Endoplasmic reticulum targeting alters regulation of expression and antigen presentation of proinsulin.
Peptide ligands presented by MHC class I (MHC-I) molecules are produced by degradation of cytosolic and nuclear, but also endoplasmic reticulum (ER)-resident, proteins by the proteasome. However, Ag processing of ER proteins remains little characterized. Studying processing and presentation of proinsulin, which plays a pivotal role in autoimmune diabetes, we found that targeting to the ER has profound effects not only on how proinsulin is degraded, but also on regulation of its cellular levels. While proteasome inhibition inhibited degradation and presentation of cytosolic proinsulin, as expected, it reduced the abundance of ER-targeted proinsulin. This targeting and protein modifications modifying protein half-life also had profound effects on MHC-I presentation and proteolytic processing of proinsulin. Thus, presentation of stable luminal forms was inefficient but enhanced by proteasome inhibition, whereas that of unstable luminal forms and of a cytosolic form were more efficient and compromised by proteasome inhibitors. Distinct stability of peptide MHC complexes produced from cytosolic and luminal proinsulin suggests that different proteolytic activities process the two Ag forms. Thus, both structural features and subcellular targeting of Ags can have strong effects on the processing pathways engaged by MHC-I-restricted Ags, and on the efficiency and regulation of their presentation.
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Hsiang-Ting
HT
Hsu
Biochemistry and Cell Biology, Molecular Life Science Center, Jacobs University Bremen, 28759 Bremen, Germany; and.
Linda
L
Janßen
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Myriam
M
Lawand
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Jessica
J
Kim
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Alicia
A
Perez-Arroyo
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Slobodan
S
Culina
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Abdel
A
Gdoura
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Anne
A
Burgevin
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Delphine
D
Cumenal
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Yousra
Y
Fourneau
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Anna
A
Moser
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France;
Roland
R
Kratzer
Centre for Endocrine and Diabetes Science, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom.
F Susan
FS
Wong
Biochemistry and Cell Biology, Molecular Life Science Center, Jacobs University Bremen, 28759 Bremen, Germany; and.
Sebastian
S
Springer
INSERM, Unité 1151, 75015 Paris, France; Centre National de la Recherche Scientifique, Unité 8253, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75015 Paris, France; peter.van-endert@inserm.fr.
Peter
P
van Endert
D017951:Antigen Presentation; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation / Q000235:genetics / Q000276:immunology*; D006367:HeLa Cells; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology*; D006801:Humans; D010455:Peptides / Q000235:genetics / Q000276:immunology; D011384:Proinsulin / Q000235:genetics / Q000276:immunology*; D059748:Proteolysis
D015395:Histocompatibility Antigens Class I; D010455:Peptides; D011384:Proinsulin