TY  - JOUR
A1  - Pitzen, Valentin
A1  - Sander, Sophia
A1  - Baumann, Otto
A1  - Gräf, Ralph
A1  - Meyer, Irene
T1  - Cep192, a novel missing link between the centrosomal core and corona in Dictyostelium amoebae
JF  - Cells : open access journal
N2  - The Dictyostelium centrosome is a nucleus-associated body with a diameter of approx. 500 nm. It contains no centrioles but consists of a cylindrical layered core structure surrounded by a microtubule-nucleating corona. At the onset of mitosis, the corona disassembles and the core structure duplicates through growth, splitting, and reorganization of the outer core layers. During the last decades our research group has characterized the majority of the 42 known centrosomal proteins. In this work we focus on the conserved, previously uncharacterized Cep192 protein. We use superresolution expansion microscopy (ExM) to show that Cep192 is a component of the outer core layers. Furthermore, ExM with centrosomal marker proteins nicely mirrored all ultrastructurally known centrosomal substructures. Furthermore, we improved the proximity-dependent biotin identification assay (BioID) by adapting the biotinylase BioID2 for expression in Dictyostelium and applying a knock-in strategy for the expression of BioID2-tagged centrosomal fusion proteins. Thus, we were able to identify various centrosomal Cep192 interaction partners, including CDK5RAP2, which was previously allocated to the inner corona structure, and several core components. Studies employing overexpression of GFP-Cep192 as well as depletion of endogenous Cep192 revealed that Cep192 is a key protein for the recruitment of corona components during centrosome biogenesis and is required to maintain a stable corona structure.
KW  - Cep192
KW  - SPD-2
KW  - centrosome
KW  - Dictyostelium
KW  - microtubule-organization
KW  - MTOC
Y1  - 2021
U6  - https://doi.org/10.3390/cells10092384
SN  - 2073-4409
VL  - 10
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Batsios, Petros
A1  - Peter, Tatjana
A1  - Baumann, Otto
A1  - Stick, Reimer
A1  - Meyer, Irene
A1  - Gräf, Ralph
T1  - A lamin in lower eukaryotes?
JF  - Nucleus
N2  - Lamins are the major components of the nuclear lamina and serve not only as a mechanical support, but are also involved in chromatin organization, epigenetic regulation, transcription and mitotic events. Despite these universal tasks, lamins have so far been found only in metazoans. Yet, recently we have identified Dictyostelium NE81 as the first lamin-like protein in a lower eukaryote. Based on the current knowledge, we draw a model for nuclear envelope organization in Dictyostelium in this Extra View and we review the experimental data that justified this classification. Furthermore we provide unpublished data underscoring the requirement of posttranslational CaaX-box processing for proper protein localization at the nuclear envelope. Sequence comparison of NE81 sequences from four Dictyostelia with bona fide lamins illustrates the evolutional relationship between these proteins. Under certain conditions these usually unicellular social amoebae congregate to form a multicellular body. We propose that the evolution of the lamin-like NE81 went along with the invention of multicellularity.
KW  - dictyostelium
KW  - lamin
KW  - intermediate filament
KW  - centrosome
KW  - nucleus
Y1  - 2012
U6  - https://doi.org/10.4161/nucl.20149
SN  - 1949-1034
VL  - 3
IS  - 3
SP  - 237
EP  - 243
PB  - Landes Bioscience
CY  - Austin
ER  -