Roles of actin-binding proteins associated with actin filament polymerization/depolymerization in the differentiation of human Wharton's jelly cells into adipocytes.
| Autor: | Kang-Wei Peng, 彭康維 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Wharton''s jelly cells (WJCs) are the mesenchymal stem cells derived from umbilical cord, and can be expanded in culture and induced to differentiate into multiple cell types. The dynamic events in cell proliferation and differentiation of WJCs require extensive remodeling of actin filaments by the action of a multitude of actin-binding proteins (ABPs). However, information is limited on how the growth-related signal is conveyed to trigger ABPs to act in the regulation of actin filament organization in WJCs. In this study, human umbilical CD105-positive WJCs were cultured to investigate the functional roles of actin-binding proteins in adipogenic differentiation. Firstly, at the early stage (Day 4) of WJCs induced adipogenesis β-actin was found to be polymerized into F-actin as formed the stress fibers, in concomitant with the decreased amount of G-actin. At the later stage of differentiation (Day 14-21), the stress fibers disappeared and the dissociated β-actin was located at the periphery of differentiated-adipocytes. Concomitantly, microtubule cytoskeleton became evidently found to be distributed within the adipogenic cells. In addition, we found functional changes in gene expression of several ABPs (i.e. formin-2, tropomyosins, and gelsolin) were associated with morphological transformation in WJCs differentiation into adipocytes. To further understand the molecular control of ABPs on actin filament organization in WJC-induced adipogenesis, specific siRNAs for several ABPs (i.e. formin-2, tropomyosin-1, caldesmon, and profilin) and gelsolin-constructed vector were introduced into WJCs. The transformed WJCs were then studied for adipogenic differentiation. Adipogenic differentiation was indicated by oil red O staining for lipid synthesis, and by using real-time qPCR to quantify the mRNA expression of PPAR-γ2, adipophilin, FAS, and leptin. Results obtained indicated that gene silence of these ABPs would promote the gene expression of PPAR-γ2、adipophilin、FAS and leptin in the adipogenesis of WJCs. However, gelsolin overexpression would inhibit the gene expression of PPAR-γ2, and that might cause to decrease the gene expression of adipophilin and FAS at the later process of adipogenesis. Apparently, reduction of F-actin formation and stability would promote WJCs differentiation into adipocytes. Severing F-actin by gelsolin overexpression would reduce the capability of WJCs to be induced into adipogenesis. Taken together, results found in this thesis indicated that the gene expression of ABPs modulating the dynamics of actin filament formation would affect the capability of WJCs to be induced into adipogenesis. Moreover, the F-action polymerization and its generated tension might play crucial roles in the process of WJCs differentiation into adipocytes |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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