Genetic identification of effectors downstream of Neu (ErbB-2) autophosphorylation sites in a Drosophila model

The ErbB-2/Neu receptor tyrosine kinase plays a causal role in tumorigenesis in mammals. Neu's carboxyl terminus contains five phosphorylated tyrosines that mediate transformation through interaction with cytoplasmic SH2 or PTB containing adaptor proteins. We show that Drosophila adaptors signal from individual phosphotyrosine sites of rat Neu. Activated Neu expression in the midline glia suppressed apoptosis, similar to that seen with activated Drosophila EGF-R expression. Expression in eye and wing tissues generated graded phenotypes suitable for dosage-sensitive modifier genetics. Suppression of ErbB-2/Neu-induced phenotypes in tissues haplosufficient for genes encoding adaptor protein or second messengers suggests that pTyr 1227(YD) signals require Shc, and that pTyr 1253 (YE) signalling does not employ Ras, but does require Raf function. Signalling from pTyr (YB) was affected by a haplosufficiency in drk (Grb-2), and in genes thought to function downstream of Grb-2: dab, sos, csw (Shp-2), and dos (Gab-1). These data demonstrate the power of Drosophila genetics to unmask the molecules that signal from oncogenic ErbB-2/Neu.

Dynamic movements of organelles containing Niemann-Pick C1 protein: NPC1 involvement in late endocytic events

People homozygous for mutations in the Niemann-Pick type C1 (NPC1) gene have physiological defects, including excess accumulation of intracellular cholesterol and other lipids, that lead to drastic neural and liver degeneration. The NPC1 multipass transmembrane protein is resident in late endosomes and lysosomes, but its functions are unknown. We find that organelles containing functional NPC1-fluorescent protein fusions undergo dramatic movements, some in association with extending strands of endoplasmic reticulum. In NPC1 mutant cells the NPC1-bearing organelles that normally move at high speed between perinuclear regions and the periphery of the cell are largely absent. Pulse-chase experiments with dialkylindocarbocyanine low-density lipoprotein showed that NPC1 organelles function late in the endocytic pathway; NPC1 protein may aid the partitioning of endocytic and lysosomal compartments. The close connection between NPC1 and the drug U18666A, which causes NPC1-like organelle defects, was established by rescuing drug-treated cells with overproduced NPC1. U18666A inhibits outward movements of NPC1 organelles, trapping membranes and cholesterol in perinuclear organelles similar to those in NPC1 mutant cells, even when cells are grown in lipoprotein-depleted serum. We conclude that NPC1 protein promotes the creation and/or movement of particular late endosomes, which rapidly transport materials to and from the cell periphery.

Genetic analysis of vein function in the Drosophila embryonic nervous system

The Drosophila epidermal growth factor receptor (EGFR) may be activated by two ligands expressed in the embryonic nervous system, Spitz and Vein. Previous studies have established Spitz as an essential activator of EGFR signaling in nervous system development. Here, we report the pattern of expression of vein mRNA in the nervous system and characterize the contribution of vein to cell lineage and axonogenesis. The number of midline glia (MG) precursors is reduced in vein mutants before the onset of embryonic apoptosis. In contrast to spitz, mis-expression of vein does not suppress apoptosis in the MG. These data indicate that early midline EGFR signaling, requiring vein and spitz, establishes MG precursor number, whereas later EGFR signals, requiring spitz, suppress apoptosis in the MG. vein mutants show early irregularities during axon tract establishment, which resolve later to variable defasciculation and thinner intersegmental axon tracts. vein and spitz phenotypes act additively in the regulation of MG cell number, but show synergism in a midline neuronal cell number phenotype and in axon tract architecture. vein appears to act downstream of spitz to briefly amplify local EGFR activation.Key words: Drosophila, vein, midline, axonogenesis, EGF receptor, lineage, neuregulin, spitz, CNS.

Genetic analysis of vein function in the Drosophila embryonic nervous system

The Drosophila epidermal growth factor receptor (EGFR) may be activated by two ligands expressed in the embryonic nervous system, Spitz and Vein. Previous studies have established Spitz as an essential activator of EGFR signaling in nervous system development. Here, we report the pattern of expression of vein mRNA in the nervous system and characterize the contribution of vein to cell lineage and axonogenesis. The number of midline glia (MG) precursors is reduced in vein mutants before the onset of embryonic apoptosis. In contrast to spitz, mis-expression of vein does not suppress apoptosis in the MG. These data indicate that early midline EGFR signaling, requiring vein and spitz, establishes MG precursor number, whereas later EGFR signals, requiring spitz, suppress apoptosis in the MG. vein mutants show early irregularities during axon tract establishment, which resolve later to variable defasciculation and thinner intersegmental axon tracts. vein and spitz phenotypes act additively in the regulation of MG cell number, but show synergism in a midline neuronal cell number phenotype and in axon tract architecture. vein appears to act downstream of spitz to briefly amplify local EGFR activation.

