umu.sePublications
Change search
Link to record
Permanent link

Direct link
BETA
Blomberg, Jeanette
Publications (10 of 14) Show all publications
Kumar, K. R., Blomberg, J. & Björklund, S. (2018). The MED7 subunit paralogs of Mediator function redundantly in development of etiolated seedlings in Arabidopsis. The Plant Journal, 96(3), 578-594
Open this publication in new window or tab >>The MED7 subunit paralogs of Mediator function redundantly in development of etiolated seedlings in Arabidopsis
2018 (English)In: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 96, no 3, p. 578-594Article in journal (Refereed) Published
Abstract [en]

MED7 is a subunit of the Mediator middle module and is encoded by two paralogs in Arabidopsis. We generated MED7 silenced lines using RNAi to study its impact on Arabidopsis growth and development. Compared with wild type, etiolated seedlings of the MED7 silenced lines exhibited reduced hypocotyl length caused by reduced cell elongation when grown in the dark. The hypocotyl length phenotype was rescued by exogenously supplied brassinosteroid. In addition, MED7 silenced seedlings exhibited defective hook opening in the dark as well as defective cotyledon expansion in the presence of the brassinosteroid inhibitor brassinazole. Whole transcriptome analysis on etiolated seedlings using RNA sequencing revealed several genes known to be regulated by auxin and brassinosteroids, and a broad range of cell wall-related genes that were differentially expressed in the MED7 silenced lines. This was especially evident for genes involved in cell wall extension and remodeling, such as EXPANSINs and XTHs. Conditional complementation with each MED7 paralog individually restored the hypocotyl phenotype as well as the gene expression defects. Additionally, conditional expression of MED7 had no effects that were independent of the Mediator complex on the observed phenotypes. We concluded that the MED7 paralogs function redundantly in regulating genes required for the normal development of etiolated Arabidopsis seedlings.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
Arabidopsis thaliana, MED7, Mediator complex, paralogs, skotomorphogenesis, transcriptional regulation
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-153697 (URN)10.1111/tpj.14052 (DOI)000447881200008 ()30058106 (PubMedID)
Funder
Swedish Cancer SocietySwedish Research CouncilKnut and Alice Wallenberg FoundationThe Kempe FoundationsCarl Tryggers foundation
Available from: 2018-12-05 Created: 2018-12-05 Last updated: 2018-12-05Bibliographically approved
Holst, M. R., Vidal-Quadras, M., Larsson, E., Song, J., Hubert, M., Blomberg, J., . . . Lundmark, R. (2017). Clathrin-Independent Endocytosis Suppresses Cancer Cell Blebbing and Invasion. Cell reports, 20(8), 1893-1905
Open this publication in new window or tab >>Clathrin-Independent Endocytosis Suppresses Cancer Cell Blebbing and Invasion
Show others...
2017 (English)In: Cell reports, ISSN 2211-1247, E-ISSN 2211-1247, Vol. 20, no 8, p. 1893-1905Article in journal (Refereed) Published
Abstract [en]

Cellular blebbing, caused by local alterations in cellsurface tension, has been shown to increase the invasiveness of cancer cells. However, the regulatory mechanisms balancing cell-surface dynamics and bleb formation remain elusive. Here, we show that an acute reduction in cell volume activates clathrinindependent endocytosis. Hence, a decrease in surface tension is buffered by the internalization of the plasma membrane (PM) lipid bilayer. Membrane invagination and endocytosis are driven by the tension- mediated recruitment of the membrane sculpting and GTPase-activating protein GRAF1 (GTPase regulator associated with focal adhesion kinase-1) to the PM. Disruption of this regulation by depleting cells of GRAF1 or mutating key phosphatidylinositol- interacting amino acids in the protein results in increased cellular blebbing and promotes the 3D motility of cancer cells. Our data support a role for clathrin-independent endocytic machinery in balancing membrane tension, which clarifies the previously reported role of GRAF1 as a tumor suppressor.

Place, publisher, year, edition, pages
Cell Press, 2017
Keywords
Endocytosis, clathrin-independent endocytosis, membrane blebbing, membrane tension, GRAF1, cancer invasion, cell migration, ARHGAP26, cell surface dynamics, GRAF1-dependent endocytosis
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-139144 (URN)10.1016/j.celrep.2017.08.006 (DOI)000408154300014 ()28834752 (PubMedID)
Available from: 2017-09-15 Created: 2017-09-15 Last updated: 2019-05-10Bibliographically approved
Hoernke, M., Mohan, J., Larsson, E., Blomberg, J., Kahra, D., Westenhoff, S., . . . Lundmark, R. (2017). EHD2 restrains dynamics of caveolae by an ATP-dependent, membrane-bound, open conformation. Proceedings of the National Academy of Sciences of the United States of America, 114(22), E4360-E4369
Open this publication in new window or tab >>EHD2 restrains dynamics of caveolae by an ATP-dependent, membrane-bound, open conformation
Show others...
2017 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 22, p. E4360-E4369Article in journal (Refereed) Published
Abstract [en]

