Involvement of cathepsin E in exogenous antigen processing in primary cultured murine microglia.
We have attempted to elucidate an involvement of cathepsin E (CE) in major histocompatibility complex class II-mediated antigen presentation by microglia. In primary cultured murine microglia, CE was localized mainly in early endosomes and its expression level was markedly increased upon stimulation with interferon-gamma. Pepstatin A, a specific inhibitor of aspartic proteases, significantly inhibited interleukin-2 production from an OVA-(266-281)-specific T helper cell hybridomas upon stimulation with native OVA presented by interferon-gamma-treated microglia. However, pepstatin A failed to inhibit the presentation of OVA-(266-281) peptide. The possible involvement of CE in the processing of native OVA into antigenic peptide was further substantiated by that digested fragments of native OVA by CE could be recognized by OVA-specific Th cells. Cathepsin D also degraded native OVA into antigenic peptide, whereas microglia prepared from cathepsin D-deficient mice retained an ability for antigen presentation. On the other hand, the requirement for cysteine proteases such as cathepsins S and B in the processing of invariant chain (Ii) was confirmed by immunoblot analyses in the presence of their specific inhibitors. In conclusion, CE is required for the generation of an antigenic epitope from OVA but not for the processing of Ii in microglia.
Nishioku
Tsuyoshi
T
Department of Pharmacology, Graduate School of Dental Science, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582, Japan.
Hashimoto
Koichi
K
Yamashita
Keizo
K
Liou
Shyh-Yuh
SY
Kagamiishi
Yoshifumi
Y
Maegawa
Hitoshi
H
Katsube
Nobuo
N
Peters
Christoph
C
von Figura
Kurt
K
Saftig
Paul
P
Katunuma
Nobuhiko
N
Yamamoto
Kenji
K
Nakanishi
Hiroshi
H
D000818:Animals; D017951:Antigen Presentation; D000941:Antigens / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism; D020059:Cathepsin E / Q000378:metabolism* / Q000502:physiology*; D002403:Cathepsins / Q000378:metabolism; D002478:Cells, Cultured; D000939:Epitopes / Q000378:metabolism; D005802:Genes, MHC Class II; D006825:Hybridomas / Q000378:metabolism; D015151:Immunoblotting; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D009457:Neuroglia / Q000166:cytology*; D010436:Pepstatins / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000941:Antigens; D000939:Epitopes; D007376:Interleukin-2; D010436:Pepstatins; D010455:Peptides; D012333:RNA, Messenger; D007371:Interferon-gamma; D002403:Cathepsins; D002401:Cathepsin B; C028217:cathepsin S; D020059:Cathepsin E; C031375:pepstatin