A Kinesin-Related Protein, Krp180, Positions Prometaphase Spindle Poles during Early Sea Urchin Embryonic Cell Division

Rogers, Gerald S.; Chui, Kitty; Lee, Edwin W.; Wedaman, Karen P.; Sharp, David J.; Holland, Gina D.; Morris, Robert L.; Scholey, Jonathan M.

doi:10.1083/jcb.150.3.499

Cited by 32 publications

(34 citation statements)

References 38 publications

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“…In Drosophila, KLP61F is sequestered in the nucleus during prophase and does not participate in the initial separation of the spindle poles, but only following nuclear envelope breakdown can KLP61F interact with MTs and exert forces that push apart the poles (18,19). Our data on sea urchin embryonic cells is consistent with the hypothesis that in this system, KRP 170 associates with cytoplasmic MTs where it interacts with MTs to help push apart the centrosomes during initial spindle assembly and anaphase spindle elongation, so that inhibiting its function leads to prophase or anaphase arrest (6).…”

Section: Discussionsupporting

confidence: 77%

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Roles of Two Homotetrameric Kinesins in Sea Urchin Embryonic Cell Division

Chui

Rogers

Kashina

et al. 2000

Journal of Biological Chemistry

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To improve our understanding of the roles of microtubule cross-linking motors in mitosis, we analyzed two sea urchin embryonic kinesin-related proteins. It is striking to note that both of these proteins behave as homotetramers, but one behaves as a more compact molecule than the other. These observations suggest that these two presumptive motors could cross-link microtubules into bundles with different spacing. Both motors localize to mitotic spindles, and antibody microinjection experiments suggest that they have mitotic functions. Thus, one of these kinesin-related proteins may crosslink spindle microtubules into loose bundles that are "tightened" by the other.Animal cell reproduction involves mitosis and cytokinesis, events that depend on the action of a bipolar protein machine, the mitotic spindle, which uses microtubules (MTs) 1 and MTbased motor proteins. A classic model system for studying mitosis and cytokinesis is the early echinoderm embryo where MTs and MT-based motor proteins are thought to position mitotic centrosomes, centrosomes dictate the positioning of the spindle, and the spindle in turn positions the cleavage plane (1). Antibody microinjection experiments are useful for probing the functions of MT-motors in sea urchin embryonic cell division (2); previously, the microinjection of pan-kinesin antibodies suggested that some kinesin motors, but apparently not conventional kinesin or heterotrimeric kinesin II, play important roles in mitosis and cell division (3-6).One of these motors is a 110-kDa polypeptide, KRP 110 , that reacts with an antibody, CHO1, to the mammalian mitotic motor, MKLP1 (3). MKLP1 is an anti-parallel MT-MT sliding motor that appears to be required for the organization of midzonal MTs and progression through mitosis and cytokinesis in several systems (7-12). The mechanism of how MKLP1 family members might function to cross-link microtubules and bundle them into the anti-parallel arrays required for cytokinesis is still unclear, because the size and subunit composition of the native holoenzyme is unclear.The microinjection of the CHO1 antibody into sea urchin embryonic cells caused a prophase or metaphase arrest, suggesting that KRP 110 is a functional homologue of MKLP1 and is required for mitosis and cell division in this system (3). Work done in several systems suggests that interdigitating MTs in the spindle midzone are required to signal the proper progression of the contractile ring and completion of cytokinesis. However, in echinoderm cells, cleavage furrows can form, and subsequent cytokinesis can occur between two adjacent MT asters in the absence of such midzonal MTs (1). This raises the possibility that the MKLP1 homologue in echinoderm embryos, KRP 110 , may be localized to the MT asters rather than the central spindle (13).Another putative MT cross-linking motor that is also likely to participate in sea urchin embryonic mitosis is KRP 170 , a member of the phylogenetically diverse bipolar bimC kinesin subfamily. Bipolar bimC kinesins are homotetramers that move ...

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Section: Discussionsupporting

confidence: 77%

“…How KRP 110 and KRP 170 may work in concert with other mitotic motors, including kinesin C (25), KRP 180 (6), and cytoplasmic dynein are topics for future work.…”

Section: Discussionmentioning

confidence: 99%

Roles of Two Homotetrameric Kinesins in Sea Urchin Embryonic Cell Division

Chui

Rogers

Kashina

et al. 2000

Journal of Biological Chemistry

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“…During anaphase, KLP-18 staining also concentrated between the separating groups of chromosomes, with a dim zone at the spindle equator (Figure 2A). These patterns are similar to those seen for Xklp2 in mitotic Xenopus cultured cells and KRP 180 in mitotic sea urchin embryos (Boleti et al, 1996;Rogers et al, 2000), although a dim zone at the anaphase equator has not been reported previously.After cytokinesis, KLP-18 accumulated somewhat around the nucleus and at the cortex near sites of cell-cell contact ( Figure 2B). During later stages of embryogenesis, KLP-18 levels gradually diminished in somatic cells but increased in the primordial germ cells Z2 and Z3, presumably due to expression in the embryonic germ line (Figure 2, C-E).…”

