0000000000116765
AUTHOR
Konstanze D. Scheffer
Inhibition by cellular vacuolar ATPase impairs human papillomavirus uncoating and infection.
ABSTRACT Several viruses, including human papillomaviruses, depend on endosomal acidification for successful infection. Hence, the multisubunit enzyme vacuolar ATPase (V-ATPase), which is mainly responsible for endosome acidification in the cell, represents an attractive target for antiviral strategies. In the present study, we show that V-ATPase is required for human papillomavirus (HPV) infection and that uncoating/disassembly but not endocytosis is affected by V-ATPase inhibition. The infection inhibitory potencies of saliphenylhalamide, a proven V-ATPase inhibitor, and its derivatives, as well as those of other V-ATPase inhibitors, were analyzed on different HPV types in relevant cell l…
The Transcription Factors TBX2 and TBX3 Interact with Human Papillomavirus 16 (HPV16) L2 and Repress the Long Control Region of HPVs
ABSTRACT The minor capsid protein L2 of human papillomaviruses (HPVs) has multiple functions during the viral life cycle. Although L2 is required for effective invasion and morphogenesis, only a few cellular interaction partners are known so far. Using yeast two-hybrid screening, we identified the transcription factor TBX2 as a novel interaction partner of HPV type 16 (HPV16) L2. Coimmunoprecipitations and immunofluorescence analyses confirmed the L2-TBX2 interaction and revealed that L2 also interacts with TBX3, another member of the T-box family. Transcription of the early genes during HPV infection is under the control of an upstream enhancer and early promoter region, the long control r…
The Extracellular δ-Domain is Essential for the Formation of CD81 Tetraspanin Webs
AbstractCD81 is a ubiquitously expressed member of the tetraspanin family. It forms large molecular platforms, so-called tetraspanin webs that play physiological roles in a variety of cellular functions and are involved in viral and parasite infections. We have investigated which part of the CD81 molecule is required for the formation of domains in the cell membranes of T-cells and hepatocytes. Surprisingly, we find that large CD81 platforms assemble via the short extracellular δ-domain, independent from a strong primary partner binding and from weak interactions mediated by palmitoylation. The δ-domain is also essential for the platforms to function during viral entry. We propose that, ins…
Isolation and Characterization of Pathogen-Bearing Endosomes Enable Analysis of Endosomal Escape and Identification of New Cellular Cofactors of Infection
Many pathogens, including viruses, bacteria, as well as bacterial toxins, enter their target cells by endocytosis leading to accumulation of pathogenic and cellular proteins in endosomes. Here, we present detailed experimental instructions on isolation of endosomes after virus infection and their subsequent biomolecular characterization. The isolation of endosomes is based on discontinuous sucrose gradient centrifugation, where different endosomal compartments accumulate at a specific sucrose interface. This enables the enrichment and separation of the virus-interacting and co-internalized cell-surface receptors and membrane-associated proteins. The endosomal fractions can be further analyz…
Tetraspanin CD151 Mediates Papillomavirus Type 16 Endocytosis
ABSTRACT Human papillomavirus type 16 (HPV16) is the primary etiologic agent for cervical cancer. The infectious entry of HPV16 into cells occurs via a so-far poorly characterized clathrin- and caveolin-independent endocytic pathway, which involves tetraspanin proteins and actin. In this study, we investigated the specific role of the tetraspanin CD151 in the early steps of HPV16 infection. We show that surface-bound HPV16 moves together with CD151 within the plane of the membrane before they cointernalize into endosomes. Depletion of endogenous CD151 did not affect binding of viral particles to cells but resulted in reduction of HPV16 endocytosis. HPV16 uptake is dependent on the C-termina…