FIN13, a novel growth factor-inducible serine-threonine phosphatase which can inhibit cell cycle progression.

We have identified a novel type 2C serine-threonine phosphatase, FIN13, whose expression is induced by fibroblast growth factor 4 and serum in late G1 phase. The protein encoded by FIN13 cDNA includes N- and C-terminal domains with significant homologies to type 2C phosphatases, a domain homologous to collagen, and an acidic domain. FIN13 expression predominates in proliferating tissues.

Variable transduction efficiency of murine leukemia retroviral vector on mammalian cells: role of cellular glycosylation.

To elucidate the cellular tropism of Moloney murine leukemia virus (MuLV), we have studied the transduction efficiency of a recombinant MuLV vector carrying the beta-galactosidase reporter gene on a variety of rodent cells. Under optimal conditions for in vitro cell transduction, primary cultures of adult rat fibroblasts derived from various organs were very poorly transduced by the ecotropic MuLV vector (0.02-0.

A simple procedure to determine the biological titer of recombinant retroviral vectors.

Retroviral vectors are widely used to deliver genetic material to live cells both in experimental and clinical settings. The ability of these vectors to transduce target cells is an important aspect of their clinical applicability and one of the factors determining their transduction efficiency is vector functional titer. Current methods for titrating retroviral vectors involve measuring the number of target cells in culture transduced by a given volume of vector solution.

Cellular aging is a critical determinant of primary cell resistance to v-src transformation.

Primary cell cultures are in general resistant to the transforming effect of a single oncogene, a finding considered consistent with the multistage theory of carcinogenesis. In the present studies, we examined whether cellular age, differentiation stage, and/or tissue origin of primary cells plays a role in determining their response to v-src transformation. To study the role of cellular age, rat mammary fibroblasts were isolated from a 50-day-old female rat and infected with a recombinant retrovirus carrying a v-src gene after 2, 7, 14, 21, and 28 days of continuous growth.

Suppression of v-Src transformation in primary rat embryo fibroblasts.

To understand the mechanism for resistance of primary cultures of rat embryo fibroblasts (REFs) to oncogene-induced transformation, we studied the transforming ability of a recombinant retrovirus, ZSV, containing v-src and neo genes in REFs and in the rat cell line F2408. The susceptibility of REFs to p60v-src transformation was markedly reduced when compared with that of F2408 cells, despite high levels of expression of functional p60v-src tyrosine kinase in the two systems. In hybrid cells obtained by somatic cell fusion between F2408 cells transformed by v-src and uninfected REFs, the transformed phenotype was suppressed despite persistent expression of p60v-src tyrosine kinase.