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The microtubule-dependent motor centromere-associated protein E (CENP-E) is an integral component of kinetochore corona fibers that link centromeres to spindle microtubules.

Yao X, Anderson KL, Cleveland DW - J. Cell Biol. (1997)

Bottom Line: Centromere-associated protein E (CENP-E) is a kinesin-related microtubule motor protein that is essential for chromosome congression during mitosis.In congressing chromosomes, CENP-E is preferentially associated with (or accessible at) the stretched, leading kinetochore known to provide the primary power for chromosome movement.Taken together, this evidence strongly supports a model in which CENP-E functions in congression to tether kinetochores to the disassembling microtubule plus ends.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Biology, Ludwig Institute for Cancer Research, School of Medicine, University of California, La Jolla, CA 92093-0660, USA.

ABSTRACT
Centromere-associated protein E (CENP-E) is a kinesin-related microtubule motor protein that is essential for chromosome congression during mitosis. Using immunoelectron microscopy, CENP-E is shown to be an integral component of the kinetochore corona fibers that tether centromeres to the spindle. Immediately upon nuclear envelope fragmentation, an associated plus end motor trafficks cytoplasmic CENP-E toward chromosomes along astral microtubules that enter the nuclear volume. Before or concurrently with initial lateral attachment of spindle microtubules, CENP-E targets to the outermost region of the developing kinetochores. After stable attachment, throughout chromosome congression, at metaphase, and throughout anaphase A, CENP-E is a constituent of the corona fibers, extending at least 50 nm away from the kinetochore outer plate and intertwining with spindle microtubules. In congressing chromosomes, CENP-E is preferentially associated with (or accessible at) the stretched, leading kinetochore known to provide the primary power for chromosome movement. Taken together, this evidence strongly supports a model in which CENP-E functions in congression to tether kinetochores to the disassembling microtubule plus ends.

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At metaphase CENP-E extends from the kinetochore  outer plate at least 50 nm along spindle microtubules. Low magnification view of a metaphase HeLa cell with chromosomes  aligned at the equator between the spindle poles (asterisks). (B)  Magnified view of one metaphase chromosome showing that  spindle microtubules indeed associate with a kinetochore with a  trilaminar structure. Five 10-nm gold particles are located to each  sister kinetochore (arrows). Five additional gold particles just to  the right of the boxed area represent CENP-E associated with the  kinetochore of another chromosome (more clearly seen in adjacent  sections). (C) Higher magnification view shows that CENP-E is located to the corona fibers of the kinetochore. op, outer plate; ip,  inner plate; cf, corona fibers. Bars: (A) 2 μm; (B) 170 nm; (C) 70 nm.
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Figure 5: At metaphase CENP-E extends from the kinetochore outer plate at least 50 nm along spindle microtubules. Low magnification view of a metaphase HeLa cell with chromosomes aligned at the equator between the spindle poles (asterisks). (B) Magnified view of one metaphase chromosome showing that spindle microtubules indeed associate with a kinetochore with a trilaminar structure. Five 10-nm gold particles are located to each sister kinetochore (arrows). Five additional gold particles just to the right of the boxed area represent CENP-E associated with the kinetochore of another chromosome (more clearly seen in adjacent sections). (C) Higher magnification view shows that CENP-E is located to the corona fibers of the kinetochore. op, outer plate; ip, inner plate; cf, corona fibers. Bars: (A) 2 μm; (B) 170 nm; (C) 70 nm.

Mentions: To probe for the localization of CENP-E in chromosomes as they congress toward the spindle equator, we examined bioriented chromosomes in prometaphase cells. Two different examples from a single cell are highlighted in Fig. 4, A–C and D–F. At higher magnifications, nine gold particles representing specific labeling of CENP-E can be clearly seen on one leading kinetochore (i.e., defined here to be the one closer to the midzone; Fig. 4 C, arrow), while five particles are found on the other (trailing kinetochore; Fig. 4 C, arrowhead). Again, there was virtually no gold staining on other microtubules or at other surface regions of the chomosome (Fig. 4, B and E). In a second example (Fig. 4, D–F), seven gold particles were associated with the trailing sister kinetochore (Fig. 4 E), while the leading one reveals 14 particles, plus two adjacent clusters of CENP-E associated with a kinetochore microtubule. By examining 23 serial sections from five bioriented chromosomes, we determined that the leading kinetochore always displayed more intense CENP-E reactivity (12 ± 4 gold particles for the leading vs 7 ± 3 for the trailing), demonstrating a difference in abundance, conformation, or accessibility of kinetochore-bound CENP-E during chromosome congression. The increased immunoreactivity on the apparently leading kinetochore was confirmed at the light microscopic level. While CENP-B showed comparable staining on leading and trailing kinetochores of a lagging chromosome pair (Fig. 4 G, arrowhead and arrow, respectively), CENP-E staining was more intense on the kinetochore closest to the midzone (Fig. 4 H, arrowhead). Furthermore, in serial sections, none displayed the clear trilaminar structure seen at metaphase (e.g., see Fig. 5 B), demonstrating that kinetochore assembly is both multistep and incomplete even as late as bipolar microtubule attachment.


