Intermediate-size Filaments: Changes in Synthesis and Distribution in Cells of the Myogenic and Neurogenic Lineages

Abstract

The number of intermediate-size filaments, their topographical distribution, and relationships with other cell organelles vary among cell types. These 10-nm filaments provide an unusual instance of an organelle that possesses a relatively constant morphology, although its constituent proteins are altered or replaced during differentiation. In this paper we focus on their qualitative and quantitative changes during myogenesis and neurogenesis. We stress the switch between the types of 10-nm filaments synthesized in precursor presumptive myoblasts and neuroblasts and those synthesized in their daughters, the postmitotic myoblasts and neuroblasts. Changes in the behavior of the 10-nm filaments are discussed in response to (1) arabinosyl-cytosine (Ara-C), (2) the cocarcinogen 12-O-tetradecanoylphorbol-13-acetate (TPA), (3) transformation with temperature-sensitive Rous sarcoma virus (RSV), and (4) cell density. We also report that the effect of Colcemid in inducing aggregation of 10-nm filaments into immense cables is blocked by taxol, a microtubule-stabilizing drug.