title: Identification of peptide sequences that target to the brain using in vivo phage display.
abstract: Phage display technology could provide a rapid means for the discovery of novel peptides. To find peptide ligands specific for the brain vascular receptors, we performed a modified phage display method. Phages were recovered from mice brain parenchyma after administrated with a random 7-mer peptide library intravenously. A longer circulation time was arranged according to the biodistributive brain/blood ratios of phage particles. Following sequential rounds of isolation, a number of phages were sequenced and a peptide sequence (CTSTSAPYC, denoted as PepC7) was identified. Clone 7-1, which encodes PepC7, exhibited translocation efficiency about 41-fold higher than the random library phage. Immunofluorescence analysis revealed that Clone 7-1 had a significant superiority on transport efficiency into the brain compared with native M13 phage. Clone 7-1 was inhibited from homing to the brain in a dose-dependent fashion when cyclic peptides of the same sequence were present in a competition assay. Interestingly, the linear peptide (ATSTSAPYA, Pep7) and a scrambled control peptide PepSC7 (CSPATSYTC) did not compete with the phage at the same tested concentration (0.2-200 pg). Labeled by Cy5.5, PepC7 exhibited significant brain-targeting capability in in vivo optical imaging analysis. The cyclic conformation of PepC7 formed by disulfide bond, and the correct structure itself play a critical role in maintaining the selectivity and affinity for the brain. In conclusion, PepC7 is a promising brain-target motif never been reported before and it could be applied to targeted drug delivery into the brain.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Fudan University, 826 Zhangheng Rd, Shanghai, 201203, People's Republic of China.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Li
authors.forename: Qizhi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Zhiqing
authors.initials: Z
authors.lastname: Pang
authors.forename: Yuchen
authors.initials: Y
authors.lastname: Wang
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Liu
authors.forename: Liangran
authors.initials: L
authors.lastname: Guo
authors.forename: Xinguo
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000818:Animals; D017104:Bacteriophage M13 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002232:Carbocyanines; D002999:Clone Cells; D016503:Drug Delivery Systems / Q000379:methods*; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D007275:Injections, Intravenous; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D019151:Peptide Library; D010456:Peptides, Cyclic / Q000008:administration & dosage / Q000737:chemistry* / Q000493:pharmacokinetics; D017422:Sequence Analysis, DNA
chemical_list: C098793:CY5.5 cyanine dye; D002232:Carbocyanines; D005456:Fluorescent Dyes; D019151:Peptide Library; D010456:Peptides, Cyclic