TNF receptor independent activation of the cytomegalovirus major immediate early enhancer in response to transplantation.
BACKGROUND
Reactivation of latent human cytomegalovirus (HCMV) infection is a significant risk factor for long term allograft dysfunction. The molecular pathways involved in reactivation of latent virus have not been identified. Previous studies suggested that tumor necrosis factor (TNF) -mediated activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-kappa B) leading to transcriptional reactivation of viral immediate early (ie) gene expression might be important in transplant-associated viral reactivation. CMV IE gene expression is controlled by the major immediate early promoter/enhancer (MIEP). Because HCMV does not infect mice, transgenic mice carrying a beta-galactosidase reporter gene under the control of the HCMV immediate early enhancer (MIEP-lacZ mice) are a valuable model for studying regulation of CMV IE gene expression in vivo. We have used TNF receptor-deficient MIEP-lacZ (MIEP-lacZ TNFR DKO) mice to study the requirement for TNF in transplant-induced activation of the MIEP.


METHODS
Allogenic kidney transplants were performed using MIEP-lacZ TNFR DKO or MIEP-lacZ TNFRwild-type donor mice. beta-Galactosidase activity was used to measure activation of the IE enhancer in donor kidneys at 2 days of posttransplantation and in contralateral controls. Transcription factor activation was assayed with Trans-Am kits.


RESULTS
Allogenic and syngenic transplantation activate the HCMV IE enhancer to the same extent. TNF receptor signaling was not required for activation of the MIEP. TNF receptor signaling was required for activation of NF-kappaB, but not for activation of activating protein 1 family members junD and Fra-1 in day 2 allografts.


CONCLUSIONS
TNF-independent pathways can activate the enhancer in response to allogenic transplantation. This may occur through activation of MIEP-binding transcription factors other than NF-kappa B.
Zhang
Zheng
Z
Transplant Division, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Kim
Soo Jung
SJ
Varghese
Thomas
T
Thomas
Gail
G
Hummel
Mary
M
Abecassis
Michael
M
D000818:Animals; D003587:Cytomegalovirus / Q000235:genetics* / Q000502:physiology; D004742:Enhancer Elements, Genetic; D007668:Kidney / Q000201:enzymology; D016030:Kidney Transplantation / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000502:physiology; D018124:Receptors, Tumor Necrosis Factor / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000502:physiology*; D015398:Signal Transduction; D014184:Transplantation, Homologous; D014775:Virus Activation / Q000502:physiology*; D001616:beta-Galactosidase / Q000378:metabolism
D016328:NF-kappa B; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D001616:beta-Galactosidase