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confidence: 67%

“…Also, amino acids 507-510 (SPAR) in this "stalk" region provide a potential cdc2 kinase phosphorylation site ([T/S]PX[K/R]; Nigg, 1993). These features are similar to those of the stalk regions of other members of the Klp2 subfamily (Boleti et al, 1996;Wittmann et al, 1998;Rogers et al, 2000).Database searches revealed that ϳ750 kb away from klp-18 in the C. elegans genome is a pair of predicted ORFs (C33H5.4 and C33H5.3) with high sequence similarity to the KLP-18 amino acid sequence. The C33H5.4 ORF, previously designated as klp-10 (Siddiqui, 2002), is separated from C33H5.3 by only 19 base pairs of genomic DNA.…”

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confidence: 61%

“…The first in vivo disruption tests of a Klp2 kinesin, sea urchin KRP 180 , used antibody injection to examine its function in mitosis. A partial inhibition of centrosome separation during early prometaphase suggests a role in spindle assembly that could depend on MT-MT cross-linking and antiparallel sliding, similar to Eg5 and other BimC kinesins (Rogers et al, 2000).This article focuses on identification and functional tests of KLP-18, a Caenorhabditis elegans Klp2 kinesin. In the female germ line of C. elegans, mature oocytes arrest at diakinesis of prophase I.…”

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confidence: 99%

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KLP-18, a Klp2 Kinesin, Is Required for Assembly of Acentrosomal Meiotic Spindles inCaenorhabditis elegans

Segbert

Barkus

Powers

et al. 2003

MBoC

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The proper segregation of chromosomes during meiosis or mitosis requires the assembly of well organized spindles. In many organisms, meiotic spindles lack centrosomes. The formation of such acentrosomal spindles seems to involve first assembly or capture of microtubules (MTs) in a random pattern around the meiotic chromosomes and then parallel bundling and bipolar organization by the action of MT motors and other proteins. Here, we describe the structure, distribution, and function of KLP-18, a Caenorhabditis elegans Klp2 kinesin. Previous reports of Klp2 kinesins agree that it concentrates in spindles, but do not provide a clear view of its function. During prometaphase, metaphase, and anaphase, KLP-18 concentrates toward the poles in both meiotic and mitotic spindles. Depletion of KLP-18 by RNAmediated interference prevents parallel bundling/bipolar organization of the MTs that accumulate around female meiotic chromosomes. Hence, meiotic chromosome segregation fails, leading to haploid or aneuploid embryos. Subsequent assembly and function of centrosomal mitotic spindles is normal except when aberrant maternal chromatin is present. This suggests that although KLP-18 is critical for organizing chromosome-derived MTs into a parallel bipolar spindle, the order inherent in centrosome-derived astral MT arrays greatly reduces or eliminates the need for KLP-18 organizing activity in mitotic spindles. INTRODUCTIONIn eukaryotes meiosis allows the exchange of genetic material between parental chromosomes and leads to the formation of haploid gametes. Reliable segregation of meiotic chromosomes depends on the correct assembly of microtubules (MTs) into a bipolar spindle. In most animal systems, female meiotic spindles lack centrosomes and their MT nucleating activity (Sawada and Schatten, 1988;Gard, 1992;Theurkauf and Hawley, 1992;Albertson and Thomson, 1993). Interestingly, vertebrate cultured cells in which centrosomes have been destroyed can use a centrosome-independent pathway to build a functional bipolar spindle (Khodjakov et al., 2000). These and other results suggest that although the diastral mode of spindle assembly dominates when centrosomes are present, chromatin-based spindle assembly can be used when centrosomes are absent. The question of how meiotic MTs become organized into a bipolar structure remains largely unanswered.Studies in Xenopus egg extracts have provided some important insights into acentrosomal spindle assembly. The observation that bipolar spindles can form around DNAcoated beads confirmed that chromatin itself can provide a platform for the nucleation, stabilization, and/or capture of MTs (Heald et al., 1996). Analysis of the effects of inactivating or depleting specific MT motor proteins from Xenopus extracts along with analysis of mutations that affect assembly of acentrosomal meiotic spindles in Drosophila (Merdes and Cleveland, 1997;Walczak et al., 1998;Walczak, 2000) have led to the following model for chromatin-based assembly of bipolar spindles. Chromatin-associated kinesins, e.g., X...

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