Nuclear Factor Kappa B Promotes Ferritin Heavy Chain Expression in Bombyx mori in Response to B. mori Nucleopolyhedrovirus Infection

Ferritin heavy chain (FerHCH) is a major component of ferritin and plays an important role in maintaining iron homeostasis and redox equilibrium. Our previous studies have demonstrated that the Bombyx mori ferritin heavy chain homolog (BmFerHCH) could respond to B. mori nucleopolyhedrovirus (BmNPV) infection. However, the mechanism by which BmNPV regulates the expression of BmFerHCH remains unclear. In this study, BmFerHCH increased after BmNPV infection and BmNPV infection enhanced nuclear factor kappa B (NF-kappa B) activity in BmN cells. An NF-kappa B inhibitor (PDTC) reduced the expression of the virus-induced BmFerHCH in BmN cells, and overexpression of BmRelish (NF-kappa B) increased the expression of virus-induced BmFerHCH in BmN cells. Furthermore, BmNPV infection enhanced BmFerHCH promoter activity. The potential NF-kappa B cis-regulatory elements (CREs) in the BmFerHCH promoter were screened by using the JASPAR CORE database, and two effective NF-kappa B CREs were identified using a dual luciferase reporting system and electrophoretic mobility shift assay (EMSA). BmRelish (NF-kappa B) bound to NF-kappa B CREs and promoted the transcription of BmFerHCH. Taken together, BmNPV promotes activation of BmRelish (NF-kappa B), and activated BmRelish (NF-kappa B) binds to NF-kappa B CREs of BmFerHCH promoter to enhance BmFerHCH expression. Our study provides a foundation for future research on the function of BmFerHCH in BmNPV infection.