Fig. 1
Identification of DAG peptide by phage screening in transgenic mouse model of AD. Schematic representation of phage screening done in transgenic hAPP-J20 tg mice a. A CX7C library (109 pfu) was injected intravenously in hAPP-J20 mice and wild-type (WT) littermate controls of different ages. After 30 min of circulation and perfusion to remove unbound phage, the hippocampus was excised and phages were recovered and quantified b. The phage DNA was subjected to high-throughput sequencing, and the sequences present in the hAPP-J20 brains were compared to sequences from WT brains c. Analysis of the hAPP-J20-specific sequences revealed a consensus motif, (A/G)BB(N/Q) (where B is basic). A cyclic 9-amino acid consensus peptide (red arrow) containing this motif (sequence CDAGRKQKC; abbreviated “DAG”) was chemically synthesized. The DAG peptide was tested in the hAPP-J20 mice d and in another AD model, Tg2576 mice e. FAM-labeled DAG peptide was intravenously injected into 9-month old hAPP-J20 and 18-month old Tg2576 mice and allowed to circulate for 30 min. The mice were perfused, the brains were fixed, sectioned and stained with anti-FAM (green channel) to detect DAG and with anti-CD31 (red channel) for blood vessels. Homing of DAG was mainly seen in the hippocampus of the J20 mice and in the cortex of the Tg2576 mice, partially co-localizing with blood vessels. n = 5 mice brains were examined from each model. Representative images are shown. Scale bars, 50 µm (panels d and e), 10 µm (insets in d and e). *P < 0.05