The EH-domain-containing protein 2 (EHD2) is a dynamin-related ATPase that confines caveolae to the cell surface by restricting the scission and subsequent endocytosis of these membrane pits. For this, EHD2 is thought to first bind to the membrane, then to oligomerize, and finally to detach, in a stringently regulated mechanistic cycle. It is still unclear how ATP is used in this process and whether membrane binding is coupled to conformational changes in the protein. Here, we show that the regulatory N-terminal residues and the EH domain keep the EHD2 dimer in an autoinhibited conformation in solution. By significantly advancing the use of infrared reflection-absorption spectroscopy, we demonstrate that EHD2 adopts an open conformation by tilting the helical domains upon membrane binding. We show that ATP binding enables partial insertion of EHD2 into the membrane, where G-domain-mediated oligomerization occurs. ATP hydrolysis is related to detachment of EHD2 from the membrane. Finally, we demonstrate that the regulation of EHD2 oligomerization in a membrane-bound state is crucial to restrict caveolae dynamics in cells.

Keywords
EHD2, caveolae, membrane-reshaping protein, membrane-bound protein structure, infrared flection-absorption spectroscopy
National Category
Biophysics
Identifiers
urn:nbn:se:umu:diva-136326 (URN)10.1073/pnas.1614066114 (DOI)000402296700009 ()28223496 (PubMedID)
Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2018-06-09Bibliographically approved
Davoine, C., Abreu, I. N., Khajeh, K., Blomberg, J., Kidd, B. N., Kazan, K., . . . Björklund, S. (2017). Functional metabolomics as a tool to analyze Mediator function and structure in plants. PLoS ONE, 12(6), Article ID e0179640.
Open this publication in new window or tab >>Functional metabolomics as a tool to analyze Mediator function and structure in plants
Show others...
2017 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 6, article id e0179640Article in journal (Refereed) Published
Abstract [en]

Mediator is a multiprotein transcriptional co-regulator complex composed of four modules; Head, Middle, Tail, and Kinase. It conveys signals from promoter-bound transcriptional regulators to RNA polymerase II and thus plays an essential role in eukaryotic gene regulation. We describe subunit localization and activities of Mediator in Arabidopsis through metabolome and transcriptome analyses from a set of Mediator mutants. Functional metabolomic analysis based on the metabolite profiles of Mediator mutants using multivariate statistical analysis and heat-map visualization shows that different subunit mutants display distinct metabolite profiles, which cluster according to the reported localization of the corresponding subunits in yeast. Based on these results, we suggest localization of previously unassigned plant Mediator subunits to specific modules. We also describe novel roles for individual subunits in development, and demonstrate changes in gene expression patterns and specific metabolite levels in med18 and med25, which can explain their phenotypes. We find that med18 displays levels of phytoalexins normally found in wild type plants only after exposure to pathogens. Our results indicate that different Mediator subunits are involved in specific signaling pathways that control developmental processes and tolerance to pathogen infections.

Place, publisher, year, edition, pages
Public Library Science, 2017
National Category
Developmental Biology Genetics
Identifiers
urn:nbn:se:umu:diva-140237 (URN)10.1371/journal.pone.0179640 (DOI)000404135800047 ()28640868 (PubMedID)
Available from: 2017-10-19 Created: 2017-10-19 Last updated: 2018-06-09Bibliographically approved
Chereji, R. V., Bharatula, V., Elfving, N., Blomberg, J., Larsson, M., Morozov, A. V., . . . Björklund, S. (2017). Mediator binds to boundaries of chromosomal interaction domains and to proteins involved in DNA looping, RNA metabolism, chromatin remodeling, and actin assembly. Nucleic Acids Research, 45(15), 8806-8821
Open this publication in new window or tab >>Mediator binds to boundaries of chromosomal interaction domains and to proteins involved in DNA looping, RNA metabolism, chromatin remodeling, and actin assembly
Show others...
2017 (English)In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 45, no 15, p. 8806-8821Article in journal (Refereed) Published
Abstract [en]

Mediator is a multi-unit molecular complex that plays a key role in transferring signals from transcriptional regulators to RNA polymerase II in eukaryotes. We have combined biochemical purification of the Sac-charomyces cerevisiae Mediator from chromatin with chromatin immunoprecipitation in order to reveal Mediator occupancy on DNA genome-wide, and to identify proteins interacting specifically with Mediator on the chromatin template. Tandem mass spectrometry of proteins in immunoprecipitates of mediator complexes revealed specific interactions between Mediator and the RSC, Arp2/Arp3, CPF, CF 1A and Lsm complexes in chromatin. These factors are primarily involved in chromatin remodeling, actin assembly, mRNA 3'-end processing, gene looping and mRNA decay, but they have also been shown to enter the nucleus and participate in Pol II transcription. Moreover, we have found that Mediator, in addition to binding Pol II promoters, occupies chromosomal interacting domain (CID) boundaries and that Mediator in chromatin associates with proteins that have been shown to interact with CID boundaries, such as Sth1, Ssu72 and histone H4. This suggests that Mediator plays a significant role in higher-order genome organization.

