The Missing Link: An Investigation into Janus Kinase 2 Phosphorylation and The Applications to Atherosclerosis
Bing Luo
Sir Winston Churchill Secondary
Floor Location : S 225 H

AbstractrnrnAtherosclerosis is a disease that plagues many North Americans. The past observed effects of oxidized low-density lipoproteins on atherogenesis have inspired various endeavors in this field of research. There have been recent discoveries attributing oxidized low-density lipoproteins to the proliferation of macrophage-derived foam cells (Hundal et al., 2003). In turn, a detailed characterization of the cell signaling pathways involved in the production and localization of foam cells can lead to potential treatments for atherosclerosis. The question of primary interest is whether or not the phosphorylation of JAK2 -- a specific isoform of JAK -- is an upstream signaling mechanism of oxLDLmediated macrophage survival. If affirmative, then the viability of the bone marrow derived macrophages that are exposed to the JAK2 inhibitor AG490 will be lower than the viability of macrophages that are not exposed to the inhibitor. rnrnThe experiment employed a cell proliferation assay to determine the cell viability after exposure to different concentrations of AG490 over a 72-hour period. The inhibition of JAK2 yielded a lower amount of viable cells because the phosphorylation of JAK2 would no longer be able to activate the oxidized low-density lipoprotein-mediated cell survival. The experiment was conducted three times, and in each trial, samples were tested in replicates of eight. The effects of the AG490 were clearly evident; the data in distinct experimental groups showed differences ranging from 85% to 175% viability. The experiment showed a clear and statistically significant correlation between the exposure of AG490 and the eventual viability of cells over a 72-hour incubation period. Confidence interval tests and t-tests were employed to determine that there was 95% confidence in the data (p<0.05).rnrnThe research conducted by Hundal et al. and Ferrand et al. corroborates the findings of my study. Whereas Hundal et al.'s research attributed oxLDL to macrophage survival, my study provides the detailed characterization of the signaling mechanisms that are involved in this process. Careful evaluation of the procedures has led to an improved experiment design for future study. Further experimentation in cytokine profiling is currently in progress. The exposure of AG490 both in increasing quantities and increasing exposure times seems to create a quantifiable pattern in its effects on macrophage viability. It thus appears that the phosphorylation of JAK is, indeed, an upstream signaling mechanism that leads to oxLDL-mediated macrophage survival. The subsequent parts of this research address this issue with further scrutiny, employing other methods of cell signaling characterization and other JAK inhibitors.