Evaluating the SERCA2 and VEGF mRNAs as Potential Molecular Biomarkers of the Onset and Progression in Huntington's Disease

Abnormalities of intracellular Ca2+ homeostasis and signalling as well as the down-regulation of neurotrophic factors in several areas of the central nervous system and in peripheral tissues are hallmarks of Huntington\u2019s disease (HD). As there is no therapy for this hereditary, neurodegenerative fatal disease, further effort should be made to slow the progression of neurodegeneration in patients through the definition of early therapeutic interventions. For this purpose, molecular biomarker(s) for monitoring disease onset and/or progression and response to treatment need to be identified. In the attempt to contribute to the research of peripheral candidate biomarkers in HD, we adopted a multiplex real-time PCR approach to analyse the mRNA level of targeted genes involved in the control of cellular calcium homeostasis and in neuroprotection. For this purpose we recruited a total of 110 subjects possessing the HD mutation at different clinical stages of the disease and 54 sex- and agematched controls. This study provides evidence of reduced transcript levels of sarco-endoplasmic reticulum-associated ATP2A2 calcium pump (SERCA2) and vascular endothelial growth factor (VEGF) in peripheral blood mononuclear cells (PBMCs) of manifest and premanifest HD subjects. Our results provide a potentially new candidate molecular biomarker for monitoring the progression of this disease and contribute to understanding some early events that might have a role in triggering cellular dysfunctions in HD

The involvement of a Na⁺- and Cl⁻-dependent transporter in the brain uptake of amantadine and rimantadine

Despite their structural similarity, the two anti-influenza adamantane compounds amantadine (AMA) and rimantadine (RIM) exhibit strikingly different rates of blood-brain barrier (BBB) transport. However, the molecular mechanisms facilitating the higher rate of in situ BBB transport of RIM, relative to AMA, remain unclear. The aim of this study, therefore, was to determine whether differences in the extent of brain uptake between these two adamantanes also occurred in vivo, and elucidate the potential carrier protein facilitating their BBB transport using immortalized human brain endothelial cells (hCMEC/D3). Following oral administration to Swiss Outbred mice, RIM exhibited 2.4-3.0-fold higher brain-to-plasma exposure compared to AMA, which was not attributable to differences in the degree of plasma protein binding. At concentrations representative of those obtained in vivo, the hCMEC/D3 cell uptake of RIM was 4.5-15.7-fold higher than that of AMA, with Michaelis-Menten constants 6.3 and 238.4 μM, respectively. The hCMEC/D3 cellular uptake of both AMA and RIM was inhibited by various cationic transporter inhibitors (cimetidine, choline, quinine, and tetraethylammonium) and was dependent on extracellular pH, membrane depolarization and Na⁺ and Cl⁻ ions. Such findings indicated the involvement of the neutral and cationic amino acid transporter B⁰,⁺ (ATB⁰,⁺) in the uptake of AMA and RIM, which was demonstrated to be expressed (at the protein level) in the hCMEC/D3 cells. Indeed, AMA and RIM appeared to interact with this transporter, as shown by a 53-70% reduction in the hCMEC/D3 uptake of the specific ATB⁰,⁺ substrate ³H-glycine in their presence. These studies suggest the involvement of ATB⁰,⁺ in the disposition of these cationic drugs across the BBB, a transporter with the potential to be exploited for targeted drug delivery to the brain