Place, publisher, year, edition, pages
Oxford University Press, 2017
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-139789 (URN)10.1093/nar/gkx491 (DOI)000409380900020 ()
Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2018-06-09Bibliographically approved
Hoernke, M., Larsson, E., Mohan, J., Blomberg, J., Westenhoff, S., Lundmark, R. & Schwieger, C. (2016). Structural Mechanism in a Membrane Remodelling ATP-ASE. Paper presented at 60th Annual Meeting of the Biophysical-Society, FEB 27-MAR 02, 2016, Los Angeles, CA. Biophysical Journal, 110(3), 578A-578A
Open this publication in new window or tab >>Structural Mechanism in a Membrane Remodelling ATP-ASE
Show others...
2016 (English)In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 110, no 3, p. 578A-578AArticle in journal, Meeting abstract (Other academic) Published
National Category
Biophysics
Identifiers
urn:nbn:se:umu:diva-121607 (URN)000375143000319 ()
Conference
60th Annual Meeting of the Biophysical-Society, FEB 27-MAR 02, 2016, Los Angeles, CA
Available from: 2016-06-21 Created: 2016-06-03 Last updated: 2018-06-07Bibliographically approved
Aguilar, X., Blomberg, J., Brännström, K., Olofsson, A., Schleucher, J. & Björklund, S. (2014). Interaction Studies of the Human and Arabidopsis thaliana Med25-ACID Proteins with the Herpes Simplex Virus VP16-and Plant-Specific Dreb2a Transcription Factors. PLoS ONE, 9(5), e98575
Open this publication in new window or tab >>Interaction Studies of the Human and Arabidopsis thaliana Med25-ACID Proteins with the Herpes Simplex Virus VP16-and Plant-Specific Dreb2a Transcription Factors
Show others...
2014 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 5, p. e98575-Article in journal (Refereed) Published
Abstract [en]

Mediator is an evolutionary conserved multi-protein complex present in all eukaryotes. It functions as a transcriptional coregulator by conveying signals from activators and repressors to the RNA polymerase II transcription machinery. The Arabidopsis thaliana Med25 (aMed25) ACtivation Interaction Domain (ACID) interacts with the Dreb2a activator which is involved in plant stress response pathways, while Human Med25-ACID (hMed25) interacts with the herpes simplex virus VP16 activator. Despite low sequence similarity, hMed25-ACID also interacts with the plant-specific Dreb2a transcriptional activator protein. We have used GST pull-down-, surface plasmon resonance-, isothermal titration calorimetry and NMR chemical shift experiments to characterize interactions between Dreb2a and VP16, with the hMed25 and aMed25-ACIDs. We found that VP16 interacts with aMed25-ACID with similar affinity as with hMed25-ACID and that the binding surface on aMed25-ACID overlaps with the binding site for Dreb2a. We also show that the Dreb2a interaction region in hMed25-ACID overlaps with the earlier reported VP16 binding site. In addition, we show that hMed25-ACID/Dreb2a and aMed25-ACID/Dreb2a display similar binding affinities but different binding energetics. Our results therefore indicate that interaction between transcriptional regulators and their target proteins in Mediator are less dependent on the primary sequences in the interaction domains but that these domains fold into similar structures upon interaction.

Keywords
Mediator, Med25, Dreb2a, VP16, conformational changes, NMR, ITC
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-91061 (URN)10.1371/journal.pone.0098575 (DOI)000336790800049 ()
Note

Originally included in thesis in manuscript form.

Available from: 2014-07-11 Created: 2014-07-10 Last updated: 2018-06-07Bibliographically approved
Blomberg, J., Aguilar, X., Brännström, K., Rautio, L., Olofsson, A., Wittung-Stafshede, P. & Björklund, S. (2012). Interactions between DNA, transcriptional regulator Dreb2a and the Med25 mediator subunit from Arabidopsis thaliana involve conformational changes. Nucleic Acids Research, 40(13), 5938-5950
Open this publication in new window or tab >>Interactions between DNA, transcriptional regulator Dreb2a and the Med25 mediator subunit from Arabidopsis thaliana involve conformational changes
Show others...
2012 (English)In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 40, no 13, p. 5938-5950Article in journal (Refereed) Published
Abstract [en]

