@article{GoosDejungWehmanetal.2019,
  author    = {Goos, Carina and Dejung, Mario and Wehman, Ann M. and M-Natus, Elisabeth and Schmidt, Johannes and Sunter, Jack and Engstler, Markus and Butter, Falk and Kramer, Susanne},
  title     = {Trypanosomes can initiate nuclear export co-transcriptionally},
  series = {Nucleic Acids Research},
  volume    = {47},
  journal   = {Nucleic Acids Research},
  number    = {1},
  doi       = {10.1093/nar/gky1136},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177709},
  pages     = {266-282},
  year      = {2019},
  abstract  = {The nuclear envelope serves as important messenger RNA (mRNA) surveillance system. In yeast and human, several control systems act in parallel to prevent nuclear export of unprocessed mRNAs. Trypanosomes lack homologues to most of the involved proteins and their nuclear mRNA metabolism is non-conventional exemplified by polycistronic transcription and mRNA processing by trans-splicing. We here visualized nuclear export in trypanosomes by intra- and intermolecular multi-colour single molecule FISH. We found that, in striking contrast to other eukaryotes, the initiation of nuclear export requires neither the completion of transcription nor splicing. Nevertheless, we show that unspliced mRNAs are mostly prevented from reaching the nucleus-distant cytoplasm and instead accumulate at the nuclear periphery in cytoplasmic nuclear periphery granules (NPGs). Further characterization of NPGs by electron microscopy and proteomics revealed that the granules are located at the cytoplasmic site of the nuclear pores and contain most cytoplasmic RNA-binding proteins but none of the major translation initiation factors, consistent with a function in preventing faulty mRNAs from reaching translation. Our data indicate that trypanosomes regulate the completion of nuclear export, rather than the initiation. Nuclear export control remains poorly understood, in any organism, and the described way of control may not be restricted to trypanosomes.},
  language  = {en}
}
@article{JahnSchrammSchnoelzeretal.2012,
  author    = {Jahn, Daniel and Schramm, Sabine and Schn{\"o}lzer, Martina and Heilmann, Clemens J. and de Koster, Chris G. and Sch{\"u}tz, Wolfgang and Benavente, Ricardo and Alsheimer, Manfred},
  title     = {A truncated lamin A in the Lmna\(^{-/-}\) mouse line: Implications for the understanding of laminopathies},
  series = {Nucleus},
  volume    = {3},
  journal   = {Nucleus},
  number    = {5},
  doi       = {10.4161/nucl.21676},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-127281},
  pages     = {463-474},
  year      = {2012},
  abstract  = {During recent years a number of severe clinical syndromes, collectively termed laminopathies, turned out to be caused by various, distinct mutations in the human LMNA gene. Arising from this, remarkable progress has been made to unravel the molecular pathophysiology underlying these disorders. A great benefit in this context was the generation of an A-type lamin deficient mouse line (Lmna\(^{-/-}\)) by Sullivan and others,1 which has become one of the most frequently used models in the field and provided profound insights to many different aspects of A-type lamin function. Here, we report the unexpected finding that these mice express a truncated Lmna gene product on both transcriptional and protein level. Combining different approaches including mass spectrometry, we precisely define this product as a C-terminally truncated lamin A mutant that lacks domains important for protein interactions and post-translational processing. Based on our findings we discuss implications for the interpretation of previous studies using Lmna\(^{-/-}\) mice and the concept of human laminopathies.},
  language  = {en}
}
@article{PaschLinkBecketal.2015,
  author    = {Pasch, Elisabeth and Link, Jana and Beck, Carolin and Scheuerle, Stefanie and Alsheimer, Manfred},
  title     = {The LINC complex component Sun4 plays a crucial role in sperm head formation and fertility},
  series = {Biology Open},
  volume    = {4},
  journal   = {Biology Open},
  doi       = {10.1242/bio.015768},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125212},
  pages     = {1792-1802},
  year      = {2015},
