title: Neurotoxicity of microglial cathepsin D revealed by secretome analysis.
abstract: Microglia-driven inflammatory responses have both neuroprotective and neurotoxic effects in the CNS. The excessive and chronic activation of microglia, however, may shift the balance towards neurotoxic effects. In this regard, proteins secreted from activated microglia likely play a key role in the neurotoxic effects. To characterize secreted proteins of activated microglia, conditioned media obtained from BV-2 mouse microglia cells were analyzed by two-dimensional gel electrophoresis or liquid chromatography coupled with tandem mass spectrometry. Among many proteins identified in the secretome of activated microglia, an aspartic endoprotease cathepsin D has been found to mediate microglial neurotoxicity based on the following results: (i) the expression of cathepsin D protein was markedly increased in lipopolysaccharide/interferon-γ-stimulated microglia compared with resting microglia as determined by western blot analysis of conditioned media; (ii) knockdown of cathepsin D expression in microglia using short hairpin RNA diminished the neurotoxicity in the coculture of microglia and neuroblastoma cells and (iii) recombinant procathepsin D protein exerted cytotoxic effects toward cultured neurons. In conclusion, cathepsin D appears to play a central role in the microglial neurotoxicity, and could be a potential biomarker or drug target for the diagnosis and treatment of neurodegenerative diseases that are associated with excessive microglial activation and subsequent neurotoxic inflammation.
authors.affiliation: Department of Pharmacology, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Sangseop
authors.initials: S
authors.lastname: Kim
authors.forename: Jiyeon
authors.initials: J
authors.lastname: Ock
authors.forename: Ae Kyung
authors.initials: AK
authors.lastname: Kim
authors.forename: Ho Won
authors.initials: HW
authors.lastname: Lee
authors.forename: Je-Yoel
authors.initials: JY
authors.lastname: Cho
authors.forename: Deok Ryong
authors.initials: DR
authors.lastname: Kim
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Park
authors.forename: Kyoungho
authors.initials: K
authors.lastname: Suk
mesh_terms: D000626:Aminopeptidases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002402:Cathepsin D / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology; D004452:Echocardiography; D047468:Immunoprecipitation; D007202:Indicators and Reagents; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000502:physiology; D051379:Mice; D008813:Mice, Inbred ICR; D017628:Microglia / Q000187:drug effects*; D020258:Neurotoxicity Syndromes / Q000473:pathology; D020543:Proteome / Q000187:drug effects*; D034741:RNA, Small Interfering; D012394:Rosaniline Dyes; D021241:Spectrometry, Mass, Electrospray Ionization; D014357:Trypsin / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D008070:Lipopolysaccharides; D020543:Proteome; D034741:RNA, Small Interfering; D012394:Rosaniline Dyes; C048139:Coomassie blue; D000626:Aminopeptidases; C019721:aminopeptidase B; D014357:Trypsin; D002402:Cathepsin D