The docking protein Cas links tyrosine phosphorylation signaling to elongation of cerebellar granule cell axons

Crk-associated substrate (Cas) is a tyrosine-phosphorylated docking protein that is indispensable for the regulation of the actin cytoskeletal organization and cell migration in fibroblasts. The function of Cas in neurons, however, is poorly understood. Here we report that Cas is dominantly enriched in the brain, especially the cerebellum, of postnatal mice. During cerebellar development, Cas is highly tyrosine phosphorylated and is concentrated in the neurites and growth cones of granule cells. Cas coimmunoprecipitates with Src family protein tyrosine kinases, Crk, and cell adhesion molecules and colocalizes with these proteins in granule cells. The axon extension of granule cells is inhibited by either RNA interference knockdown of Cas or overexpression of the Cas mutant lacking the YDxP motifs, which are tyrosine phosphorylated and thereby interact with Crk. These findings demonstrate that Cas acts as a key scaffold that links the proteins associated with tyrosine phosphorylation signaling pathways to the granule cell axon elongation.     

Clear cell carcinoma arising in a cesarean section scar. Report of a case with fine needle aspiration cytology

BACKGROUND: Clear cell carcinoma arising in a cesarean section scar is an extremely rare disease. To the best of our knowledge, there is no published report on the aspiration cytology. CASE: A 56-year-old woman presented with a mass in a cesarean section scar. Initially an abdominal desmoid was considered, but the features of fine needle aspiration (FNA) cytology suggested an adenocarcinoma. The resected tumor was histologically composed of clear cell carcinoma showing cystic, solid and papillary patterns. CONCLUSION: FNA cytology of masses arising in a surgical scar can be a useful tool in obtaining an accurate pathologic diagnosis of a malignant neoplasm.     

A Novel Zinc Finger Protein, Zic, Is Involved in Neurogenesis, Especially in the Cell Lineage of Cerebellar Granule Cells

Abstract: To clarify the mechanism of cerebellar development, we have cloned a gene, named zic, encoding a zinc finger protein that is expressed abundantly in granule cells throughout development of the cerebellum. zic has a significant homology to the zinc finger domain of the Caenorhabditis elegans tra1 gene, the Drosophila cubitus interruptus Dominant gene, and the human GLI oncogene. An in situ hybridization study revealed that zic showed a restricted expression pattern in the granule cells and their putative precursor cells. It is also expressed at an early embryonic stage in the dorsal half of the neural tube. The expression pattern and nuclear localization were confirmed by immunohistochemical study. Furthermore, the bacterially expressed zic protein containing the zinc finger domains bound to the GLI -binding sequence. These findings suggest that zic is one of a number of nuclear factors involved in both differentiation in early development and maintenance of properties of the cerebellar granule cells.     

Interleukin 6-producing malignant mesothelioma

Systemic amyloidosis of the amyloid A (AA) type, is occasionally associated with various neoplasms, but the cause is still unclear. We obtained interleukin 6 (IL-6)-producing cells designated YO from a primary culture of a malignant peritoneal mesothelioma of epithelial type obtained from a 62-year-old woman. Post mortem examination revealed that the patient had systemic amyloidosis of the AA type. The supernatant media of YO cells, as well as recombinant human IL-6, successfully induced nonneoplastic liver cells to produce serum AA (SAA). Our data suggest that IL-6 produced by the tumor cells may have played an important role in the paraneoplastic syndrome of AA amyloidosis in this patient.     

ADP-ribosylation of the rho/rac proteins induces growth inhibition, neurite outgrowth and acetylcholine esterase in cultured PC-12 cells

Botulinum ADP-ribosyltransferase C3 (C3 exoenzyme) was purified to homogeneity and added to cultured rat pheochromocytoma PC-12 cells. Incubation with this exoenzyme caused inhibition of cell growth and induced neurites as well as acetylcholine esterase in these cells. These changes were dependent on the amount of the enzyme added to the culture, which correlated with the in situ ADP-ribosylation of the rho/rac proteins in the cells. Preincubation with a specific anti-C3 exoenzyme monoclonal antibody inhibited both the ADP-ribosyltransferase activity and the neurite-inducing activity of the enzyme preparation. These results suggest that C3 exoenzyme affected the cellular function of the rho/rac proteins by ADP-ribosylation to induce these changes in the cells.     

