TY  - JOUR
A1  - Batsios, Petros
A1  - Ren, Xiang
A1  - Baumann, Otto
A1  - Larochelle, Denis A.
A1  - Gräf, Ralph
T1  - Src1 is a Protein of the Inner Nuclear Membrane Interacting with the Dictyostelium Lamin NE81
JF  - Cells
N2  - The nuclear envelope (NE) consists of the outer and inner nuclear membrane (INM), whereby the latter is bound to the nuclear lamina. Src1 is a Dictyostelium homologue of the helix-extension-helix family of proteins, which also includes the human lamin-binding protein MAN1. Both endogenous Src1 and GFP-Src1 are localized to the NE during the entire cell cycle. Immuno-electron microscopy and light microscopy after differential detergent treatment indicated that Src1 resides in the INM. FRAP experiments with GFP-Src1 cells suggested that at least a fraction of the protein could be stably engaged in forming the nuclear lamina together with the Dictyostelium lamin NE81. Both a BioID proximity assay and mis-localization of soluble, truncated mRFP-Src1 at cytosolic clusters consisting of an intentionally mis-localized mutant of GFP-NE81 confirmed an interaction of Src1 and NE81. Expression GFP-Src11–646, a fragment C-terminally truncated after the first transmembrane domain, disrupted interaction of nuclear membranes with the nuclear lamina, as cells formed protrusions of the NE that were dependent on cytoskeletal pulling forces. Protrusions were dependent on intact microtubules but not actin filaments. Our results indicate that Src1 is required for integrity of the NE and highlight Dictyostelium as a promising model for the evolution of nuclear architecture.
KW  - Dictyostelium
KW  - lamin
KW  - nuclear lamina
KW  - nucleus
KW  - nucleolus
KW  - HeH-protein
KW  - LEM-domain protein
Y1  - 2016
U6  - https://doi.org/10.3390/cells5010013
SN  - 2073-4409
VL  - 5
IS  - 1
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  -