Figure 2. Regulation of PDK1 during rat cortical development.

A, B, At postnatal days 1, 7, and 21 (P1, P7, and P21, respectively), both total PDK1 and phospho-Ser-241 PDK1 were detected by western blotting of lysates from rat cortex. Note that the pSer241-PDK1/total PDK1 ratio remained similar at all developmental stages examined. In contrast, the PDK1-mediated phosphorylation of RSK1/2 Ser221/227 decreased over the studied ages. Thus, PDK1-RSK1/2 signaling is active in developing forebrain during synaptogenesis when neurons are highly dependent on extracellular survival signals. At P1 and P7, electromobility of total- or pSer241 PDK1 was lower than at P21 indicating possible hyperphosphorylation at non-Ser241 sites. In A, same amounts of protein lysates were analyzed in each lane. In B, data represent averages of 3 animals at each developmental stage ±SEM; the pSer241 PDK1 or pSer221/227 RSK1/2 levels were normalized against total PDK1 or RSK1/2, respectively; *, p<0.05.