Novel Sp Family-like Transcription Factors Are Present in Adult Insect Cells and Are Involved in Transcription from the Polyhedrin Gene Initiator Promoter

Abstract

We earlier documented the involvement of a cellular factor, polyhedrin (polh) promoter-binding protein, in transcription from the Autographa californica nuclear polyhedrosis virus polh gene promoter. Sequences upstream of the polh promoter were found to influence polh promoter-driven transcription. Analysis of one such region, which could partially compensate for the mutated polh promoter and also activate transcription from the wild-type promoter, revealed a sequence (AcSp) containing a CACCC motif and a loose GC box resembling the binding motifs of the transcription factor Sp1. AcSp and the consensus Sp1 sequence (cSp) specifically bound factor(s) in HeLa and Spodoptera frugiperda (Sf9) insect cell nuclear extracts to generate identical binding patterns, indicating the similar nature of the factor(s) interacting with these sequences. The AcSp and cSp oligonucleotides enhanced in vivo expression of a polh promoter-driven luciferase gene. In vivo mopping of these factor(s) significantly reduced transcription from the polh promoter. Recombinant viruses carrying deletions in the upstream AcSp sequence confirmed the requirement of these factor(s) in polh promoter-driven transcription in the viral context. We demonstrate for the first time DNA-protein interactions involving novel members of the Sp family of proteins in adult insect cells and their involvement in transcription from the polh promoter.

An inducible system for highly efficient production of recombinant adeno-associated virus (rAAV) vectors in insect Sf9 cells

“…It is unlikely that IE-1 directly binds to P19 because we were unable to identify the canonical IE-1 binding element within the tested P19 fragment. More likely, hr-bound IE-1 interacts with Sf9 host cell factors such as SP1 described recently in Sf9 cells, a transcription factor that was also shown to be capable of binding to the canonical SP1-response element from mammalian cells (23,24). Incidentally, 2 SP1-binding sites (SP1-130 and SP1-50, Fig.…”

Characterization of Emerging European-Like Porcine Reproductive and Respiratory Syndrome Virus Isolates in the United States

“…2). CACCC stretches have been shown to be important in binding to host cell transcription factors important in growth control, apoptosis, and angiogenesis (4,44) and are also utilized for double-stranded DNA virus and retroviral transcription (38,44,56). Strict maintenance of these CACCC domains was seen in all but a few known PRRSV leader sequences (Fig.…”

The Homologous Region Sequence (hr1) of Autographa californica Multinucleocapsid Polyhedrosis Virus Can Enhance Transcription from Non-baculoviral Promoters in Mammalian Cells

“…The dual promoter reporter recombinant virus used here provides an ideal tool to study baculovirus-mediated gene delivery into mammalian cells. The baculovirus polyhedrin gene promoter requires insect cell host factors (27)(28)(29)(30)(31)(32)(33) for its activation and therefore cannot function in a non-insect environment. The transcription ability of the constitutive hsp70 promoter, however, is relatively uniform in different cell lines, except that HepG2 cells show higher levels of reporter activity, consistent with earlier reports that these cells are able to take up baculoviruses more efficiently than other cell lines.…”