Figure 7. Periostin isoforms comparably promote angiogenesis in ECs in vitro.

(A) Generation of isoform-specific murine periostin. Left: PCR of DNA from adenoviruses that contain the long or short periostin isoform. Primer pair 2 (see Figure 1A) was used. Right: Western blot analysis of COS7 cell-conditioned media. COS7 cells were infected with adenoviruses (Ad) that carried the long or short isoform of periostin or LacZ, and the conditioned media were collected. (B–D) Tube formation assay (B), migration assay (C), and 3D vasculogenesis assay (D) for human coronary artery ECs. ECs were stimulated with COS7-conditioned media, prepared as described in A. Both the long and short isoforms of periostin significantly and comparably promoted tube formation and mobilization. The formed luminal structures are shown by arrows in D. Scale bars: 100 μm. *P < 0.05 versus LacZ. (E) FAK activation in ECs by periostin stimulation. L, long periostin isoform; S, short periostin isoform. (F) Apoptosis assay for ECs. ECs were stimulated with or without the long isoform of periostin either in 10% FBS or under serum starvation conditions for 24 hours. Periostin significantly inhibited serum starvation–induced EC apoptosis. *P < 0.05. (G) Periostin-induced Akt activation in ECs. (H) BrdU incorporation assay for ECs stimulated with or without the long isoform of periostin. Periostin did not affect EC proliferation.