[Modulation of cellular transcriptional factors by human bocavirus 1 nonstructural protein NP1]

We studied the regulating effect of human bocavirus 1 (HBoV1) nonstructural protein NP1 on the activity of cellular transcription factors and the expression of inflammatory cytokine TNF-alpha and IL-6.

The modulation of NP1 was measured by the Dual Luciferase Reporter Assay System and the expression of cytokines TNF-alpha and IL-6 was detected by ELISA and Real-time PCR. The luciferase based mammalian two-hybrid system was used to analyze whether the function of NP1 protein aroused from oligomerization.

The transcription factors AP-1, STAT3 and STAT1 but not NF-kappaB were up-regulated by NP1, which was evidenced by approximately 2-3-fold increase of the luciferase activity compared to the control vector. Moreover, NP1 increased the TNF-alpha mRNA expression, but not contributed to cytokine IL-6 secretion. We also found that the self-interaction did not exist when NPI was solely expressed in 293T cells.

This study demonstrates for the first time that NP1 may play important roles in activation of transcription factors and up-regulation of inflammatory cytokines expression, suggesting that NP1 be involved in HBoV1 pathogenesis.