keratan-sulfate and Amyotrophic-Lateral-Sclerosis

The functional role of 5D4 antibody-reactive keratan sulfate (KS) in the pathogenesis of neurodegenerative diseases is unknown. We therefore studied the expression of 5D4-reactive KS in amyotrophic lateral sclerosis (ALS), a motor neuron-degenerative disease, with the use of SOD1(G93A) ALS model mice and patients with ALS. Histochemical and immunoelectron microscopic characterizations showed that the 5D4-reactive KS is expressed in Mac2/galectin-3-positive activated or proliferating microglia of SOD1(G93A) ALS model mice at disease end stage and that the KS is an O-linked glycan modified with sialic acid and fucose, which was thus far shown to exist in cartilage. Intriguingly, microglial KS was detected in the spinal cord and brainstem but not in the cerebral cortex of SOD1(G93A) mice. We found that KSGal6ST, a galactose-6-sulfotransferase, is required for biosynthesis of the microglial 5D4-reactive KS by generating SOD1(G93A)/KSGal6ST(-/-) mice. The requirement of GlcNAc6ST1 for this synthesis was corroborated by analyzing SOD1(G93A)/GlcNAc6ST1(-/-) mice. These results indicate that both galactose-6- and N acteylglucosamine-6-sulfated KS elicited in the spinal cord and brainstem are associated with the degeneration of spinal and bulbar lower motor neurons in ALS pathology and may play a role in disease progression via microglial activation and proliferation.

Topics: Aged; Aged, 80 and over; Amyotrophic Lateral Sclerosis; Animals; Brain; Carbohydrate Sulfotransferases; Disease Models, Animal; Epitopes; Female; Galectin 3; Humans; Keratan Sulfate; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microglia; Middle Aged; Motor Neurons; Mutation, Missense; Spinal Cord; Sulfotransferases; Superoxide Dismutase

Biopolymers consist of three major classes, i.e., polynucleotides (DNA, RNA), polypeptides (proteins) and polysaccharides (sugar chains). It is widely accepted that polynucleotides and polypeptides play fundamental roles in the pathogenesis of neurodegenerative diseases. But, sugar chains have been poorly studied in this process, and their biological/clinical significance remains largely unexplored. Amyotrophic lateral sclerosis (ALS) is a motoneuron-degenerative disease, the pathogenesis of which requires both cell autonomous and non-cell autonomous processes. Here, we investigated the role of keratan sulfate (KS), a sulfated long sugar chain of proteoglycan, in ALS pathogenesis. We employed ALS model SOD1(G93A) mice and GlcNAc6ST-1(-/-) mice, which are KS-deficient in the central nervous system. Unexpectedly, SOD1(G93A)GlcNAc6ST-1(-/-) mice exhibited a significantly shorter lifespan than SOD1(G93A) mice and an accelerated appearance of clinical symptoms (body weight loss and decreased rotarod performance). KS expression was induced exclusively in a subpopulation of microglia in SOD1(G93A) mice, and became detectable around motoneurons in the ventral horn during the early disease phase before body weight loss. During this phase, the expression of M2 microglia markers was transiently enhanced in SOD1(G93A) mice, while this enhancement was attenuated in SOD1(G93A)GlcNAc6ST-1(-/-) mice. Consistent with this, M2 microglia were markedly less during the early disease phase in SOD1(G93A)GlcNAc6ST-1(-/-) mice. Moreover, KS expression in microglia was also detected in some human ALS cases. This study suggests that KS plays an indispensable, suppressive role in the early phase pathogenesis of ALS and may represent a new target for therapeutic intervention.

Topics: Amyotrophic Lateral Sclerosis; Animals; B7-2 Antigen; Biomarkers; Carbohydrate Sulfotransferases; Gene Expression Regulation; Humans; Keratan Sulfate; Mice; Microglia; Mutation; Spinal Cord; Sulfotransferases; Superoxide Dismutase; Superoxide Dismutase-1; Time Factors

To identify novel disease-causing genes for amyotrophic lateral sclerosis (ALS).. We carried out a systematic mutation screening of the entire coding regions of 29 candidate genes encoding critically important proteins for proper differentiation and development of corticospinal motor neurons in 190 patients with familial and sporadic ALS.. We focused our analysis on coding variants and evaluated the distribution of nonsynonymous and synonymous variants in our cohort of patients with ALS.. We identified 40 novel nonsynonymous variants and showed a significant excess of unique nonsynonymous variants in our cohort of patients with ALS, which suggests the presence of ALS-predisposing mutations.. Using a multifaceted approach based on the functional prediction of missense variants, the conservation of the altered amino acid, and the cosegregation of the variants identified in familial cases, we identified several promising novel genes for ALS such as LUM and CRYM. We have also highlighted the analytical challenges of large-scale sequencing screens to detect disease-causing variants.

Topics: Amyotrophic Lateral Sclerosis; Chondroitin Sulfate Proteoglycans; Crystallins; DNA Mutational Analysis; Female; Genetic Predisposition to Disease; Humans; Keratan Sulfate; Lumican; Male; Middle Aged; Motor Neurons; mu-Crystallins; Mutation, Missense; Pyramidal Tracts