CD99, keratin, and vimentin staining of sex cord-stromal tumors, normal ovary, and testis

CD99, a marker for MIC-2, reacts with normal Sertoli cells and granulosa cells. We investigated CD99 expression in the development of normal ovary and testis as well as in 25 sex cord-stromal tumors (SCSTs), 7 epithelial neoplasms, and 6 germ cell tumors. Normal Sertoli cells and mature granulosa cells showed 3+ staining with CD99. Pregranulosa cells of primordial follicles were negative. All of the eight Sertoli-Leydig cell tumors were positive with antibody to CD99, with the well-differentiated tumors showing the greatest degree of staining intensity. Reactivity of 2+ to 3+ with CD99 was observed in all of the 11 granulosa cell tumors and in yolk sac components of the germ cell tumors investigated. All of the poorly differentiated carcinomas were negative with CD99. We concluded that CD99 might be a useful marker for SCSTs and that its degree of reactivity correlates with the degree of differentiation in Sertoli-Leydig cell tumors. Additionally, CD99 might aid in distinguishing granulosa cell tumors of the ovary from poorly differentiated carcinomas.

Intraosseous malignant peripheral nerve sheath tumor in a patient with neurofibromatosis

Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon sarcomas that almost always arise in soft tissue. They can develop in pre-existing neurofibromas or schwannomas, de novo from peripheral nerves, or following radiation therapy. Primary intraosseous MPNST is rare and has been reported most frequently in the mandible. Of the reported cases involving the long bones, none has been associated with neurofibromatosis type 1 (NF-1). We report a case of MPNST arising in the femur in a patient with NF-1.

New polyazaporphine chemistry for the origin of life

Molecular orbital spectral predictions suggest that 2,5,7,10,12,15,17,20-octaaza-21H, 23H-porphine has a visible spectral range closely matching that of chlorophyll-a. Since the octaazaporphine is, in its core, a simple derivative of an (HCN)12 oligomer, this fact, together with its spectral properties, would suggest that it occupies a high rank as a primordial porphinic solar energy transducer for photochemistry essential to life's formation. The demonstration that the mass 324 hexahydrooctaazaporphine is formed in protic media by the cyclotetramerization of imidazol-4-aminohydroxonium ion or the derived nitrenium ion, and that a mass 318 species consonant with that of the Huckel aromatic octaazaporphine is observed in the course of these studies, strongly supports the proposed octaazaporphine synthesis in a prebiotic hydrocyanic acid milieu.

Esophageal intramural pseudodiverticulosis

A 66-year-old man presented with severe chronic dysphagia and weight loss. A barium esophagogram revealed a proximal esophageal stricture and multiple pseudodiverticula. After death from aspiration pneumonia, a postmortem examination revealed extensive esophageal pseudodiverticulosis. Clinical presentation, pathogenesis, diagnosis, and management of this unusual disorder are reviewed.

Plexiform neurofibromatosis involving the uterine cervix, endometrium, myometrium, and ovary

BACKGROUND

Neurofibromatosis involving the female genital tract is unusual. The vulva appears to be most frequently affected, with only rare reports of vaginal, cervical, and ovarian involvement in patients with known von Recklinghausen's disease.

CASE

We present a case of diffuse neurofibromatosis involving the cervix, endometrium, myometrium, ovarian cortex, and serosa in a patient with uncontrollable pelvic pain, diagnosed initially as endometriosis. No gross pathology was appreciated, and the histologic features of the small lesions were consistent with plexiform neurofibromas.

CONCLUSION

The case presented is an example of diffuse involvement of the female genital tract by neurofibromatosis in a patient without a family history of von Recklinghausen's disease and without other clinical manifestations of the disease.

New developments in sex cord-stromal and germ cell tumors of the ovary

This article examines unusual and recently described neoplasms such as variants of Sertoli-Leydig cell tumors, monodermal teratomas, and small cell carcinoma, both the hypercalcemic and pulmonic types. Additionally, clues to assist in differentiating metastatic from primary tumors of the ovary are discussed.