  abstract  = {LINC complexes are evolutionarily conserved nuclear envelope bridges, physically connecting the nucleus to the peripheral cytoskeleton. They are pivotal for dynamic cellular and developmental processes, like nuclear migration, anchoring and positioning, meiotic chromosome movements and maintenance of cell polarity and nuclear shape. Active nuclear reshaping is a hallmark of mammalian sperm development and, by transducing cytoskeletal forces to the nuclear envelope, LINC complexes could be vital for sperm head formation as well. We here analyzed in detail the behavior and function of Sun4, a bona fide testis-specific LINC component. We demonstrate that Sun4 is solely expressed in spermatids and there localizes to the posterior nuclear envelope, likely interacting with Sun3/Nesprin1 LINC components. Our study revealed that Sun4 deficiency severely impacts the nucleocytoplasmic junction, leads to mislocalization of other LINC components and interferes with the formation of the microtubule manchette, which finally culminates in a globozoospermia-like phenotype. Together, our study provides direct evidence for a critical role of LINC complexes in mammalian sperm head formation and male fertility.},
  language  = {en}
}
@article{GoebMeyerNatusBenaventeetal.2011,
  author    = {G{\"o}b, Eva and Meyer-Natus, Elisabeth and Benavente, Ricardo and Alsheimer, Manfred},
  title     = {Expression of individual mammalian Sun1 isoforms depends on the cell type},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68750},
  year      = {2011},
  abstract  = {Mammalian Sun1 belongs to an evolutionarily conserved family of inner nuclear membrane proteins, which are known as SUN domain proteins. SUN domain proteins interact with KASH domain partners to form bridging complexes, so-called LINC complexes, that physically connect the nuclear interior to the cytoskeleton. LINC complexes are critical for nuclear integrity and play fundamental roles in nuclear positioning, shaping and movement. The mammalian genome codes for at least five different SUN domain proteins used for the formation of a number of different LINC complexes. Recently, we reported on the identification of everal Sun1 isoforms, which tremendously enlarges the alternatives to form functional LINC complexes. We now confirmed that Sun1 actually exists in at least seven distinct splice variants. Besides that, we observed that expression of individual Sun1 isoforms remarkably depends on the cell type, suggesting a cell type-specific adaption of Sun1 dependent LINC complexes to specific cellular and physiological requirements.},
  subject      = {Biologie},
  language  = {en}
}
@article{BenaventeScheerChaly1989,
  author    = {Benavente, Ricardo and Scheer, Ulrich and Chaly, Nathalie},
  title     = {Nucleocytoplasmic sorting of macromolecules following mitosis: fate of nuclear constituents after inhibition of pore complex function},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-40777},
  year      = {1989},
  abstract  = {PtK2 cells in which pore complex-mediated transport is blocked by microinjection early in mitosis of a monoclonal antibody (specific for an Mr 68000 pore complex glycoprotein) or of wheat germ agglutinin (WGA) complete cytokinesis. However, their nuclei remain stably arrested in a telophase-like organization characterized by highly condensed chromatin and the absence of nucleoli, indicating a requirement for pore-mediated transport for the reassembly of interphase nuclei. We have now examined this requirement more closely by monitoring the behavior of individual nuclear macromolecules in microinjected cells using immunofluorescence microscopy and have investigated the effect of microinjecting the antibody or WGA on cellular ultrastructure. The absence of nuclear transport did not affect the sequestration into daughter nuclei of components such as DNA, DNA topoisomerase I and the nucleolar protein fibrillarin that are carried through mitosis on chromosomes. On the other hand, lamins, snRNAs and the p68 pore complex glycoprotein, all cytoplasmic during mitosis, remained largely cytoplasmic in the telophase-arrested cells. Electron microscopy showed the nuclei to be surrounded by a doublelayered membrane with some inserted pore complexes. In addition, however, a variety of membranous structures with associated pore complexes was regularly noted in the cytoplasm, suggesting that chromatin may not be essential for the postmitotic formation of pore complexes. We propose that cellular compartmentalization at telophase is a two-step process. First, a nuclear envelope tightly encloses the condensed chromosomes, excluding non-selectively all macromolecules not associated with the chromosomes. Interphase nuclear organization is then progressively restored by selective pore complex-mediated uptake of nuclear proteins from the cytoplasm.},
  subject      = {Cytologie},
  language  = {en}
}