Niemann-Pick type C (NP-C) disease, a fatal neurovisceral disorder, is characterized by lysosomal accumulation of low density lipoprotein (LDL)–derived cholesterol. By positional cloning methods, a gene ( NPC1) with insertion, deletion, and missense mutations has been identified in NP-C patients. Transfection of NP-C fibroblasts with wild-type NPC1 cDNA resulted in correction of their excessive lysosomal storage of LDL cholesterol, thereby defining the critical role of NPC1 in regulation of intracellular cholesterol trafficking. The 1278–amino acid NPC1 protein has sequence similarity to the morphogen receptor PATCHED and the putative sterol-sensing regions of SREBP cleavage-activating protein (SCAP) and 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase.

Intravenous infusions of alpha-gal A are safe and have widespread therapeutic efficacy in Fabry disease.

Although cyclin-dependent kinase 5 (Cdk5) is closely related to other cyclin-dependent kinases, its kinase activity is detected only in the postmitotic neurons. Cdk5 expression and kinase activity are correlated with the extent of differentiation of neuronal cells in developing brain. CdkS purified from nervous tissue phosphorylates neuronal cytoskeletal proteins including neurofilament proteins and microtubule-associated protein tau in vitro. These findings indicate that Cdk5 may have unique functions in neuronal cells, especially in the regulation of phosphorylation of cytoskeletal molecules. We report here generation of CdkS(-/-) mice through gene targeting and their phenotypic analysis.CdkS(-/-) mice exhibit unique lesions in the central nervous system associated with perinatal mortality. The brains of CdkS(-/-) mice lack cortical laminar structure and cerebellar foliation. In addition, the large neurons in the brain stem and in the spinal cord show chromatolytic changes with accumulation of neurofilament immunoreactivity. These findings indicate that Cdk5 is an important molecule for brain development and neuronal differentiation and also suggest that Cdk5 may play critical roles in neuronal cytoskeleton structure and organization.

Functional activity of N-methyl-D-aspartate (NMDA) receptors requires both glutamate binding and the binding of an endogenous coagonist that has been presumed to be glycine, although D-serine is a more potent agonist. Localizations of D-serine and it biosynthetic enzyme serine racemase approximate the distribution of NMDA receptors more closely than glycine. We now show that selective degradation of D-serine with D-amino acid oxidase greatly attenuates NMDA receptor-mediated neurotransmission as assessed by using whole-cell patch-clamp recordings or indirectly by using biochemical assays of the sequelae of NMDA receptor-mediated calcium flux. The inhibitory effects of the enzyme are fully reversed by exogenously applied D-serine, which by itself did not potentiate NMDA receptormediated synaptic responses. Thus, D-serine is an endogenous modulator of the glycine site of NMDA receptors and fully occupies this site at some functional synapses. D-Amino acids play prominent roles in bacteria but have not been thought to occur in substantial quantity or to have any important function in vertebrates. Recently, techniques to distinguish isomers of amino acids in routine assays have led to the identification in some mammalian tissues of substantial amounts of at least two D-amino acids, D-serine and D-aspartate (1). Although D-aspartate is present in selected neuronal populations in the brain, it is concentrated mainly in glands, especially the epinephrine-containing cells of the adrenal medulla, the posterior pituitary, and the pineal gland (2-4).In contrast, D-serine occurs primarily in the brain, with highest concentrations in regions enriched in N-methyl-D-aspartate (NMDA) receptors (5-7). In these areas immunohistochemical studies have localized D-serine to protoplasmic astrocytes, which ensheathe nerve terminals especially in areas of the brain enriched in NMDA receptors (7). Stimulation of the kainate subtype of glutamate receptor releases D-serine from protoplasmic astrocytes (7).Because exogenous D-serine potentiates NMDA receptormediated neurotransmission (8-11) and D-[ 3 H]serine selectively binds to the glycine site (6), D-serine has been proposed as an endogenous ligand for the strychnine-insensitive glycine site of the NMDA receptor (6). Activation of NMDA receptors requires the presence of a coagonist, initially thought to be glycine (8,(12)(13)(14), and a glycine-selective recognition domain has been localized on NMDA receptors (15-17). However, D-serine is at least as potent as glycine as a coagonist at this site (8,10,14). In addition, immunohistochemical studies have revealed an overlapping distribution of D-serine and NMDA receptor immunoreactivity in forebrain (7). In the developing cerebellum, D-serine is localized to Bergmann glia that regulate granule cell migration during development via NMDA receptors (7). In contrast, glycine immunoreactivity is localized differently from that of NMDA receptors except in the brainstem, where it closely parallels the distribution of NMDA receptors (7). Extracell...

