The conserved oligomeric Golgi (COG) complex is a tethering factor composed of eight subunits that is involved in the retrograde transport of intra-Golgi components. Deficient biosynthesis of COG subunits leads to alterations of protein trafficking along the secretory pathway and thereby to severe diseases in humans. Since the COG complex affects the localization of several Golgi glycosyltransferase enzymes, COG deficiency also leads to defective protein glycosylation, thereby explaining the classification of COG deficiencies as forms of congenital disorders of glycosylation (CDG). To date, mutations in COG1, COG4, COG7 and COG8 genes have been associated with diseases, which range from severe multi-organ disorders to moderate forms of neurological impairment. In the present study, we describe a new type of COG deficiency related to a splicing mutation in the COG5 gene. Sequence analysis in the patient identified a homozygous intronic substitution (c.1669-15T>C) leading to exon skipping and severely reduced expression of the COG5 protein. This defect was associated with a mild psychomotor retardation with delayed motor and language development. Analysis of different serum glycoproteins revealed a CDG phenotype with typical undersialylation of N- and O-glycans. Retrograde Golgi-to-endoplasmic reticulum trafficking was markedly delayed in the patient's fibroblast upon brefeldin-A treatment, which is a hallmark of COG deficiency. This trafficking delay could be restored to normal values by expressing a wild-type COG5 cDNA in the patient cells. This case demonstrates that COG deficiency and thereby CDG must be taken into consideration even in children presenting mild neurological impairments.

Inhibition of constitutive active signaling pathways, which are a characteristic phenomenon for many tumors, can be an effective therapeutic strategy. In contrast, oncogenic transcription factors, often activated by mutational events, are in general less amenable to small-molecule inhibition despite their obvious importance as therapeutic targets. One example of this is alveolar rhabdomyosarcoma (aRMS), in which specific translocations lead to the formation of the chimeric transcription factor PAX3/FKHR. Here, we found unexpectedly that the transcriptional activity of PAX3/FKHR can be inhibited by the kinase inhibitor PKC412. This occurs via specific phosphorylation sites in the PAX3 domain, phosphorylation of which is required for efficient DNA-binding and subsequent transcriptional activity. Consequently, we show that PKC412 exerts a potent antitumorigenic potential for aRMS treatment both in vitro and in vivo. Our study suggests that posttranscriptional modifications of oncogenic transcription factors can be explored as a promising avenue for targeted cancer therapy. [Cancer Res 2008;68(10):3767-76]

S100A3 is a unique member of the Ca 2؉ -binding S100 protein family with the highest cysteine content and affinity for Zn 2؉ . This protein is highly expressed in the differentiating cuticular cells within the hair follicle and organized into mature hair cuticles. Previous studies suggest a close association of S100A3 with epithelial differentiation, leading to hair shaft formation, but its molecular function is still unknown. By two-dimensional PAGE-Western blot analyses using a modified citrulline antibody, we discovered that more than half of the arginine residues of native S100A3 are progressively converted to citrullines by Ca 2؉ -dependent peptidylarginine deiminases. Confocal immunofluorescent microscopy showed that the cytoplasmic S100A3 within the cuticular layer is mostly co-localized with the type III isoform of peptidylarginine deiminase (PAD3) but not with PAD1. Recombinant PAD1 and PAD2 are capable of converting all 4 arginines in recombinant S100A3, whereas PAD3 specifically converts only Arg-51 into citrulline. Gel filtration analyses showed that either enzymatic conversion of Arg-51 in S100A3 to citrulline or its mutational substitution with alanine (R51A) promotes a homotetramer assembly. Fluorescent titration of R51A suggested that its potential Ca 2؉ binding property increased during tetramerization. A prototype structural model of the globular Ca 2؉ -bound S100A3 tetramer with citrulline residues is presented. High concentrations of S100A3 homotetramer might provide the millimolar level of Ca 2؉ required for hair cuticular barrier formation.

Based on the spin-density-matrix approach, both the electric-field-induced spin accumulation and the spin current are systematically studied for the two-dimensional Rashba model. Eigenmodes of spin excitations give rise to resonances in the frequency domain. Utilizing a general and physically well-founded definition of the spin current, we obtain results that differ remarkably from previous findings. It is shown that there is a close relationship between the spin accumulation and the spin current, which is due to the prescription of a quasi-chemical potential and which does not result from a conservation law. Physical ambiguities are removed that plagued former approaches with respect to a spin-Hall current that is independent of the electric field. For the clean Rashba model, the intrinsic spin-Hall conductivity exhibits a logarithmic divergency in the low-frequency regime.