TY  - JOUR
A1  - Batsios, Petros
A1  - Gräf, Ralph
A1  - Koonce, Michael P.
A1  - Larochelle, Denis A.
A1  - Meyer, Irene
T1  - Nuclear envelope organization in Dictyostelium discoideum
JF  - The international journal of developmental biology
N2  - The nuclear envelope consists of the outer and the inner nuclear membrane, the nuclear lamina and the nuclear pore complexes, which regulate nuclear import and export.The major constituent of the nuclear lamina of Dictyostelium is the lamin NE81. It can form filaments like B-type lamins and it interacts with Sun 1, as well as with the LEM/HeH-family protein Src1. Sun 1 and Src1 are nuclear envelope transmembrane proteins involved in the centrosome-nucleus connection and nuclear envelope stability at the nucleolar regions, respectively. In conjunction with a KASH-domain protein, Sun 1 usually forms a so-called LINC complex.Two proteins with functions reminiscent of KASH-domain proteins at the outer nuclear membrane of Dictyostelium are known; interaptin which serves as an actin connector and the kinesin Kif9 which plays a role in the microtubule-centrosome connector. However, both of these lack the conserved KASH-domain. The link of the centrosome to the nuclear envelope is essential for the insertion of the centrosome into the nuclear envelope and the appropriate spindle formation. Moreover, centrosome insertion is involved in perm eabilization of the mitotic nucleus, which ensures access of tubulin dimers and spindle assembly factors. Our recent progress in identifying key molecular players at the nuclear envelope of Dictyostelium promises further insights into the mechanisms of nuclear envelope dynamics.
KW  - nuclear envelop
KW  - Dictyostelium
KW  - lamin
KW  - NET
KW  - centrosome
KW  - centromere
Y1  - 2019
U6  - https://doi.org/10.1387/ijdb.190184rg
SN  - 0214-6282
SN  - 1696-3547
VL  - 63
IS  - 8-10
SP  - 509
EP  - 519
PB  - UBC Pr
CY  - Bilbao
ER  - 
TY  - JOUR
A1  - Tikhonenko, Irina
A1  - Magidson, Valentin
A1  - Gräf, Ralph
A1  - Khodjakov, Alexey
A1  - Koonce, Michael P.
T1  - A kinesin-mediated mechanism that couples centrosomes to nuclei
JF  - Cellular and molecular life sciences
N2  - The M-type kinesin isoform, Kif9, has recently been implicated in maintaining a physical connection between the centrosome and nucleus in Dictyostelium discoideum. However, the mechanism by which Kif9 functions to link these two organelles remains obscure. Here we demonstrate that the Kif9 protein is localized to the nuclear envelope and is concentrated in the region underlying the centrosome point of attachment. Nuclear anchorage appears mediated through a specialized transmembrane domain located in the carboxyl terminus. Kif9 interacts with microtubules in in vitro binding assays and effects an endwise depolymerization of the polymer. These results suggest a model whereby Kif9 is anchored to the nucleus and generates a pulling force that reels the centrosome up against the nucleus. This is a novel activity for a kinesin motor, one important for progression of cells into mitosis and to ensure centrosome-nuclear parity in a multinuclear environment.
KW  - Centrosome
KW  - Kinesin
KW  - Microtubule
KW  - Dictyostelium
Y1  - 2013
U6  - https://doi.org/10.1007/s00018-012-1205-0
SN  - 1420-682X
VL  - 70
IS  - 7
SP  - 1285
EP  - 1296
PB  - Springer
CY  - Basel
ER  -