PMID- 1664047
OWN - NLM
STAT- MEDLINE
DCOM- 19920310
LR  - 20131121
IS  - 0888-8809 (Print)
IS  - 0888-8809 (Linking)
VI  - 5
IP  - 11
DP  - 1991 Nov
TI  - Altered effects of glucocorticoids on the trafficking and processing of mouse 
      mammary tumor virus glycoproteins constitutively expressed in rat hepatoma cells 
      in the absence of nonglycosylated viral components.
PG  - 1696-706
AB  - We have documented previously that glucocorticoid hormones modulate the 
      posttranslational localization of cell surface mouse mammary tumor virus (MMTV) 
      glycoproteins in the viral-infected M1.54 rat HTC hepatoma cell line. To 
      determine whether glucocorticoids affect the trafficking of individually 
      synthesized MMTV glycoproteins, HTC cells were transfected with a constitutively 
      expressed MMTV glycoprotein gene lacking the viral phosphoprotein and polymerase 
      genes. This construct also allows equivalent levels of MMTV glycoproteins to be 
      compared in the presence or absence of glucocorticoids. Indirect 
      immunofluorescence and immunoprecipitation of radiolabeled cells revealed that in 
      transfected cells the transmembrane MMTV glycoproteins are efficiently expressed, 
      transported to the cell surface, and proteolytically cleaved in the presence or 
      in the absence of the synthetic glucocorticoid dexamethasone. Cell surface 
      immunoprecipitation of [35S]methionine-labeled cells showed that the level of 
      plasma membrane gp78 appeared to be stimulated 2-fold after dexamethasone 
      treatment, even though fluorescence-activated cell sorting revealed no 
      discernible change in the total concentration of cell surface MMTV glycoproteins. 
      Analysis of oligosaccharide side chain maturation through a pulse-chase 
      radiolabeling revealed that the rate of rough endoplasmic reticulum-Golgi 
      transport was essentially identical in dexamethasone-treated and untreated 
      transfected cells and was similar to that observed in dexamethasone-treated M1.54 
      cells. Thus, in contrast to viral-infected hepatoma cells, mostly constitutive 
      cellular machinery mediates the trafficking and maturation of cell surface MMTV 
      glycoproteins expressed outside of the proviral context. Taken together, our 
      results suggest that the glucocorticoid-stimulated synthesis of nonglycosylated 
      viral components may contribute to or be responsible for the regulated 
      trafficking of MMTV glycoproteins observed in viral-infected rat hepatoma cells.
FAU - Platt, E J
AU  - Platt EJ
AD  - Department of Molecular and Cell Biology, University of California, Berkeley 
      94720.
FAU - Goodman, L J
AU  - Goodman LJ
FAU - Kain, S R
AU  - Kain SR
FAU - Zettl, K S
AU  - Zettl KS
FAU - Firestone, G L
AU  - Firestone GL
LA  - eng
GR  - CA-09041/CA/NCI NIH HHS/United States
GR  - DK-42799/DK/NIDDK NIH HHS/United States
GR  - F32-CA-09053/CA/NCI NIH HHS/United States
GR  - etc.
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Mol Endocrinol
JT  - Molecular endocrinology (Baltimore, Md.)
JID - 8801431
RN  - 0 (Orosomucoid)
RN  - 0 (Viral Envelope Proteins)
RN  - 7S5I7G3JQL (Dexamethasone)
SB  - IM
GS  - env
MH  - Amino Acid Sequence
MH  - Animals
MH  - Cell Line
MH  - Dexamethasone/*pharmacology
MH  - Fluorescent Antibody Technique
MH  - Genes, env
MH  - Glycosylation
MH  - Kinetics
MH  - Liver Neoplasms, Experimental
MH  - Mammary Tumor Virus, Mouse/*genetics
MH  - Molecular Sequence Data
MH  - Orosomucoid/genetics
MH  - Plasmids
MH  - *Protein Processing, Post-Translational/drug effects
MH  - Rats
MH  - Transfection
MH  - Viral Envelope Proteins/biosynthesis/*genetics
EDAT- 1991/11/01 00:00
MHDA- 1991/11/01 00:01
CRDT- 1991/11/01 00:00
PHST- 1991/11/01 00:00 [pubmed]
PHST- 1991/11/01 00:01 [medline]
PHST- 1991/11/01 00:00 [entrez]
AID - 10.1210/mend-5-11-1696 [doi]
PST - ppublish
SO  - Mol Endocrinol. 1991 Nov;5(11):1696-706. doi: 10.1210/mend-5-11-1696.