Expression of a complete and functional complement system by human neuronal cells in vitro.
We demonstrate in vitro expression of complement components, i.e. C3, factor H (FH), factor B (FB), C4, C1-inhibitor (C1-inh), C1q, C5, C6, C7 and C9, by four human neuroblastoma cell lines IMR32, SKNSH, SH-SY5Y and KELLY. Activating proteins C4, C9 and C1q, and regulatory proteins FH and C1-inh were produced constitutively by the four cell lines. C3, C6 and FB were mainly produced by SKNSH and SH-SY5Y. Western blot experiments showed that secreted proteins were structurally similar to their serum counterparts. An additional polypeptide of 43 kDa with FH immunoreactivity was detected, which could correspond to the N-terminal truncated form found in plasma. Regulation of complement expression by inflammatory cytokines, lipopolysaccharide and dexamethasone was tested in vitro. These factors had no significant effects on activating synthesis of components C3, FB and C4, but expression of regulating components C1-inh and FH was strongly increased particularly by IFN-gamma and tumor necrosis factor-alpha. The rate of synthesis of complement components was dependent on the differentiation of neuroblastoma cells. This effect of differentiation was also observed on normal rat neurons. Rat cerebellar granule cells constitutively expressed mRNA for C4 and C1q, but expression of C3 mRNA was induced by differentiation. This study shows that neurons could be another local source of complement in the brain, besides astrocytes and microglia. Human neuroblastoma cell lines can constitute an interesting model to analyze complement biosynthesis by human neurons. Local complement expression by neurons in vivo may be implicated in some physio-pathological processes.
Thomas
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A
Institut Fédératif de Recherches Multidisciplinaires sur les Peptides no. 23, INSERM U78, Faculté de Médecine et Pharmacie, 22 Boulevard Gambetta, 76183 Rouen Cedex, France.
Gasque
P
P
Vaudry
D
D
Gonzalez
B
B
Fontaine
M
M
D000818:Animals; D003176:Complement C3 / Q000502:physiology; D003181:Complement C4 / Q000502:physiology; D011415:Complement Factor B / Q000502:physiology; D017242:Complement Factor H / Q000502:physiology; D003165:Complement System Proteins / Q000235:genetics / Q000502:physiology*; D016207:Cytokines / Q000494:pharmacology; D006801:Humans; D009474:Neurons / Q000276:immunology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
C493495:CFH protein, human; D003176:Complement C3; D003181:Complement C4; D016207:Cytokines; D012333:RNA, Messenger; D017242:Complement Factor H; D003165:Complement System Proteins; D011415:Complement Factor B