Figure 1

Release of sAPPα is increased by dyn I K44A overexpression. HEK-M3 cells were transiently transfected with APP₆₉₅ and dyn I K44A or empty vector. After 48 hours, the growth medium was replaced with serum-free medium, and collected after 2 hours. Proteins in media extracts and cell lysates were size-fractionated on SDS gels and analyzed by immunoblotting. A. Expression of dyn I K44A increased release of endogenous and co-transfected sAPPα (upper panel; bands were detected with 6E10 antibodies) and levels of cellular APP (middle panel; bands were detected with anti-APP-CT). Arrows indicate mature (m) and immature (im) isoforms of endogenous and transfected APP. The mutant dynamin was expressed at high levels in transfected cells (lower panel). The lanes depicted in each panel were derived from the same blot. B. Levels of sAPPα in the media extracts were quantitated by densitometry and values were expressed as means ± SEM from 3 experiments. *, significantly different from the other two groups, by analysis of variance and Fisher's Least Significant Difference test.