title: Matrix metalloproteinase-3: a novel signaling proteinase from apoptotic neuronal cells that activates microglia.
abstract: Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative human brain disorders. We sought to investigate molecular signaling mechanisms that govern activation of microglia in apoptotic neuronal degeneration. We report here that the active form of matrix metalloproteinase-3 (MMP-3) was released into the serum-deprived media (SDM) of PC12 cells and other media of apoptotic neuronal cells within 2-6 h of treatment of the cells, and SDM and catalytic domain of recombinant MMP-3 (cMMP-3) activated microglia in primary microglia cultures as well as BV2 cells, a mouse microglia cell line. Both SDM and cMMP-3 induced generation of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), IL-1beta, and interleukin-1 receptor antagonist but not IL-12 and inducible nitric oxide synthase, which are readily induced by lipopolysaccharide, in microglia, suggesting that there is a characteristic pattern of microglial cytokine induction by apoptotic neurons. Neither glial cell line-derived neurotrophic factor nor anti-inflammatory cytokines, such as IL-10 and transforming growth factor-beta1, were induced. SDM and cMMP-3 extensively released TNF-alpha from microglia and activated the nuclear factor-kappaB pathway, and these microglial responses were totally abolished by preincubation with an MMP-3 inhibitor, NNGH [N-isobutyl-N-(4-methoxyphenylsulfonyl)-glycylhydroxamic acid]. MMP-3-mediated microglial activation mostly depended on ERK (extracellular signal-regulated kinase) phosphorylation but not much on either JNK (c-Jun N-terminal protein kinase) or p38 activation. Conditioned medium of SDM- or cMMP-3-activated BV2 cells caused apoptosis of PC12 cells. These results strongly suggest that the distinctive signal of neuronal apoptosis is the release of active form of MMP-3 that activates microglia and subsequently exacerbates neuronal degeneration. Therefore, the release of MMP-3 from apoptotic neurons may play a major role in degenerative human brain disorders, such as Parkinson's disease.
authors.affiliation: Burke Medical Research Institute, Weill Medical College and Graduate School of Medical Sciences of Cornell University, White Plains, New York 10605, USA.
authors.forename: Yoon Seong
authors.initials: YS
authors.lastname: Kim
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Jeong Je
authors.initials: JJ
authors.lastname: Cho
authors.forename: Dong Hee
authors.initials: DH
authors.lastname: Choi
authors.forename: Onyou
authors.initials: O
authors.lastname: Hwang
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Shin
authors.forename: Hong Sung
authors.initials: HS
authors.lastname: Chun
authors.forename: M Flint
authors.initials: MF
authors.lastname: Beal
authors.forename: Tong H
authors.initials: TH
authors.lastname: Joh
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004347:Drug Interactions; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity; D019278:Matrix Metalloproteinase 3 / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D017628:Microglia / Q000187:drug effects / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism; D009474:Neurons / Q000201:enzymology*; D051381:Rats; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors
chemical_list: D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D016207:Cytokines; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D020928:Mitogen-Activated Protein Kinases; D019278:Matrix Metalloproteinase 3