Cell News 2/2014
18
Coevolution of centrosomes and nuclear lamina
Ralph Gräf
Universität Potsdam, Institut für Biochemie und Biologie, Potsdam-Golm, Germany.
Correspondence to:
In most eukaryotes microtubule organization is tightly asso-
ciated with the nuclear envelope (NE). The nuclear envelope
consists of an outer and inner membrane. The outer nuclear
membrane (ONM) is directly connected both to the endoplas-
mic reticulum and, at the nuclear pore complexes (NPCs), to
the inner nuclear membrane (INM). The perinuclear space se-
parates the INM and ONM and is directly linked to the lumen
of the ER. In metazoans, the INM is associated with the nuclear
lamina mainly consisting of specialized intermediate filaments
(IF) called lamins (Herrmann et al., 2007). The lamin-based
nuclear lamina is indirectly connected with all cytoplasmic
cytoskeletal elements through so-called LINC (linker of nuc-
leoskeleton and cytoskeleton) complexes (Crisp et al., 2006).
These complexes consist of a SUN-protein in the INM and a
KASH-domain protein in the ONM, while the respective KASH
and SUN domain interact within the perinuclear space. On the
cytoplasmic side, individual KASH domain proteins interact di-
rectly or indirectly with actin filaments, IFs or the centrosome
and, thus, with microtubules. At the nuclear face, Sun proteins
bind to lamins and NPCs (Starr and Fridolfsson, 2010). In addi-
tion, lamins associate with chromatin and are involved in for-
mation of lamina-associated heterochromatin domains. Thus,
they also regulate gene expression and differentiation (Van
Bortle and Corces, 2013). Due to the many binding activities of
lamins, especially to cytoskeletal elements, the nucleus serves
also as an abutment against mechanical forces for the whole
cell (Dahl et al., 2004). While centrosomal structures are found
in most eukaryotes except higher plants, until recently little
was known about the molecular basis of the nuclear lamina
in organisms other than metazoans. Meanwhile comparative
cell biology and database analyses of centrosomal structures
and the nuclear lamina have provided novel insights into early
events in eukaryotic evolution (Fig. 1).
Figure 1.
Tree of life and phylogenetic tree of eukaryotes. (A) Three-domain-tree of life based on rRNA sequences (Pace, 2006). (B) Current view of eukaryotic evo-
lution (Adl et al., 2012). FECA/LECA = first/last eukaryotic common ancestor; SAR-CCTH = Stramenophile, Alveolata, Rhizaria + Cryptophyta,
Centrohelida, Telonemia, Haptophyta.
Original figure corrected by the author (06/11/2014)
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