activity was also required for keeping NPCs and ALPCs disassembled during mitosis. In Agreement recombinant Cdk1/cyclin B was able to induce phosphorylation and dissociation of nucleoporins from the NPCs in vitro. Conversely, reassembly of NPCs and ALPCs was dependent on the activity of protein phosphatases, sensitive to okadaic acid (OA). Our findings suggest a model where mitotic disassembly/reassembly of the NPCs is regulated by a dynamic equilibrium of Cdk1 and OA-sensitive phosphatase activities and provide evidence that mitotic phosphorylation mediates disassembly of the NPC.

National Category
Cell Biology
Identifiers
urn:nbn:se:sh:diva-14439 (URN)10.1091/mbc.E05-07-0642 (DOI)000233025000011 ()16120647 (PubMedID)2-s2.0-27644495950 (Scopus ID)
Available from: 2012-01-31 Created: 2011-12-23 Last updated: 2017-07-19Bibliographically approved
Onischenko, E. A., Gubanova, N. V., Kieselbach, T., Kiseleva, E. V. & Hallberg, E. (2004). Annulate lamellae play only a minor role in the storage of excess nucleoporins in Drosophila embryos. Traffic: the International Journal of Intracellular Transport, 5(3), 152-164
Open this publication in new window or tab >>Annulate lamellae play only a minor role in the storage of excess nucleoporins in Drosophila embryos
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2004 (English)In: Traffic: the International Journal of Intracellular Transport, ISSN 1398-9219, E-ISSN 1600-0854, Vol. 5, no 3, p. 152-164Article in journal (Refereed) Published
Abstract [en]

The nuclear pore complexes (NPCs), multiprotein assemblies embedded in the nuclear envelope, conduct nucleo-cytoplasmic traffic of macromolecules. Mimics of NPCs, called annulate lamellae pore complexes (ALPCs), are usually found in cytoplasmic membranous stacks in oocytes and early embryonic cells. They are believed to constitute storage compartments for excess premade nucleoporins. To evaluate the extent to which ALPCs store nucleoporins in early embryonic cells we took advantage of syncytial Drosophila embryos, containing both AL and rapidly proliferating nuclei in the common cytoplasm. Electron microscopic morphometric analysis showed that the number of ALPCs did not decrease to compensate for the growing number of NPCs during syncytial development. We performed Western blot analysis to quantify seven different nucleoporins and analyzed their intraembryonal distribution by confocal microscopy and subcellular fractionation. Syncytial embryos contained a large maternally contributed stockpile of nucleoporins. However, even during interphases, only a small fraction of the excess nucleoporins was assembled into ALPCs, whereas the major fraction was soluble and contained at least one phosphorylated nucleoporin. We conclude that in Drosophila embryos ALPCs play only a minor role in storing the excess maternally contributed nucleoporins. Factors that may prevent nucleoporins from assembly into ALPCs are discussed.

National Category
Cell Biology
Identifiers
urn:nbn:se:sh:diva-15486 (URN)10.1111/j.1600-0854.2004.0166.x (DOI)000189142900004 ()15086791 (PubMedID)2-s2.0-1642376626 (Scopus ID)
Available from: 2012-02-21 Created: 2012-02-20 Last updated: 2017-12-07Bibliographically approved
Kihlmark, M., Rustum, C., Eriksson, C., Beckman, M., Iverfeldt, K. & Hallberg, E. (2004). Correlation between nucleocytoplasmic transport and caspase-3-dependent dismantling of nuclear pores during apoptosis. Experimental Cell Research, 293(2), 346-356
Open this publication in new window or tab >>Correlation between nucleocytoplasmic transport and caspase-3-dependent dismantling of nuclear pores during apoptosis
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2004 (English)In: Experimental Cell Research, ISSN 0014-4827, E-ISSN 1090-2422, Vol. 293, no 2, p. 346-356Article in journal (Refereed) Published
Abstract [en]

