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Hallberg, Einar
Publications (10 of 26) 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
Gatsinzi, T., Ramberg, V., Figueroa, R., Iverfeldt, K. & Hallberg, E. (2010). Localized caspase sensors for live cell imaging of amyloid-β induced apoptosis. Alzheimer's & Dementia, 6(4, Supplement), S259-S260
Open this publication in new window or tab >>Localized caspase sensors for live cell imaging of amyloid-β induced apoptosis
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2010 (English)In: Alzheimer's & Dementia, ISSN 1552-5260, E-ISSN 1552-5279, Vol. 6, no 4, Supplement, p. S259-S260Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Background: Apoptosis is an evolutionary conserved cellular process important for normal development, maintenance of tissue homeostasis and an effective immune system. Cysteine-aspartic proteases, or caspases, are the major mediators of apoptosis, triggering processes which lead to cellular disruption. Dysregulation of apoptotic signaling has been shown to be involved in several pathological conditions, like cancer and degenerative disorders. Alzheimer's disease (AD) is the most common form of dementia involving massive cell death of neurons. However, the cause of AD at the present time is still unknown, although, amyloid-β (Aβ) peptide has been suggested to be the triggering factor. 

Methods:In order to detect localized caspase activation in live cells we designed sensors for caspase-3, -6 and -9 utilizing fluorescence resonance energy transfer (FRET). The FRET-ing sensor molecules, consisting of CFP and YFP separated by a linker containing a specific caspase cleavage motif, were designed to signal caspase cleavage by the loss of FRET. Differentiated SH-SY5Y cells were used as a model system for neurodegeneration. The cells were treated with oligomeric Aβ42 or staurosporine as a positive control of apoptosis. The cleavage of the sensors during induced apoptosis was verified by western blot analysis. Time-lapse FRET microscopy was used to monitor caspase activity in different parts of the cells. 

Results: In our study, when the cells were exposed to staurosporine we were able to detect local activity of caspase-6 initially in the soma of the cells, whereas caspase-6 activity in the neurites was delayed. Furthermore, our study shows that oligomeric Aβ42 is able to activate caspase-3, -6 and -9. In contrast to staurosporine, in Aβ42 treated cells loss of FRET occurred globally indicating that caspase was activated simultaneously in soma and axons. 

Conclusions: In conclusion, we show that our caspase-sensors are able to detect local caspase activity in vitro. We also show that exposure to oligomeric Aβ42 results in global activation of caspases in differentiated SH-SY5Y cells.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-35269 (URN)10.1016/j.jalz.2010.05.849 (DOI)
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-06-19Bibliographically 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
Olsson, V., Samuelsson, M., Figueroa, R., Zhang, M., Hallberg, E. & Iverfeldt, K. (2006). Analysis of apoptotic processes in live cells. Alzheimer's & Dementia, 2(3, Supplement), S439-S440
Open this publication in new window or tab >>Analysis of apoptotic processes in live cells
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2006 (English)In: Alzheimer's & Dementia, ISSN 1552-5260, E-ISSN 1552-5279, Vol. 2, no 3, Supplement, p. S439-S440Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Background: Neuronal and synaptic loss can be observed in several neurologic disorders, like Alzheimer’s disease (AD). The mechanism behind cell death in AD has been intensively studied and apoptosis has been proposed to play a central role in death processes, primary affecting cholinergic neurons in the cerebral cortex and the limbic lobe. There are numerous potential death stimuli that may be relevant in AD, including inflammatory responses, growth factor deprivation, oxidative stress and direct effects of the β- amyloid peptide. Objective: In order to get further insights in the initiation of apoptotic processes, we have developed a set of caspase sensors. 

