Characterization of mitosis-specific phosphorylation of tumor-associated microtubule-associated protein

다국어 초록 (Multilingual Abstract)

Tumor-associated microtubule-associated protein
(TMAP), also known as cytoskeleton associated protein
2 (CKAP2), has been recently shown to be involved
in the assembly and maintenance of mitotic spindle
and also plays an essential role in maintaining the fidelity
of chromosome segregation during mitosis. We
have previously reported that TMAP is phosphorylated
at multiple residues specifically during mitosis, and
characterized the mechanism and functional importance
of phosphorylation at one of the mitosis-specific
phosphorylation residues (i.e., Thr-622). However,
the phosphorylation events at the remaining mitotic
phosphorylation sites of TMAP have not been fully
characterized in detail. Here, we report on generation
and characterization of phosphorylated Thr-578- and
phosphorylated Thr-596-specific antibodies. Using
the antibodies, we show that phosphorylation of TMAP
at Thr-578 and Thr-596 indeed occurs specifically during
mitosis. Immunofluorescent staining using the antibodies
shows that these residues become phosphorylated
starting at prophase and then become rapidly
dephosphorylated soon after initiation of anaphase.
Subtle differences in the kinetics of phosphorylation
between Thr-578 and Thr-596 imply that they
may be under different mechanisms of phosphorylation
during mitosis. Unlike the phosphorylation-
deficient mutant form for Thr-622, the mutant in
which both Thr-578 and Thr-596 had been mutated to
alanines did not induce significant delay in progression
of mitosis. These results show that the majority
of mitosis-specific phosphorylation of TMAP is
limited to pre-anaphase stages and suggest that the
multiple phosphorylation may not act in concert but
serve diverse functions.

참고문헌 (Reference)

1 Bae CD, "Up-regulation of cytoskeletalassociated protein 2 in primary human gastric adenocarcinomas" 129 : 621-630, 2003

2 Kyung Uk Hong, "Transient phosphorylation of tumor associated microtubule associated protein (TMAP)/cytoskeleton associated protein 2 (CKAP2) at Thr-596 during early phases of mitosis" 생화학분자생물학회 40 (40): 377-386, 2008

3 Clute P, "Temporal and spatial control of cyclin B1 destruction in metaphase" 1 : 82-87, 1999

4 Hong KU, "TMAP/CKAP2 is essential for proper chromosome segregation" 8 : 314-324, 2009a

5 Eichmuller S, "Serological detection of cutaneous T-cell lymphoma-associated antigens" 98 : 629-634, 2001

6 Blangy A, "Phosphorylation by p34cdc2 regulates spindle association of human Eg5, a kinesin-related motor essential for bipolar spindle formation in vivo" 83 : 1159-1169, 1995

7 Hendzel MJ, "Mitosis-specific phosphorylation of histone H3 initiates primarily within pericentromeric heterochromatin during G2 and spreads in an ordered fashion coincident with mitotic chromosome condensation" 106 : 348-360, 1997

8 Whitfield ML, "Identification of genes periodically expressed in the human cell cycle and their expression in tumors" 13 : 1977-2000, 2002

9 Maouche-Chretien L, "Identification of a novel cDNA, encoding a cytoskeletal associated protein, differentially expressed in diffuse large B cell lymphomas" 17 : 1245-1251, 1998

10 Jin Y, "Identification of a mouse cytoskeleton-associated protein, CKAP2, with microtubule-stabilizing properties" 95 : 815-821, 2004

11 Hong KU, "Functional importance of the anaphase-promoting complex-Cdh1-mediated degradation of TMAP/CKAP2 in regulation of spindle function and cytokinesis" 27 : 3667-3681, 2007

12 Mishima M, "Cell cycle regulation of central spindle assembly" 430 : 908-913, 2004

13 Hong KU, "Cdk1-cyclin B1-mediated phosphorylation of tumorassociated microtubule-associated protein/cytoskeleton associated protein 2 in mitosis" 284 : 16501-16512, 2009b

14 Ohsugi M, "Cdc2-mediated phosphorylation of Kid controls its distribution to spindle and chromosomes" 22 : 2091-2103, 2003

15 Jeon SM, "A cytoskeleton-associated protein, TMAP/CKAP2, is involved in the proliferation of human foreskin fibroblasts" 348 : 222-228, 2006