Intravenous administration of macrophage-targeted glucocerebrosidase produces objective clinical improvement in patients with type 1 Gaucher's disease. The hematologic and visceral responses to enzyme replacement develop more rapidly than the skeletal response.

Fabry disease is an X-linked lysosomal storage disease caused by deficiency of ␣-galactosidase A that affects males and shows disease expression in heterozygotes. The characteristic progressive renal insufficiency, cardiac involvement, and neuropathology usually are ascribed to globotriaosylceramide accumulation in the endothelium. However, no direct correlation exists between lipid storage and clinical manifestations, and treatment of patients with recombinant enzymes does not reverse several key signs despite clearance of lipid from the endothelium. We therefore investigated the possibility that globotriaosylceramide metabolites are a missing link in the pathogenesis. We report that deacylated globotriaosylceramide, globotriaosylsphingosine, and a minor additional metabolite are dramatically increased in plasma of classically affected male Fabry patients and plasma and tissues of Fabry mice. Plasma globotriaosylceramide levels are reduced by therapy. We show that globotriaosylsphingosine is an inhibitor of ␣-galactosidase A activity. Furthermore, exposure of smooth muscle cells, but not fibroblasts, to globotriaosylsphingosine at concentrations observed in plasma of patients promotes proliferation. The increased intima-media thickness in Fabry patients therefore may be related to the presence of this metabolite. Our findings suggest that measurement of circulating globotriaosylsphingosine will be useful to monitor Fabry disease and may contribute to a better understanding of the disorder.

Fabry disease (alpha-galactosidase A deficiency) is an X-linked recessive lysosomal storage disorder. Although the disease presents in childhood and culminates in cardiac, cerebrovascular, and end-stage renal disease, diagnosis is often delayed or missed. This paper reviews the key signs and symptoms of Fabry disease and provides expert recommendations for diagnosis, follow-up, medical management, and the use of enzyme replacement therapy. Recommendations are based on reviews of the literature on Fabry disease, results of recent clinical trials, and expertise of the authors, all of whom have extensive clinical experience with Fabry disease and lysosomal storage disorders and represent subspecialties involved in treatment. All males and female carriers affected with Fabry disease should be followed closely, regardless of symptoms or treatment status. Clinical trials have shown that recombinant human alpha-galactosidase A replacement therapy--the only disease-specific therapy currently available for Fabry disease--is safe and can reverse substrate storage in the lysosome, the pathophysiologic basis of the disease. Enzyme replacement therapy in all males with Fabry disease (including those with end-stage renal disease) and female carriers with substantial disease manifestations should be initiated as early as possible. Additional experience is needed before more specific recommendations can be made on optimal dosing regimens for reversal; maintenance; and prevention of disease manifestations in affected males, symptomatic carrier females, children, and patients with compromised renal function.

A novel family of candidate gustatory receptors (GRs) was recently identified in searches of the Drosophila genome. We have performed in situ hybridization and transgene experiments that reveal expression of these genes in both gustatory and olfactory neurons in adult flies and larvae. This gene family is likely to encode both odorant and taste receptors. We have visualized the projections of chemosensory neurons in the larval brain and observe that neurons expressing different GRs project to discrete loci in the antennal lobe and subesophageal ganglion. These data provide insight into the diversity of chemosensory recognition and an initial view of the representation of gustatory information in the fly brain.