title: The immunomodulation of acetylcholinesterase in zhikong scallop Chlamys farreri.
abstract: BACKGROUND
  Acetycholinesterase (AChE; EC 3.1.1.7) is an essential hydrolytic enzyme in the cholinergic nervous system, which plays an important role during immunomodulation in vertebrates. Though AChEs have been identified in most invertebrates, the knowledge about immunomodulation function of AChE is still quite meagre in invertebrates.
  
  
  METHODS
  A scallop AChE gene was identified from Chlamys farreri (designed as CfAChE), and its open reading frame encoded a polypeptide of 522 amino acids. A signal peptide, an active site triad, the choline binding site and the peripheral anionic sites (PAS) were identified in CfAChE. The recombinant mature polypeptide of CfAChE (rCfAChE) was expressed in Pichia pastoris GS115, and its activity was 71.3±1.3 U mg(-1) to catalyze the hydrolysis of acetylthiocholine iodide. The mRNA transcripts of CfAChE were detected in haemocytes, hepatopancreas, adductor muscle, mantle, gill, kidney and gonad, with the highest expression level in hepatopancreas. The relative expression level of CfAChE mRNA in haemocytes was both up-regulated after LPS (0.5 mg mL(-1)) and human TNF-α (50 ng mL(-1)) stimulations, and it reached the highest level at 12 h (10.4-fold, P<0.05) and 1 h (3.2-fold, P<0.05), respectively. After Dichlorvos (DDVP) (50 mg L(-1)) stimulation, the CfAChE activity in the supernatant of haemolymph decreased significantly from 0.16 U mg(-1) at 0 h to 0.03 U mg(-1) at 3 h, while the expression level of lysozyme in the haemocytes was up-regulated and reached the highest level at 6 h, which was 3.0-fold (P<0.05) of that in the blank group.
  
  
  CONCLUSIONS
  The results collectively indicated that CfAChE had the acetylcholine-hydrolyzing activity, which was in line with the potential roles of AChE in the neuroimmune system of vertebrates which may help to re-balance the immune system after immune response.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Shi
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Yue
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Wang
authors.forename: Chuanyan
authors.initials: C
authors.lastname: Yang
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic; D006434:Hemocytes / Q000378:metabolism; D056747:Immunomodulation / Q000235:genetics*; D008969:Molecular Sequence Data; D049897:Pectinidae / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D000110:Acetylcholinesterase