During apoptosis (also called programmed cell death), the chromatin condenses and the DNA is cleaved into oligonucleosomal fragments. Caspases are believed to play a major role in nuclear apoptosis. However, the relation between dismantling of nuclear pores, disruption of the nucleocytoplasmic barrier, and nuclear entry of caspases is unclear. We have analyzed nuclear import of the green fluorescent protein fused to a nuclear localization signal (GFP-NLS) in tissue culture cells undergoing apoptosis. Decreased nuclear accumulation of GFP-NLS could be detected at the onset of nuclear apoptosis manifested as dramatic condensation and redistribution of chromatin toward the nuclear periphery. At this step, dismantling of nuclear pores was already evident as indicated by proteolysis of the nuclear pore membrane protein POM121. Thus, disruption of nuclear compartmentalization correlated with early signs of nuclear pore damage. Both these events clearly preceded massive DNA fragmentation, detected by TUNEL assay. Furthermore, we show that in apoptotic cells, POM121 is specifically cleaved at aspartate-531 in its large C-terminal portion by a caspase-3-dependent mechanism. Cleavage of the C-terminal portion of POM121, which is adjoining the nuclear pore complex, is likely to disrupt interactions with other nuclear pore proteins affecting the stability of the pore complex. A temporal correlation of apoptotic events supports a model where caspase-dependent disassembly of nuclear pores and disruption of the nucleocytoplasmic barrier paves the way for nuclear entry of caspases and subsequent activation of CAD-mediated DNA fragmentation.

National Category
Cell Biology
Identifiers
urn:nbn:se:sh:diva-15492 (URN)10.1016/j.yexcr.2003.10.019 (DOI)000188462700017 ()14729472 (PubMedID)2-s2.0-0347722245 (Scopus ID)
Available from: 2012-02-21 Created: 2012-02-20 Last updated: 2017-12-07Bibliographically approved
Beckman, M., Kihlmark, M., Iverfeldt, K. & Hallberg, E. (2004). Degradation of GFP-labelled POM121, a non-invasive sensor of nuclear apoptosis, precedes clustering of nuclear pores and externalisation of phosphatidylserine. Apoptosis (London), 9(3), 363-368
Open this publication in new window or tab >>Degradation of GFP-labelled POM121, a non-invasive sensor of nuclear apoptosis, precedes clustering of nuclear pores and externalisation of phosphatidylserine
2004 (English)In: Apoptosis (London), ISSN 1360-8185, E-ISSN 1573-675X, Vol. 9, no 3, p. 363-368Article in journal (Refereed) Published
Abstract [en]

The nuclear pore membrane protein POM121 is specifically degraded during apoptosis by a caspase-3-dependent process enabling early detection of apoptosis in living cells expressing POM121-GFP. Here we further investigated temporal aspects of apoptotic degradation of POM121-GFP. We demonstrate that decreased POM121-GFP fluorescence precedes annexin V-labelling of apoptotic cells. This indicates that degradation of the nuclear pore complex starts prior to redistribution of plasma membrane phosphatidylserine, which serves as a signal for phagocytotic elimination of apoptotic cells. Furthermore, a caspase-resistant GFP-labelled mutant of POM121 resisted degradation even in late apoptosis and was detected in clustered nuclear pores. Thus, it can be concluded that loss of POM121-GFP is a specific sensor of the activation of caspase-3-dependent proteolysis at the nuclear pores.

National Category
Biochemistry and Molecular Biology Cell Biology
Identifiers
urn:nbn:se:sh:diva-15480 (URN)10.1023/B:APPT.0000025813.75258.b5 (DOI)000221102700012 ()15258468 (PubMedID)2-s2.0-3242805164 (Scopus ID)
Available from: 2012-02-21 Created: 2012-02-20 Last updated: 2017-12-07Bibliographically approved
Eriksson, C., Rustum, C. & Hallberg, E. (2004). Dynamic properties of nuclear pore complex proteins in gp210 deficient cells. FEBS Letters, 572(1-3), 261-265
Open this publication in new window or tab >>Dynamic properties of nuclear pore complex proteins in gp210 deficient cells
2004 (English)In: FEBS Letters, ISSN 0014-5793, E-ISSN 1873-3468, Vol. 572, no 1-3, p. 261-265Article in journal (Refereed) Published
Abstract [en]

Gp210, an integral membrane protein of the nuclear pore complex (NPC), is believed to be involved in NPC biogenesis. To test this hypothesis, we have investigated dynamic properties of the NPC and distribution of NPC proteins in NIH/ 3T3 cells lacking gp210. POM121 (the other integral NPC protein) and NUP107 (of the NUP107/160 complex) were correctly distributed at the nuclear pores in the absence of gp210. Furthermore, fluorescence recovery after photobleaching experiments showed that POM121 and NUP107 remained stably associated at the NPCs. We conclude that gp210 cannot be required for incorporation of POM121 or NUP107 or be required for maintaining NPC stability.

National Category
Biochemistry and Molecular Biology Cell Biology
Identifiers
urn:nbn:se:sh:diva-15469 (URN)10.1016/j.febslet.2004.07.044 (DOI)000223519300047 ()15304359 (PubMedID)2-s2.0-4143137715 (Scopus ID)
Available from: 2012-02-21 Created: 2012-02-20 Last updated: 2017-12-07Bibliographically approved
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