Culturing hippocampal and cortical neurons.

Primary cultures of rat and mouse hippocampus and cerebral cortex are widely used to study neuronal properties such as axonal extension, synaptic transmission, and excitotoxicity. Short-term culturing of these neurons can be very straightforward and is perhaps easier than culturing cells lines once dissections are made and cell stocks are frozen. Long-term cultures of relatively pure neuronal populations require slightly more effort, but protocols are described that are less complicated than most published protocols. These include simpler ways to clean and coat coverslips, as well as using glia-conditioned medium to eliminate the need to make individual cocultures of neurons and glia. These methods consistently yield hippocampal and cortical cultures expressing dendritic spines and synapses that survive over 3 weeks in culture. For investigators employing biochemical assays where a fairly large amount of protein is necessary, cortical neurons may be especially attractive to use as large amounts of tissue are obtained and available for culture.

ADF/cofilin mediates actin cytoskeletal alterations in LLC-PK cells during ATP depletion.

Ischemic injury induces actin cytoskeleton disruption and aggregation, but mechanisms affecting these changes remain unclear. To determine the role of actin-depolymerizing factor (ADF)/ cofilin participation in ischemic-induced actin cytoskeletal breakdown, we utilized porcine kidney cultured cells, LLC-PK(A4.8), and adenovirus containing wild-type (wt), constitutively active, and inactive Xenopus ADF/cofilin linked to green fluorescence protein [XAC(wt)-GFP] in an ATP depletion model. High adenoviral infectivity (70%) in LLC-PK(A4.8) cells resulted in linearly increasing XAC(wt)-GFP and phosphorylated (p)XAC(wt)-GFP (inactive) expression. ATP depletion rapidly induced dephosphorylation, and, therefore, activation, of endogenous pcofilin as well as pXAC(wt)-GFP in conjunction with the formation of fluorescent XAC(wt)-GFP/actin aggregates and rods. No significant actin cytoskeletal alterations occurred with short-term ATP depletion of LLC-PK(A4.8) cells expressing GFP or the constitutively inactive mutant XAC(S3E)-GFP, but cells expressing the constitutively active mutant demonstrated nearly instantaneous actin disruption with aggregate and rod formation. Confocal image three-dimensional volume reconstructions of normal and ATP-depleted LLC-PK(A4.8) cells demonstrated that 25 min of ATP depletion induced a rapid increase in XAC(wt)-GFP apical and basal signal in addition to XAC-GFP/actin aggregate formation. These data demonstrate XAC(wt)-GFP participates in ischemia-induced actin cytoskeletal alterations and determines the rate and extent of these ATP depletion-induced cellular alterations.