title: Involvement of Fractin in TGF-beta-induced apoptosis in oligodendroglial progenitor cells.
abstract: Transforming growth factor-beta (TGF-beta) induces apoptotic cell death during the development of the nervous system. We recently identified that TGF-beta induced apoptosis in oligodendroglial progenitor cells (primary cells as well as oligodendroglial cell line OLI-neu) is characterized by down-regulation of Bcl-xl. In this report, we now focused on mechanisms that mediate TGF-beta dependent Bcl-xl down-regulation in oligodendroglial cells. We showed that the caspase-specific cleavage product Fractin is produced in oligodendroglial cells during TGF-beta-mediated apoptosis, which represents an early event of the cascade. Cleavage of actin into Fractin was dependent on functional actin and caspases, and occurred simultaneously with a Fractin-Bcl-xl-interaction. This Fractin-Bcl-xl interaction indicated a connection between Bcl-xl down-regulation and Fractin appearance, since Bcl-xl regulation was also dependent on caspases and functional actin, and an overexpression of Fractin induced a Bcl-xl protein down-regulation. Further analysis of Fractin-Bcl-xl interaction in other culture systems confirmed these data. In conclusion, we show that Fractin is not only an apoptotic marker, but has indeed a functional role in apoptotic signaling in oligodendrocytes.
authors.affiliation: Center of Anatomy, Department of Neuroanatomy, Georg-August-University, Goettingen, Germany.
authors.forename: Ramona
authors.initials: R
authors.lastname: Schulz
authors.forename: Tanja
authors.initials: T
authors.lastname: Vogel
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Mashima
authors.forename: Takashi
authors.initials: T
authors.lastname: Tsuruo
authors.forename: Kerstin
authors.initials: K
authors.lastname: Krieglstein