The MEN mediates the effects of the spindle assembly checkpoint on Kar9-dependent spindle pole body inheritance in budding yeast
Volume 11, Issue 16
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August 15, 2012
Pages 3109 - 3116http://dx.doi.org/10.4161/cc.21504
: Clb5, Kar9 asymmetry, SPB inheritance, SPB specification, mitotic exit network, spindle assembly checkpoint
Authors: Manuel Hotz, Jette Lengefeld and Yves Barral View affiliations
Many asymmetrically dividing cells segregate the poles of the mitotic spindle non-randomly between their two daughters. In budding yeast, the protein Kar9 localizes almost exclusively to the astral microtubules emanating from the old spindle pole body (SPB) and promotes its movement toward the bud. Thereby, Kar9 orients the spindle relative to the division axis. Here, we show that beyond perturbing Kar9 distribution, activation of the spindle assembly checkpoint (SAC) randomizes SPB inheritance. Inactivation of the B-type cyclin Clb5 led to a SAC-dependent defect in Kar9 orientation and SPB segregation. Furthermore, unlike the Clb4-dependent pathway, the Clb5- and SAC-dependent pathways functioned genetically upstream of the mitotic exit network (MEN) in SPB specification and Kar9-dependent SPB inheritance. Together, our study indicates that Clb5 functions in spindle assembly and that the SAC controls the specification and inheritance of yeast SPBs through inhibition of the MEN.
Received: April 29, 2012; Accepted: July 16, 2012; Published Online: August 8, 2012
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