Disease relevance of B4galnt1

• The genes for cytidine monophospho-N-acetylneuraminic acid hydroxylase (NeuAc-H) and beta-1,4-N-acetylgalactosaminyl transferase (GalNAc-T) were examined using reverse transcription-PCR in two experimental mouse brain tumors, EPEN and CT-2A [1].
• F-11A cells are a substrain of murine neuroblastoma F-11 cells that contain only low endogenous ST2 and GalNAcT activity [2].
• Ganglioside functions in tumor metastasis were analyzed by carbohydrate remodeling of a mouse Lewis lung cancer (subline P29) by introducing beta1,4GalNAc-T cDNA [3].

Psychiatry related information on B4galnt1

• Despite their motor deficits, Mag- and Galgt1-null mice demonstrated hyperactivity, with spontaneous locomotor activity significantly above that of wild type mice [4].

High impact information on B4galnt1

• To determine the role of ganglioside synthesis within the CNS, mice carrying null mutations in two critical ganglioside-specific glycosyltransferase genes, Siat9 (encoding GM3 synthase) and Galgt1 (encoding GM2 synthase), were generated [5].
• UDP-N-acetylgalactosamine (GalNAc): polypeptide N-acetylgalactosaminyltransferase (polypeptide GalNAc-T) catalyzes transfer of the monosaccharide GalNAc to serine and threonine residues, thereby initiating O-linked oligosaccharide biosynthesis [6].
• To address this issue and to determine the relevance of Oglycosylation variation in T-cell ontogeny, we have directed Cre/loxP mutagenic recombination to the polypeptide GalNAc-T locus in gene-targeted mice [6].
• We reported previously that the expression of Sd(a) carbohydrate structures and beta1,4-N-acetylgalactosaminyltransferase (beta1,4GalNAcT) activity responsible for Sd(a) synthesis were remarkably decreased in cancer lesions of the gastrointestinal tract [7].
• NeuAc-H is required for the synthesis of gangliosides containing N-glycolylneuraminic acid, whereas GalNAc-T is required for the synthesis of ganglioside GM2 [1].

Biological context of B4galnt1

• GalNAc-T gene expression was significantly lower in CT-2A cells stably transfected with the antisense GalNAc-T plasmid, pcDNA3.1/TNG (CT-2A/TNG) than in either non-transfected CT-2A or mock-transfected (CT-2A/V) control tumor cells [8].
• Resulting deletion in the catalytic region of polypeptide GalNAc-T occurred to completion on both alleles in thymocytes and was found in peripheral T cells, but not among other cell types [6].
• beta-1,4-N-Acetylgalactosaminyltransferase involved in ganglioside synthesis: cDNA sequence, expression, and chromosome mapping of the mouse gene [9].
• In a previous study of GalNAc-T(-/-) mice engineered to lack beta1,4-N-acetylgalactos-aminyltransferase (GM2/GD2 synthase) to abolish any, complex gangliosides, we observed the reduction of nerve conduction velocity but did not find any obvious morphological change in the brain [10].
• Differences in GalNAc-T gene expression between the solid tumors and the cultured tumor cells correlate with the expression of ganglioside GM2 [1].

Anatomical context of B4galnt1

• Postnatal cerebellar neurons from mice deficient in the GalNAcT gene are insensitive to MAG with regard to neurite outgrowth and lack in the activation of RhoA [11].
• Galgt1-null mice produce similar amounts of total myelin compared to wild-type mice, but as the mice age, they exhibit axon degeneration and dysmyelination with accompanying motor behavioral deficits [12].
• The GalNAc-T transcript was most abundantly expressed in brain, liver, lung, spleen, and testis among the eight adult tissues examined [9].
• In GalNAc-T(-/-) mice, the number of degenerated axons was markedly increased in the dorsal funiculus, tract of Lissauer, and dorsolateral funiculus of the cervical segment of the spinal cord as well as the dorsal funiculus and tract of Lissauer of the lumbar segment of the spinal cord [10].
• Comparison of the ganglioside expression in liver and erythrocytes of the same backcross mice suggested that the gene controlling GM2(NeuGc) expression in the liver (Ggm-2) is also responsible for the expression of GM2(NeuGc) in erythrocytes [13].

Associations of B4galnt1 with chemical compounds

• Knock-out (KO) mice lacking gangliotetraose gangliosides attributable to disruption of the gene for GM2/GD2 synthase [GalNAcT (UDP-N-acetylgalactosamine:GM3/GD3 beta-1,4-N-acetylgalactosaminyltransferase; EC 2.4.1.92 [EC])] are revealing key neural functions for the complex gangliosides of brain [14].
• To measure UDP-N-acetylgalactosamine: beta-galactose beta 1,4-N-acetylgalactosaminyltransferase (beta 1,4-GalNActransferase) in crude cell and tissue extracts we designed an assay containing UDP-[3H]N-acetylgalactosamine as donor and biotinylated human glycophorin A as an acceptor [15].
• In contrast to GalNAcT, the activity of ST-II and the amount of immunostained enzyme were reduced concomitantly by 75% upon incubation with castanospermine [16].
• These changes may be, in part, due to the reduction of sialidase and UDP-N-acetylgalactosamine:GM3 N-acetylgalactosaminyltransferase (GalNAc-T) activities in MPS IIID caprine brain [17].
• This epitope, whose structure is Siaalpha2,3[GalNAcbeta1,4]Gal beta1,4GlcNAc, is synthesized by a beta1,4 N-acetylgalactosaminyltransferase (beta4GalNAc-T) that transfers a beta1,4-linked GalNAc to the galactose residue of an alpha2,3-sialylated chain [18].

Other interactions of B4galnt1

• To further restrict the expression of gangliosides, the GD3S mutant mice were crossbred with mice carrying a disrupted GalNAcT gene encoding beta1,4-N-acetylgalactosaminyltransferase [19].
• Here, we analyze the effects of genetically depriving NPC neurons of complex gangliosides by creating mice doubly deficient in both NPC1 and the GSL synthetic enzyme, GM2/GD2 synthase (GalNAcT) [20].
• In the current studies, CNS and PNS histopathology and behavior of Mag-null, Galgt1-null, and double-null mice were compared on the same mouse strain background [4].
• Expression of the major myelin proteins (myelin basic protein and proteolipid protein) was not reduced in Galgt1-null mice compared to wild type [12].
• Mice with a disrupted Galgt1 gene lack UDP-GalNAc:GM3/GD3 N-acetylgalactosaminyltransferase (GM2/GD2 synthase) and fail to express complex brain gangliosides, including GD1a and GT1b, instead expressing a comparable amount of the simpler gangliosides GM3, GD3, and O-acetyl-GD3 [12].

Analytical, diagnostic and therapeutic context of B4galnt1

• In RT-PCR using specific primers to this PCR product, Sda-GalNAcT mRNA was detected in all samples of normal stomach and small intestine examined and the majority of normal colonic specimens [21].

References