Characterisation of de novo MAPK10/JNK3 truncation mutations associated with cognitive disorders in two unrelated patients

The c-Jun N-terminal kinases (JNKs) are stress-activated serine-threonine kinases that have recently been linked to various neurological disorders. We previously described a patient with intellectual disability (ID) and seizures (Patient 1), carrying a de novo chromosome translocation affecting the CNS-expressed MAPK10/JNK3 gene. Here, we describe a second ID patient (Patient 2) with a similar translocation that likewise truncates MAPK10/JNK3, highlighting a role for JNK3 in human brain development. We have pinpointed the breakpoint in Patient 2, which is just distal to that in Patient 1. In both patients, the rearrangement resulted in a predicted protein interrupted towards the C-terminal end of the kinase domain. We demonstrate that these truncated proteins, although capable of weak interaction with various known JNK scaffolds, are not capable of phosphorylating the classical JNK target c-Jun in vitro, which suggests that the patient phenotype potentially arises from partial loss of JNK3 function. We next investigated JNK3-binding partners to further explore potential disease mechanisms. We identified PSD-95, SAP102 and SHANK3 as novel interaction partners for JNK3, and we demonstrate that JNK3 and PSD-95 exhibit partially overlapping expression at synaptic sites in cultured hippocampal neurons. Moreover, JNK3, like JNK1, is capable of phosphorylating PSD-95 in vitro, whereas disease-associated mutant JNK3 proteins do not. We conclude that reduced JNK3 activity has potentially deleterious effects on neuronal function via altered regulation of a set of post-synaptic proteins.     

Gibberellin formation in microorganisms

Several microorganisms possess the capacity of synthesizing gibberellins (GAs) in axenic culture. GA concentrations in the range of approximately 20 to 200 milligrams per litre of culture filtrate are produced by wild-type strains of the following fungi: Gibberella fujikuroi (GA₃, GA₄, GA₇, GA₁ and others), Sphaceloma manihoticola and other species of this genus (GA₄, GA₉ and others), Phaeosphaeria sp. (GA₁, GA₄, GA₉ and others). Neurospora crassa is capable of producing GA₃ in the range of micrograms per kilogram of mycelium. Nanogram amounts per litre of culture are present in fermentations of the bacteria Rhizobium phaseoli (GA₁, GA₄, GA₉, GA₂₀) and in Azospirillum lipoferum and A. brasilense (GA₁, GA₃). Of the high-producing organisms, G. fujikuroi and the Sphaceloma spp. appear to have an almost identical GA metabolism except that Sphaceloma is, in particular, unable to produce GA₇ and GA₁. Phaeosphaeria sp. converts GA₉ via GA₄ or GA₂₀ into GA₁, reactions not known from G. fujikuroi. Generally however, GA metabolism in these organisms appears to be very similar to the one known from higher plants. Most likely, the GAs formed play no hormonal or other immediate physiological role in the producing organism and can, thus, be regarded as secondary metabolites. On the other hand, evidence is available that GA-producing microorganisms often induce reactions in host plants which are beneficial to their growth.     

Network theory of glycosylation--etiologic and pathogenic implications of changes in IgG glycoform levels in autoimmunity.

It is now well established that glycoproteins are populations of individual glycoforms. While it has been inferred from in vitro experiments that the differential glycosylation of glycoproteins diversifies their function, evidence is lacking for such a role in vivo. Alterations in IgG glycosylation in both normal and disease states in vivo, however, provide strong evidence that glycosylation is not static and may be a highly regulated event. The large amount of data correlating disease activity and severity in autoimmune diseases which have a strong B cell component with changes in the incidence of IgG glycoforms, now suggest that glycoform population shifts may not be just a marker of disease activity, but may also contribute directly to disease persistence and pathogenesis.     

Isolation of Undegraded Free and Membrane-Bound Polysomal mRNA from Rat Brain

A new procedure is described for the isolation of undegraded free and membrane-bound polysomal mRNA from rat brain in which polysomes are simultaneously separated from soluble components of the cell and slowly sedimenting ribosome species and concentrated by rate-zonal centrifugation on short linear sucrose gradients. This avoids the problem encountered in conventional procedures of pelleting polysomes along with membranous materials that are not solubilized by detergents and that appear to contain traces of nucleases. It also permits a more thorough analysis of the mRNA populations actively engaged in protein synthesis, since both polyadenylated and nonpolyadenylated mRNAs are isolated together. Moreover, the likelihood of sedimenting nonpolysomal mRNP particles along with polysomes is reduced by using rate-zonal rather than pelleting centrifugation. The translational activity in vitro of free and membrane-bound polysomal RNA prepared in this way is high and is about 1.5 times that of RNA prepared by a conventional pelleting technique. The difference is attributable to better preservation of large mRNAs, as inferred from two-dimensional gel electrophoretic analysis of translation product abundance. The recovery of both classes of polysomal RNA is about 90%. The method is simple, efficient, and adapted for isolation of small amounts of polysomal RNA.     

