After intravascular delivery of genetically marked adult mouse bone marrow into lethally irradiated normal adult hosts, donor-derived cells expressing neuronal proteins (neuronal phenotypes) developed in the central nervous system. Flow cytometry revealed a population of donor-derived cells in the brain with characteristics distinct from bone marrow. Confocal microscopy of individual cells showed that hundreds of marrow-derived cells in brain sections expressed gene products typical of neurons (NeuN, 200-kilodalton neurofilament, and class III beta-tubulin) and were able to activate the transcription factor cAMP response element-binding protein (CREB). The generation of neuronal phenotypes in the adult brain 1 to 6 months after an adult bone marrow transplant demonstrates a remarkable plasticity of adult tissues with potential clinical applications.

This study addresses the binding of ions and the permeation of substrates during function of the GABA transporter GAT1. GAT1 was expressed in Xenopus oocytes and studied electrophysiologically as well as with [3 H]GABA flux; GAT1 was also expressed in mammalian cells and studied with [3 H]GABA and [ 3 H]tiagabine binding. Voltage jumps, Na ϩ and Cl Ϫ concentration jumps, and exposure to high-affinity blockers (NO-05-711 and SKF-100330A) all produce capacitive charge movements. Occlusive interactions among these three types of perturbations show that they all measure the same population of charges. The concentration dependences of the charge movements reveal (1) that two Na ϩ ions interact with the transporter even in the absence of GABA, and (2) that Cl Ϫ facilitates the binding of Na ϩ . Comparison between the charge movements and the transport-associated current shows that this initial Na ϩ -transporter interaction limits the overall transport rate when [GABA] is saturating. However, two classes of manipulation-treatment with high-affinity uptake blockers and the W68L mutation-"lock" Na ϩ onto the transporter by slowing or preventing the subsequent events that release the substrates to the intracellular medium. The Na ϩ substitutes Li ϩ and Cs ϩ do not support charge movements, but they can permeate the transporter in an uncoupled manner. Our results (1) support the hypothesis that efficient removal of synaptic transmitter by the GABA transporter GAT1 depends on the previous binding of Na ϩ and Cl Ϫ , and (2) indicate the important role of the conserved putative transmembrane domain 1 in interactions with the permeant substrates.

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IntroductionWilms ' tumour (WT; nephroblastoma) is the most frequent tumour of the genitourinary tract in children and rated fourth in overall incidence among childhood cancers [1] Abstract During development, renal stem cells reside in the nephrogenic blastema. Wilms' tumour (WT), a common childhood malignancy, is suggested to arise from the nephrogenic blastema that undergoes partial differentiation and as such is an attractive model to study renal stem cells leading to cancer initiation and maintenance. Previously we have made use of blastema-enriched WT stem-like xenografts propagated in vivo to define a 'WT-stem' signature set, which includes cell surface markers convenient for cell isolation (frizzled homolog 2 [Drosophila] -FZD2, FZD7, G-protein coupled receptor 39, activin receptor type 2B, neural cell adhesion molecule -NCAM).We show by fluorescenceactivated cell sorting analysis of sphere-forming heterogeneous primary WT cultures that most of these markers and other stem cell surface antigens (haematopoietic, CD133, CD34, mesenchymal, CD105, CD90, CD44; cancer, CD133, MDR1; hESC, CD24 and putative renal, cadherin 11)