Dynamics of γ-tubulin cytoskeleton in HL-60 leukemia cells undergoing             differentiation and apoptosis by all-trans retinoic acid.
Microtubules are important components of the cell cytoskeleton, participating             in protein localization and cell signaling. The capacity of leukemia cells to             re-organize their microtubules is considered an integral part of differentiation             in these cells in order to become mature granulocytes through treatment with all-trans             retinoic acid (ATRA), an established drug for treating acute promyelocytic leukemia.             In this study we examined γ-, α- and acetylated-α-tubulin content, their patterns             of distribution in the cytoplasm, and the potency of centrosomes in re-organizing             microtubules in different stages of ATRA-induced differentiation and apoptosis             of the HL-60 cell line. The γ-tubulin content was dramatically increased following             differentiation of HL-60 cells, and was then decreased after apoptosis. We also             found that γ-tubulin had a diffuse, cytoplasmic pattern following apoptosis compared             to the focal, centrosomal accumulation of γ-tubulin in differentiated cells. Differentiated             cells had the ability to re-organize their microtubule network following nocodazole             challenge testing, whereas undifferentiated cells did not show a similar ability.             α-tubulin was more regularly organized in differentiated cells, and did not reveal             any specific pattern of polymerization in apoptotic cells. Acetylated-α-tubulin             generally followed the same organization patterns after differentiation, as that             which occurred for α-tubulin. Our data is suggestive of a centrosomal and organized             nucleation pattern of microtubules in HL-60 cells following differentiation, possibly             mediated through up-regulation of γ-tubulin.
Department of Clinical Biochemistry, Tehran University of Medical                     Sciences, Tehran, Iran.
Ahmad
A
Shariftabrizi
Shahin
S
Ahmadian
Yaghub
Y
Pazhang
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002454:Cell Differentiation / Q000187:drug effects; D003599:Cytoskeleton / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia; D014212:Tretinoin / Q000494:pharmacology*; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation
D000970:Antineoplastic Agents; D014404:Tubulin; D014212:Tretinoin