Figure 1.

PC12 cells overexpressing α9 integrin extend neurites on TN-C, independent of the cytoplasmic domain. A, Quantification of neurite length from differentiated PC12 cells at 48 h, mock transfected or transfected with α4, α5, or α9 integrin. The asterisk (*) indicates significantly (p < 0.05) greater neurite outgrowth in α9-expressing PC12 cells on TN-C and plastic compared with mock transfected, α4, and α5-expressing PC12 cells. B–G, Immunofluorescent labeling of neurofilament in PC12 cells transduced with a lentivirus expressing fGFP (B–D) or α9 integrin-IRES-fGFP (E–G) grown on laminin (B, E), TN-C (C, F), or plastic (D, G). H, Quantification of neurite length from differentiated PC12 cells at 48 h, mock transfected or transfected with α9 integrin constructs (α5/α9, α9/α4, α9/α5, α9NOCYT). The asterisk (*) indicates significantly (p < 0.05) greater neurite outgrowth on TN-C or plastic in the presence of the α9 extracellular domain. I, Quantification of neurite length from differentiated PC12 cells at 24 h, mock transfected or transfected with α9/α9, α9/α4, or α9/α5 incubated in the presence or absence of anti-human α9β1 blocking antibody (“a9BLK”). All neurite outgrowth assays were repeated three times. The length of at least 50 randomly selected neurons was analyzed. The asterisk (*) indicates significantly (p < 0.05) less neurite outgrowth with α9β1 blocking antibody treatment of α9 integrin-expressing PC12 cells on TN-C or plastic. Error bars indicate SEM. Scale bar, 50 μm.