scholarly journals A non-canonical ESCRT pathway, including histidine domain phosphotyrosine phosphatase (HD-PTP), is used for down-regulation of virally ubiquitinated MHC class I

2015 ◽  
Vol 471 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Michael D.J. Parkinson ◽  
Siân C. Piper ◽  
Nicholas A. Bright ◽  
Jennifer L. Evans ◽  
Jessica M. Boname ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Canonical Pathway ◽  
Class I ◽  
Multivesicular Bodies ◽  
Down Regulation ◽  
Phosphotyrosine Phosphatase ◽  
Endosomal Sorting

Using RNAi, a non-canonical pathway of endosomal sorting complexes required for transport was identified that is responsible for sorting virally ubiquitinated MHC class I into multivesicular bodies (MVBs) during down-regulation of this protein from the cell surface.

ESCRT proteins and the regulation of endocytic delivery to lysosomes

2009 ◽  
Vol 37 (1) ◽  
pp. 178-180 ◽  
Author(s):  
J. Paul Luzio ◽  
Siân C. Piper ◽  
Katherine Bowers ◽  
Michael D.J. Parkinson ◽  
Paul J. Lehner ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Mammalian Cells ◽  
Transport Proteins ◽  
Class I ◽  
Multivesicular Bodies ◽  
Down Regulation ◽  
Morphological Effect ◽  
Endosomal Sorting ◽  
Endocytic Compartments

In mammalian cells, there is evidence of cargo specificity in the requirement for particular ESCRT (endosomal sorting complex required for transport) proteins to sort cargo into the luminal vesicles of MVBs (multivesicular bodies). We have focussed on studying the ESCRT requirements for delivery of MHC class I to lysosomes following polyubiquitination by the Kaposi's sarcoma-associated herpesvirus protein K3. Down-regulation of polyubiquitinated cell-surface MHC class I in HeLa cells stably expressing K3 is achieved via clathrin-mediated endocytosis, followed by sorting into the luminal vesicles of MVBs and eventual delivery to lysosomes. Depletion of ESCRT-I and some ESCRT-III components interferes with this sorting and allows recycling of MHC class I to the cell surface. Depletion of ESCRT-II components has no effect on K3-mediated down-regulation of MHC class I and no gross morphological effect on endocytic compartments. Thus virally polyubiquitinated MHC class I does not require all of the ESCRT proteins in order to be sorted into the luminal vesicles of MVBs. However, there may be a further requirement for ESCRT-III proteins to ensure the efficient fusion of MVBs with lysosomes.

scholarly journals Efficient Class I Major Histocompatibility Complex Down-Regulation by Simian Immunodeficiency Virus Nef Is Associated with a Strong Selective Advantage in Infected Rhesus Macaques

2001 ◽  
Vol 75 (21) ◽  
pp. 10532-10536 ◽  
Author(s):  
Jan Münch ◽  
Nicole Stolte ◽  
Dietmar Fuchs ◽  
Christiane Stahl-Hennig ◽  
Frank Kirchhoff
Keyword(s):  
Major Histocompatibility Complex ◽  
Cell Surface ◽  
Simian Immunodeficiency Virus ◽  
Mhc Class I ◽  
Rhesus Macaques ◽  
Selective Advantage ◽  
Class I ◽  
Down Regulation ◽  
Histocompatibility Complex ◽  
Immunodeficiency Virus

ABSTRACT Substitution of Y223F disrupts the ability of simian immunodeficiency virus (SIV) Nef to down-modulate major histocompatibility complex (MHC) class I from the cell surface but has no effect on other Nef functions, such as down-regulation of CD4, CD28, and CD3 cell surface expression or stimulation of viral replication and enhancement of virion infectivity. Inoculation of three rhesus macaques with the SIVmac239 Y223F-Nef variant revealed that this point mutation consistently reverts and that Nef activity in MHC class I down-modulation is fully restored within 4 weeks after infection. Our results demonstrate a strong selective pressure for a tyrosine at amino acid position 223 in SIV Nef, and they constitute evidence that Nef-mediated MHC class I down-regulation provides a selective advantage for viral replication in vivo.