Molecular clearance of ataxin-3 is regulated by a mammalian E4

Insoluble aggregates of polyglutamine-containing proteins are usually conjugated with ubiquitin in neurons of individuals with polyglutamine diseases. We now show that ataxin-3, in which the abnormal expansion of a polyglutamine tract is responsible for spinocerebellar ataxia type 3 (SCA3), undergoes ubiquitylation and degradation by the proteasome. Mammalian E4B (UFD2a), a ubiquitin chain assembly factor (E4), copurified with the polyubiquitylation activity for ataxin-3. E4B interacted with, and thereby mediated polyubiquitylation of, ataxin-3. Expression of E4B promoted degradation of a pathological form of ataxin-3. In contrast, a dominant-negative mutant of E4B inhibited degradation of this form of ataxin-3, resulting in the formation of intracellular aggregates. In a Drosophila model of SCA3, expression of E4B suppressed the neurodegeneration induced by an ataxin-3 mutant. These observations suggest that E4 is a rate-limiting factor in the degradation of pathological forms of ataxin-3, and that targeted expression of E4B is a potential gene therapy for SCA3.     

Molecular cloning of mouse type 2 and type 3 inositol 1,4,5-trisphosphate receptors and identification of a novel type 2 receptor splice variant

We isolated cDNAs encoding type 2 and type 3 inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)R2 and IP(3)R3, respectively) from mouse lung and found a novel alternative splicing segment, SI(m2), at 176-208 of IP(3)R2. The long form (IP(3)R2 SI(m2)(+)) was dominant, but the short form (IP(3)R2 SI(m2)(-)) was detected in all tissues examined. IP(3)R2 SI(m2)(-) has neither IP(3) binding activity nor Ca(2+) releasing activity. In addition to its reticular distribution, IP(3)R2 SI(m2)(+) is present in the form of clusters in the endoplasmic reticulum of resting COS-7 cells, and after ATP or Ca(2+) ionophore stimulation, most of the IP(3)R2 SI(m2)(+) is in clusters. IP(3)R3 is localized uniformly on the endoplasmic reticulum of resting cells and forms clusters after ATP or Ca(2+) ionophore stimulation. IP(3)R2 SI(m2)(-) does not form clusters in either resting or stimulated cells. IP(3) binding-deficient site-directed mutants of IP(3)R2 SI(m2)(+) and IP(3)R3 fail to form clusters, indicating that IP(3) binding is involved in the cluster formation by these isoforms. Coexpression of IP(3)R2 SI(m2)(-) prevents stimulus-induced IP(3)R clustering, suggesting that IP(3)R2 SI(m2)(-) functions as a negative coordinator of stimulus-induced IP(3)R clustering. Expression of IP(3)R2 SI(m2)(-) in CHO-K1 cells significantly reduced ATP-induced Ca(2+) entry, but not Ca(2+) release, suggesting that the novel splice variant of IP(3)R2 specifically influences the dynamics of the sustained phase of Ca(2+) signals.     

Studies on Camellia sasanqua Thunb

A glycoside “Sasanquin” was separated from methanol extract of young leaves of Camellia sasanqua Thunb. It was not able to be found in young leaves of Camellia japonica L. and Thea sinensis L. on paper chromatogram. Investigations showed that this glycoside is composed of eugenol, D-glucose and D-xylose, and it has a structure of 3-methoxy-4-β-primeverosidoxy-allylbenzene.     

The Chemical Constitution of Rubrofusarin

Alkaline degradation of rubrofusarin and nor-rubrofusarin were studied; nor-rubrofusarin readily underwent hydrolysis to give a tetrahydroxynaphthalenc, acetone, and acetic acid; whereas, rubrofusarin, after prolonged time of hydrolysis, yielded a β-methoxytrihydroxynaphthalene instead of the naphthol. Physical and chemical studies revealed that the naphthol is 1,3,6,8-tetrahydroxynaphthalene and it has been confirmed by the synthesis from chromotropic acid (disodium salt). Thus, evidently, rubrofusarin has a naphthalene nucleus to which a methoxyl group is attached at β-position. The formation, on the hydrolysis, of acetone and acetic acid, along with the naphthol, indicates the presence of 2-methyl-γ-pyrone structure in rubrofusarin.