title: Recombinant human heparin-binding neurite-promoting factor expressed with yeast stimulates neurites outgrowth.
abstract: OBJECTIVE
  Heparin-binding neurite-promoting factor (HBNF) is a heparin-binding protein primarily found in the brain, which can stimulate neurite outgrowth in vitro. We expressed recombinant human heparin-binding neurite-promoting factor (hrHBNF) using a yeast system, and observed its activity in stimulating neurite outgrowth in vitro.
  
  
  METHODS
  cDNA encoding mature human HBNF was amplified from total RNA isolated from an 18-week aborted human fetal brain by RT-PCR method. After amplification, the HBNF cDNA gene was cloned into pPIC9K, a shuttle expression vector for yeast system. The positive clone of expression vector bearing HBNF cDNA gene was obtained by screening. Verified recombinant vector was then used to transform Pichia strain GS115 by electroporation. His(+) transformants were selected on minimal dextrose medium (MD) plates which were histidine free. His(+) yeast recombinants with multi-copy inserts were screened in vivo by their resistance to G418. PCR analysis was used to confirm the integration of the HBNF cDNA gene into the Pichia genome. Secreted expression of hrHBNF protein in culture medium was obtained when the positive clone containing the HBNF cDNA gene was induced by methanol. The hrHBNF product purified by gel chromatography was added to cultured rat pheochromocytoma (PC12) cells to observe its ability to stimulate neurite outgrowth.
  
  
  RESULTS
  In the recombinant expression vector, the insert was sequenced to show exactly the sequence encoding human HBNF according to Genbank data. The HBNF cDNA gene was cloned downstream to the alpha-factor, and its open reading frame was in frame with the alpha-factor signal sequence in pPIC9K. SDS-PAGE showed that the molecular weight of the induced expression product was about 18 kDa, consistent with that of human HBNF reported in the literature. The protein product did promote neurite outgrowth in cultured rat pheochromocytoma (PC12) cells.
  
  
  CONCLUSIONS
  Recombinant human heparin-binding neurite-promoting factor can be expressed with a yeast system, and its product possesses the biological activity to promote neurite outgrowth.
authors.affiliation: Department of Orthopaedics, Zhongshan Hospital, Medical Center of Fudan University, Shanghai 200032, China.
authors.forename: Yichao
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhengrong
authors.initials: Z
authors.lastname: Chen
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiaoqun
authors.initials: X
authors.lastname: Guan
authors.forename: Houyan
authors.initials: H
authors.lastname: Song
authors.forename: Xin
authors.initials: X
authors.lastname: Wu
authors.forename: Yinkun
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry; D005822:Genetic Vectors; D006801:Humans; D008969:Molecular Sequence Data; D016501:Neurites / Q000187:drug effects* / Q000502:physiology; D016716:PC12 Cells; D010843:Pichia / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D002352:Carrier Proteins; D016207:Cytokines; D018076:DNA, Complementary; D011994:Recombinant Proteins; C066845:pleiotrophin