cis-acting elements that mediate the negative regulation of Moloney murine leukemia virus in mouse early embryos

Abstract

We have addressed the question of the nature of Moloney murine leukemia virus (MoMuLV) repression in mouse embryos by assaying for the transient expression of MoMuLV-derived constructs microinjected into early cleavage embryos. We show that the same cis-acting DNA sequences responsible for the block in MoMuLV expression in embryonal carcinoma cell lines operate in early embryos: (i) the MoMuLV long terminal repeat is nonfunctional, and (ii) the ؉147 to ؉163 repressor binding site, or negative regulatory element, negatively regulates the expression from an active promoter.

Imaging Cells in the Developing Nervous System with Retrovirus Expressing Modified Green Fluorescent Protein

“…We introduced additional transcriptional elements into the LZRS vector to augment the level of reporter gene expression, as the retrovirus long-terminal repeat (LTR) transcriptional element appeared to be less effective in some cells (e.g., pyramidal neurons) than in others (e.g., glia) (Weimann and McConnell, unpublished observations). This is consistent with observations by others of the variability in virus LTR activity in different cell types (32,44).…”

TRIM28 Mediates Primer Binding Site-Targeted Silencing of Murine Leukemia Virus in Embryonic Cells

“…RBS-mediated repression of M-MLV is not limited to mouse ES and EC lines but has been observed in early mouse embryos as well as primary stromal cells from mouse bone marrow (Haas et al, 2003;Vernet and Cebrian, 1996). Most intriguingly, it has also been observed to occur in a human hematopoietic cell line and primary human hematopoietic cells isolated from umbilical cord blood (Haas et al, 2003).…”

Silencing of retroviral vector transduced LacZ reporter gene by frameshift mutation

“…(1) methylation of proviral DNA sequences (Challita and Kohn, 1994;Challita et al,1995;Hejnar et al, 2001); (2) noncoding proviral sequences acting as cis-silencing elements (Osborne et al, 1999;Vernet and Cebrian, 1996); (3) chromatin structure and scaffold attachment region in vicinity of integration site, in particular (Agarwal et al, 1998;Lorincz et al, 2000).…”