Tubulin isoforms: Involvement in the formation of stable microtubule arrays during neural differentiation.

Tubulin isoforms: Involvement in the formation of stable microtubule arrays during neural differentiation.

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Title: Tubulin isoforms: Involvement in the formation of stable microtubule arrays during neural differentiation.
Author: Falconer, Marcia M.
Abstract: In this thesis, commitment is defined as the events that constrain a cell (and its progeny) to follow a particular developmental path, while differentiation is narrowly considered to involve events that result in attainment of a specific cell shape and does not consider functional or other characteristics. Therefore the P19 culture system was used to investigate the involvement of alpha and beta tubulin isoforms in formation of the stable microtubule (MT) array during neural differentiation. Two posttranslational modifications of alpha tubulin, acetylation and detryosination, are associated with stable MT populations including those of neural processes. Uncommitted embryonal carcinoma (EC) cells have minimal arrays of acetylated and detyrosinated MTs. Following neural induction with retinoic acid (RA), indirect immunofluorescence microscopy shows that the first MT modifications occur during commitment, before any morphological change is observed. RA-induced cells initially polymerize a temporarily enlarged population of MTs. Included in this population is a new array of acetylated MTs arranged in a bundle of parallel MTs. This bundle is colchicine stable and only MT-associated protein (MAP) 1B is detected in association with this bundle. In cells which proceed to differentiate directly after commitment, this bundle apparently extends to form a neural process. MAP2C is first detected at about the time of neurite extension but is not limited to dendritic processes. During a brief period early in differentiation, indirect immunofluorescence staining shows the colocalization of colchicine stable acetylated MTs, vimentin and MAP2C. This thesis shows that acetylated MTs, MAP2 and vimentin intermediate filaments are arranged in an interdependent cytoskeletal array. This array may serve to stabilize processes in neural stem cells thereby allowing the stem cell to receive signals which influence the final decision to differentiate into neurons or glia. Finally, the involvement of beta tubulin isotypes in formation of the stable MT array during neural differentiation in P19 cells is analyzed by indirect immunofluorescence staining and by immunoblotting. (Abstract shortened by UMI.)
Date: 1990
URI: http://hdl.handle.net/10393/5558

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