Mediator is a multiprotein coregulatory complex that conveys signals from DNA-bound transcriptional regulators to the RNA polymerase II transcription machinery in eukaryotes. The molecular mechanisms for how these signals are transmitted are still elusive. By using purified transcription factor Dreb2a, mediator subunit Med25 from Arabidopsis thaliana, and a combination of biochemical and biophysical methods, we show that binding of Dreb2a to its canonical DNA sequence leads to an increase in secondary structure of the transcription factor. Similarly, interaction between the Dreb2a and Med25 in the absence of DNA results in conformational changes. However, the presence of the canonical Dreb2a DNA-binding site reduces the affinity between Dreb2a and Med25. We conclude that transcription regulation is facilitated by small but distinct changes in energetic and structural parameters of the involved proteins.

Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2012
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-54407 (URN)10.1093/nar/gks265 (DOI)000306970700019 ()22447446 (PubMedID)
Available from: 2012-04-26 Created: 2012-04-25 Last updated: 2018-06-08Bibliographically approved
Blomberg, J., Höglund, A., Eriksson, D., Ruuth, K., Jacobsson, M., Nilsson, J. & Lundgren, E. (2011). Inhibition of cellular FLICE-like inhibitory protein abolishes insensitivity to interferon-α in a resistant variant of the human U937 cell line. Apoptosis (London), 16(8), 783-794
Open this publication in new window or tab >>Inhibition of cellular FLICE-like inhibitory protein abolishes insensitivity to interferon-α in a resistant variant of the human U937 cell line
Show others...
2011 (English)In: Apoptosis (London), ISSN 1360-8185, E-ISSN 1573-675X, Vol. 16, no 8, p. 783-794Article in journal (Refereed) Published
Abstract [en]

Type I interferons constitute a family of pleiotropic cytokines that have a key role in both adaptive and innate immunity. The interferon signalling pathways mediate transcriptional regulation of hundreds of genes, which result in mRNA degradation, decreased protein synthesis, cell cycle inhibition and induction of apoptosis. To elucidate regulatory networks important for interferon induced cell death, we generated interferon resistant U937 cells by selection in progressively increasing concentrations of interferon-α (IFN-α). The results show that IFN-α activates the death receptor signalling pathway and that IFN resistance was associated with cross-resistance to several death receptor ligands in a manner similar to previously described Fas resistant U937 cell lines. Increased expression of the long splice variant of the cellular FLICE-like inhibitor protein (cFLIP-L) was associated with the resistance to death receptor and IFN-α stimulation. Accordingly, inhibition of cFLIP-L expression with cycloheximide or through cFLIP short harpin RNA interference restored sensitivity to Fas and/or IFN-α. Thus, we now show that selection for interferon resistance can generate cells with increased expression of cFLIP, which protects the cells from both IFN-α and death receptor mediated apoptosis.

Keywords
Apoptosis, Death receptor, Resistance, Fas, Interferon, cFLIP
National Category
Biophysics Cell and Molecular Biology Medical and Health Sciences Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-3478 (URN)10.1007/s10495-011-0606-0 (DOI)
Available from: 2008-09-22 Created: 2008-09-22 Last updated: 2018-06-09Bibliographically approved
Elfving, N., Davoine, C., Benlloch, R., Blomberg, J., Brännström, K., Müller, D., . . . Björklund, S. (2011). The Arabidopsis thaliana Med25 mediator subunit integrates environmental cues to control plant development. Proceedings of the National Academy of Sciences of the United States of America, 108(20), 8245-8250
Open this publication in new window or tab >>The Arabidopsis thaliana Med25 mediator subunit integrates environmental cues to control plant development
Show others...
2011 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 20, p. 8245-8250Article in journal (Refereed) Published
Abstract [en]

Development in plants is controlled by abiotic environmental cues such as day length, light quality, temperature, drought, and salinity. These signals are sensed by a variety of systems and transmitted by different signal transduction pathways. Ultimately, these pathways are integrated to control expression of specific target genes, which encode proteins that regulate development and differentiation. The molecular mechanisms for such integration have remained elusive. We here show that a linear 130-amino-acids-long sequence in the Med25 subunit of the Arabidopsis thaliana Mediator is a common target for the drought response element binding protein 2A, zinc finger homeodomain 1, and Myb-like transcription factors which are involved in different stress response pathways. In addition, our results show that Med25 together with drought response element binding protein 2A also function in repression of PhyB-mediated light signaling and thus integrate signals from different regulatory pathways.

Keywords
transcriptional regulation, phytochrome flowering time 1, RNA polymerase II
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-46758 (URN)10.1073/pnas.1002981108 (DOI)21536906 (PubMedID)
Available from: 2011-09-13 Created: 2011-09-13 Last updated: 2018-06-08Bibliographically approved
Organisations

Search in DiVA

Show all publications