Figure 4

Hsp27 continues to be expressed and localized with cytoskeletal elements in neurons and neuritic networks. In these experiments, neurons were plated on laminin (no added neurotrophins) and fixed 24 hrs after plating. As shown in the images, many neurons exhibit extensive neuritic growth under these conditions. A-F: Neurons were labelled with rhodamine-phalloidin (A, D, red), and immunostained for pHsp27 (B, green) and Hsp27 (E, green); C, F – merged images. G-L: Neurons were immunostained for tubulin (G, green; J, red), pHsp27 (H, red), Hsp27 (K, green); I, L – merged images. Hsp27 and pHsp27 are expressed throughout the neuritic network, and there is colocalization of these with actin (C, F) and less so with tubulin (I, L). Note the accumulation of pHsp27 and Hsp27 at point of branching of neurites (arrowheads- B, C, E, F, H, I, K, L). The cortical colocalization of tubulin with pHsp27 and Hsp27 is still evident at this stage of neurite growth (arrows – I, L). Scale bar – 50 μm.