Reprogramming of connexin landscape fosters fast gap junction intercellular communication in human papillomavirus-infected epithelia

Abstract

Human papillomaviruses (HPVs) are highly prevalent commensal viruses that require epithelial stratification to complete their replicative cycle. While HPV infections are most often asymptomatic, certain HPV types can cause lesions, that are usually benign. In rare cases, these infections may progress to non-replicative viral cycles associated with high HPV oncogene expression promoting cell transformation, and eventually cancer when not cleared by host responses. While the consequences of HPV-induced transformation on keratinocytes have been extensively explored, the impact of viral replication on epithelial homeostasis remains largely unexplored. Gap junction intercellular communication (GJIC) is critical for stratified epithelium integrity and function. This process is ensured by a family of proteins named connexins (Cxs), including 8 isoforms that are expressed in stratified squamous epithelia. GJIC was reported to be impaired in HPV-transformed cells, which was attributed to the decreased expression of the Cx43 isoform. However, it remains unknown whether and how HPV replication might impact on the expression of Cx isoforms and GJIC in stratified squamous epithelia. To address this question, we have used 3D-epithelial cell cultures (3D-EpCs), the only model supporting the productive HPV life cycle. We report a transcriptional downregulation of most epithelial Cx isoforms except Cx45 in HPV-replicating epithelia. At the protein level, HPV replication results in a reduction of Cx43 expression while that of Cx45 increases and displays a topological shift toward the cell membrane. To quantify GJIC, we pioneered quantitative gap-fluorescence loss in photobleaching (FLIP) assay in 3D-EpCs, which allowed us to show that the reprogramming of Cx landscape in response to HPV replication translates into accelerated GJIC in living epithelia. Supporting the pathophysiological relevance of our observations, the HPV-associated Cx43 and Cx45 expression pattern was confirmed in human cervical biopsies harboring HPV. In conclusion, the reprogramming of Cx expression and distribution in HPV-replicating epithelia fosters accelerated GJIC, which may participate in epithelial homeostasis and host immunosurveillance.

Acute Adenoviral Infection Elicits an Arrhythmogenic Substrate Prior to Myocarditis

“…99 Additionally, a recent study found that in a complex epithelial model, human papillomavirus infection reduced Cx43 protein and increased both protein expression of Cx45 and localization at the cell membrane, and this resulted in an increase of GJIC. 100 While changes to connexin phosphorylation caused by acute viral infection are most commonly studied in the context of cancer biology, clearly such changes to gap junction phosphorylation will also impact cardiomyocyte coupling across a variety of viral infections.…”

Diversity of Intercellular Communication Modes: A Cancer Biology Perspective

“…Last but not least, rather than using GJs as a mode of transfer, many oncogenic viruses including human papillomavirus (HPV), simian virus 40 (SV40) and avian sarcoma virus impair GJIC mainly by decreasing expression levels [ 252 , 253 , 254 , 255 , 256 ], altering trafficking and recycling to the membrane [ 257 ] of connexin-43 (Cx43). This effect is in accord with the fact that cancerous cells often lose their ability to communicate via GJIC [ 1 ].…”

Acute adenoviral infection elicits an arrhythmogenic substrate prior to myocarditis

“…Adenoviruses push cells into S phase via E1A, E1B, and E4 protein interaction with host mechanisms, and this is required for viral replication [110][111][112] . Cardiomyocytes, themselves, are typically quiescent several days after birth, and therefore, are particularly recalcitrant to entering the cell cycle 113 . We must also now consider how activation of these signaling pathways shuts down gap junction intercellular communication in addition to facilitating S-phase entry.…”