Ligand Design for Specific MHC Class I Molecules on the Cell Surface

2020 ◽  
Author(s):  
Xizheng Sun ◽  
Reika Tokunaga ◽  
Yoko Nagai ◽  
Ryo Miyahara ◽  
Akihiro Kishimura ◽  
...  
Keyword(s):  
Cell Surface ◽  
Mhc Class I ◽  
Targeted Delivery ◽  
Peptide Ligands ◽  
Class I ◽  
Class I Mhc ◽  
Mhc I ◽  
Histocompatibility Complex ◽  
High Binding Affinity ◽  
Mhc Class I Molecules

<p><a></a><a></a><a>We have validated that ligand peptides designed from antigen peptides could be used for targeting specific major histocompatibility complex class I (MHC-I)</a> molecules on cell surface. To design the ligand peptides, we used reported antigen peptides for each MHC-I molecule with high binding affinity. From the crystal structure of the peptide/MHC-I complexes, we determined a modifiable residue in the antigen peptides and replaced this residue with a lysine with an ε-amine group modified with functional molecules. The designed ligand peptides successfully bound to cells expressing the corresponding MHC-I molecules via exchange of peptides bound to the MHC-I. We demonstrated that the peptide ligands could be used to transport a protein or a liposome to cells expressing the corresponding MHC-I. The present strategy may be useful for targeted delivery to cells overexpressing MHC-I, which have been observed autoimmune diseases.</p>

scholarly journals Oligomerization and endocytosis of Hedgehog is necessary for its efficient exovesicular secretion

2015 ◽  
Vol 26 (25) ◽  
pp. 4700-4717 ◽  
Author(s):  
Anup Parchure ◽  
Neha Vyas ◽  
Charles Ferguson ◽  
Robert G. Parton ◽  
Satyajit Mayor
Keyword(s):  
Cell Surface ◽  
Long Range ◽  
Imaginal Discs ◽  
Multivesicular Bodies ◽  
Selective Effect ◽  
Endosomal Sorting ◽  
Drosophila Wing ◽  
Dependent Process ◽  
Wing Imaginal Discs ◽  
Hh Signaling

Hedgehog (Hh) is a secreted morphogen involved in both short- and long-range signaling necessary for tissue patterning during development. It is unclear how this dually lipidated protein is transported over a long range in the aqueous milieu of interstitial spaces. We previously showed that the long-range signaling of Hh requires its oligomerization. Here we show that Hh is secreted in the form of exovesicles. These are derived by the endocytic delivery of cell surface Hh to multivesicular bodies (MVBs) via an endosomal sorting complex required for transport (ECSRT)–dependent process. Perturbations of ESCRT proteins have a selective effect on long-range Hh signaling in Drosophila wing imaginal discs. Of importance, oligomerization-defective Hh is inefficiently incorporated into exovesicles due to its poor endocytic delivery to MVBs. These results provide evidence that nanoscale organization of Hh regulates the secretion of Hh on ESCRT-derived exovesicles, which in turn act as a vehicle for long-range signaling.

The role of DNA methylation in the down-regulation of MHC class I in a series of murine lymphoma variants

1994 ◽  
Vol 40 ◽  
pp. 60
Author(s):  
R. Rubocki ◽  
B. Berrigan ◽  
S. Shepherd ◽  
J. Wisecarver
Keyword(s):  
Dna Methylation ◽  
Mhc Class I ◽  
Class I ◽  
Down Regulation ◽  
Murine Lymphoma

scholarly journals Activation of transcription factor NF-kappaB by the adenovirus E3/19K protein requires its ER retention.

1996 ◽  
Vol 132 (4) ◽  
pp. 511-522 ◽  
Author(s):  
H L Pahl ◽  
M Sester ◽  
H G Burgert ◽  
P A Baeuerle
Keyword(s):  
Transcription Factor ◽  
Cell Surface ◽  
Mhc Class I ◽  
Signal Sequence ◽  
Signal Transduction Pathway ◽  
Cyclopiazonic Acid ◽  
Class I ◽  
Mhc Molecules ◽  
Er Retention ◽  
Nf Kappab

