alpha-synuclein and Vascular-Diseases

Although α-synuclein (SNCA) is a well-known pathological molecule involved in synucleinopathy in neurons, its physiological roles remain largely unknown. We reported that serum SNCA levels have a close inverse correlation with blood pressure and age, which indicates the involvement of SNCA in age-related endothelial dysfunction. Therefore, this study aimed to elucidate the molecular functions of SNCA in the endothelium. We confirmed that SNCA was expressed in and secreted from endothelial cells (ECs). Exogenous treatment with recombinant SNCA (rSNCA) activated the Akt-eNOS axis and increased nitric oxide production in ECs. Treatment with rSNCA also suppressed TNF-α- and palmitic acid-induced NF-κB activation, leading to the suppression of VCAM-1 upregulation and restoration of eNOS downregulation in ECs. As for endogenous SNCA expression, replicative senescence resulted in the attenuation of SNCA expression in cultured ECs, similar to the effects of physiological aging on mice aortas. The siRNA-mediated silencing of SNCA consistently resulted in senescent phenotypes, such as eNOS downregulation, increased β-gal activity, decreased Sirt1 expression, and increased p53 expression, in ECs. Ex vivo assessment of endothelial functions using aortic rings revealed impaired endothelium-dependent acetylcholine-induced relaxation in SNCA knockout (KO) mice. Furthermore, SNCA KO mice, especially those on a high-fat diet, displayed elevated blood pressure compared with wild-type mice; this could be eNOS dysfunction-dependent because of the lower difference caused by L-NAME administration. These results indicate that exogenous and endogenous SNCA in ECs might physiologically maintain vascular integrity, and age-related endothelial dysfunction might be partially ascribed to loss-of-function of SNCA in ECs.

Topics: Acetylcholine; alpha-Synuclein; Animals; Endothelial Cells; Mice; Mice, Knockout; NF-kappa B; NG-Nitroarginine Methyl Ester; Nitric Oxide; Palmitic Acid; Proto-Oncogene Proteins c-akt; RNA, Small Interfering; Sirtuin 1; Tumor Necrosis Factor-alpha; Tumor Suppressor Protein p53; Vascular Cell Adhesion Molecule-1; Vascular Diseases

Immunocytochemistry for transactive response binding protein-43 (TDP43) was assessed in the granular cell layer of the dentate gyrus in 250 cases displaying hippocampal pathology identified by haematoxylin-eosin staining. 18%, nearly one in five displayed TDP43 immunoreactive pathology in the granular cell layer of hippocampus. This percentage increased to 43% when only subjects with hippocampal pathology other than vascular in origin were included. When only subjects with severe Alzheimer's disease-related pathology were included, 42% displayed TDP43-immunoreactive pathology, increasing to 60% when concomitant Alzheimer's disease and α-synuclein pathology were present. Within this setting, TDP43-immunoreactive pathology was observed to be present in 6% of subjects with hippocampal pathology but without any cognitive impairment. Our findings justify assessment of TDP43 pathology in every case where a pathological alteration is observed in the hippocampus using a routine stain.

Topics: Aged; Aged, 80 and over; alpha-Synuclein; Alzheimer Disease; Brain Diseases; Chi-Square Distribution; DNA-Binding Proteins; Female; Hippocampus; Humans; Male; Middle Aged; Retrospective Studies; Vascular Diseases