The apolipoprotein E (APOE) ε2 allele has been associated with both Parkinson's disease (PD) and lower low density lipoprotein cholesterol (LDL-C). The study is to test the hypothesis that lower LDL-C may be associated with PD. This case-control study used fasting lipid profiles obtained from 124 PD cases and 110 controls, the PD cases recruited from consecutive cases presenting at our tertiary Movement Disorder Clinic, and controls recruited from the spouse populations of the same clinic. Multivariate odds ratios (OR) and 95% confidence intervals (CI) were calculated from unconditional logistic regressions, adjusting for age, gender, smoking status, and use of cholesterollowering agents. Lower LDL-C concentrations were associated with a higher prevalence of PD. Compared with participants with the highest LDL-C (≥139 mg/dL), the OR was 2.2 (95% CI 0.9-5.1) for participants with LDL-C of 115-138, 3.5 (95% CI 1.6-8.1) for LDL-C of 93-114, and 2.6 (95% CI 1.1 -5.9) for LDL-C ≤ 92. Interestingly, use of cholesterol lowering drugs or just statins was related to lower PD prevalence. Our data provide preliminary evidence that low LDL-C may be associated with higher occurrence of PD, and/or that statin use may lower PD occurrence; either of which findings warrant further investigations. KeywordsParkinson's disease; LDL cholesterol; apolipoprotein E; statin; case control study Parkinson's disease (PD) is an age-related progressive neurodegenerative disorder affecting 1-2% of the population over the age of 60 years. The lifetime risk for PD is higher in men than in women. 1 Although a few PD cases are due to several known genetic mutations, the disorder is largely idiopathic, and likely involves interactions of the genome and the environment 2 .The role of apolipoprotein (APOE) in Alzheimer's disease (AD), another age-related neurodegenerative disease, has been elucidated in the past decade. It is generally believed that the ε4 allele is a major susceptibility gene, whereas the ε2 allele is protective for AD and possibly other neurological disorders see review 3 . A recent systematic review, however, Previous epidemiological evidence on dietary fats/cholesterol and PD risk has not been consistent. 10;11 Further, these studies are not directly relevant to the potential role of cholesterol in PD etiology, as non-dietary factors may play more important roles in regulating serum lipid levels. For example, the APOE ε4 allele has been associated with higher low density lipid cholesterol (LDL-C), whereas the ε2 allele has been consistently associated with lower plasma LDL-C. 12;13 Interestingly, there has been one published abstract reporting lower plasma cholesterol concentrations in PD patients than in controls. 14 Further, Musanti et al. 15 reported dramatically lower cholesterol biosynthesis in PD patients than in controls, although there has been no subsequent follow up on this association. The above evidence, coupled with the association between ε2 and PD, led us to test hypothesis that lower serum LDL-C may be ass...

Activation of ERK-1 and -2 by

Members of the STAT family of transcriptional regulators modulate the expression of a variety of gene products that promote cell proliferation, survival and transformation. Although initially identi®ed as mediators of cytokine signaling, the STAT proteins are also activated by, and thus may contribute to the actions of, polypeptide growth factors. To de®ne the mechanism by which these factors activate STATs, we examined the process of Stat3 activation in Balb/c-3T3 ®broblasts treated with platelet-derived growth factor (PDGF). As STATs are activated by tyrosine phosphorylation, and as PDGF receptors are ligand-activated tyrosine kinases, we considered the possibility that Stat3 interacts with and is phosphorylated by PDGF receptors. We ®nd that Stat3 associates with PDGF b receptors in both the presence and, surprisingly, the absence of PDGF. Moreover, Stat3 was phosphorylated on tyrosine in PDGF b receptor immunoprecipitates of PDGF-treated but not untreated cells. Although required, receptor activation was insucient for Stat3 activation. When added to cells in combination with a pharmacologic agent (PD180970) that speci®cally inhibits the activity of Src family tyrosine kinases, PDGF did not activate Stat3 as monitored by electrophoretic mobility shift assay. PD180970 did not aect MAPK activation by PDGF or the JAK-dependent activation of Stat3 by interleukin-6. The necessity of Src activity for Stat3 activation by PDGF was further evidenced by data showing the presence of Src in complexes containing both Stat3 and PDGF b receptors in PDGF-treated cells. These results suggest a novel mechanism of STAT activation in which inactive Stat3 pre-assembles with inactive PDGF receptors, and in response to ligand binding and in a manner dependent on Src kinase activity, is rapidly phosphorylated and activated. Additional data demonstrate that Src kinase activity is also required for PDGF stimulation of DNA synthesis in density-arrested cells.