1). cognition were unaffected in VCS-treated mice. To determine whether VCS was neuroprotectivein vivo, we injected kainic acid around the 25th day of infusion to inducestatus epilepticus. Kainic acid induced a robust lesion of the CA3 hippocampal subfield in aCSF-treated regulates. In contrast, all hippocampal regions in VCS-treated mice were largely intact. VCS did not protect against seizures. These results demonstrate that strategic degradation of complex gangliosides and GD3 can be used to accomplish neuroprotection without adversely affecting behavior. == Introduction == The central nervous system is usually enriched with glycosphingolipids that carry anionic sialic acids in the outer leaflet of the plasma membranes of cells[1]. Sialic acids are a family of nine-carbon sugars that are generally found as part of glycoconjugates, mostly as terminal components like (23) or (26) links to hexoses or (28) links to other sialic acids[2]. Important gangliosides in the central nervous system include GM1, GD1a, GD1b, GT1b, and GD3 (Fig. 1). Among these, GD3 and GM1 have received 16-Dehydroprogesterone the most attention due to their involvement in cell death and neuroprotection, respectively. The role of GD3 as a critical mediator of apoptosis induced by Fas, ceramide, and amyloid- (A) is usually well documented[3][5]. In contrast, GM1 ganglioside is usually neuroprotectivein vitroand in a number of lesion models[6][11], and has been used therapeutically to treat patients with Parkinson’s disease[12][14]. == Determine 1. Effects ofV. choleraesialidase (VCS) and GD3S deletion on ganglioside biosynthesis and hydrolysis. == (a) The ganglioside biosynthetic pathway; the four major brain gangliosides are circled. Gangliosides are synthesized by sequential addition of sialic acid residues to a sphingosine backbone. GD3 synthase (GD3S) converts GM3 to GD3, and is ultimately responsible for synthesis of all of the b-series gangliosides. GD3S/ mice lack the b-series gangliosides including the apoptogenic GD3 and two of the four major brain gangliosides. Levels of GM1 and GD1a are elevated in GD3S null mice, as 16-Dehydroprogesterone constitutively high levels 16-Dehydroprogesterone of Lac-Cer are converted to a-series rather than b-series gangliosides[15]. (b)Vibrio choleraesialidase (VCS) hydrolyzes the sialic acid 28 (reddish) linkages, and terminal 23 linkages (reddish, underlined). Internal 23 linkages (blue) are unaffected by 16-Dehydroprogesterone VCS. Thus GD1b, GT1b, and GD1a, are converted to GM1. In addition, the apoptogenic GD3 is usually degraded. (c) Ganglioside degradative pathway; the four major brain gangliosides are circled. VCS hydrolyzes three of the four 16-Dehydroprogesterone major brain gangliosides into GM1. In addition, GD3 ganglioside is usually degraded. The resulting brain ganglioside profile is similar to that induced by GD3S removal except that GD1a is also hydrolyzed and levels of GM1 ganglioside are much higher[21]. Abbreviations: Gal, galactose; Glc-Cer, glucosylceramide; Lac-Cer, UDP-galactose-glucosylceramide (lactosyl ceramide); GalNac, N-acetylgalatosamine; NeuAc, N-acetylneuraminic acid (sialic acid). Given the broad range of activity of both GM1 and GD3, experimental methods that simultaneously Rabbit Polyclonal to SERPINB4 decrease GD3 and elevate GM1 may have additive neuroprotective effects. There are several ways to accomplish thisin vivo. Targeted deletion ofSt8sia1, the gene that codes for the ganglioside biosynthetic enzyme GD3 synthase (GD3S), eliminates GD3 and elevates levels of GM1 as the constitutively normal amount of ganglioside synthesized is usually converted to a-series rather than b-series gangliosides (Fig. 1a). Main neurons missing GD3S are resistant to cell death induced by exogenous A or hyperhomocysteinemia, andin vivothe deletion nearly eliminates A and associated neuropathology and enhances memory in a mouse model of Alzheimer’s disease[15]. An alternate to disrupting biosynthesis is usually to enhance degradation. Sialidases hydrolyze sialic acid linkages on gangliosides, and can be used to degrade complex gangliosides and GD3 while increasing GM1. Even though neuroprotective effect of sialidase has not been assessedin vivo, Yang et al.[16]showed that chronic peripheral infusion of a sialidase fromClostridium perfringensenhanced spinal axon regeneration in peripheral nerve grafts after injury. This is consistent with the known effects of exogenous GM1 on nerve repair[17]. The present study was conducted to determine whether intracranial administration of sialidase would be neuroprotective against kainate-induced lesions. We used a sialidase isolated fromVibrio choleraebecause it produces a ganglioside profile similar to that of GD3S deletion. Specifically,V. choleraesialidase (VCS) cleaves the glycosidic linkages between terminal sialic acids of complex gangliotetraose gangliosides GD1a, GD1b, and GT1b, to yield increased levels of endogenous GM1 (Fig.1b;[18][20]). GD3 is also hydrolyzed by VCS. Thus the primary difference between VCS-treated and GD3S-null neural tissue is that GD1a is.