We have recently shown that the accumulation of diverse viral and cellular membrane proteins in the ER activates the higher eukaryotic transcription factor NF-kappaB. This defined a novel ER-nuclear signal transduction pathway, which is distinct from the previously described unfolded protein response (UPR). The well characterized UPR pathway is activated by the presence of un- or malfolded proteins in the ER. In contrast, the ER stress signal which activates the NF-kappaB pathway is not known. Here we used the adenovirus early region protein E3/19K as a model to investigate the nature of the NF-kappaB-activating signal emitted by the ER. E3/19K resides in the endoplasmic reticulum where it binds to MHC class I molecules, thereby preventing their transport to the cell surface. It is maintained in the ER by a retention signal sequence in its carboxy terminus, which causes the protein to be continuously retrieved to the ER from post-ER compartments. Mutation of this sequence allows E3/19K to reach the cell surface. We show here that expression of E3/19K potently activates a functional NF-kappaB transcription factor. The activated NF-kappaB complexes contained p50/p65 and p50/c-rel heterodimers. E3/19K interaction with MHC class I was not important for NF-kappaB activation since mutant proteins which no longer bind MHC molecules remained fully capable of inducing NF-kappaB. However, activation of both NF-kappaB DNA binding and kappaB-dependent transactivation relied on E3/19K ER retention: mutants, which were expressed on the cell surface, could no longer activate the transcription factor. This identifies the NF-kappaB-activating signal as the accumulation of proteins in the ER membrane, a condition we have termed "ER overload." We show that ER overload-mediated NF-kappaB activation but not TNF-stimulated NF-kappaB induction can be inhibited by the intracellular Ca2+ chelator TMB-8. Moreover, treatment of cells with two inhibitors of the ER-resident Ca(2+) -dependent ATPase, thapsigargin and cyclopiazonic acid, which causes a rapid release of Ca2+ from the ER, strongly activated NF-kappaB. We therefore propose that ER overload activates NF-kappaB by causing Ca2+ release from the ER. Because NF-kappaB plays a key role in mounting an immune response, ER overload caused by viral proteins may constitute a simple antiviral response with broad specificity.

scholarly journals Lymphoid Tumors ofXenopus laeviswith Different Capacities for Growth in Larvae and Adults

1994 ◽  
Vol 3 (4) ◽  
pp. 297-307 ◽  
Author(s):  
Jacques Robert ◽  
Chantal Guiet ◽  
Louis Du Pasquier
Keyword(s):  
Cell Surface ◽  
Tumor Cell ◽  
Tumor Cells ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Cell Lineage ◽  
Cell Types ◽  
Class Ii ◽  
Class I ◽  
Specific Marker

Three new lymphoid tumors offering an assortment of variants in terms of MHC class I expressions, MHC class II expression, and Ig gene transcription have been discovered in the amphibianXenopus. One was developed in an individual of the isogenic LG15 clone (LG15/0), one in a frog of the LG15/40 clone (derived from a small egg recombinant of LG15), and one (ff-2) in a maleffsib of the individual in which MAR1, the first lymphoid tumor in Xenopus was found 2 years ago. These tumors developed primarily as thymus outgrowths and were transplantable in histocompatible tadpoles but not in nonhistocompatible hosts. Whereas LG15/0 and LG15/40 tumor cells also grow in adult LG15 frogs, theff-2 tumor, like the MAR1 cell line, is rejected by adultffanimals. Using flow cytometry with fluorescence-labeled antibodies and immunoprecipitation analysis, we could demonstrate that, like MAR1, these three new tumors express on their cell surface lymphopoietic markers recognized by mAbs FIF6 and RC47, as well as T-cell lineage markers recognized by mAbs AM22 (CD8-1ike) and X21.2, but not by immunologobulin (Ig) nor MHC class II molecules. Another lymphocyte-specific marker AM15 is expressed by 15/0 and 15/40 but notff-2 tumor cells. Theff-2 tumor cell expresses MHC class molecule in association withβ2-microglobulin on the surface, 15/40 cells contain cytoplasmic Iαchain that is barely detected at the cell surface by fluocytometry, and 15/0 cells do not synthesize class Iαchain at all. The three new tumors all produce large amounts of IgM mRNA of two different sizes but no Ig protein on the membrane nor in the cytoplasm. All tumor cell types synthesize large amount of Myc mRNA and MHC class I-like transcripts considered to be non classical.

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