Investigation of the Brain Biodistribution of the Lipoprotein-Associated Phospholipase A (Lp-PLA) Inhibitor [F]GSK2647544 in Healthy Male Subjects.

Purpose: GSK2647544 is a potent and specific inhibitor of lipoprotein-associated phospholipase A (Lp-PLA), which was in development as a potential treatment for Alzheimer's disease (AD). In order to refine therapeutic dose predictions and confirm brain penetration, a radiolabelled form of the inhibitor, [F]GSK2647544, was manufactured for use in a positron emission tomography (PET) biodistribution study.

Procedures: [F]GSK2647544 was produced using a novel, copper iodide (Cu(I)) mediated, [F]trifluoromethylation methodology.

Diabetes and hypercholesterolemia increase blood-brain barrier permeability and brain amyloid deposition: beneficial effects of the LpPLA2 inhibitor darapladib.

Diabetes mellitus (DM) and hypercholesterolemia (HC) have emerged as major risk factors for Alzheimer's disease, highlighting the importance of vascular health to normal brain functioning. Our previous study showed that DM and HC favor the development of advanced coronary atherosclerosis in a porcine model, and that treatment with darapladib, an inhibitor of lipoprotein-associated phospholipase A2, blocks atherosclerosis progression and improves animal alertness and activity levels. In the present study, we examined the effects of DM and HC on the permeability of the blood-brain barrier (BBB) using immunoglobulin G (IgG) as a biomarker.

Hydrophilic anti-migraine triptans are substrates for OATP1A2, a transporter expressed at human blood-brain barrier.

OATP1A2 is expressed in the luminal membrane of human blood-brain barrier (BBB). The human tissue with the highest OATP1A2 mRNA expression is the brain. We have established a robust BacMam2-OATP1A2 transduced HEK293 system.

Leading tip drives soma translocation via forward F-actin flow during neuronal migration.

Neuronal migration involves coordinated extension of the leading process and translocation of the soma, but the relative contribution of different subcellular regions, including the leading process and cell rear, in driving soma translocation remains unclear. By local manipulation of cytoskeletal components in restricted regions of cultured neurons, we examined the molecular machinery underlying the generation of traction force for soma translocation during neuronal migration. In actively migrating cerebellar granule cells in culture, a growth cone (GC)-like structure at the leading tip exhibits high dynamics, and severing the tip or disrupting its dynamics suppressed soma translocation within minutes.

Long-range Ca2+ signaling from growth cone to soma mediates reversal of neuronal migration induced by slit-2.

Neuronal migration and growth-cone extension are both guided by extracellular factors in the developing brain, but whether these two forms of guidance are mechanistically linked is unclear. Application of a Slit-2 gradient in front of the leading process of cultured cerebellar granule cells led to the collapse of the growth cone and the reversal of neuronal migration, an event preceded by a propagating Ca(2+) wave from the growth cone to the soma. The Ca(2+) wave was required for the Slit-2 effect and was sufficient by itself to induce the reversal of migration.

Ca2+-dependent regulation of rho GTPases triggers turning of nerve growth cones.

Cytoplasmic Ca2+ elevation and changes in Rho GTPase activity are both known to mediate axon guidance by extracellular factors, but the causal relationship between these two events has been unclear. Here we show that direct elevation of cytoplasmic Ca2+ by extracellular application of a low concentration of ryanodine, which activated Ca2+ release from intracellular stores, upregulated Cdc42/Rac, but downregulated RhoA, in cultured cerebellar granule cells and human embryonic kidney 293T cells. Chemoattractive turning of the growth cone triggered by a gradient of ryanodine was blocked by overexpression of mutant forms of Cdc42 but not of RhoA in Xenopus spinal cord neurons.

Calcium signaling in chemorepellant Slit2-dependent regulation of neuronal migration.

Migration of neuronal precursor cells in the developing brain is guided by extracellular cues, but intracellular signaling processes underlying the guidance of neuronal migration are largely unknown. By examining the migration of cerebellar granule neurons along the surface of cocultured astroglial cells, we found that an extracellular gradient of Slit2, a chemorepellant for neuronal migration in vivo, caused a reversal in the direction of migration without affecting the migration speed. A Slit2 gradient elevated the intracellular concentration of Ca2+, probably due to calcium release from the internal store, led to a reversal of the preexisting asymmetric intracellular Ca2+ distribution in the soma of migrating neurons, and this reversal was closely related with its action of reversing the migrating direction.