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  • Prophase-Specific Perinuclear Actin Coordinates Centrosome Separation and Positioning to Ensure Accurate Chromosome Segregation.

Prophase-Specific Perinuclear Actin Coordinates Centrosome Separation and Positioning to Ensure Accurate Chromosome Segregation.

Cell reports (2020-05-28)
Tom Stiff, Fabio R Echegaray-Iturra, Harry J Pink, Alex Herbert, Constantino Carlos Reyes-Aldasoro, Helfrid Hochegger
ABSTRACT

Centrosome separation in late G2/ early prophase requires precise spatial coordination that is determined by a balance of forces promoting and antagonizing separation. The major effector of centrosome separation is the kinesin Eg5. However, the identity and regulation of Eg5-antagonizing forces is less well characterized. By manipulating candidate components, we find that centrosome separation is reversible and that separated centrosomes congress toward a central position underneath the flat nucleus. This positioning mechanism requires microtubule polymerization, as well as actin polymerization. We identify perinuclear actin structures that form in late G2/early prophase and interact with microtubules emanating from the centrosomes. Disrupting these structures by breaking the interactions of the linker of nucleoskeleton and cytoskeleton (LINC) complex with perinuclear actin filaments abrogates this centrosome positioning mechanism and causes an increase in subsequent chromosome segregation errors. Our results demonstrate how geometrical cues from the cell nucleus coordinate the orientation of the emanating spindle poles before nuclear envelope breakdown.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Cytochalasin D, from Zygosporium mansonii, ≥98% (TLC and HPLC), powder
Sigma-Aldrich
Phalloidin–Tetramethylrhodamine B isothiocyanate, sequence from Amanita phalloides(synthetic: peptide sequence)
Sigma-Aldrich
(+)-S-Trityl-L-cysteine, 97%
Sigma-Aldrich
PP1 Analog II, 1NM-PP1, PP1 Analog II, CAS 221244-14-0, is a cell-permeable PP1 analog that acts as a potent, reversible, selective, ATP-competitive inhibitor of mutant over wild-type kinases.