Structural characterization of the asparagine-linked oligosaccharides from Trypanosoma brucei type II and type III variant surface glycoproteins

The complete primary structures of the major Asn-linked oligosaccharides from the type II variant surface glycoproteins (VSGs), MITat 1.2 and MITat 1.7, and the type III VSG, MITat 1.5, were determined using a combination of exo- and endoglycosidase digestions, methylation analysis, acetolysis, and 500 MHz 1H NMR spectroscopy. Each variant contained classical branched oligomannose-type and biantennary complex oligosaccharides, a proportion of the latter substituted with terminal alpha(1-3)-linked galactose residues, the first report of the presence of this epitope in Trypanosoma brucei. In addition both the type II variants contained relatively large amounts of the unusual small oligomannose-type oligosaccharides, Man4GlcNAc2 and Man3GlcNAc2, and a diverse array of novel branched poly-N-acetyllactosamine oligosaccharides, similar but not identical to those from mammalian glycoproteins. These latter structures were also partially substituted with terminal alpha(1-3)-linked galactose residues. Glycosylation in the type II variants showed site specificity in that the poly-N-acetyllactosamine and Man(9-5)GlcNAc2 oligosaccharides were located exclusively at Asn-glycosylation site 1 very close to the C terminus, whereas the Man(4-3)GlcNAc2 and biantennary complex oligosaccharides were located exclusively at site 2. This is the first report of the presence of poly-N-acetyllactosamine oligosaccharides in protozoa.     

Use of large-scale hydrazinolysis in the preparation ofN-linked oligosaccharide libraries: application to brain tissue

In this report, we describe the preparation of a library ofN-linked glycans from whole murine brain obtained by the large-scale hydrazinolysis of an acetone powder of the tissue followed by chromatographic procedures. 84% of the characterized oligosaccharides were found to be anionic, the remainder neutral. The anionic species were successively neutralized by neuraminidase (29%), aq. hydrofluoric acid (30%), and methanolysis (26%), indicating that approximately equal portions were sensitive to desialylation, dephosphorylation and desulfation, respectively. The presence of the sulfated fraction was confirmed by direct³⁵SO₄ metabolic labelling. A residual partially characterized fraction was found to be anionic through possession of carboxylic acid groups, unrelated to sialic acid. The purified oligosaccharides, in the absence of their original protein conjugates, were shown to retain those immunological characteristics essential for recognition by a specific monoclonal antibody, LS (412), that is known to recognize a carbohydrate epitope present on a number of neural adhesion molecules and functional in neural cell adhesion. These properties confirm the viability of scaling up the size of the hydrazinolysis procedure and adapting it to whole tissue for the production of glycan libraries and for the probing of structures of interest.Abbreviations ConA concanavalin A - ELISA enzyme-linked immunosorbent assay - Fuc fucose - Gal galactose - GalNAc N-acetylgalactosamine - GlcNAc N-acetylglucosamine - g.u. glucose units - HRP horseradish peroxidase - HVE high voltage electrophoresis - Man mannose - MS mass spectrometry - N-CAM neural cell adhesion molecule     

Noradrenaline as a putative neurotransmitter mediating hypotension—induced FOs—like immunoreactivity in the supraoptic nucleus of the rat

Hemorrhage or hypotension induces extensive Fos-like immunoreactivity in the magnocellular neurosecretory cells in the supraoptic nucleus of the hypothalamus in rat,especially in the vasopressin neurons.The present study was to explore the neurotransmitter mediating this effect,Microinfusion of the alpha-adrenergic blocker into the supraoptic nucleus reduced the hypotension-induced FOs.whereas beta-antagonist did not affect it significantly.Alaha1-and alpha2-antagonist,prazosin and yohimbine,both reduced the Fos-Positive cell counts.However,the effective dosage of yohimbine was much larger,Alpha1-agonist,methoxamine,induced abundant Fos-like immunoreactivity in the vasopressin cells in this nucleus,while beta-and alpha2-agonist did not elicit such effect.Administration of the noradrenergic re-uptake inhibitor desipramine,to this nucleus to locally accumulate the spontaneously released noradrenaline from the nerve terminals also induced Fos expression,mostly in the vasopressin cells.     

Solution conformation of the biantennary N-linked oligosaccharide of human serotransferrin using H NMR nuclear Overhauser effect measurements

The conformation in solution of the biantennary complex type oligosaccharide unit derived from human serotransferrin has been investigated using ¹H—¹H Nuclear Overhauser Effect (NOE) measurements at 300 MHz. From quantitation of the NOE, the (1–3) antenna is shown to exist in a preferred solution conformation with respect to the mannosyl-chitobiose core. The flexibility of the (1–6) arm, together with the absence of NOE data between this arm and the core, indicates that, in contrast to the (1–3) arm the (1–6) arm has no preferred conformation with respect to the core.