Synthetic Lethal Interactions Identify Phenotypic “Interologs” of the Spindle Assembly Checkpoint Components

Abstract

Here, we report genetic interactions with mdf-1(gk2)/MAD1 in Caenorhabditis elegans. Nine are evolutionarily conserved or phenotypic ''interologs'' and two are novel enhancers, hcp-1 and bub-3. We show that HCP-1 and HCP-2, the two CENP-F-related proteins, recently implicated in the spindle assembly checkpoint (SAC) function, do not have identical functions, since hcp-1(RNAi), but not hcp-2(RNAi), enhances the lethality of the SAC mutants.

Systematic Analysis inCaenorhabditis elegansReveals that the Spindle Checkpoint Is Composed of Two Largely Independent Branches

“…Depletion of these proteins in cells with either bipolar or monopolar spindles triggers a Mad2 MDF-2 /Mad3 SAN-1 -dependent cell cycle delay, but the magnitude of this delay is less than that when HCP-1/2 are present. Synthetic genetic screens have identified HCP-1, but not HCP-2, as a contributor to checkpoint signaling in C. elegans (Tarailo et al, 2007;Hajeri et al, 2008)-our results extend these studies by showing that HCP-1/2 are not required for Mad2 MDF-2 enrichment at kinetochores; HCP-1/2 may control the extent of Mad2 MDF-2 accumulation or they may act at a different step that affects the potency of the inhibitory signal. Analogous conclusions have been made from studies on vertebrate CENP-F (for discussion, see Tarailo et al, 2007;Hajeri et al, 2008).…”

“…The second class (II), which includes MCAK and the nonessential kinetochore protein KBP-5 ( Figure 2C; data not shown), was dispensable for the monopolar spindle-induced delay. The third class (III) includes proteins whose depletion induces a cell cycle delay on their own, regardless of whether spindles were bipolar or monopolar; HCP-1/2, which are functionally analogous to CENP-F in vertebrates (Moore and Roth, 2001;Cheeseman et al, 2005;Encalada et al, 2005;Tarailo et al, 2007;Hajeri et al, 2008), fell into this class ( Figure 2C). The delay in HCP-1/2-depleted embryos was abolished by Mad2 MDF-2 or Mad3 SAN-1 codepletion, but it was of lower magnitude compared with the delay induced by monopolar spindles ( Figure 2C).…”

“…The role of KNL-1 family proteins in checkpoint signaling is conserved in vertebrates (Kittler et al, 2007;Kiyomitsu et al, 2007). A delay in mitosis after treatment with microtubule-depolymerizing drugs has been documented in the gonad and in embryos (Kitagawa and Rose, 1999;Nystul et al, 2003;Encalada et al, 2005;Stein et al, 2007;Tarailo et al, 2007;Hajeri et al, 2008), and spindle checkpoint proteins have been implicated in cessation of activity under anoxia (Nystul et al, 2003) and starvationinduced arrest of germ cell precursors (Watanabe et al, 2008).…”

Cyclin B3 and dynein heavy chain cooperate to increase fitness in the absence ofmdf-1/MAD1inCaenorhabditis elegans

“…2,3 The core components of the spindle assembly checkpoint [Mad1, Mad2, Mad3 (also named BubR1 in some organisms), Bub1, and Bub3] are conserved in Caenorhabditis elegans. [4][5][6][7] In the absence of MDF-1, an essential SAC component in C. elegans, genetic errors arise and accumulate leading to extinction of mdf-1(gk2) lines in 3 generations. 4 The unique phenotype of mdf-1(gk2) allows for identification of enhancers (strains with enhancer mutations cease propagating before the third generation when MDF-1 is defective) 7 and suppressors (strains which propagate beyond the third generation when MDF-1 is defective) [8][9][10] in genetic screens.…”

siRNA screening of the kinome identified Aurora A kinase as a therapeutic target gene in cervical cancer

“…There are many examples of a synthetic lethality approach being used successfully to identify novel target genes (Luo et al, 2009, Tarailo et al, 2007, Ashworth, 2008. For example, Barbie and colleagues sought to identify synthetic lethal genes that associate with KRAS-driven cancers using high-throughput siRNA screens (Barbie et al, 2009).…”