Interactions Between the Major Filamentous Components of the Cytoskeleton

Abstract

Implicit in current concepts of the organization of the cytoskeleton and the cytoplasmic matrix is the idea that the networks of the major filament systems are interconnected and interacting. Cooperation among the components of the cytoskeleton is clearly involved in many aspects of cell behavior, cellular and subcellular motility, and morphogenesis. Interactions, or their purposeful absence, may be viewed as a key aspect of the organization of the cytoskeleton. Surprisingly, however, compared to the staggering amount of morphological and biochemical information on the individual filament systems and their associated proteins, the development, maintenance, and control of interfilament interactions is relatively poorly understood. Some motile activities may require only interactions between fibers of the same type. For example, the movement of the axostyle of Saccinobaculus is exclusively microtubule-based and crossbridge-mediated, and extension of the acrosomal process of Thyone or Limulus sperm is dependent solely on actin filaments. Other events may depend on a cooperative interaction between different filaments. Linking the networks of different fiber classes has the advantage of extending the range of their properties and helping to construct more powerful and versatile “superstructures”. Thus, interactions between microtubular and actin-based networks could combine the flexural rigidity of the former with the potential for rapid changes in consistency ot the latter.