Regulated mitosis is essential for development and maintenance of cell populations throughout life. Microtubules (MTs) are the main component of the mitotic machinery. MTs are nucleated from the centrosomes, and their plus ends exhibit dynamic instability. The dynamics of MTs are highly regulated by MT associated proteins (MAPs). Proteins of the conserved XMAP215 family are major regulators of MT polymerization that preferentially localize to MT plus ends. During mitosis the XMAP215 family localizes to centrosomes and kinetochores (MT plus ends). Studies of XMAP215 family members have shown that they play an essential role during mitosis, as their depletion leads to short spindles or defects in spindle architecture in S. pombe, C. elegans, Xenopus egg extracts, Drosophila and HeLa cells. Members of the XMAP215 family contain a varying number of N-terminal TOG (tumor over expressed gene) domains that bind to tubulin heterodimers, however what remains to be determined is the structure and functional role of the C-terminal domain. I hypothesize that the Drosophila XMAP215 family member, Minispindles (Msps), uses distinct, conserved determinants to localize to centrosomes and kinetochore plus ends. I hypothesize that Msps activity at each of these locations differentially contributes to mitotic spindle structure. The activity of Msps at each of these locations will affect MT dynamics by promoting nucleation at the centrosomes and increasing MT dynamics at the kinetochore. I will examine these hypotheses by: (1) determining the effect of Msps localization on mitotic spindle architecture, (2) establishing the role of Msps at distinct spindle substructures on MT dynamics (3) elucidate the structure of the Msps C-terminal domain.
These aims span the atomic to cellular allowing me to gain a complete understating of how the conserved C-terminal domain of the XMAP215 family member, Msps, affects MT dynamics during mitosis.

Public Health Relevance

The microtubules (MTs) of the mitotic spindle are highly dynamic, polymerizing and depolymerizing at their ends. MT dynamics are necessary for the establishment of a proper bipolar spindle. If MT dynamics are altered, aberrant mitotic structures arise, which can lead to aneuploidy, a hallmark of cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31GM116476-02
Application #
9234410
Study Section
Special Emphasis Panel (ZRG1-F05-U (20)L)
Program Officer
Smith, Ward
Project Start
2016-02-01
Project End
2018-01-31
Budget Start
2017-02-01
Budget End
2018-01-31
Support Year
2
Fiscal Year
2017
Total Cost
$33,932
Indirect Cost
Name
University of North Carolina Chapel Hill
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Adikes, Rebecca C; Hallett, Ryan A; Saway, Brian F et al. (2018) Control of microtubule dynamics using an optogenetic microtubule plus end-F-actin cross-linker. J Cell Biol 217:779-793