The microtubule-dependent motor centromere-associated protein E (CENP-E) is an integral component of kinetochore corona fibers that link centromeres to spindle microtubules.

Yao X, Anderson KL, Cleveland DW - J. Cell Biol. (1997)

At metaphase CENP-E extends from the kinetochore  outer plate at least 50 nm along spindle microtubules. Low magnification view of a metaphase HeLa cell with chromosomes  aligned at the equator between the spindle poles (asterisks). (B)  Magnified view of one metaphase chromosome showing that  spindle microtubules indeed associate with a kinetochore with a  trilaminar structure. Five 10-nm gold particles are located to each  sister kinetochore (arrows). Five additional gold particles just to  the right of the boxed area represent CENP-E associated with the  kinetochore of another chromosome (more clearly seen in adjacent  sections). (C) Higher magnification view shows that CENP-E is located to the corona fibers of the kinetochore. op, outer plate; ip,  inner plate; cf, corona fibers. Bars: (A) 2 μm; (B) 170 nm; (C) 70 nm.
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Figure 5: At metaphase CENP-E extends from the kinetochore outer plate at least 50 nm along spindle microtubules. Low magnification view of a metaphase HeLa cell with chromosomes aligned at the equator between the spindle poles (asterisks). (B) Magnified view of one metaphase chromosome showing that spindle microtubules indeed associate with a kinetochore with a trilaminar structure. Five 10-nm gold particles are located to each sister kinetochore (arrows). Five additional gold particles just to the right of the boxed area represent CENP-E associated with the kinetochore of another chromosome (more clearly seen in adjacent sections). (C) Higher magnification view shows that CENP-E is located to the corona fibers of the kinetochore. op, outer plate; ip, inner plate; cf, corona fibers. Bars: (A) 2 μm; (B) 170 nm; (C) 70 nm.
Mentions: To probe for the localization of CENP-E in chromosomes as they congress toward the spindle equator, we examined bioriented chromosomes in prometaphase cells. Two different examples from a single cell are highlighted in Fig. 4, A–C and D–F. At higher magnifications, nine gold particles representing specific labeling of CENP-E can be clearly seen on one leading kinetochore (i.e., defined here to be the one closer to the midzone; Fig. 4 C, arrow), while five particles are found on the other (trailing kinetochore; Fig. 4 C, arrowhead). Again, there was virtually no gold staining on other microtubules or at other surface regions of the chomosome (Fig. 4, B and E). In a second example (Fig. 4, D–F), seven gold particles were associated with the trailing sister kinetochore (Fig. 4 E), while the leading one reveals 14 particles, plus two adjacent clusters of CENP-E associated with a kinetochore microtubule. By examining 23 serial sections from five bioriented chromosomes, we determined that the leading kinetochore always displayed more intense CENP-E reactivity (12 ± 4 gold particles for the leading vs 7 ± 3 for the trailing), demonstrating a difference in abundance, conformation, or accessibility of kinetochore-bound CENP-E during chromosome congression. The increased immunoreactivity on the apparently leading kinetochore was confirmed at the light microscopic level. While CENP-B showed comparable staining on leading and trailing kinetochores of a lagging chromosome pair (Fig. 4 G, arrowhead and arrow, respectively), CENP-E staining was more intense on the kinetochore closest to the midzone (Fig. 4 H, arrowhead). Furthermore, in serial sections, none displayed the clear trilaminar structure seen at metaphase (e.g., see Fig. 5 B), demonstrating that kinetochore assembly is both multistep and incomplete even as late as bipolar microtubule attachment.

Bottom Line: Centromere-associated protein E (CENP-E) is a kinesin-related microtubule motor protein that is essential for chromosome congression during mitosis.In congressing chromosomes, CENP-E is preferentially associated with (or accessible at) the stretched, leading kinetochore known to provide the primary power for chromosome movement.Taken together, this evidence strongly supports a model in which CENP-E functions in congression to tether kinetochores to the disassembling microtubule plus ends.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Biology, Ludwig Institute for Cancer Research, School of Medicine, University of California, La Jolla, CA 92093-0660, USA.

ABSTRACT
Centromere-associated protein E (CENP-E) is a kinesin-related microtubule motor protein that is essential for chromosome congression during mitosis. Using immunoelectron microscopy, CENP-E is shown to be an integral component of the kinetochore corona fibers that tether centromeres to the spindle. Immediately upon nuclear envelope fragmentation, an associated plus end motor trafficks cytoplasmic CENP-E toward chromosomes along astral microtubules that enter the nuclear volume. Before or concurrently with initial lateral attachment of spindle microtubules, CENP-E targets to the outermost region of the developing kinetochores. After stable attachment, throughout chromosome congression, at metaphase, and throughout anaphase A, CENP-E is a constituent of the corona fibers, extending at least 50 nm away from the kinetochore outer plate and intertwining with spindle microtubules. In congressing chromosomes, CENP-E is preferentially associated with (or accessible at) the stretched, leading kinetochore known to provide the primary power for chromosome movement. Taken together, this evidence strongly supports a model in which CENP-E functions in congression to tether kinetochores to the disassembling microtubule plus ends.

Show MeSH
Related in: MedlinePlus