The Journal of Biological Chemistry, 284(48), 33549C33560. of scientific and medical interests, especially as a model system to study gene therapy and novel preclinical therapeutic approaches to treat the spontaneous murine model for GLD. Here, we review recent findings in the field of Krabbe disease, with particular emphasis on novel aspects E-3810 of GALC physiology, GLD pathophysiology, and therapeutic strategies. gene, that encodes a lysosomal enzyme catabolizing the myelin lipid component galactosylceramide (GalCer) (Physique 1). GALC deficiency causes rapid and severe demyelination, neurodegeneration, and neuroinflammation of both the CNS and PNS (Figures 2 and ?and3).3). The incidence of GLD is usually estimated at 1:100,000C1:250,000 (Barczykowski, Foss, Duffner, Yan, & Carter, 2012) and is classified either as infantile-onset (presentation within the first year of life, mean survival 24 months) or late-onset (presentation after the first year Rabbit Polyclonal to CELSR3 of life, mean survival 4C6 years after onset; Orsini, Escolar, Wasserstein, & Caggana, 1993). Open in a separate window Physique 1 Galactosphingolipid biology in myelinating oligodendrocyte. The myelin sheath is usually a compact layer of lipid-rich membranes produced by oligodendrocytes in the central nervous system and by Schwann cells in E-3810 the peripheral nervous system. Galactosylceramide (GalCer), a glycosphingolipid synthesized by ceramide synthase (CERS2) and ceramide galactosyl transferase (CGT), is usually a major component of myelin, present in the extracellular side of the membrane (so-called intraperiod line), see inset. GalCer can be further processed into sulfatides by addition of a sulfate group (red dots) by cerebroside sulfotransferase (CST). GalCer is usually catabolized into galactose (blue hexagons) and ceramide by galactosylceramidase and saposin A in the lysosome. Deficiency of these enzymes cause globoid cell leukodystrophy. CERS2, Ceramide synthase 2; CGT, ceramide galactosyl transferase; CST, cerebroside sulfotransferase; MBP, myelin basic protein; PLP, proteolipid protein E-3810 Open in a separate window Physique 2 Cell-specific pathophysiology in the CNS of globoid cell leukodystrophy. GALC + area depicts cells that express galactosylceramidase enzyme and are physiologically normal. GALC Null area contains cells that lack galactosylceramidase enzyme and represent globoid cell leukodystrophy (GLD). GALC Null oligodendrocytes produce psychosine from GalCer via acid ceramidase, undergo diffuse loss of myelin, and contribute to secondary axonal degeneration. Psychosine in neurons causes axonal degeneration. Microglia and globoid cells are unable to digest myelin (GalCer) efficiently, accumulate cytosolic crystals and become proinflammatory, further contributing to axonal degeneration and compromising remyelination. Astrocytes become activated, presumably E-3810 in response to the surrounding pathology Open in a separate window Physique 3 Demyelination, axonal degeneration and globoid cells in the nervous system of GLD-Krabbe patients. (a) Luxol-Fast-Blue, periodic acid schiff (PAS) staining of the cerebellar white matter from a GLD patient shows profound demyelination (absence of blue-stained myelin), neurodegeneration (low density of purple stained axons, arrows) and Globoid cells filled with PAS positive glycolipids storage (arrowhead). (b) Epon semithin sections of brachial plexus nerve from a globoid Leukodystrophy patient show very low density of myelinated fibers, myelinated fibers with onion bulbs (arrowhead) and many demyelinated fibers (double arrowheads), all indicative of chronic demyelination. Fiber density is also low, suggestive of chronic axonal degeneration. A globoid cell macrophage is usually indicated with an asterisk. Tissue (a) and image (b) courtesy of Dr. Julia Kofler and the NDRD brain and tissue lender at the University of Pittsburgh and Krabbe Partners for Research The human gene is usually mapped to chromosome 14q13 (Cannizzaro, Chen, Rafi, & Wenger, 1994) and more than 130 mutations have thus far been catalogued in the Human Gene Mutation Database (HGMD). At least 128 of those mutations have been reported to cause GLD (http://www.hgmd.org; Wenger, Rafi, Luzi, Datto, & Costantino-Ceccarini, 2000). The most common mutation in the European patient population is usually a large deletion spanning exons 11C17 (Rafi, Luzi, Chen, & Wenger, 1995), c.1161+6532_polyA+9kbdel (IVS10del30kb) that is always present with a c.550C T (502C T) polymorphism on the same allele, which eliminates the entire coding region for the 30-kDa enzyme subunit and about 15% of the coding region for the 50-kDa subunit. This mutation is usually absent in the Japanese population, which is usually another large GLD cohort. Instead, Japanese patients have a 12 bp deletion along with a 3 bp new insertion either c.683_694del12insCTC or c.2002A C (635_646del12insCTC or 1954A C; C. Xu, Sakai, Taniike, Inui, & Ozono, 2006), resulting in deletion of 5 amino acids and insertion of 2 amino acids that affects the formation of GALC quaternary structure (Tatsumi et al., 1995; Wenger, Rafi, & Luzi, 1997). In E-3810 addition, a high prevalence of the infantile form was detected in two.