Positive and negative regulation of chicken anemia virus transcription.
Chicken anemia virus (CAV) is a small circular single-stranded DNA virus with a single promoter-enhancer region containing four consensus cyclic AMP response element sequences (AGCTCA), which are similar to the estrogen response element (ERE) consensus half-sites (A)GGTCA. These sequences are arranged as direct repeats, an arrangement that can be recognized by members of the nuclear receptor superfamily. Transient-transfection assays which use a short CAV promoter construct that ended at the transcription start site and drive expression of enhanced green fluorescent protein (EGFP) showed high basal activity in DF-1, LMH, LMH/2A, and primary theca and granulosa cells. The estrogen receptor-enhanced cell line, LMH/2A, had significantly greater expression than LMH cells, and this expression was significantly increased with estrogen treatment. A long promoter construct which included GGTCA-like sequences downstream of the first CAV protein translation start site was found to have significantly less EGFP expression in DF-1 cells than the short promoter, which was largely due to decreased RNA transcription. DNA-protein binding assays indicated that proteins recognizing a consensus ERE palindrome also bind GGTCA-like sequences in the CAV promoter. Estrogen receptor and other members of the nuclear receptor superfamily may provide a mechanism to regulate CAV activity in situations of low virus copy number.
Miller
Myrna M
MM
Unit of Avian Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Jarosinski
Keith W
KW
Schat
Karel A
KA
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D017727:Chicken anemia virus / Q000235:genetics*; D002645:Chickens; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005260:Female; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D006107:Granulosa Cells / Q000378:metabolism / Q000821:virology; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000378:metabolism; D013799:Theca Cells / Q000378:metabolism / Q000821:virology; D014158:Transcription, Genetic; D014162:Transfection
D004279:DNA, Viral; D011960:Receptors, Estrogen