Presynaptic PICK1 facilitates trafficking of AMPA-receptors between active zone and synaptic vesicle pool.

Previous studies have indicated that presynaptic α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs) contribute to the regulation of neurotransmitter release. In hippocampal synapses, the presynaptic surface expression of several AMPAR subunits, including GluA2, is regulated in a ligand-dependent manner. However, the molecular mechanisms underlying the presynaptic trafficking of AMPARs are still unknown. Here, using bright-field immunocytochemistry, western blots, and quantitative immunogold electron microscopy of the hippocampal CA1 area from intact adult rat brain, we demonstrate the association of AMPA receptors with the presynaptic active zone and with small presynaptic vesicles, in Schaffer collateral synapses in CA1 of the hippocampus. Furthermore, we show that GluA2 and protein interacting with C kinase 1 (PICK1) are colocalized at presynaptic vesicles. Similar to postsynaptic mechanisms, overexpression of either PICK1 or pep2m, which inhibit the N-ethylmaleimide sensitive fusion protein (NSF)-GluA2 interaction, decreases the concentration of GluA2 in the presynaptic active zone membrane. These data suggest that the interacting proteins PICK1 and NSF act as regulators of presynaptic GluA2-containing AMPAR trafficking between the active zone and a vesicle pool that may provide the basis of presynaptic components of synaptic plasticity.

Composition characterization and clinical efficacy study of a salmon egg extract.

OBJECTIVE: There is an increasing demand for scientifically documented over-the-counter products on the cosmetic market. Salmon eggs are rich in proteins, vitamins and minerals with anti-oxidative and anti-inflammatory properties, as well as free amino acids and lipids documented to be beneficial for skin. Of the fatty acids, several are commonly used as skin penetration enhancers. The unique combination of active substances led us to study whether an extract from salmon eggs could serve as an ingredient for skin care. METHODS: We conducted a double-blinded, randomized clinical trial with 66 healthy female volunteers. Efficacy of the salmon egg extract was evaluated at concentrations of 1% and 5% in vehicle formulation, and responses after 7, 14, 28 and 56 days of treatment were compared with baseline. Composition of the extract was analysed to improve the understanding of the effects of the extract on skin. The salmon egg extract was safety-tested by repeat insult patch test. RESULTS: Treatment of facial skin with the salmon egg extract significantly improved all parameters investigated, wrinkles, pigmentation, redness, brightness and hydration and led to global improvement of the facial skin. Efficacy of the extract was dose dependent and time dependent. There were no adverse reactions noted during the course of the repeat insult patch test, demonstrating that the extract causes neither skin irritation nor sensitization. Furthermore, chemical analyses of the extract revealed the composition of a vast number of active substances, including unsaturated fatty acids, vitamins, proteins, minerals, DNA and RNA. CONCLUSION: The salmon egg extract serves as a skin care ingredient that significantly improves characteristics important for perception of skin ageing and health. The efficacy of the treatment is conceivably accounted for by the unique combination of numerous active substances present in the salmon egg extract.

Protein interacting with C kinase 1 (PICK1) and GluR2 are associated with presynaptic plasma membrane and vesicles in hippocampal excitatory synapses.

AMPA receptors have been identified in different populations of presynaptic terminals and found to be involved in the modulation of neurotransmitter release. The mechanisms that govern the expression of presynaptic AMPA receptors are not known. One possibility is that pre- and postsynaptic AMPA receptors are regulated according to the same principles. To address this hypothesis we investigated whether protein interacting with C kinase 1 (PICK1), known to interact with AMPA receptors postsynaptically, also is expressed presynaptically, together with AMPA receptors. Subfractionation and high-resolution immunogold analyses of the rat hippocampus revealed that GluR2 and PICK1 are enriched postsynaptically, but also in presynaptic membrane compartments, including the active zone and vesicular membranes. PICK1 and GluR2 are associated with the same vesicles, which are immunopositive also for synaptophysin and vesicle-associated membrane protein 2. Based on what is known about the function of PICK1 postsynaptically, the present data suggest that PICK1 is involved in the regulation of presynaptic AMPA receptor trafficking and in determining the size of the AMPA receptor pool that modulates presynaptic glutamate release.

Neuronal enriched endosomal protein of 21 kDa colocalizes with glutamate receptor subunit GLUR2/3 at the postsynaptic membrane.

Functional evidence suggests that neuronal enriched endosomal protein of 21 kDa (NEEP21) takes part in facilitating transport of AMPA receptors (AMPAR) in the synapse. To explore the anatomical basis for a role in this synaptic trafficking, we investigated the ultrastructural localization of NEEP21 in rodent brain. Using immunogold electron microscopy, we show that NEEP21 is colocalized with the AMPAR subunits GluR2/3 in postsynaptic spines. Quantitative analysis of gold particle distribution along an axis perpendicular to the postsynaptic specialization indicated that NEEP21 occurs in the postsynaptic membrane but also in the interior of the spines. NEEP21 positive endosomes/multivesicular bodies were found throughout cell bodies and dendrites. In light microscopical preparations, the NEEP21 antibody produced a labeling pattern in the neocortex, hippocampus and cerebellum that mimicked that of GluR2/3 and not that of GluR1 or 4. Our findings are consistent with a role for NEEP21 in facilitating vesicular transport of GluR2 between intracellular compartments and the postsynaptic plasma membrane.