Methods: We have used fluorescence resonance energy transfer (FRET) technology to, in real time and at single cell level, monitor the crucial event of the activation cysteine aspartate proteases, central in apoptosis. The two chromophores ECFP and EYFP, separated by a caspase cleavage site, have been used to visualize the caspase cleavage event at a chosen subcellular location in different cellular models, including differentiated neuronal cells. Since several apoptotic signalling pathways may be involved, we have designed sensors that can be cleaved by caspase-3, -8 or -9, representing two possible pathways, the death receptor pathway and the mitochondrial pathway. The in vitromodel used initially to characterize the caspase sensors has been HeLa cells, stimulated with staurosporin. The condition of the cells and the different stages of apoptosis were identified by nuclear staining with Hoechst 33258. 

Results: Our preliminary data indicate that caspase cleavage is an early event in the apoptotic cascade initiated by staurosporin, and that it most likely begins central in the cell body as FRET signals can be detected at later stages only in the cell periphery. Over-expression of the sensors did not result in any detectable toxicity since cells were able to divide successfully and no morphological changes could be revealed. 

Conclusion: Using this approach, a better temporal and spatial understanding of the apoptotic processes will be achieved. This is necessary in order to identify therapeutic targets to prevent the massive loss of neurons in AD and related disorders.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-35287 (URN)10.1016/j.jalz.2006.05.1488 (DOI)
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-06-19Bibliographically approved
Samuelsson, M., Fisher, L., Jiang, Y., Olsson, V., Figueroa, R., Hallberg, E., . . . Iverfeldt, K. (2006). Transcription factors as targets to block inflammation in neurodegenerative disorder: s. Alzheimer's & Dementia, 2(3, Supplement), S457
Open this publication in new window or tab >>Transcription factors as targets to block inflammation in neurodegenerative disorder: s
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2006 (English)In: Alzheimer's & Dementia, ISSN 1552-5260, E-ISSN 1552-5279, Vol. 2, no 3, Supplement, p. S457-Article in journal, Meeting abstract (Other academic) Published
Abstract [en]

Background: Accumulating evidence supports the importance of inflammation in neurodegenerative disorders like Alzheimer’s disease (AD). Epidemiological studies have revealed that patients taking anti-inflammatory drugs for conditions like arthritis have a lower prevalence of Alzheimer’s than others. In addition, there are reports that show that inflammation indeed can cause neurodegeneration in vivo. “The glial loop hypothesis” describes the model where surrounding glial cells are activated and produce neurotoxic products and therefore lead to neuronal death. One of the most important transcription factors involved in the inflammatory signalling cascade is NF-κB (nuclear factor κB). Supporting a role for NF-κB in AD, this transcription factor has been shown to be upregulated in brains from patients suffering from the disease. Another transcription factor family, thought to work together with NF-κB, is CCAAT enhancer binding protein (C/EBP). C/EBPδ has also been shown to be overexpressed in brains from Alzheimer patients. 

Objective: Our aim was to characterize the activation of transcription factors that may be involved in AD and to investigate the possibilities to block the effects of these transcription factors. 

Methods: We have used a delivery system that we have previously developed with a decoy non-covalently bound to a cell-penetrating peptide (CPP). In our studies primary mixed glial cultures from rat (5-10% microglia and 90-95% astrocytes) were used as a modelsystem. Transcription factor activation and cytokine mRNA expression were analyzed by electrophoretic mobility shift assay and RT-PCR, respectively. Cellular uptake studies were performed using confocal laser scanning microscopy. 

Results: Our studies show that a β-amyloid peptide alone or in combination with the inflammatory cytokine interleukin-1β upregulates NF-κB binding activity as well as the mRNA expression of its downstream target gene interleukin-6 (IL-6). Using our delivery system with an NF-κB decoy resulted in inhibition of upregulated NF-κB binding activity by approx. 80% and IL-6 mRNA expression by approx. 50%. We observed a clear uptake of the CPP-coupled decoy. In parallel, we have also investigated the possibility to use C/EBP as a therapeutic target. 

Conclusion: Facilitated uptake of transcription factor decoys may be a promising strategy to target the inflammation in neurodegenerative disorders like AD.

National Category
Biological Sciences
Identifiers
urn:nbn:se:sh:diva-35288 (URN)10.1016/j.jalz.2006.05.1547 (DOI)
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-06-19Bibliographically 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
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