Role of vacuolar H(+)-ATPase in interferon-induced inhibition of viral glycoprotein transport.
We have shown previously that interferon-beta (IFN-beta) induces the alkalinization of trans-Golgi network (TGN) and inhibits the transport of G protein of vesicular stomatitis virus (VSV) in L(B) cells and gD protein of herpes simplex virus (HSV-1) in LMtk- cells transfected with gD cDNA. The vacuolar H(+)-ATPase (V-ATPase) is responsible for maintaining pH in TGN, and V-ATPase-mediated acidification is required for normal transport of proteins. To examine whether alkalinization caused by IFN is mediated through V-ATPase, the activity of V-ATPase was determined in IFN-treated cells by coupling ATP hydrolysis to NADH oxidation. Bafilomycin (Baf) was used as positive control, as it specifically inhibits V-ATPase. The activity of V-ATPase was reduced in IFN-treated or Baf-treated cells compared with untreated cells. Doses of IFN-beta or Baf that neither alter pHi nor inhibit the transport of viral glycoproteins concomitantly inhibited the transport of G and gD proteins in TGN, as demonstrated by indirect immunofluorescence studies, and raised the pH of TGN as demonstrated by a decrease in the uptake of DAMP. Further, the effect of Baf on IFN-induced antiviral activity against VSV was examined to correlate the biologic significance of these findings. Data showed that Baf significantly enhances (5-50-fold) the IFN-induced antiviral activity as demonstrated by viral titers from supernatants. These findings suggest that the inhibition of transport of G and gD proteins by IFN-beta, may be related to the inhibition of V-ATPase-mediated acidification of TGN.
Sidhu
G S
GS
Center for Combat Casualty & Life Sustainment Research, Department of Pathology, Uniformed Services University of Health Sciences, Bethesda, MD 20814, USA.
Singh
A K
AK
Sundarrajan
R N
RN
Sundar
S V
SV
Maheshwari
R K
RK
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019084:Fluorescent Antibody Technique, Indirect; D006868:Hydrolysis; D007372:Interferons / Q000494:pharmacology*; D051379:Mice; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D014617:Vacuoles / Q000201:enzymology*; D014760:Viral Fusion Proteins / Q000493:pharmacokinetics*
D014760:Viral Fusion Proteins; D007372:Interferons; D006180:Proton-Translocating ATPases