title: Interaction of HmC1q with leech microglial cells: involvement of C1qBP-related molecule in the induction of cell chemotaxis.
abstract: BACKGROUND
  In invertebrates, the medicinal leech is considered to be an interesting and appropriate model to study neuroimmune mechanisms. Indeed, this non-vertebrate animal can restore normal function of its central nervous system (CNS) after injury. Microglia accumulation at the damage site has been shown to be required for axon sprouting and for efficient regeneration. We characterized HmC1q as a novel chemotactic factor for leech microglial cell recruitment. In mammals, a C1q-binding protein (C1qBP alias gC1qR), which interacts with the globular head of C1q, has been reported to participate in C1q-mediated chemotaxis of blood immune cells. In this study, we evaluated the chemotactic activities of a recombinant form of HmC1q and its interaction with a newly characterized leech C1qBP that acts as its potential ligand.
  
  
  METHODS
  Recombinant HmC1q (rHmC1q) was produced in the yeast Pichia pastoris. Chemotaxis assays were performed to investigate rHmC1q-dependent microglia migration. The involvement of a C1qBP-related molecule in this chemotaxis mechanism was assessed by flow cytometry and with affinity purification experiments. The cellular localization of C1qBP mRNA and protein in leech was investigated using immunohistochemistry and in situ hybridization techniques.
  
  
  RESULTS
  rHmC1q-stimulated microglia migrate in a dose-dependent manner. This rHmC1q-induced chemotaxis was reduced when cells were preincubated with either anti-HmC1q or anti-human C1qBP antibodies. A C1qBP-related molecule was characterized in leech microglia.
  
  
  CONCLUSIONS
  A previous study showed that recruitment of microglia is observed after HmC1q release at the cut end of axons. Here, we demonstrate that rHmC1q-dependent chemotaxis might be driven via a HmC1q-binding protein located on the microglial cell surface. Taken together, these results highlight the importance of the interaction between C1q and C1qBP in microglial activation leading to nerve repair in the medicinal leech.
authors.affiliation: Laboratoire de Spectrométrie de Masse Biologique Fondamentale et Appliquée - EA4550, Microglial activation group, Université Lille Nord de France, Université Lille 1, IFR 147, bâtiment SN3, 59655 Villeneuve d'Ascq, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Tahtouh
authors.forename: Annelise
authors.initials: A
authors.lastname: Garçon-Bocquet
authors.forename: Françoise
authors.initials: F
authors.lastname: Croq
authors.forename: Jacopo
authors.initials: J
authors.lastname: Vizioli
authors.forename: Pierre-Eric
authors.initials: PE
authors.lastname: Sautière
authors.forename: Christelle
authors.initials: C
authors.lastname: Van Camp
authors.forename: Michel
authors.initials: M
authors.lastname: Salzet
authors.forename: Patricia
authors.initials: P
authors.lastname: Nagnan-le Meillour
authors.forename: Joël
authors.initials: J
authors.lastname: Pestel
authors.forename: Christophe
authors.initials: C
authors.lastname: Lefebvre
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019921:Biotinylation; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology*; D015922:Complement C1q / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D017124:Conserved Sequence; D018274:Electroporation; D005434:Flow Cytometry; D017952:Ganglia, Invertebrate / Q000166:cytology; D047709:Hirudo medicinalis / Q000166:cytology*; D006801:Humans; D017628:Microglia / Q000187:drug effects / Q000502:physiology*; D009420:Nervous System / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013997:Time Factors; D020196:Trauma, Nervous System / Q000378:metabolism / Q000473:pathology
chemical_list: D002352:Carrier Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C007105:c1q-binding proteins; D015922:Complement C1q