Centrobin/Nip2 expression in vivo suggests its involvement in cell proliferation.
Centrobin/Nip2 was initially identified as a centrosome protein that is critical for centrosome duplication and spindle assembly. In the present study, we determined the expression and subcellular localization of centrobin in selected mouse tissues. Immunoblot analysis revealed that the centrobin-specific band of 100 kDa was detected in all tissues tested but most abundantly in the thymus, spleen and testis. In the testis, centrobin was localized at the centrosomes of spermatocytes and early round spermatids, but no specific signal was detected in late round spermatids and elongated spermatids. Our results also revealed that the centrosome duplication occurs at interphase of the second meiotic division of the mouse male germ cells. The centrobin protein was more abundant in the mitotically active ovarian follicular cells and thymic cortex cells than in non-proliferating corpus luteal cells and thymic medullary cells. The expression pattern of centrobin suggests that the biological functions of centrobin are related to cell proliferation. Consistent with the proposal, we observed reduction of the centrobin levels when NIH3T3 became quiescent in the serum-starved culture conditions. However, a residual amount of centrobin was also detected at the centrosomes of the resting cells, suggesting its role for maintaining integrity of the centrosome, especially of the daughter centriole in the cells.
Lee
Jungmin
J
Department of Biological Sciences, Seoul National University, Seoul 151-747, Korea.
Kim
Sunmi
S
Jeong
Yeontae
Y
Rhee
Kunsoo
K
D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D049109:Cell Proliferation; D018385:Centrosome / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008970:Molecular Weight; D041681:NIH 3T3 Cells; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism; D013087:Spermatids / Q000166:cytology / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology / Q000378:metabolism; D013154:Spleen / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D013950:Thymus Gland / Q000378:metabolism*
D018797:Cell Cycle Proteins; C541774:Cntrob protein, mouse