The Regulation of Cytoskeletal Elements in Differentiating Human Neuroblastoma and Rat Pheochromocytoma PC-12 Cells

Abstract

The appearance of neurofibrillary tangles (NFT) is one of the major structural changes that occur in neurons during Alzheimer’s disease. They are composed almost entirely of paired helical filaments (PHF), intermixed with some straight filaments. Immunocytochemical studies of NFT have revealed that they have antigenic determinants in common with noncytoskeletal elements, neurofilaments (Perry et al., 1984) and microtubule associated tau proteins (Brion et al., 1984; Wood et al., 1986; Kosik et al., 1986, 1988a,b; Nukina and Ihara, 1986; Goedert et al., 1988), while the presence of microtubule-associated protein 2 (MAP2) in NFT has yet to be established (Rosemblatt et al., 1989). Both MAP2 and tau proteins have been shown to bind to peptides derived from the carboxyl-terminal region of β-tubulin. In addition, tau proteins but not MAP2 display a strong interaction with a peptide derived from the amino-terminal domain of α-tubulin (Littauer et al., 1986). Recently, it was found that tau proteins contain three 18 amino acid repeated sequences which appear to be involved in the binding to tubulin (Lee et al., 1988; Goedert et al., 1988, 1989; Lee et al., 1989; Kosik, 1989). It was also observed that MAP2 shares the tau repeated regions (Lewis et al., 1988). However, this is not the case for a recently cloned tubulin binding protein designated neuraxin, which does not contain the tau and MAP2 repeated sequences. Neuraxin was found to be immunologically related to MAPS and is perhaps identical to this high molecular weight MAP (Rienitz et al., 1989).