Hexamethylene bisacetamide can convert nonpermissive human cells to a permissive state for expressing the major immediate-early genes of human cytomegalovirus by up-regulating NF-kappaB activity.
Expression of the major immediate-early (MIE) genes of human cytomegalovirus (HCMV) in the human thyroid papillary carcinoma cell line TPC-1 is repressed at the transcriptional level. However, treatment of these cells with hexamethylene bisacetamide (HMBA), a chemical inducer of differentiation, for 12 to 24 h before infection enabled the cells to support IE1 and IE2 gene expression and consequently HCMV replication. In HMBA-treated cells the transcription factor NF-kappaB was induced and the MIE promoter (MIEP) was activated. The presence of a NF-kappaB inhibitory peptide SN-50 or expression of a dominant negative IkappaBalpha protein during the HMBA pretreatment period efficiently prevented the HMBA-induced MIEP activation and MIE protein synthesis. Moreover, introduction of mutations into the NF-kappaB binding sites in the MIEP in a plasmid expressing the IE1 protein diminished its ability to express the protein in HMBA-treated cells. Therefore, the NF-kappaB activity previously induced in HMBA-treated cells and the NF-kappaB sites in the MIEP were shown to be essential for HCMV to respond to HMBA action and to express the MIE genes. Investigation of the mechanisms by which HMBA activates NF-kappaB revealed that degradation of IkappaBalpha and translocation of the phosphorylated NF-kappaB p65 subunit to the nucleus, both of which are known to be critical steps in NF-kappaB activation, are stimulated in the HMBA-treated cells. These results indicate that treatment of nonpermissive TPC-1 cells with HMBA induces MIE gene permissiveness by up-regulating NF-kappaB activity.
Kitagawa
Ryoko
R
Department of Clinical Laboratory Science, School of Health Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kodatsuno, Ishikawa, Japan.
Takahashi
Yusuke
Y
Takahashi
Mitsuko
M
Imazu
Hiromi
H
Yasuda
Makoto
M
Sadanari
Hidetaka
H
Tanaka
Junji
J
D000081:Acetamides / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003587:Cytomegalovirus / Q000502:physiology*; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis*; D007155:Immunologic Factors / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D015534:Trans-Activators / Q000096:biosynthesis*; D014779:Virus Replication
D000081:Acetamides; C088645:IE1 protein, cytomegalovirus; C069186:IE2 protein, Cytomegalovirus; D017874:Immediate-Early Proteins; D007155:Immunologic Factors; D016328:NF-kappa B; D015534:Trans-Activators; C014026:hexamethylene bisacetamide