Efficient transfection of DNA or shRNA vectors into neurons using magnetofection

Efficient and long-lasting transfection of primary neurons is an essential tool to address many questions in current neuroscience using functional gene analysis. Neurons are sensitive to cytotoxicity and difficult to transfect with most methods. We provide a protocol for transfection of cDNA and RNA interference (shRNA) vectors, using magnetofection, into rat hippocampal neurons (E18/19) cultured for several hours to 21 days in vitro. This protocol even allows for double-transfection of DNA into a small subpopulation of hippocampal neurons (GABAergic interneurons), as well as achieving long-lasting expression of DNA and shRNA constructs without interfering with neuronal differentiation. The protocol, which uses inexpensive equipment and reagents, takes 1 h, utilizes mixed hippocampal cultures, a transfection reagent, CombiMag and a magnetic plate, shows low toxicity and is suited for single cell analysis. Modifications as done by our three laboratories are detailed

Bcl-xl regulates metabolic efficiency of neurons through interaction with the mitochondrial F1FoATP synthase

Anti-apoptotic Bcl2 family proteins such as Bcl-xL protect cells from death by sequestering apoptotic molecules, but also contribute to normal neuronal function. We find in hippocampal neurons that Bcl-xL enhances the efficiency of energy metabolism. Our evidence indicates that Bcl-xLinteracts directly with the ?-subunit of the F1FO ATP synthase, decreasing an ion leak within the F1FO ATPase complex and thereby increasing net transport of H+ by F1FO during F1FO ATPase activity. By patch clamping submitochondrial vesicles enriched in F1FO ATP synthase complexes, we find that, in the presence of ATP, pharmacological or genetic inhibition of Bcl-xL activity increases the membrane leak conductance. In addition, recombinant Bcl-xL protein directly increases the level of ATPase activity of purified synthase complexes, and inhibition of endogenous Bcl-xL decreases the level of F1FO enzymatic activity. Our findings indicate that increased mitochondrial efficiency contributes to the enhanced synaptic efficacy found in Bcl-xL-expressing neurons

Spatiotemporal dynamics of nicotinic acetylcholine receptors and lipid platforms

Abstract: The relationships between neurotransmitter receptors and their membrane environment are complex, mutual (bidirectional) and physiologically important. Some of these relationships are established with subsets of the membrane lipid population, in the form of lipid platforms, lateral heterogeneities of the bilayer lipid having a dynamic chemical composition distinct from that of the bulk membrane. In addition to the equilibrium between the biosynthetic production, exocytic delivery and recycling of receptors on the one hand, and the endocytic internalization on the other, lateral diffusion, clustering and anchorage of receptors at the lipid platforms play key roles in determining the amount of active receptors at the synapse. Mobile receptors traffic between reservoir non-synaptic membranes and the synapse predominantly by thermally driven Brownian motion, and become immobilized at the perisynaptic region or the synapse proper by various mechanisms. These comprise: (a) clustering mediated by homotropic inter-molecular receptor-receptor associations; (b) heterotropic associations with non-receptor scaffolding proteins or the subjacent cytoskeletal meshwork, leading to diffusional “trapping”, and (c) protein-lipid interactions, particularly with the neutral lipid cholesterol. Preceded by a brief introduction on the currently used methods to study protein lateral mobility in membranes, this review assesses the contribution of some of these mechanisms to the supramolecular organization and dynamics of the paradigm neurotransmitter receptor of muscle and neuronal cells—the nicotinic acetylcholine receptor (nAChR). The translational mobility of nAChRs at these two cell surfaces differs in terms of diffusion coefficients and residence intervals at the synapse, which cover an ample range of time regimes. Neuronal α7 nAChRs exhibit diffusion coefficients similar to those of other neurotransmitter receptors and spend part of their lifetime confined to the perisynaptic region of glutamatergic (excitatory) and GABAergic (inhibitory) synapses; they may also be involved in the regulation of the dynamic equilibrium between excitation and inhibition in brain