Human papillomavirus type 16 E5 protein affects cell-cell communication in an epithelial cell line

Abstract

The human papillomavirus type 16 (HPV16) E5 protein is considered to have weak oncogenic properties, and its function in infected human keratinocytes is unknown. HPV16 E5 protein has been found to localize to the Golgi apparatus and the plasma membrane. To analyze the effect of E5 on plasma membrane properties, cells from the human keratinocyte cell line HaCaT were transfected with the HPV16 E5 open reading frame under the control of an inducible promoter. The gap junction-mediated cell-cell communication of E5-and vectortransfected cells was analyzed by microinjection of Lucifer yellow to measure dye coupling of the cells. A strong impairment of dye transfer in E5-transfected cells but not in vector-transfected cells was observed, with more than 80% dye transfer inhibition 40 min after injection. This impairment correlated with dephosphorylation of connexin 43, the major gap junctional protein in HaCaT cells. Furthermore, the dye coupling inhibition was not the result of differentiation of the E5-expressing cells, since no overexpression of cytokeratin 1 or filaggrin, markers of HaCaT cell differentiation, could be observed. These results therefore strongly suggest a correlation between expression of the HPV16 E5 open reading frame, impairment of gap junction-mediated dye coupling, and dephosphorylation of connexin 43.

Glial connexins and gap junctions in CNS inflammation and disease

“…However, some viruses and viral proteins are capable of inhibiting GJC (Ennaji et al. 1995; Oelze et al. 1995; Knabb et al.…”

Connexin43 phosphorylation state and intercellular communication in cultured astrocytes following hypoxia and protein phosphatase inhibition

“…1998) and its dephosphorylation is correlated with either decreased GJIC (Godwin et al . 1993; Oelze et al . 1995) or increased channel conductance (Moreno et al .…”

Mind the gap

“…Firstly, it has been known for some years that infection with viruses can interfere with the function of gap junctions. This was first shown for avian sarcoma virus, then for the E5 protein of HPV16 and then for HSV2 [5][6][7].…”