title: Identifying N-linked glycan moiety and motifs in the cysteine-rich domain critical for N-glycosylation and intracellular trafficking of SR-AI and MARCO.
abstract: BACKGROUND
  The accumulation of soluble oligomeric amyloid-β peptide (oAβ) proceeding the formation of senile plaques contributes to synaptic and memory deficits in Alzheimer's disease. Our previous studies have indentified scavenger receptor A (SR-A), especially SR-A type I (SR-AI), as prominent scavenger receptors on mediating oAβ clearance by microglia while glycan moiety and scavenger receptor cysteine-rich (SRCR) domain may play the critical role. Macrophage receptor with collagenous structure (MARCO), another member of class A superfamily with a highly conserved SRCR domain, may also play the similar role on oAβ internalization. However, the role of N-glycosylation and SRCR domain of SR-AI and MARCO on oAβ internalization remains unclear.
  
  
  RESULTS
  We found that oAβ internalization was diminished in the cells expressing SR-AI harboring mutations of dual N-glycosylation sites (i.e. N120Q-N143Q and N143Q-N184Q) while they were normally surface targeted. Normal oAβ internalization was observed in 10 SR-AI-SRCR and 4 MARCO-SRCR surface targeted mutants. Alternatively, the SRCR mutants at β-sheet and α-helix and on disulfide bone formation obstructed receptor's N-glycosylation and surface targeting.
  
  
  CONCLUSIONS
  Our study reveals that N-glycan moiety is more critical than SRCR domain for SR-A-mediated oAβ internalization.
authors.affiliation: Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. hjtsay@ym.edu.tw.
authors.forename: Huey-Jen
authors.initials: HJ
authors.lastname: Tsay
authors.affiliation: Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, 112, Taiwan, R.O.C. jeremy0681@gmail.com.
authors.forename: Yung-Cheng
authors.initials: YC
authors.lastname: Huang
authors.affiliation: Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. cc5mail@hotmail.com.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Chen
authors.affiliation: Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. hjtsay@ym.edu.tw.
authors.forename: Yun-Hao
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Institute of Neuroscience, Brain Research Center, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. k76003@gmail.com.
authors.forename: Shu-Meng
authors.initials: SM
authors.lastname: Hsu
authors.affiliation: Division of Chinese Materia Medica Development, National Research Institute of Chinese Medicine, Taipei, 11221, Taiwan, R.O.C. rebiocadd@gmail.com.
authors.forename: Keng-Chang
authors.initials: KC
authors.lastname: Tsai
authors.affiliation: Institute of Anatomy and Cell Biology, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. cnyang880@yahoo.com.tw.
authors.forename: Cheng-Ning
authors.initials: CN
authors.lastname: Yang
authors.affiliation: Institute of Anatomy and Cell Biology, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. flhuang@ym.edu.tw.
authors.forename: Fong-Lee
authors.initials: FL
authors.lastname: Huang
authors.affiliation: Center for Neuropsychiatric Research, National Health Research Institutes, No. 35 Keyan Road, Zhunan Town, Miaoli County, 350, Taiwan, R.O.C. fshie@nhri.org.tw.
authors.forename: Feng-Shiun
authors.initials: FS
authors.lastname: Shie
authors.affiliation: Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, 11220, Taiwan, R.O.C. swordtop@yahoo.com.tw.
authors.forename: Lin-Chien
authors.initials: LC
authors.lastname: Lee
authors.affiliation: Division of Basic Chinese Medicine, National Research Institute of Chinese Medicine, Taipei, 11221, Taiwan, R.O.C. yshiao@nricm.edu.tw.|Institute of Biopharmaceutical Science, National Yang-Ming University, Taipei, 11221, Taiwan, R.O.C. yshiao@nricm.edu.tw.
authors.forename: Young-Ji
authors.initials: YJ
authors.lastname: Shiao
mesh_terms: D019943:Amino Acid Substitution; D016229:Amyloid beta-Peptides; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors
chemical_list: D016229:Amyloid beta-Peptides; D002352:Carrier Proteins; C490460:MARCO protein, human; D011971:Receptors, Immunologic; C503566:SCAF1 protein, human; D000068103:Serine-Arginine Splicing Factors