All procedures relating to animal care and treatment conformed to institutional and NIH guidelines. Whole-mount tyrosine hydroxylase immunohistochemistry was performed on E16.5–E18.5 mouse embryos, as previously described (Kuruvilla et al., 2004). For NFAT immunostaining, sympathetic neurons were treated with 100 ng/ml NGF for 30 min, and neurons were fixed and immunostained using pan-NFAT antibody, β-III-tubulin, and DAPI (4′,6-diamidino-2-phenylindole). Images representing 1 μm optical slices were acquired using a Zeiss LSM 510 confocal scanning microscope equipped with diode (405 nm), Ar (458–488 nm),

and He/Ne (543–633) lasers. Sympathetic neurons were harvested from P0.5 Sprague-Dawley rats and were grown in mass cultures or compartmentalized cultures, as described previously (Kuruvilla et al., 2004). Dissociated DRG neurons were isolated from E15–16 rats and were grown in mass cultures or compartmentalized cultures, using CFTR activator culture conditions similar to that described for sympathetic neurons. Plasmids, adenoviral vectors, pharmacological reagents, and see more antibodies used in this study

are described in detail in Supplemental Experimental Procedures. Axon growth in compartmentalized cultures was quantified by capturing phase contrast images of the distal axon compartments over 8 hr or consecutive 24 hr intervals using a Zeiss Axiovert 200 microscope with a Retiga EXi camera. Rate of axonal growth (μm/day) was measured using Openlab 4.04. For all neurite growth assays in mass cultures, images were taken using an Axio Imager M1 (Zeiss) microscope, and length of the longest neurite was measured using Axiovision software (Zeiss). Measurements from 30 to 50 neurons were averaged for each condition for a single experiment. Details of analyses of neurotrophin-dependent neurite growth with dynamin1 phosphopeptides and short-term changes in growth cone morphologies are described in Supplemental Experimental

Procedures. Sympathetic neurons were Phosphatidylinositol diacylglycerol-lyase infected with NFAT-luciferase reporter adenovirus for 24 hr, and then neurons were stimulated with control media, NGF, or NT-3 (100 ng/ml) for 2, 8, and 24 hr; reporter gene activity was assessed with Luciferase Reporter Assay System (Promega, E1910). Similar analyses were used to report NFAT transcriptional activity in DRG neurons. Cell-surface biotinylation assays were performed in cultured sympathetic neurons as previously described (Kuruvilla et al., 2004). Live cell antibody feeding assays were performed as previously described (Ascano et al., 2009). For analysis of tyrosine phosphorylation of PLC-γ, sympathetic neurons were treated with NGF or NT-3 (100 ng/ml) for 30 min at 37°C. Cells were lysed with RIPA solution, and lysates were subjected to immunoprecipitation with anti-phosphotyrosine (PY-20; Sigma) and were incubated with Protein-A agarose beads (Santa Cruz Biotechnology). Immunoprecipitates were then immunoblotted for PLC-γ.