Nuclear localization and dynamic properties of the Marek's disease virus oncogene products Meq and Meq/vIL8.
Marek's disease virus (MDV) is an avian herpesvirus that causes T-cell lymphomas and immune suppression in susceptible chickens. At least one gene product, MDV Eco Q-encoded protein (Meq), is essential for the oncogenicity of MDV. Alternative splicing permits the meq gene to give rise to two major transcripts encoding proteins designated Meq and Meq/vIL8. Meq is a basic leucine zipper protein capable of modulating transcription. The Meq/vIL8 protein retains a modified leucine zipper, along with the mature receptor-binding portion of vIL8, but lacks the domain of Meq responsible for transcriptional modulation. In this report, we describe studies using fusions between either Meq or Meq/vIL8 and fluorescent proteins to characterize the distribution and properties of these products in chicken embryo fibroblasts (CEFs). Meq and Meq/vIL8 both localized to the nucleoplasm, nucleoli, and Cajal bodies of transfected cells. Similar distributions were found for fluorescent fusion proteins and native Meq or Meq/vIL8. Fluorescence recovery after photobleaching and photoactivatable green fluorescent protein revealed that Meq exhibited mobility properties similar to those of other transcription factors, while Meq/vIL8 was far less mobile. In addition, fluorescence resonance energy transfer studies indicated the formation of Meq/vIL8 homodimers in CEFs. Time lapse studies revealed the coordinated elimination of a portion of Meq and Meq/vIL8 from the nucleus. Our data provide new insight regarding the dynamic cellular properties of two forms of a herpesvirus-encoded oncoprotein and suggest that these forms may have fundamentally different functions in MDV-infected cells.
Anobile
Jonathan M
JM
Department of Animal and Food Sciences, University of Delaware, Newark, DE 19717, USA.
Arumugaswami
Vaithilingaraja
V
Downs
Danielle
D
Czymmek
Kirk
K
Parcells
Mark
M
Schmidt
Carl J
CJ
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000821:virology; D002478:Cells, Cultured; D002642:Chick Embryo; D004279:DNA, Viral / Q000235:genetics; D031541:Fluorescence Resonance Energy Transfer; D005814:Genes, Viral; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008381:Herpesvirus 2, Gallid / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D009856:Oncogene Proteins, Viral / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D004279:DNA, Viral; C100369:Eco-Q protein, Gallid herpesvirus 2; D009856:Oncogene Proteins, Viral; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins