Involvement of cathepsin B in the processing and secretion of interleukin-1beta in chromogranin A-stimulated microglia.
Cathepsin B (CB) is a cysteine lysosomal protease implicated in a number of inflammatory diseases. Although it is now evident that caspase-1, an essential enzyme for maturation of interleukin-1beta (IL-1beta), can be activated through the inflammasome, there is still evidence suggesting the existence of lysosomal-proinflammatory caspase pathways. In the present study, a marked induction of pro-IL-1beta, its processing to the mature form and secretion were observed in the primary cultured microglia prepared from wild-type mice after stimulation with chromogranin A (CGA). Although pro-IL-1beta also markedly increased in microglia prepared from CB-deficient mice, CB-deficiency abrogated the pro-IL-1beta processing. CA-074Me, a specific inhibitor for CB, inhibited the pro-IL-1beta maturation and its release from microglia. Furthermore, the caspase-1 activation was also inhibited by CA-074Me and E-64d, a broad cysteine protease inhibitor. After treatment with CGA, CB was markedly induced at both protein and mRNA levels. The induced pro-CB was rapidly processed to its mature form. The immunoreactivity for CB co-localized with both that for caspase-1 and the cleaved IL-1beta, in the acidic enlarged lysosomes. Inconsistent with these in vitro observations, the immunoreactivity for the cleaved IL-1beta was markedly observed in microglia of the hippocampus from aged wild-type but not CB-deficient mice. These observations strongly suggest that CB plays a key role in the pro-IL-1beta maturation through the caspase-1 activation in enlarged lysosomes of CGA-treated microglia. Therefore, either pharmacological or genetic inhibition of CB may provide therapeutic intervention in inflammation-associated neurological diseases.
Terada
Kayo
K
Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan.
Yamada
Jun
J
Hayashi
Yoshinori
Y
Wu
Zhou
Z
Uchiyama
Yasuo
Y
Peters
Christoph
C
Nakanishi
Hiroshi
H
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D020170:Caspase 1 / Q000378:metabolism; D002401:Cathepsin B / Q000172:deficiency / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D053379:Chromogranin A / Q000494:pharmacology*; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005786:Gene Expression Regulation / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism*; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D010436:Pepstatins / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
D053379:Chromogranin A; D004791:Enzyme Inhibitors; D053583:Interleukin-1beta; D051907:Lysosomal Membrane Proteins; D009573:Nitrites; D010436:Pepstatins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D002401:Cathepsin B; D020170:Caspase 1; C031375:pepstatin