Gerisch G, Albrecht R, De Hostos E, Wallraff E, Heizer C, Kreitmeier M, Müller-Taubenberger A
Max-Planck-Institut für Biochemie, Martinsried, Germany.
Symp Soc Exp Biol. 1993;47:297-315.
The amoeboid cells of Dictyostelium discoideum are amenable to a combined biochemical, genetic, and cell biological approach that can be focussed to the study of molecular interactions underlying the chemotactic responses of eukaryotic cells. In these responses the actin-based motility system is involved. This system is characterised in Dictyostelium cells by a large number and variety of regulatory proteins. Most of these proteins belong to families that are likewise represented in the cytoskeletons of higher eukaryotes including man. Elimination of some of these actin-binding proteins by chemical mutagenesis or gene disruption is being used to simplify the system by separating essential proteins from non-essential ones. These studies are complemented by the selection and analysis of mutants with altered motility or chemotaxis. Quantitative motion analysis of mutants is employed to establish a link between defects on the molecular level and alterations in cell behaviour. Dictyostelium cells respond to local stimulation by extending a newly formed leading edge towards a chemoattractant within less than a minute, thereby changing their polarity. The leading edge is formed by the recruitment of soluble proteins from the cytoplasm and their coassembly with actin into a complicated framework of microfilaments. Patterns of assembly are shown in this report for two proteins, the talin-like filopodin and coronin. Elucidation of the control mechanisms of this ordered assembly will provide the key for understanding the molecular processes responsible for a chemotactic response.
盘基网柄菌的变形细胞适合采用生物化学、遗传学和细胞生物学相结合的方法进行研究，这种方法可聚焦于真核细胞趋化反应背后分子相互作用的研究。在这些反应中，基于肌动蛋白的运动系统发挥着作用。在盘基网柄菌细胞中，该系统的特点是有大量且多样的调节蛋白。这些蛋白大多属于在包括人类在内的高等真核细胞骨架中也有代表的家族。通过化学诱变或基因敲除去除其中一些肌动蛋白结合蛋白，旨在通过区分必需蛋白和非必需蛋白来简化该系统。对运动性或趋化性改变的突变体进行筛选和分析，对这些研究起到了补充作用。对突变体进行定量运动分析，以建立分子水平缺陷与细胞行为改变之间的联系。盘基网柄菌细胞在不到一分钟的时间内，通过向趋化因子延伸新形成的前缘来响应局部刺激，从而改变其极性。前缘是由从细胞质中募集可溶性蛋白并使其与肌动蛋白共同组装成复杂的微丝框架形成的。本报告展示了两种蛋白——类踝蛋白丝足蛋白和冠蛋白的组装模式。阐明这种有序组装的控制机制将为理解趋化反应背后的分子过程提供关键线索。
